Physics and Astronomy › Atomic and Molecular Physics, and Optics

Photonic Crystals and Applications

Works Count: 59017

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This cluster of papers focuses on the advances in photonic crystal research, including topics such as nanocavities, slow light, colloidal crystals, structural coloration, biomimicry, optical sensors, waveguides, and bandgap materials. The research covers a wide range of applications and fabrication techniques for photonic crystals.

Keywords

Photonic Crystals; Nanocavities; Slow Light; Colloidal Crystals; Structural Coloration; Biomimicry; Optical Sensors; Waveguides; Bandgap Materials; Electromagnetic Simulations

On-chip natural assembly of silicon photonic bandgap crystals

2001-11-01

Yurii A. Vlasov , Xiang-Zheng Bo , J. C. Sturm +1 more

Trapping and emission of photons by a single defect in a photonic bandgap structure

2000-10-01

Susumu Noda , Alongkarn Chutinan , Masahiro Imada

A three-dimensional photonic crystal operating at infrared wavelengths

1998-07-01

Shawn-Yu Lin , J. G. Fleming , Dale L. Hetherington +7 more

Guided modes in photonic crystal slabs

1999-08-15

Steven G. Johnson , Shanhui Fan , Pierre R. Villeneuve +2 more

We analyze the properties of two-dimensionally periodic dielectric structures that have a band gap for propagation in a plane and that use index guiding to confine light in the third … We analyze the properties of two-dimensionally periodic dielectric structures that have a band gap for propagation in a plane and that use index guiding to confine light in the third dimension. Such structures are more amenable to fabrication than photonic crystals with full three-dimensional band gaps, but retain or approximate many of the latter's desirable properties. We show how traditional band-structure analysis can be adapted to slab systems in the context of several representative structures, and describe the unique features that arise in this framework compared to ordinary photonic crystals.

Photonic band structure: The face-centered-cubic case employing nonspherical atoms

1991-10-01

Eli Yablonovitch , T. J. Gmitter , K. Leung

We introduce a practical, new, face-centered-cubic dielectric structure which simultaneously solves two of the outstanding problems in photonic band structure. In this new ``photonic crystal'' the atoms are nonspherical, lifting … We introduce a practical, new, face-centered-cubic dielectric structure which simultaneously solves two of the outstanding problems in photonic band structure. In this new ``photonic crystal'' the atoms are nonspherical, lifting the degeneracy at the W point of the Brillouin zone, and permitting a full photonic band gap rather than a pseudogap. Furthermore, this fully three-dimensional fcc structure lends itself readily to microfabrication on the scale of optical wavelengths. It is created by simply drilling three sets of holes 35.26\ifmmode^\circ\else\textdegree\fi{} off vertical into the top surface of a solid slab or wafer, as can be done, for example, by chemical-beam-assisted ion etching.

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Vacuum Rabi splitting with a single quantum dot in a photonic crystal nanocavity

2004-11-01

Tomoyuki Yoshie , Axel Scherer , J. Hendrickson +6 more

Quantum nature of a strongly coupled single quantum dot–cavity system

2007-01-28

K. Hennessy , A. Badolato , Martin Winger +6 more

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Template-directed colloidal crystallization

1997-01-01

Alfons van Blaaderen , R. Ruel , Pierre Wiltzius

Motion of Electrons and Holes in Perturbed Periodic Fields

1955-02-15

J. M. Luttinger , W. Kohn

A new method of developing an "effective-mass" equation for electrons moving in a perturbed periodic structure is discussed. This method is particularly adapted to such problems as arise in connection … A new method of developing an "effective-mass" equation for electrons moving in a perturbed periodic structure is discussed. This method is particularly adapted to such problems as arise in connection with impurity states and cyclotron resonance in semiconductors such as Si and Ge. The resulting theory generalizes the usual effective-mass treatment to the case where a band minimum is not at the center of the Brillouin zone, and also to the case where the band is degenerate. The latter is particularly striking, the usual Wannier equation being replaced by a set of coupled differential equations.

Possible Realization of Directional Optical Waveguides in Photonic Crystals with Broken Time-Reversal Symmetry

2008-01-10

F. D. M. Haldane , S. Raghu

We show how, in principle, to construct analogs of quantum Hall edge states in "photonic crystals" made with nonreciprocal (Faraday-effect) media. These form "one-way waveguides" that allow electromagnetic energy to … We show how, in principle, to construct analogs of quantum Hall edge states in "photonic crystals" made with nonreciprocal (Faraday-effect) media. These form "one-way waveguides" that allow electromagnetic energy to flow in one direction only.

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Elastic and acoustic wave band structure

1992-10-01

M. M. Sigalas , E. N. Economou

Full Three-Dimensional Photonic Bandgap Crystals at Near-Infrared Wavelengths

2000-07-28

Susumu Noda , Katsuhiro Tomoda , Noritsugu Yamamoto +1 more

An artificial crystal structure has been fabricated exhibiting a full three-dimensional photonic bandgap effect at optical communication wavelengths. The photonic crystal was constructed by stacking 0.7-micrometer period semiconductor stripes with … An artificial crystal structure has been fabricated exhibiting a full three-dimensional photonic bandgap effect at optical communication wavelengths. The photonic crystal was constructed by stacking 0.7-micrometer period semiconductor stripes with the accuracy of 30 nanometers by advanced wafer-fusion technique. A bandgap effect of more than 40 decibels (which corresponds to 99.99% reflection) was successfully achieved. The result encourages us to create an ultra-small optical integrated circuit including a three-dimensional photonic crystal waveguide with a sharp bend.

The Structure of Electronic Excitation Levels in Insulating Crystals

1937-08-01

Gregory H. Wannier

In this article, a method is devised to study the energy spectrum for an excited electron configuration in an ideal crystal. The configuration studied consists of a single excited electron … In this article, a method is devised to study the energy spectrum for an excited electron configuration in an ideal crystal. The configuration studied consists of a single excited electron taken out of a full band of $N$ electrons. The multiplicity of the state is ${N}^{2}$. It is shown that because of the Coulomb attraction between the electron and its hole ${N}^{\frac{8}{5}}$ states are split off from the bottom of the excited Bloch band; for these states the electron cannot escape its hole completely. The analogy of these levels to the spectrum of an atom or molecule is worked out quantitatively. The bottom of the Bloch band appears as "ionization potential" and the Bloch band itself as the continuum above this threshold energy.

