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Showing papers on "Photonic crystal published in 2017"


Journal ArticleDOI
TL;DR: A simple scheme to realize ultracompact rejection ratio tunable notch microwave photonic filter (MPF) based on a silicon photonic crystal (PhC) nanocavity with fixed extinction ratio is proposed and experimentally demonstrated.
Abstract: Driven by the increasing demand on handing microwave signals with compact device, low power consumption, high efficiency and high reliability, it is highly desired to generate, distribute, and process microwave signals using photonic integrated circuits. Silicon photonics offers a promising platform facilitating ultracompact microwave photonic signal processing assisted by silicon nanophotonic devices. In this paper, we propose, theoretically analyze and experimentally demonstrate a simple scheme to realize ultracompact rejection ratio tunable notch microwave photonic filter (MPF) based on a silicon photonic crystal (PhC) nanocavity with fixed extinction ratio. Using a conventional modulation scheme with only a single phase modulator (PM), the rejection ratio of the presented MPF can be tuned from about 10 dB to beyond 60 dB. Moreover, the central frequency tunable operation in the high rejection ratio region is also demonstrated in the experiment.

845 citations


Journal ArticleDOI
TL;DR: This work proposes a concept of valley photonic crystals with electromagnetic duality symmetry but broken inversion symmetry, and shows the independent control of valley and topology in a single system that has been long pursued in electronic systems, resulting in topologically-protected flat edge states.
Abstract: A theoretically proposed photonic crystal design with valley-dependent spin-split bulk bands allows for the independent control of valley and topology in a single system. Photonic crystals offer unprecedented opportunity for light manipulation and applications in optical communication and sensing1,2,3,4. Exploration of topology in photonic crystals and metamaterials with non-zero gauge field has inspired a number of intriguing optical phenomena such as one-way transport and Weyl points5,6,7,8,9,10. Recently, a new degree of freedom, valley, has been demonstrated in two-dimensional materials11,12,13,14,15. Here, we propose a concept of valley photonic crystals with electromagnetic duality symmetry but broken inversion symmetry. We observe photonic valley Hall effect originating from valley-dependent spin-split bulk bands, even in topologically trivial photonic crystals. Valley–spin locking behaviour results in selective net spin flow inside bulk valley photonic crystals. We also show the independent control of valley and topology in a single system that has been long pursued in electronic systems, resulting in topologically-protected flat edge states. Valley photonic crystals not only offer a route towards the observation of non-trivial states, but also open the way for device applications in integrated photonics and information processing using spin-dependent transportation.

485 citations


Journal ArticleDOI
TL;DR: It is revealed that isolated subwavelength dielectric resonators support states with giant Q-factors similar to bound states in the continuum formed via destructive interference between strongly coupled eigenmodes and characterized by singularities of the Fano parameters.
Abstract: Recent progress in nanoscale optical physics is associated with the development of a new branch of nanophotonics exploring strong Mie resonances in dielectric nanoparticles with a high refractive index. The high-index resonant dielectric nanostructures form building blocks for novel photonic metadevices with low losses and advanced functionalities. However, unlike extensively studied cavities in photonic crystals, such dielectric resonators demonstrate low quality factors (Q factors). Here, we uncover a novel mechanism for achieving giant Q factors of subwavelength nanoscale resonators by realizing the regime of bound states in the continuum. In contrast to the previously suggested multilayer structures with zero permittivity, we reveal strong mode coupling and Fano resonances in homogeneous high-index dielectric finite-length nanorods resulting in high-Q factors at the nanoscale. Thus, high-index dielectric resonators represent the simplest example of nanophotonic supercavities, expanding substantially the range of applications of all-dielectric resonant nanophotonics and meta-optics.