Monodispersed Colloidal Spheres: Old Materials with New Applications

2000-05-01

Y. Xia , Byron D. Gates , Yadong Yin +1 more

This article presents an overview of current research activities that center on monodispersed colloidal spheres whose diameter falls anywhere in the range of 10 nm to 1 μm. It is … This article presents an overview of current research activities that center on monodispersed colloidal spheres whose diameter falls anywhere in the range of 10 nm to 1 μm. It is organized into three parts: The first part briefly discusses several useful methods that have been developed for producing monodispersed colloidal spheres with tightly controlled sizes and well-defined properties (both surface and bulk). The second part surveys some techniques that have been demonstrated for organizing these colloidal spheres into two- and three-dimensionally ordered lattices. The third part highlights a number of unique applications of these crystalline assemblies, such as their uses as photonic bandgap (PBG) crystals; as removable templates to fabricate macroporous materials with highly ordered and three-dimensionally interconnected porous structures; as physical masks in lithographic patterning; and as diffractive elements to fabricate new types of optical sensors. Finally, we conclude with some personal perspectives on the directions towards which future research in this area might be directed.

Low frequency plasmons in thin-wire structures

1998-06-08

J. B. Pendry , A.J. Holden , David Robbins +1 more

A photonic structure consisting of an extended 3D network of thin wires is shown to behave like a low density plasma of very heavy charged particles with a plasma frequency … A photonic structure consisting of an extended 3D network of thin wires is shown to behave like a low density plasma of very heavy charged particles with a plasma frequency in the GHz range. We show that the analogy with metallic behaviour in the visible is rather complete, and the picture is confirmed by three independent investigations: analytic theory, computer simulation and experiments on a model structure. The fact that the wires are thin is crucial to the validity of the picture. This new composite dielectric, which has the property of negative below the plasma frequency, opens new possibilities for GHz devices.

Guiding and confining light in void nanostructure

2004-06-01

Vilson R. Almeida , Qianfan Xu , Carlos Angulo Barrios +1 more

We present a novel waveguide geometry for enhancing and confining light in a nanometer-wide low-index material. Light enhancement and confinement is caused by large discontinuity of the electric field at … We present a novel waveguide geometry for enhancing and confining light in a nanometer-wide low-index material. Light enhancement and confinement is caused by large discontinuity of the electric field at high-index-contrast interfaces. We show that by use of such a structure the field can be confined in a 50-nm-wide low-index region with a normalized intensity of 20 microm(-2). This intensity is approximately 20 times higher than what can be achieved in SiO2 with conventional rectangular waveguides.

High Transmission through Sharp Bends in Photonic Crystal Waveguides

1996-10-28

Attila Mekis , J. C. Chen , I. Kurland +3 more

We demonstrate highly efficient transmission of light around sharp corners in photonic band-gap waveguides. Numerical simulations reveal complete transmission at certain frequencies, and very high transmission $(>95%)$ over wide frequency … We demonstrate highly efficient transmission of light around sharp corners in photonic band-gap waveguides. Numerical simulations reveal complete transmission at certain frequencies, and very high transmission $(>95%)$ over wide frequency ranges. High transmission is observed even for 90\ifmmode^\circ\else\textdegree\fi{} bends with zero radius of curvature, with a maximum transmission of 98% as opposed to 30% for analogous conventional dielectric waveguides. We propose a simple one-dimensional scattering theory model with a dynamic frequency-dependent well depth to describe the transmission properties.

Analysis of guided resonances in photonic crystal slabs

2002-06-07

Shanhui Fan , John D. Joannopoulos

We present a three-dimensional analysis of guided resonances in photonic crystal slab structures that leads to a new understanding of the complex spectral properties of such systems. Specifically, we calculate … We present a three-dimensional analysis of guided resonances in photonic crystal slab structures that leads to a new understanding of the complex spectral properties of such systems. Specifically, we calculate the dispersion diagrams, the modal patterns, and transmission and reflection spectra of these resonances. From these calculations, a key observation emerges involving the presence of two temporal pathways for transmission and reflection processes. Using this insight, we introduce a general physical model that explains the essential features of complex spectral properties. Finally, we show that the quality factors of these resonances are strongly influenced by the symmetry of the modes and the strength of the index modulation.

Photonic Band Gap Guidance in Optical Fibers

1998-11-20

J. C. Knight , Jes Broeng , T. A. Birks +1 more

A fundamentally different type of optical waveguide structure is demonstrated, in which light is confined to the vicinity of a low-index region by a two-dimensional photonic band gap crystal. The … A fundamentally different type of optical waveguide structure is demonstrated, in which light is confined to the vicinity of a low-index region by a two-dimensional photonic band gap crystal. The waveguide consists of an extra air hole in an otherwise regular honeycomb pattern of holes running down the length of a fine silica glass fiber. Optical fibers based on this waveguide mechanism support guided modes with extraordinary properties.

Observation of trapped light within the radiation continuum

2013-07-01

Chia Wei Hsu , Bo Zhen , Jeongwon Lee +4 more

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Theory of light propagation in strongly modulated photonic crystals: Refractionlike behavior in the vicinity of the photonic band gap

2000-10-15

Masaya Notomi

Although light propagation in weakly modulated photonic crystals is basically similar to propagation in a diffraction grating in which conventional refractive index loses its meaning, we demonstrate that light propagation … Although light propagation in weakly modulated photonic crystals is basically similar to propagation in a diffraction grating in which conventional refractive index loses its meaning, we demonstrate that light propagation in strongly modulated two-dimensional (2D)/3D photonic crystals becomes refractionlike in the vicinity of the photonic bandgap. Such a crystal behaves as a material having an effective refractive index controllable by the band structure. This situation is analogous to the effective-mass approximation in electron-band theory. By utilizing this phenomenon, negatively refractive material can be realized, which has interesting optical properties such as mirror-image refraction.

Ultra-high-Q photonic double-heterostructure nanocavity

2005-02-13

Bong-Shik Song , Susumu Noda , Takashi Asano +1 more

Mechanism of formation of two-dimensional crystals from latex particles on substrates

1992-12-01

Nikolai D. Denkov , Orlin D. Velev , P. Kralchevski +3 more

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMechanism of formation of two-dimensional crystals from latex particles on substratesN. Denkov, O. Velev, P. Kralchevski, I. Ivanov, H. Yoshimura, and K. NagayamaCite this: Langmuir 1992, 8, … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMechanism of formation of two-dimensional crystals from latex particles on substratesN. Denkov, O. Velev, P. Kralchevski, I. Ivanov, H. Yoshimura, and K. NagayamaCite this: Langmuir 1992, 8, 12, 3183–3190Publication Date (Print):December 1, 1992Publication History Published online1 May 2002Published inissue 1 December 1992https://pubs.acs.org/doi/10.1021/la00048a054https://doi.org/10.1021/la00048a054research-articleACS PublicationsRequest reuse permissionsArticle Views8543Altmetric-Citations1010LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Extremely Large Group-Velocity Dispersion of Line-Defect Waveguides in Photonic Crystal Slabs

2001-11-30

Masaya Notomi , Koji Yamada , Akihiko Shinya +3 more

We reveal experimentally waveguiding characteristics and group-velocity dispersion of line defects in photonic crystal slabs as a function of defect widths. The defects have waveguiding modes with two types of … We reveal experimentally waveguiding characteristics and group-velocity dispersion of line defects in photonic crystal slabs as a function of defect widths. The defects have waveguiding modes with two types of cutoff within the photonic band gap. Interference measurements show that they exhibit extraordinarily large group dispersion, and we found waveguiding modes whose traveling speed is 2 orders of magnitude slower than that in air. These characteristics can be tuned by controlling the defect width, and the results agree well with theoretical calculations, indicating that we can design light paths with made-to-order dispersion.