460 citations


Journal ArticleDOI
TL;DR: A designer surface plasmon crystal comprising metallic patterns deposited on a dielectric substrate is demonstrated, which can become a valley-Hall photonic topological insulator by exploiting the mirror-symmetry-breaking mechanism, enabling the direct observation of topological states.
Abstract: The extensive research of two-dimensional layered materials has revealed that valleys, as energy extrema in momentum space, could offer a new degree of freedom for carrying information. Based on this concept, researchers have predicted valley-Hall topological insulators that could support valley-polarized edge states at non-trivial domain walls. Recently, several kinds of photonic and sonic crystals have been proposed as classical counterparts of valley-Hall topological insulators. However, direct experimental observation of valley-polarized edge states in photonic crystals has remained difficult until now. Here, we demonstrate a designer surface plasmon crystal comprising metallic patterns deposited on a dielectric substrate, which can become a valley-Hall photonic topological insulator by exploiting the mirror-symmetry-breaking mechanism. Topological edge states with valley-dependent transport are directly visualized in the microwave regime. The observed edge states are confirmed to be fully valley-polarized through spatial Fourier transforms. Topological protection of the edge states at sharp corners is also experimentally demonstrated.

273 citations


Journal ArticleDOI
TL;DR: In this article, a 3D photonic topological metacrystal based on an all-dielectric metamaterial platform shows robust propagation of surface states along 2D domain walls, making it a promising solution for photonics applications.
Abstract: The theoretical study of a 3D photonic topological metacrystal based on an all-dielectric metamaterial platform shows robust propagation of surface states along 2D domain walls, making it a promising solution for photonics applications. The proposed metacrystal design might also open the way for the observation of elusive fundamental physical phenomena.

265 citations


Journal ArticleDOI
TL;DR: In this article, three-dimensional laser-written waveguide arrays are used to demonstrate type-II Weyl points, along with Fermi arc-like surface states, for light at optical wavelengths.
Abstract: Three-dimensional laser-written waveguide arrays are used to demonstrate type-II Weyl points, along with Fermi arc-like surface states, for light at optical wavelengths.

253 citations


Journal ArticleDOI
TL;DR: This review focuses on single nanoparticle detection using optical whispering gallery microcavities and photonic crystal microc Cavities, both of which have been developing rapidly over the past few years.
Abstract: Detection of nanoscale objects is highly desirable in various fields such as early-stage disease diagnosis, environmental monitoring and homeland security. Optical microcavity sensors are renowned for ultrahigh sensitivities due to strongly enhanced light-matter interaction. This review focuses on single nanoparticle detection using optical whispering gallery microcavities and photonic crystal microcavities, both of which have been developing rapidly over the past few years. The reactive and dissipative sensing methods, characterized by light-analyte interactions, are explained explicitly. The sensitivity and the detection limit are essentially determined by the cavity properties, and are limited by the various noise sources in the measurements. On the one hand, recent advances include significant sensitivity enhancement using techniques to construct novel microcavity structures with reduced mode volumes, to localize the mode field, or to introduce optical gain. On the other hand, researchers attempt to lower the detection limit by improving the spectral resolution, which can be implemented by suppressing the experimental noises. We also review the methods of achieving a better temporal resolution by employing mode locking techniques or cavity ring up spectroscopy. In conclusion, outlooks on the possible ways to implement microcavity-based sensing devices and potential applications are provided.

250 citations


Journal ArticleDOI
TL;DR: In this article, the deep subwavelength resonant elements of metamaterials are patterned onto specific lattices and created crystalline metammaterials that can develop complex nonlocal properties due to multiple scattering, despite their very sub-wavelength spatial scale.
Abstract: The exciting discovery of topological condensed matter systems has lately triggered a search for their photonic analogues, motivated by the possibility of robust backscattering-immune light transport However, topological photonic phases have so far only been observed in photonic crystals and waveguide arrays, which are inherently physically wavelength scaled, hindering their application in compact subwavelength systems In this letter, we tackle this problem by patterning the deep subwavelength resonant elements of metamaterials onto specific lattices, and create crystalline metamaterials that can develop complex nonlocal properties due to multiple scattering, despite their very subwavelength spatial scale that usually implies to disregard their structure These spatially dispersive systems can support subwavelength topological phases, as we demonstrate at microwaves by direct field mapping Our approach gives a straightforward tabletop platform for the study of photonic topological phases, and allows to envision applications benefiting the compactness of metamaterials and the amazing potential of topological insulators

217 citations


Journal ArticleDOI
TL;DR: It is shown that the extreme light concentration in the design can enable ultrastrong Kerr nonlinearities, even at the single-photon level, which open new directions in cavity quantum electrodynamics, spectroscopy, and quantum nonlinear optics.
Abstract: We propose a photonic crystal nanocavity design with self-similar electromagnetic boundary conditions, achieving ultrasmall mode volume (V_{eff}). The electric energy density of a cavity mode can be maximized in the air or dielectric region, depending on the choice of boundary conditions. We illustrate the design concept with a silicon-air one-dimensional photon crystal cavity that reaches an ultrasmall mode volume of V_{eff}∼7.01×10^{-5}λ^{3} at λ∼1550 nm. We show that the extreme light concentration in our design can enable ultrastrong Kerr nonlinearities, even at the single-photon level. These features open new directions in cavity quantum electrodynamics, spectroscopy, and quantum nonlinear optics.