Two-Dimensional Photonic Band-Gap Defect Mode Laser

1999-06-11

Oskar Painter , R. K. Lee , A. Scherer +4 more

A laser cavity formed from a single defect in a two-dimensional photonic crystal is demonstrated. The optical microcavity consists of a half wavelength-thick waveguide for vertical confinement and a two-dimensional … A laser cavity formed from a single defect in a two-dimensional photonic crystal is demonstrated. The optical microcavity consists of a half wavelength-thick waveguide for vertical confinement and a two-dimensional photonic crystal mirror for lateral localization. A defect in the photonic crystal is introduced to trap photons inside a volume of 2.5 cubic half-wavelengths, approximately 0.03 cubic micrometers. The laser is fabricated in the indium gallium arsenic phosphide material system, and optical gain is provided by strained quantum wells designed for a peak emission wavelength of 1.55 micrometers at room temperature. Pulsed lasing action has been observed at a wavelength of 1.5 micrometers from optically pumped devices with a substrate temperature of 143 kelvin.

A Dielectric Omnidirectional Reflector

1998-11-27

Yoel Fink , Joshua N. Winn , Shanhui Fan +4 more

A design criterion that permits truly omnidirectional reflectivity for all polarizations of incident light over a wide selectable range of frequencies was used in fabricating an all-dielectric omnidirectional reflector consisting … A design criterion that permits truly omnidirectional reflectivity for all polarizations of incident light over a wide selectable range of frequencies was used in fabricating an all-dielectric omnidirectional reflector consisting of multilayer films. The reflector was simply constructed as a stack of nine alternating micrometer-thick layers of polystyrene and tellurium and demonstrates omnidirectional reflection over the wavelength range from 10 to 15 micrometers. Because the omnidirectionality criterion is general, it can be used to design omnidirectional reflectors in many frequency ranges of interest. Potential uses depend on the geometry of the system. For example, coating of an enclosure will result in an optical cavity. A hollow tube will produce a low-loss, broadband waveguide, whereas a planar film could be used as an efficient radiative heat barrier or collector in thermoelectric devices.

High-Q photonic nanocavity in a two-dimensional photonic crystal

2003-10-01

Yoshihiro Akahane , Takashi Asano , Bong-Shik Song +1 more

Existence of a photonic gap in periodic dielectric structures

1990-12-17

K. M. Ho , C. T. Chan , C. M. Soukoulis

Using a plane-wave expansion method, we have solved Maxwell's equations for the propagation of electromagnetic waves in a periodic lattice of dielectric spheres (dielectric constant ${\mathrm{\ensuremath{\epsilon}}}_{\mathit{a}}$) in a uniform dielectric … Using a plane-wave expansion method, we have solved Maxwell's equations for the propagation of electromagnetic waves in a periodic lattice of dielectric spheres (dielectric constant ${\mathrm{\ensuremath{\epsilon}}}_{\mathit{a}}$) in a uniform dielectric background (${\mathrm{\ensuremath{\epsilon}}}_{\mathit{b}}$). Contrary to experiment, we find that fcc dielectric structures do not have a ``photonic band gap'' that extends throughout the Brillouin zone. However, we have determined that dielectric spheres arranged in the diamond structure do possess a full photonic band gap. This gap exists for refractive-index contrasts as low as 2.

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Optical Properties of Photonic Crystals

2005-01-01

Kazuaki Sakoda

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Fabrication of photonic crystals for the visible spectrum by holographic lithography

2000-03-01

M. Campbell , David N. Sharp , Mike T. Harrison +2 more

Photonic crystals: putting a new twist on light

1997-03-13

John D. Joannopoulos , Pierre R. Villeneuve , Shanhui Fan

Reflection-Free One-Way Edge Modes in a Gyromagnetic Photonic Crystal

2008-01-10

Zheng Wang , Y. D. Chong , John D. Joannopoulos +1 more

We point out that electromagnetic one-way edge modes analogous to quantum Hall edge states, originally predicted by Raghu and Haldane in 2D photonic crystals possessing Dirac point-derived band gaps, can … We point out that electromagnetic one-way edge modes analogous to quantum Hall edge states, originally predicted by Raghu and Haldane in 2D photonic crystals possessing Dirac point-derived band gaps, can appear in more general settings. We show that the TM modes in a gyromagnetic photonic crystal can be formally mapped to electronic wave functions in a periodic electromagnetic field, so that the only requirement for the existence of one-way edge modes is that the Chern number for all bands below a gap is nonzero. In a square-lattice yttrium-iron-garnet crystal operating at microwave frequencies, which lacks Dirac points, time-reversal breaking is strong enough that the effect should be easily observable. For realistic material parameters, the edge modes occupy a 10% band gap. Numerical simulations of a one-way waveguide incorporating this crystal show 100% transmission across strong defects.

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Photonic band-gap structures

1993-02-01

Eli Yablonovitch

The analogy between electromagnetic wave propagation in multidimensionally periodic structures and electron-wave propagation in real crystals has proven to be a fruitful one. Initial efforts were motivated by the prospect … The analogy between electromagnetic wave propagation in multidimensionally periodic structures and electron-wave propagation in real crystals has proven to be a fruitful one. Initial efforts were motivated by the prospect of a photonic band gap, a frequency band in three-dimensional dielectric structures in which electromagnetic waves are forbidden irrespective of the propagation direction in space. Today many new ideas and applications are being pursued in two and three dimensions and in metallic, dielectric, and acoustic structures. We review the early motivations for this research, which were derived from the need for a photonic band gap in quantum optics. This need led to a series of experimental and theoretical searches for the elusive photonic band-gap structures, those three-dimensionally periodic dielectric structures that are to photon waves as semiconductor crystals are to electron waves. We describe how the photonic semiconductor can be doped, producing tiny electromagnetic cavities. Finally, we summarize some of the anticipated implications of photonic band structure for quantum electronics and for other areas of physics and electrical engineering.