198 citations


Journal ArticleDOI
TL;DR: In this article, an ultra-compact indium phosphide-on-silicon laser diode with low current threshold, high wall-plug efficiency and high integrability is demonstrated.
Abstract: By exploiting one-dimensional photonic crystal nanocavities, an ultra-compact indium phosphide-on-silicon laser diode with low current threshold, high wall-plug efficiency and high integrability is demonstrated. The most-awaited convergence of microelectronics and photonics promises to bring about a revolution for on-chip data communications and processing1. Among all the optoelectronic devices to be developed, power-efficient nanolaser diodes able to be integrated densely with silicon photonics and electronics are essential to convert electrical data into the optical domain. Here, we report a demonstration of ultracompact laser diodes based on one-dimensional (1D) photonic crystal (PhC) nanocavities2,3,4 made in InP nanoribs heterogeneously integrated on a silicon-waveguide circuitry. The specific nanorib design enables an efficient electrical injection of carriers in the nanocavity without spoiling its optical properties. Room-temperature continuous-wave (CW) single-mode operation is obtained with a low current threshold of 100 µA. Laser emission at 1.56 µm in the silicon waveguides is obtained with wall-plug efficiencies greater than 10%. This result opens up exciting avenues for constructing optical networks at the submillimetre scale for on-chip interconnects and signal processing.

179 citations


Journal ArticleDOI
TL;DR: Repeated thermal oxidation and an oxide removal process applied after the removal of the buried oxide layer underneath the nanocavities realized an experimental Q factor greater than eleven million, which is the highest experimental Q ever recorded.
Abstract: Photonic crystal nanocavities that simultaneously possess small modal volumes and high quality (Q) factors have opened up novel research areas in photonics during this decade. Here, we present an important key for the increase of Q factors to ranges beyond ten million. A systematic investigation on photon lifetimes of air-bridge-type heterostructure nanocavities fabricated from silicon on insulator (SOI) substrates indicated the importance of cleaning the bottom side (buried oxide side) of the nanaocavites. Repeated thermal oxidation and an oxide removal process applied after the removal of the buried oxide layer underneath the nanocavities realized an experimental Q factor greater than eleven million, which is the highest experimental Q ever recorded. The results provide important information not only for Si PC nanocavities but also for general Si nanophotonic devices and photonic electronic convergence systems.

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate an ultrasmall laser with a mirror, which is based on Fano interference between a continuum of waveguide modes and the discrete resonance of a nanocavity.
Abstract: Fano interference and nonlinearity are exploited to achieve self-pulsing of a laser at gigahertz frequencies. The semiconductor lasers in use today rely on various types of cavity, making use of Fresnel reflection at a cleaved facet1, total internal reflection between two different media2, Bragg reflection from a periodic stack of layers3,4,5,6,7,8, mode coupling in a high contrast grating9,10 or random scattering in a disordered medium11. Here, we demonstrate an ultrasmall laser with a mirror, which is based on Fano interference between a continuum of waveguide modes and the discrete resonance of a nanocavity. The rich physics of Fano resonances12 has recently been explored in a number of different photonic and plasmonic systems13,14. The Fano resonance leads to unique laser characteristics. In particular, because the Fano mirror is very narrowband compared to conventional laser mirrors, the laser is single mode and can be modulated via the mirror. We show, experimentally and theoretically, that nonlinearities in the mirror may even promote the generation of a self-sustained train of pulses at gigahertz frequencies, an effect that has previously been observed only in macroscopic lasers15,16,17,18. Such a source is of interest for a number of applications within integrated photonics.