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Large-scale synthesis of a silicon photonic crystal with a complete three-dimensional bandgap near 1.5 micrometres

2000-05-01

Álvaro Blanco , Emmanuel Chomski , Serguei Grabtchak +7 more

All-silica single-mode optical fiber with photonic crystal cladding

1996-10-01

J. C. Knight , T. A. Birks , P. St. J. Russell +1 more

We report the fabrication of a new type of optical waveguide: the photonic crystal fiber. It consists of a pure silica core surrounded by a silica-air photonic crystal material with … We report the fabrication of a new type of optical waveguide: the photonic crystal fiber. It consists of a pure silica core surrounded by a silica-air photonic crystal material with a hexagonal symmetry. The fiber supports a single robust low-loss guided mode over a very broad spectral range of at least 458-1550 nm.

Surface plasmon subwavelength optics

2003-08-01

William L. Barnes , Alain Dereux , Thomas W. Ebbesen

Slow light in photonic crystals

2008-07-31

Toshihiko Baba

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Self-Assembled Plasmonic Nanoparticle Clusters

2010-05-27

Jonathan A. Fan , Chihhui Wu , Kui Bao +7 more

Optical Nanoengineering Optics and electronics operate at very different length scales. Surface plasmons are light-induced electronic excitations that are being pursued as a route to bridge the length scales and … Optical Nanoengineering Optics and electronics operate at very different length scales. Surface plasmons are light-induced electronic excitations that are being pursued as a route to bridge the length scales and bring the processing speed offered by optical communication down to the size scales of electronic chip circuitry. Now, Fan et al. (p. 1135 ) describe the self-assembly of nanoscale dielectric particles coated with gold. Functionalization of the gold surface with polymer ligands allowed controlled production of clusters of nanoparticles. The optical properties of the self-assembled nanostructures depended on the number of components within the cluster and each structure could be selected for its unique optical properties. Such a bottom-up approach should help in fabricating designed optical circuits on the nanoscale.

Photonic structures in biology

2003-08-13

Pete Vukusic , J. R. Sambles

Single-Crystal Colloidal Multilayers of Controlled Thickness

1999-07-15

Peng Jiang , Jane F. Bertone , Kao‐Shing Hwang +1 more

Materials whose dielectric constant varies spatially with submicrometer periodicity exhibit diffractive optical properties which are potentially valuable in a number of existing and emerging applications. Here, such systems are fabricated … Materials whose dielectric constant varies spatially with submicrometer periodicity exhibit diffractive optical properties which are potentially valuable in a number of existing and emerging applications. Here, such systems are fabricated by exploiting the spontaneous crystallization of monodisperse silica spheres into close-packed arrays. By reliance on a vertical deposition technique to pack the spherical colloids into close-packed silica−air arrays, high quality samples can be prepared with thicknesses up to 50 μm. These samples are planar and thus suitable for optical characterization. Scanning electron microscopy (SEM) of these materials illustrates the close-packed ordering of the spherical colloids in planes parallel to the substrate; cross-sectional SEM micrographs of the arrays as well as optical methods are used to measure sample thickness and uniformity. Normal-incidence transmission spectra in the visible and near-infrared regions show distinct peaks due to diffraction from the colloidal layer...

Direct laser writing of three-dimensional photonic-crystal templates for telecommunications

2004-06-13

M. Deubel , Georg von Freymann , Martin Wegener +3 more

Carbon Structures with Three-Dimensional Periodicity at Optical Wavelengths

1998-10-30

Anvar Zakhidov , Ray H. Baughman , Zafar Iqbal +5 more

Porous carbons that are three-dimensionally periodic on the scale of optical wavelengths were made by a synthesis route resembling the geological formation of natural opal. Porous silica opal crystals were … Porous carbons that are three-dimensionally periodic on the scale of optical wavelengths were made by a synthesis route resembling the geological formation of natural opal. Porous silica opal crystals were sintered to form an intersphere interface through which the silica was removed after infiltration with carbon or a carbon precursor. The resulting porous carbons had different structures depending on synthesis conditions. Both diamond and glassy carbon inverse opals resulted from volume filling. Graphite inverse opals, comprising 40-angstrom-thick layers of graphite sheets tiled on spherical surfaces, were produced by surface templating. The carbon inverse opals provide examples of both dielectric and metallic optical photonic crystals. They strongly diffract light and may provide a route toward photonic band-gap materials.

Responsive Photonic Crystals

2011-01-20

Jianping Ge , Yadong Yin

This Review summarizes recent developments in the field of responsive photonic crystal structures, including principles for design and fabrication and many strategies for applications, for example as optical switches or … This Review summarizes recent developments in the field of responsive photonic crystal structures, including principles for design and fabrication and many strategies for applications, for example as optical switches or chemical and biological sensors. A number of fabrication methods are now available to realize responsive photonic structures, the majority of which rely on self-assembly processes to achieve ordering. Compared with microfabrication techniques, self-assembly approaches have lower processing costs and higher production efficiency, however, major efforts are still needed to further develop such approaches. In fact, some emerging techniques such as spin coating, magnetic assembly, and flow-induced self-assembly have already shown great promise in overcoming current challenges. When designing new systems with improved performance, it is always helpful to bear in mind the lessons learnt from natural photonic structures.

Magnetism from conductors and enhanced nonlinear phenomena

1999-01-01

J. B. Pendry , A.J. Holden , David Robbins +1 more

We show that microstructures built from nonmagnetic conducting sheets exhibit an effective magnetic permeability /spl mu//sub eff/, which can be tuned to values not accessible in naturally occurring materials, including … We show that microstructures built from nonmagnetic conducting sheets exhibit an effective magnetic permeability /spl mu//sub eff/, which can be tuned to values not accessible in naturally occurring materials, including large imaginary components of /spl mu//sub eff/. The microstructure is on a scale much less than the wavelength of radiation, is not resolved by incident microwaves, and uses a very low density of metal so that structures can be extremely lightweight. Most of the structures are resonant due to internal capacitance and inductance, and resonant enhancement combined with compression of electrical energy into a very small volume greatly enhances the energy density at critical locations in the structure, easily by factors of a million and possibly by much more. Weakly nonlinear materials placed at these critical locations will show greatly enhanced effects raising the possibility of manufacturing active structures whose properties can be switched at will between many states.

Controlling the dynamics of spontaneous emission from quantum dots by photonic crystals

2004-08-01

Peter Lodahl , A. Floris van Driel , Ivan S. Nikolaev +4 more

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Preparation of Photonic Crystals Made of Air Spheres in Titania

1998-08-07

Judith E. G. J. Wijnhoven , Willem L. Vos

Three-dimensional crystals of air spheres in titania (TiO2) with radii between 120 and 1000 nanometers were made by filling the voids in artificial opals by precipitation from a liquid-phase chemical … Three-dimensional crystals of air spheres in titania (TiO2) with radii between 120 and 1000 nanometers were made by filling the voids in artificial opals by precipitation from a liquid-phase chemical reaction and subsequently removing the original opal material by calcination. These macroporous materials are a new class of photonic band gap crystals for the optical spectrum. Scanning electron microscopy, Raman spectroscopy, and optical microscopy confirm the quality of the samples, and optical reflectivity demonstrates that the crystals are strongly photonic and near that needed to exhibit band gap behavior.

Light Emitting Diodes

2005-07-15

E. Fred Schubert , Thomas Gessmann , Jong Kyu Kim

Abstract Inorganic semiconductor light‐emitting diodes (LEDs) are environmentally benign and have already found widespread use as indicator lights, large‐area displays, and signage applications. In addition, LEDs are very promising candidates … Abstract Inorganic semiconductor light‐emitting diodes (LEDs) are environmentally benign and have already found widespread use as indicator lights, large‐area displays, and signage applications. In addition, LEDs are very promising candidates for future energy‐saving light sources suitable for office and home lighting applications. Today, the entire visible spectrum can be covered by light‐emitting semiconductors: AlGaInP and AlGaInN compound semiconductors are capable of emission in the red to yellow wavelength range and ultraviolet (uv) to green wavelength range, respectively. Currently, two basic approaches exist for white light sources: The combination of one or more phosphorescent materials with a semiconductor LED and the use of multiple LEDs emitting at complementary wavelengths. Both approaches are suitable for high efficiency sources that have the potential to replace incandescent and fluorescent lights. In this article, the properties of inorganic LEDs will be presented, including emission spectra, electrical characteristics, and current‐flow patterns. Structures providing high internal quantum efficiency, namely, heterostructures and multiple quantum well structures, will be discussed. Advanced techniques enhancing the external quantum efficiency will be reviewed, including resonant‐cavities, die shaping (chip shaping), omnidirectional reflectors, and photonic crystals. Different approaches to white LEDs will be presented and figures‐of‐merit such as the color rendering index, luminous efficacy, and luminous efficiency will be explained. Finally, the packaging of low power and high power LED dies will be discussed.

Inverse design in nanophotonics

2018-10-23

Sean Molesky , Zin Lin , Alexander Y. Piggott +3 more

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Optical Properties of Photonic Crystals

2001-01-01

Kazuaki Sakoda

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Anisotropy-Induced flattened dispersion and higher-order topology in C2v symmetry triangular photonic crystals

2025-06-24

Liyun Tao , Ya-Hong Liu , Yue He +7 more | Photonics Research

Optical Characterization of Chiral Three-dimensionally Periodic Photonic Crystals Fabricated by Temporally Periodic Physical Vapor Deposition on Two-dimensionally Periodic Substrates

2025-06-24

Ricardo A. Fiallo , Mark W. Horn , Akhlesh Lakhtakia | Journal of Physics Communications

Abstract We fabricated chiral three-dimensionally periodic photonic crystals (3D-PPCs) with nanoscale features&#xD;by: first etching two-dimensionally periodic patterns (either square or equiangled-triangular lattices)&#xD;in fused silica and silicon substrates, and then implementing … Abstract We fabricated chiral three-dimensionally periodic photonic crystals (3D-PPCs) with nanoscale features&#xD;by: first etching two-dimensionally periodic patterns (either square or equiangled-triangular lattices)&#xD;in fused silica and silicon substrates, and then implementing temporally periodic physical vapor&#xD;deposition (TP-PVD) whereby a collimated vapor flux was directed towards rotating substrates. The&#xD;patterned substrates as well as the 3D-PPCs were optically characterized in transmission and reflection,&#xD;for both linear (s- and p-polarized) and circular (right-handed and left-handed) polarization states&#xD;of the incident plane wave, in relation to the direction of the incident plane wave and the wavelength&#xD;in the 500-900 nm range. Before TP-PVD, the patterned substrates exhibited opal-like iridescence,&#xD;and the optical characterization detected nonspecular transmission and Rayleigh–Wood anomalies in&#xD;accordance with the mathematical predictions for two-dimensional photonic crystals. Iridescence was&#xD;maintained after TP-PVD. The 3D-PPCs comprise discrete clumps of nanohelixes growing on the unetched&#xD;regions. Optical characterization of the 3D-PPCs revealed circular-polarization-discriminatory&#xD;reflection and transmission, Fabry–Pérot resonances, Dyakonov–Tamm waves, nonspecular transmission,&#xD;and a high-loss regime, but Rayleigh–Wood anomalies could not be unambiguously identified. We expect&#xD;applications in diverse scenarios wherein matter and circularly polarized light interact.

Topological stability and transitions of photonic meron lattices at the metal/uniaxial crystal interface

2025-06-24

Shiqian Cao , Xiaodong Xie , Peng Shi +3 more | Photonics Research

Magneto‐Responsive Photonic Liquid Gate with Color‐Indicated Gas Transport Switching Threshold

2025-06-24

Liting Pan , Shijie Yu , Zemin Chen +4 more | Advanced Functional Materials

Abstract Liquid gates, which combine the characteristics of both solid and liquid materials, possess unique advantages of reconfigurable interfaces, dynamic responsiveness, and adaptability, demonstrating great promise for various practical applications. … Abstract Liquid gates, which combine the characteristics of both solid and liquid materials, possess unique advantages of reconfigurable interfaces, dynamic responsiveness, and adaptability, demonstrating great promise for various practical applications. Currently, a major challenge for liquid gates is the observation of their switching behavior in real‐time and in situ, which directly limits the applicability across various scenarios. Here, a magneto‐responsive photonic liquid gate is developed to enable instantaneous, in situ monitoring of gas transport switching threshold through dynamic structural color changes. By leveraging particle reconfiguration within confined magnetic colloidal suspensions, both the interfacial mechanical properties and diffracted light are simultaneously tuned by the magnetic field, creating a direct correspondence between the gas transport switching thresholds and the observable color state of liquid gates. This visual system features responsive changes in both appearance and functionality, enabling real‐time modulation of gas release to be perceived with the naked eye. Furthermore, this material strategy, characterized by direct recognition, rapid predictability, and straightforward manipulation, opens new opportunities for visual chemical detection, dynamic fluid control, and multifunctional integrated systems.