Journal ArticleDOI
TL;DR: The development of brush block copolymers as photonic crystals that can reflect visible to near-infrared wavelengths of light is highlighted.
Abstract: Brush block copolymers are a class of comb polymers that feature polymeric side chains densely grafted to a linear backbone These polymers display interesting properties due to their dense functionality, low entanglement, and ability to rapidly self-assemble to highly ordered nanostructures The ability to prepare brush polymers with precise structures has been enabled by advancements in controlled polymerization techniques This Feature Article highlights the development of brush block copolymers as photonic crystals that can reflect visible to near-infrared wavelengths of light Fabrication of these materials relies on polymer self-assembly processes to achieve nanoscale ordering, which allows for the rapid preparation of photonic crystals from common organic chemical feedstocks The characteristic physical properties of brush block copolymers are discussed, along with methods for their preparation Strategies to induce self-assembly at ambient temperatures and the use of blending techniques to tune photonic properties are emphasized

Journal ArticleDOI
TL;DR: 2D photonic crystals are shown to afford lasing with ultralow lasing thresholds at room temperature and the impact of surface defects is substantially mitigated upon imprint.
Abstract: Photonic nanostructures are created in organo-metal halide perovskites by thermal nanoimprint lithography at a temperature of 100 °C. The imprinted layers are significantly smoothened compared to the initially rough, polycrystalline layers and the impact of surface defects is substantially mitigated upon imprint. As a case study, 2D photonic crystals are shown to afford lasing with ultralow lasing thresholds at room temperature.

Journal ArticleDOI
TL;DR: In this paper, an electric-field-assisted multicolor printing is reported based on electrically responsive and photocurable colloidal photonic crystal, which is prepared by supersaturation-induced self-assembly of SiO2 particles in the mixture of propylene carbonate (PC) and trimethylolpropane ethoxylate triacrylate (ETPTA).
Abstract: Efficient and large scale printing of photonic crystal patterns with multicolor, multigrayscale, and fine resolution is highly desired due to its application in smart prints, sensors, and photonic devices. Here, an electric-field-assisted multicolor printing is reported based on electrically responsive and photocurable colloidal photonic crystal, which is prepared by supersaturation-induced self-assembly of SiO2 particles in the mixture of propylene carbonate (PC) and trimethylolpropane ethoxylate triacrylate (ETPTA). This colloidal crystal suspension, named as E-ink, has tunable structural color, controllable grayscale, and instantly fixable characteristics at the same time because the SiO2/ETPTA-PC photonic crystal has metastable and reversible assembly as well as polymerizable features. Lithographical printing with photomask and maskless pixel printing techniques are developed respectively to efficiently prepare multicolor and high-resolution photonic patterns using a single-component E-ink.

Journal ArticleDOI
TL;DR: This simple and yet powerful technique unlocks new possibilities in designing the visual appearance of such iridescent films, paving the way for the development of truly sustainable photonic pigments in coatings, cosmetics, and security labeling.
Abstract: The self-assembly of cellulose nanocrystals is a powerful method for the fabrication of biosourced photonic films with a chiral optical response. While various techniques have been exploited to tune the optical properties of such systems, the presence of external fields has yet to be reported to significantly modify their optical properties. In this work, by using small commercial magnets (≈ 0.5–1.2 T) the orientation of the cholesteric domains is enabled to tune in suspension as they assemble into films. A detailed analysis of these films shows an unprecedented control of their angular response. This simple and yet powerful technique unlocks new possibilities in designing the visual appearance of such iridescent films, ranging from metallic to pixelated or matt textures, paving the way for the development of truly sustainable photonic pigments in coatings, cosmetics, and security labeling.

Journal ArticleDOI
27 Feb 2017-ACS Nano
TL;DR: The incorporation of structural color into 3D printed parts is reported, presenting an alternative to the need for pigments or dyes for colored parts produced through additive manufacturing.
Abstract: The incorporation of structural color into 3D printed parts is reported, presenting an alternative to the need for pigments or dyes for colored parts produced through additive manufacturing. Thermoplastic build materials composed of dendritic block copolymers were designed, synthesized, and used to additively manufacture plastic parts exhibiting structural color. The reflection properties of the photonic crystals arise from the periodic nanostructure formed through block copolymer self-assembly during polymer processing. The wavelength of reflected light could be tuned across the visible spectrum by synthetically controlling the block copolymer molecular weight and manufacture parts that reflected violet, green, or orange light with the capacity to serve as selective optical filters and light guides.

Journal ArticleDOI
TL;DR: In this article, the photonic valley-hall effect with valley-chirality locked beam splitting, and topological valley-polarized edge states, are demonstrated for the first time on a photonic platform.
Abstract: The valley Hall effect and topological valley edge states are two fundamental properties in gapped valleytronic materials, such as MoS${}_{2}$ and biased bilayer graphene. Such properties have paved the way for applications in valleytronics. Here, the authors experimentally demonstrate a valley surface-wave photonic crystal on a single metal surface, as the photonic analog of the valley-Hall topological insulator phase. The photonic valley-Hall effect with valley-chirality locked beam splitting, and topological valley-polarized edge states, are demonstrated for the first time on a photonic platform.

Journal ArticleDOI
Hanxiao Liang1, Rui Luo1, Yang He1, Haowei Jiang1, Qiang Lin1 
20 Oct 2017
TL;DR: In this paper, LiN niobate (LN) photonic crystal nanobeam resonators with optical Q as high as 105, more than two orders of magnitude higher than other LN photonic nanocavities reported to date, were demonstrated.
Abstract: Lithium niobate (LN) exhibits unique material characteristics that have found many important applications. Scaling LN devices down to a nanoscopic scale can dramatically enhance light–matter interaction that would enable nonlinear and quantum photonic functionalities beyond the reach of conventional means. However, developing LN-based nanophotonic devices turns out to be nontrivial. Although significant efforts have been devoted to this in recent years, the LN photonic crystal structures developed to date exhibit fairly low quality (Q). Here we demonstrate LN photonic crystal nanobeam resonators with optical Q as high as 105, more than two orders of magnitude higher than other LN photonic crystal nanocavities reported to date. The high optical Q, together with tight mode confinement, leads to an extremely strong nonlinear photorefractive effect, with a resonance tuning rate of ∼0.64 GHz/aJ, or equivalently ∼84 MHz/photon, three orders of magnitude greater than other LN resonators. In particular, we observed an intriguing quenching of photorefraction that has never been reported before. The devices also exhibit strong optomechanical coupling with a gigahertz nanomechanical mode with a significant f·Q product of 1.47×1012 Hz. The demonstration of high-Q LN photonic crystal nanoresonators paves a crucial step toward LN nanophotonics that could integrate the outstanding material properties with versatile nanoscale device engineering for diverse and intriguing functionalities.

Journal ArticleDOI
TL;DR: In this paper, the optical response of atoms and other quantum emitters coupled to one-dimensional photonic structures, such as cavities, waveguides, and photonic crystals, is studied based on a formalism that describes atomlight interactions in terms of the classical electromagnetic Green's function.
Abstract: Based on a formalism that describes atom-light interactions in terms of the classical electromagnetic Green's function, we study the optical response of atoms and other quantum emitters coupled to one-dimensional photonic structures, such as cavities, waveguides, and photonic crystals. We demonstrate a clear mapping between the transmission spectra and the local Green's function, identifying signatures of dispersive and dissipative interactions between atoms. We also demonstrate the applicability of our analysis to problems involving three-level atoms, such as electromagnetically induced transparency. Finally we examine recent experiments, and anticipate future observations of atom-atom interactions in photonic band gaps.

Journal ArticleDOI
TL;DR: In this article, a nonlinear 3-channel demultiplexer is used to quantize the input analog signal according to its optical intensity and the coder will convert the quantized levels into 2-bit binary codes.
Abstract: A novel design for realizing all optical analog to digital converter will be proposed in this paper. The proposed structure consists of two main parts; a nonlinear 3-channel demultiplexer, followed by an optical coder. The nonlinear demultiplexer will be used to quantize the input analog signal according to its optical intensity and the coder will convert the quantized levels into 2-bit binary codes. The nonlinear demultiplexer will be realized using three nonlinear resonant cavities. At appropriate values of input signal optical intensity one of the cavities can drop the optical beam to its corresponding output port. The proposed structure is capable of supporting maximum sampling rate up to 52 GS/s and total footprint of the structure is about 924 µm2.