Holomorphic operator function method for calculation of band structures of dispersive photonic crystals

2025-06-23

Xiao Wang , Wenqiang Xiao , Yang Liu | Advances in Continuous and Discrete Models

One-dimensional DNG-DPS photonic structure with a Kolakoski Quasicrystal lattice

2025-06-23

Harshit Poddar , Chittaranjan Nayak | Journal of Optics

Extremely narrow band in moiré photonic time crystal

2025-06-23

NULL AUTHOR_ID | Physical Review Letters

Multi-channel photonic crystal diodes based on nonlinear Fano resonances

2025-06-20

Longpan Wang , Dezhong Sun , Shuangshuang Li +7 more | Optical and Quantum Electronics

Probing the topological Anderson transition in quasiperiodic photonic lattices via chiral displacement and wavelength tuning

2025-06-20

NULL AUTHOR_ID | Physical review. A/Physical review, A

Inverse Design of 3D-Printable Metalenses with Complementary Dispersion for Terahertz Imaging

2025-06-20

Mo Chen , Ka Fai Chan , Alec M. Hammond +2 more | ACS Photonics

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Magnetically induced topological evolutions of exceptional points in photonic bands

2025-06-20

NULL AUTHOR_ID | Physical Review Letters

Photonic-spin-governed absorption in a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>μ</mml:mi></mml:math> -near-zero subwavelength gyromagnetic cylinder

2025-06-20

NULL AUTHOR_ID | Physical review. A/Physical review, A

Electrochemical Engineering of Wide Photonic Bandgap in Silicon Nanostructures for Omnidirectional Mirror Applications

2025-06-19

Mohamed Shaker Salem , Asmaa Mohamed Abdelaleem , G. M. Nasr +1 more | Physica Scripta

Abstract We report the optimized design and theoretical analysis of broadband omnidirectional mirrors made of silicon nanostructures. The design principle is based on regulating the electrochemical etching process of single-crystalline … Abstract We report the optimized design and theoretical analysis of broadband omnidirectional mirrors made of silicon nanostructures. The design principle is based on regulating the electrochemical etching process of single-crystalline silicon substrates in acidic solution using train of sinusoidal current waveforms with tightly-spaced frequencies. The individual frequency of the etching current waveform is calibrated to produce a specific photonic band in the reflectance spectrum. A linear relationship is obtained between the frequency of the current signal and the resonant position of the photonic band. The frequency range of the etching waveform is selected to produce a broad photonic peak resulting from the bandgap overlap among multiple photonic bands associated with the individual frequency of each current signal. The transfer matrix method is utilized to calculate the angular reflectance spectra of the experimentally obtained omnidirectional mirrors for both transverse electric (TE) and transverse magnetic (TM) polarization of the incident light. Good agreement is found between the experimental and theoretical reflectivity spectra.&#xD;

Sub-diffraction limited focusing with quasi-periodic photonic crystal multilayers

2025-06-19

Hang Xue , Yanyan Zhou , Wenpeng Zhang +4 more | Optical Materials Express

Design and analysis of efficient biosensors based on 1D ternary photonic crystals for malaria detection

2025-06-19

Hassan S. Ashour , Khedr M. Abohassan , Mazen M. Abadla +1 more | Modern Physics Letters B

This study presents an optical biosensor design based on a one-dimensional ternary photonic crystal to detect the malaria stages in human blood. The biosensor’s structure consists of periodic unit cells, … This study presents an optical biosensor design based on a one-dimensional ternary photonic crystal to detect the malaria stages in human blood. The biosensor’s structure consists of periodic unit cells, each encompassing three layers of silica, sapphire, and zinc selenide. A gap in the middle of the structure is designated to be filled with serum. The functionality of the biosensor is assessed through numerical simulations of its transmittance spectra, utilizing the well-known transfer matrix method. The influence of various factors, including the number of periods, gap thickness, and incident angle of radiation, on the biosensor’s performance is explored. Performance parameters, such as sensitivity (S), quality factor (Q), figure of merit (FOM), and limit of detection (LOD), are calculated using the shift in resonant wavelength and the width of the resonant peaks. The sensor exhibits a notable average sensitivity of 680[Formula: see text]nm/refractive index unit (RIU) across different blood samples. Additionally, it achieves a high-quality factor, a substantial figure of merit, and a low detection limit of 27,434, 79,823/RIU, and [Formula: see text] RIU, respectively. Therefore, due to its exceptional performance characteristics, compact design, ease of fabrication, and low cost, the proposed biosensor is deemed an effective device for biosensing applications.

Programmable 2D photonic quasicrystals with real-time reconfigurability

2025-06-18

Peisheng Sun , Xuesong Hu , Ruonan Li +6 more | Optics Letters

Design and Fabrication of Silicon-Based Triangular Lattice Photonic Crystals Using Electron Beam Lithography and Reactive Ion Etching

2025-06-18

Rajni Bala | Research Square (Research Square)

<title>Abstract</title> This study presents the theoretical modeling and fabrication of an efficient silicon-based photonic crystal waveguide. The structure consists of a two-dimensional triangular lattice of air holes etched into a … <title>Abstract</title> This study presents the theoretical modeling and fabrication of an efficient silicon-based photonic crystal waveguide. The structure consists of a two-dimensional triangular lattice of air holes etched into a silicon substrate, with a lattice constant of 400 nm and rod radius of 160 nm, designed to precisely control light propagation. Various defect configurations—such as point defects, missing lattice elements, and shape-modified holes—are introduced to tailor the photonic bandgap and enable waveguiding functionalities. The fabrication process employs high-resolution electron beam lithography (EBL) followed by capacitive coupled reactive ion etching (RIE). Special attention is given to mitigating the proximity effect and optimizing the electron dose parameters to achieve high pattern fidelity. The results contribute to the scalable fabrication of nanophotonic devices for integrated photonic circuits.

Tunable Photonic Paints via Block Copolymer Self-Assembly and Refractive Index Engineering

2025-06-18

Simone Bertucci , Remi Schobinger , Liviana Mummolo +7 more | ACS Applied Polymer Materials

Customized bandgap engineering in plasmonic-photonic crystal structures for advanced broadband and narrowband optical filtering

2025-06-17

Sara Gholinezhad Shafagh , Hassan Kaatuzian , Mohammad Danaie | Optical and Quantum Electronics

Optical Asymmetric filter Using Graphene Plasmonic embedded in Photonic Crystal Fiber

2025-06-17

| Muthanna Journal of Pure Science

This work exhibits simulation and design of a small-scale graphene plasmonic filter based photonic crystal fiber through finite element method investigation. Some cladding holes inside the PCF possess deposited 2-D … This work exhibits simulation and design of a small-scale graphene plasmonic filter based photonic crystal fiber through finite element method investigation. Some cladding holes inside the PCF possess deposited 2-D graphene enabling the light transmission interaction which leads to surface plasmonic resonance (SPR). Improved optical filter performance results from this process because it enables better control and higher sensitivity and reduced signal loss so filters become optimal for use. A finite element method analyzes both polarization properties and spectral loss performance in the proposed structural design. The simulation evaluation was divided into two testing periods while changing the dimensions of PCF geometry. The investigation of first design components incorporated r = 6 and r = 5 while the second design components incorporated r = 6 and r = 7. The introduction of graphene materials into PCF rings comprises the two design models progressively from one to four rings. The design suffered maximum loss when four graphene rings were inserted in both designs. The absorption increases results in the creation of plasmonic polaritons. In the first design, when r = 6 and r = 5, the quasi-TE guided mode exhibits losses of -113000 dB/ mm for wavelengths λ = 1.14 μm. The quasi-TM guided mode exhibits losses of -109100 dB/ mm for wavelengths λ = 1.17 μm . In the second design, r = 6 and r = 7, the losses of the quasi-TE guided mode are -146800 dB/ mm for wavelengths λ = 1.16 μm. The quasi-TM guided mode exhibits losses of -146600 dB/mm at wavelengths λ = 1.2 μm.

Transmission property of 1D Dirac-Semimetal-defected Photonic Crystal in Terahertz Multi-bandgap

2025-06-16

Jikai Wang , Jiang Li , Xuefei Yang +1 more | Chinese Physics B

Abstract In this paper, a symmetrical 1D photonic crystal structure with a Dirac semimetal defect layer is proposed. The material properties of the Dirac semimetal are governed by three key … Abstract In this paper, a symmetrical 1D photonic crystal structure with a Dirac semimetal defect layer is proposed. The material properties of the Dirac semimetal are governed by three key parameters: Fermi level, Fermi velocity, and degeneracy factor. Simulation results demonstrate that the proposed structure generates multiple photonic bandgaps within the THz frequency range. In the low-THz region, pronounced resonant transmission peaks emerge, enabling near-perfect filtering performance. The positions of these defect modes can be dynamically tuned by adjusting the Fermi level and degeneracy factor. In mid- and high-THz frequency bands, the Dirac semimetal begins to exhibit metallic behavior, leading to attenuation of the transmission peaks and the appearance of absorption. The elevation of the Fermi level delays the critical threshold for the transition from the dielectric state to the metallic state, while an increase in Fermi velocity suppresses metallic behavior. Therefore, enhancing both the Fermi level and Fermi velocity contributes to strengthening the defect peak intensity. Conversely, increasing the degeneracy factor strengthens the metallic characteristics, thereby disrupting the high-frequency photonic bandgap. Notably, the defect layer thickness and incident angle exert significant influence on the transmission behavior: a larger incident angle causes the defect peak to shift toward higher frequencies and reduces its intensity, whereas a thicker defect layer shifts the defect peak toward lower frequencies. The modulation effects of both parameters become more pronounced as frequency increases. Compared with conventional photonic crystals, our work can provide a tunable structure over transmission properties, offering novel strategies for designing tunable filters and optical sensors.

Recent advances in photonic crystal-based encoder and decoder designs: a comprehensive review

2025-06-16

Ayesha Sultana , Haraprasad Mondal , Himanshu Ranjan Das +2 more | The European Physical Journal Plus

Magnetically controllable and topologically protected bound states in the continuum in photonic crystals

2025-06-16

Zhenbin Zhang , Chao Liu , Hongjian Li +2 more | Journal of Applied Physics

In this study, we theoretically introduce magnetically controllable, topologically protected bound states in the continuum (BICs) arising from a two-dimensional photonic crystal composed of yttrium iron garnet. The system’s electromagnetic … In this study, we theoretically introduce magnetically controllable, topologically protected bound states in the continuum (BICs) arising from a two-dimensional photonic crystal composed of yttrium iron garnet. The system’s electromagnetic properties change markedly based on the magnetization state of the YIG. Different magnetization directions of the YIG disks induce chiral edge states in the photonic crystal, enabling the formation of BICs. Our findings show that magnetization can be used to control BICs, presenting new possibilities for designing robust, adaptable optical devices. This work opens up future possibilities for exploring and utilizing magnetically tunable photonic structures in advanced optical technologies.

Harnessing Translational Symmetry in Moiré Photonic Crystal Nano-cavities for Enhanced Cavity Quantum Electrodynamics

2025-06-16

Kisalaya Chakrabarti , Angsuman Sarkar | Research Square (Research Square)

<title>Abstract</title> We present a theoretical and computational investigation of integrating Chakrabarti’s translational symmetry concepts with cavity quantum electrodynamics (CQED) in moiré photonic crystal nanocavities. We demonstrate that applying node–antinode translational … <title>Abstract</title> We present a theoretical and computational investigation of integrating Chakrabarti’s translational symmetry concepts with cavity quantum electrodynamics (CQED) in moiré photonic crystal nanocavities. We demonstrate that applying node–antinode translational symmetry filters to moiré field profiles yields localized cavity modes with enhanced light-matter coupling. Compared to standalone moiré or CQED methods, our integrated approach achieves quantitatively superior Purcell enhancements, confirmed via field intensity and effective index simulations. While the idealized model shows promise, we discuss real-world constraints such as photon loss and temperature sensitivity. This cross-disciplinary framework enables progress toward scalable, entanglement-preserving photonic networks.

Scalable Production of High-Strength Recycled Noniridescent Structural Color Models via Twin-Screw Extrusion and 3D Printing

2025-06-16

Pengyu Gu , Yibo Wu , Qikuan Cheng +7 more | ACS Applied Materials & Interfaces

The integration of 3D printing into the manufacture of recycled structural color components presents a compelling alternative to conventional dyes and pigments. This paper proposes a processing strategy combining colloidal … The integration of 3D printing into the manufacture of recycled structural color components presents a compelling alternative to conventional dyes and pigments. This paper proposes a processing strategy combining colloidal nanosphere self-assembly, twin-screw extrusion, and FDM 3D printing to rapidly produce noniridescent structural color components. The twin-screw extrusion mixes nanospheres with resin by using thermal shear forces to arrange nanospheres uniformly, creating structural color filaments (SCFs) for 3D printing. Using FDM 3D printing, various structural color patterns and three-dimensional structural color models (SCMs) are successfully fabricated. The results demonstrate that colloidal nanospheres can achieve regular arrangement within seconds under thermal shear, with the extruded filaments and printed models exhibiting pronounced noniridescent structural colors on a black substrate. Furthermore, SCFs and 3D-printed SCMs demonstrate excellent mechanical properties, with tensile strengths reaching 20.1 and 11.5 MPa, respectively. Moreover, this technology also features advantages such as material recyclability, low cost, low energy consumption, and flexibility in customization flexibility. These findings provide valuable insights into the integration of photonic crystals with 3D printing, underscoring the extensive application potential of noniridescent structural color materials in the production of complex patterns and functional components.