Journal ArticleDOI
Xi Wang1, Xing Jiang1, Qi You1, Jun Guo1, Xiaoyu Dai1, Yuanjiang Xiang1 
TL;DR: In this article, a composite structure where graphene is coated on one-dimensional photonic crystal (1DPC) separated by a dielectric was proposed to achieve perfect absorption at terahertz frequencies.
Abstract: In this paper, we have shown that perfect absorption at terahertz frequencies can be achieved by using a composite structure where graphene is coated on one-dimensional photonic crystal (1DPC) separated by a dielectric. Due to the excitation of optical Tamm states (OTSs) at the interface between the graphene and 1DPC, a strong absorption phenomenon occurs induced by the coupling of the incident light and OTSs. Although the perfect absorption produced by a metal–distributed Bragg reflector structure has been researched extensively, it is generally at a fixed frequency and not tunable. Here, we show that the perfect absorption at terahertz frequency not only can be tuned to different frequencies but also exhibits a high absorption over a wide angle range. In addition, the absorption of the proposed structure is insensitive to the polarization, and multichannel absorption can be realized by controlling the thickness of the top layer.

Journal ArticleDOI
TL;DR: In this article, the authors introduce the concepts of periodicity, quasi-periodicity, and disorder in photonic crystals, focussing on the one-dimensional case, and report different types of disorder in 1D photonic structures and discuss their properties in terms of light transmission.

Journal ArticleDOI
TL;DR: Simulated results illustrate that the perfect absorption with critical coupling is achieved by choosing suitably the ration of the hole radius to the period of the photonic crystal slab, and that the tunability of absorption peaks is obtained by a small change in the period and the thickness of the slab.
Abstract: Transition-metal dichalcogenides with exceptional electrical and optical properties have emerged as a new platform for atomic-scale optoelectronic devices. However, the poor optical absorption resists their potential applications. The novel method of critical coupling with guided resonances is proposed to realize total absorption of light in monolayer MoS2 both theoretically and numerically. Simulated results illustrate that the perfect absorption with critical coupling is achieved by choosing suitably the ration of the hole radius to the period of the photonic crystal slab, and that the tunability of absorption peaks is obtained by a small change in the period and the thickness of the slab. Intriguingly, such device manifests the unusual polarization-insensitive feature and the good absorption stability over a wide angle range of incidence. The total absorption in monolayer MoSe2, WS2, and WSe2 is realized handily by the same principle. Hence, our results may open up new possibilities for improving the light-matter interaction in monolayer transition-metal dichalcogenides and find utility in wavelength-selective photoluminescence and photodetection.

Journal ArticleDOI
Cheng Guo, Meng Xiao1, Momchil Minkov1, Yu Shi1, Shanhui Fan1 
TL;DR: In this paper, the authors introduce an implementation of a Laplace differentiator based on a photonic crystal slab that operates at transmission mode. And they show that the LDA can be implemented provided that the guided resonances near the $\Gamma$ point exhibit an isotropic band structure.
Abstract: We introduce an implementation of a Laplace differentiator based on a photonic crystal slab that operates at transmission mode. We show that the Laplace differentiator can be implemented provided that the guided resonances near the $\Gamma$ point exhibit an isotropic band structure. Such a device may facilitate nanophotonics-based optical analog computing for image processing.

Journal ArticleDOI
TL;DR: Guanine crystals are widely used in nature to manipulate light as discussed by the authors and are used in a wide range of biological functions such as in camouflage, display, and vision, and exhibit a degree of versatility, tunability, and complexity that is difficult to incorporate into artificial devices using conventional engineering approaches.
Abstract: Guanine crystals are widely used in nature to manipulate light. The first part of this feature article explores how organisms are able to construct an extraordinary array of optical “devices” including diffuse scatterers, broadband and narrowband reflectors, tunable photonic crystals, and image-forming mirrors by varying the size, morphology, and arrangement of guanine crystals. The second part presents an overview of some of the properties of crystalline guanine to explain why this material is ideally suited for such optical applications. The high reflectivity of many natural optical systems ultimately derives from the fact that guanine crystals have an extremely high refractive index—a product of its anisotropic crystal structure comprised of densely stacked H-bonded layers. In order to optimize their reflectivity, many organisms exert exquisite control over the crystal morphology, forming plate-like single crystals in which the high refractive index face is preferentially expressed. Guanine-based optics are used in a wide range of biological functions such as in camouflage, display, and vision, and exhibit a degree of versatility, tunability, and complexity that is difficult to incorporate into artificial devices using conventional engineering approaches. These biological systems could inspire the next generation of advanced optical materials.