Glass transition in colloidal monolayers controlled by light-induced caging

2025-06-16

NULL AUTHOR_ID | Physical review. E

Glass transition in colloidal monolayers controlled by light-induced caging

2025-06-16

NULL AUTHOR_ID | Physical review. E

Design and optimization of polymer-doped perfect annular photonic crystal for gamma radiation sensing application

2025-06-16

Hussein A. Elsayed , Suryakanta Nayak , Ayman A. Ameen +5 more | Radiation Physics and Chemistry

Design of Robust Topological Edge States Clock-shaped Multiplexer in Anisotropic Photonic Crystals Enhanced by Neural Networks

2025-06-15

Hang Sun , Zheng-Da Hu , Jingjing Wu +1 more | Photonics and Nanostructures - Fundamentals and Applications

Plasmonic Color Printing Via Photoreduction of ZnO

2025-06-15

June-Sik Hwang , Hongseok Youn , Huseung Lee +1 more | Journal of The Korean Society of Manufacturing Technology Engineers

A review on photonic crystal-based components of all-optical ALU

2025-06-14

Ayesha Sultana , Haraprasad Mondal , Himanshu Ranjan Das +2 more | Journal of Optics

Reflection and refraction of directrons at the interface

2025-06-13

Xing‐Zhou Tang , Chaoyi Li , Zhi‐Jun Huang +6 more | Proceedings of the National Academy of Sciences

Reflection and refraction are ubiquitous phenomena with extensive applications, yet minimizing energy loss and information distortion during these processes remains a significant challenge. This study examines the behavior of structurally … Reflection and refraction are ubiquitous phenomena with extensive applications, yet minimizing energy loss and information distortion during these processes remains a significant challenge. This study examines the behavior of structurally stable solitons, known as directrons, in nematic liquid crystals interacting with an interface where the director field orientation changes, despite identical physical properties, external potentials, and boundary anchoring in the two regions. During reflection and refraction, the directrons maintain nearly constant structure and velocity, ensuring energy conservation and information integrity. Microscopic analyses of the director field and macroscopic evaluations of effective potential are employed to elucidate the dependence of reflection and refraction probabilities on the directron’s incident angle and the orientation difference across the interface. The findings provide valuable insights into the dynamics of solitary waves in structured liquid crystal systems, offering significant implications for the development of tunable photonic devices, reconfigurable optical systems, and nanoscale material engineering.

Nonreciprocal Photonic Spin Hall Effect in a Bulk Dirac Semimetal based Tribonacci Photonic Crystal

2025-06-12

Zhi Ji , Ningyi Wang , Wentao Liu +4 more | Research Square (Research Square)

<title>Abstract</title> Nonreciprocal photonic spin Hall effect manifests it as the different spin dependent reflected/transmitted transverse splittings of linearly polarized incident waves at two opposite wave propagation directions. However, its realization … <title>Abstract</title> Nonreciprocal photonic spin Hall effect manifests it as the different spin dependent reflected/transmitted transverse splittings of linearly polarized incident waves at two opposite wave propagation directions. However, its realization remains obscure. Here, we report the discovery of the prominent nonreciprocal photonic spin Hall effect in a bulk Dirac semimetal based on quasiperiodic Tribonacci photonic crystal, which is evidenced by the significantly large reflected spin shift along one propagation direction but the trivial spin shift along the opposite propagation direction due to its asymmetrical geometrical structure and electromagnetic field distribution. In addition, the Fermi energy of the bulk Dirac semimetal can be continuously modified by the external stimulus, which enables the effective control of the nonreciprocal photonic spin Hall effect in the Dirac semimetal based Tribonacci photonic crystal. Our results open up the alternative platform to generate the controllably nonreciprocal photonic spin Hall effect in the quasiperiodic systems via the combination of the bulk Dirac semimetals and Tribonacci photonic crystal. <bold>PACS:</bold> 78.67.-n, 73.20.Mf, 73.43.-f

Dual-Broadband Topological Photonic Crystal Edge State Based on Liquid Crystal Tunability

2025-06-12

Jinying Zhang , Bingnan Wang , Jiacheng Wang +2 more | Materials

The rapid advancements in optical communication and sensing technologies have significantly increased the demand for advanced tunable spectral systems. This study presents a dual-band terahertz transmission and manipulation approach by … The rapid advancements in optical communication and sensing technologies have significantly increased the demand for advanced tunable spectral systems. This study presents a dual-band terahertz transmission and manipulation approach by leveraging the topologically protected properties of valley-topological photonic crystal edge states. The designed structure facilitates the excitation of the K valley within the range of 0.851–0.934 THz and the K′ valley from 1.604 to 1.686 THz, while also demonstrating anomalous refraction and birefringence. The calculated emission angles, derived through momentum matching, enable transitions between single-wave and dual-wave emissions and allow for precise angle control. The introduction of the liquid crystal material NJU-LDn-4 enables continuous tuning of the dual-band spectral range under a varying electric field, broadening the operating frequency bands to the ranges of 0.757–0.996 THz and 1.426–1.798 THz, respectively. These findings suggest promising applications in tunable filter design, optical communication, photonic computing, optical sensing, and high-resolution imaging, particularly in novel optical devices requiring precise control over spectral characteristics and light propagation.

Cation Exchange Capacity Controlled Exfoliation of Monolayer Montmorillonite as Inorganic Liquid Crystals

2025-06-12

Sheng-kai Chang , Jiarong Liu , Jiayu Chen +4 more | Small

Abstract Clays, pivotal in human civilization for millennia, are re‐emerging as promising candidates in applications such as liquid crystals (LCs) after 2D delamination. However, the scalable exfoliation of monolayer clays … Abstract Clays, pivotal in human civilization for millennia, are re‐emerging as promising candidates in applications such as liquid crystals (LCs) after 2D delamination. However, the scalable exfoliation of monolayer clays with high geometric anisotropy remains challenging, hindering fundamental investigations and applications of 2D clay LCs. Here, a cation exchange capacity (CEC)‐controlled exfoliation to achieve monolayer production of montmorillonite (MMT), a typical aluminosilicate clay, is developed. The optimized exchange ratios based on the CEC of MMT enable stepwise swelling and delamination, thus achieving 2D MMT with a record‐high aspect ratio of ≈600. Then, lyotropic liquid crystalline behavior in 2D MMT is observed, and its electro‐birefringence Kerr effect with a high sensitivity of ≈1.0 × 10 −3 m V −2 is discovered. By leveraging the interference from electro‐birefringence, electrochromic devices capable of reversible electro‐optical switching and dynamic coloration are demonstrated. This work provides an effective strategy to prepare monolayer clays and bridges natural resources with novel 2D LCs, advancing sustainable materials in smart optics and beyond.

Strain sensor based on terahertz spectral modulation of periodic circular hole array

2025-06-12

Ruan Jiangtao , Tan Ke-yu , Wang Zhiyong | Optics & Laser Technology