Journal ArticleDOI
TL;DR: The main advantages of the proposed designation can be highlighted as its small sizing as well as simplicity, and the other improvement can be regarded as providing proper distinct space in output between “0” and “1” as logical states.
Abstract: The present study was designed and simulated for an all optical half-adder, based on 2D photonic crystals. The proposed structure in this work contains a hexagonal lattice. The main advantages of the proposed designation can be highlighted as its small sizing as well as simplicity. Furthermore, the other improvement of this half-adder can be regarded as providing proper distinct space in output between "0" and "1" as logical states. This improvement reduces the error in the identification of logical states (i.e., 0 and 1) at output. Because of the high photonic band gap for transverse electric (TE) polarization, the TE mode calculations are done to analyze the defected lines of light. The logical values of "0" and "1" were defined according to the amount of electrical field.

Journal ArticleDOI
11 Aug 2017-Sensors
TL;DR: It is theoretically demonstrated that single-layer and coupled bi-layer photonic crystal slabs (PCS) possess simultaneously high S and high Q near the bound states in the continuum (BIC) in refractive index sensing in the 1400–1600 nm telecom optical wavelength bands.
Abstract: High sensitivity (S) and high quality factor (Q) are desirable to achieve low detection limit in label-free optical sensors. In this paper, we theoretically demonstrate that single-layer and coupled bi-layer photonic crystal slabs (PCS) possess simultaneously high S and high Q near the bound states in the continuum (BIC). We theoretically achieved S > 800 nm/RIU and Q > 107 in refractive index sensing in the 1400–1600 nm telecom optical wavelength bands. We experimentally demonstrated an S of 94 nm/RIU and a Q of 1.2 × 104, with a detection limit of 6 × 10−5 refractive index unit. These sensor designs can find applications in biochemical sensing, environmental monitoring, and healthcare.

Journal ArticleDOI
TL;DR: It is demonstrated that anisotropic all-dielectric metamaterials open a new degree of freedom in total internal reflection to shorten the decay length of evanescent waves, and can reduce cross-talk and bending loss, which limit the integration density in photonic circuits.
Abstract: Ultra-compact, densely integrated optical components manufactured on a CMOS-foundry platform are highly desirable for optical information processing and electronic-photonic co-integration. However, the large spatial extent of evanescent waves arising from nanoscale confinement, ubiquitous in silicon photonic devices, causes significant cross-talk and scattering loss. Here, we demonstrate that anisotropic all-dielectric metamaterials open a new degree of freedom in total internal reflection to shorten the decay length of evanescent waves. We experimentally show the reduction of cross-talk by greater than 30 times and the bending loss by greater than 3 times in densely integrated, ultra-compact photonic circuit blocks. Our prototype all-dielectric metamaterial-waveguide achieves a low propagation loss of approximately 3.7 dB/cm, comparable to those of silicon strip waveguides. Our approach marks a departure from interference-based confinement as in photonic crystals or slot waveguides, which utilize nanoscale field enhancement. Its ability to suppress evanescent waves without substantially increasing the propagation loss shall pave the way for all-dielectric metamaterial-based dense integration.

Journal ArticleDOI
TL;DR: In this article, a polymer-stabilized blue phase (PSBP) I film with the self-organized 3D nanostructure is fabricated, and an electrically tunable photonic bandgap (PBG) is achieved.
Abstract: Electrically responsive photonic crystals represent one of the most promising intelligent materials for technological applications in optoelectronics. In this research, a polymer-stabilized blue phase (PSBP) I film with the self-organized 3D nanostructure is fabricated, and an electrically tunable photonic bandgap (PBG) is achieved. Interestingly, the large-scale shift of the PBG covering the entire visible spectrum is found to be asymmetric and can be modulated by the polarity and magnitude of bias voltage. Moreover, to demonstrate the usability in optical devices, blue phase lasers are developed by doping the PSBP material with fluorescent dyes. And mirrorless lasing emission with electrically tunable wavelength is observed. This self-assembled soft material is prospective to produce large-scale electrically responsive photonic crystals in facile fabrication process and has enormous potential applications in intelligent optoelectronic devices, such as 3D tunable lasers, reflective full-color displays, or photonic integrated circuits.