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Topological Photonic Integrated Circuits Based on Valley Kink States
摘要： Valley pseudospin, a new degree of freedom in photonic lattices, provides an intriguing way to manipulate photons and enhance the robustness of optical networks. Here, topological waveguiding, refracting, resonating, and routing of valley-polarized photons in integrated circuits are experimentally demonstrated. Specifically, it is shown that at the domain wall between photonic crystals of different topological valley phases, there exists a topologically protected valley kink state that is backscattering-free at sharp bends and terminals. These valley kink states are further harnessed for constructing high-Q topological photonic crystal cavities with tortuously shaped cavity geometries. A novel optical routing scheme at an intersection of multiple valley kink states is also demonstrated, where light splits counterintuitively due to the valley pseudospin of photons. These results can not only lead to robust optical communication and signal processing, but also open the door for fundamental research of topological photonics in areas such as lasing, quantum photon-pair generation, and optomechanics.
关键词： silicon photonics,nanophotonic devices,photonic crystals,topological photonics,photonic integration
更新于2025-09-12 10:27:22
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Characterization of Waveguide Photonic Crystal Reflectors on Indium Phosphide Membranes
摘要： We present waveguide photonic crystal re?ectors on the InP-membrane-on-silicon (IMOS) platform, and a method to accurately measure the re?ectivity of those re?ectors. The photonic crystal holes are patterned on a waveguide using electron-beam lithography and etched through the waveguiding layer to create a broadband distributed Bragg re?ector. We show simulations of these re?ectors and experimental results of fabricated devices, both showing a high, free-to-choose re?ectivity, and high quality factor Fabry-P′erot cavities. We experimentally show re?ectivities higher than 95% for the re?ectors and a quality factor as high as 15,911±511 for a Fabry-P′erot cavity, using re?ectors with a length of only 4 microns. For the ?rst time, to our knowledge, two methods for measuring the re?ectivity are used for characterization of on-chip re?ectors to accurately determine the re?ection. The ?rst method is based on analysis of the transmission through a Fabry-P′erot cavity, the second is based on a direct four-port measurement of the re?ector. A systematic error is made in both methods, resulting in an upper and lower boundary for the actual re?ection coef?cient.
关键词： photonic crystals,nanophotonics,Photonic integrated circuits
更新于2025-09-12 10:27:22
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Plasmon-polariton fractal spectra in quasiperiodic photonic crystals with graphene
摘要： In this work we study the plasmon-polariton spectra in one-dimensional photonic crystals based on the Fibonacci, Thue-Morse and double-period sequences, where we have graphene at the interface of one of the constituent building blocks (A = SiO2/graphene, B = SiO2). The dispersion relations for each quasicrystal are numerically calculated by using a transfer-matrix approach. The spectra of these structures are shown to be fractals (for the bulk bands distribution), obeying a power law in a particular frequency region and these are induced specifically by the quasiperiodic ordering in the unit cells of each system studied. We also report a strong dependence of the width of the bulk bands on the wave vector for this particular frequency region, whereas for large wave vectors the fractal properties in these spectra are absent.
关键词： transfer-matrix approach,plasmon-polariton,quasiperiodic photonic crystals,fractal spectra,graphene
更新于2025-09-12 10:27:22
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Design of a hydrogen sulfide gas sensor based on a photonic crystal cavity using graphene
摘要： We report the design and simulation of a high sensitivity H2S gas sensor using a combination of graphene properties as a hydrogen sulfide-sensitive nanomaterial and features of photonic crystal cavity. The shoulder-coupled resonant cavity is introduced in the photonic crystal that consists of a triangular array of air holes on the silicon-on-insulator substrate. To adsorb H2S gas, a graphene layer is deposited on the inner wall of the two cavity air holes. Changes in the concentration of hydrogen sulfide gas alter the refractive index of graphene, thereby resulting in wavelength shift in the sensor transmittance spectrum. We achieved a sensitivity of 1.2 ×104 nm /RIU and a detection limit of 1.87×10-6 RIU. To the best of our knowledge, the sensitivity of our sensor is much higher than other sensors previously reported in the literature.
关键词： Q factor,Cavity resonators,Sensitivity,Gas detectors,Photonic crystals,Sensors
更新于2025-09-12 10:27:22
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High-Efficiency Thermophotovoltaic System That Employs an Emitter Based on a Silicon Rod-Type Photonic Crystal
摘要： Thermophotovoltaic systems in principle enable utilization of heat that is usually regarded as wasted energy. However, the wavelength selectivity of the thermal emitter required for high e?ciencies is di?cult to control with conventional designs. Here, we design a thermophotovoltaic system, comprising silicon rods as thermal emitter with a relatively narrow emission spectrum and photovoltaic cells with a band gap corresponding to 1.76 μm, and verify e?cient power generation. By accurately measuring the heat ?ux that enters the emitter, the emitter temperature, and the electrical output power of the photovoltaic cells, we ?nd that the actual system e?ciency (ratio of output power to ingoing heat ?ux) is 11.2% at an emitter temperature of 1338 K and the output power density footprint is 0.368 W/cm2. The obtained e?ciency is relatively high, i.e., 1.65 times that of the previously reported record value (6.8%). Further e?ciency improvements may lead to development of distributed energy supplies using combustion heat.
关键词： thermal emitter,photonics for energy materials,photonic crystals,thermophotovoltaics
更新于2025-09-12 10:27:22
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Effect of photonic crystals on the light extraction of GaN-based LED for different polarization modes of spontaneous radiation
摘要： The light extraction efficiency (LEE) of different polarization modes have been simulated by FDTD solutions for three photonic crystal (PhC) structures, which are spherical-PhC LED, cylindrical-PhC LED and compound-PhC LED. The TE-and TM-mode LEE are simulated seperately. It shows that the discontinuity of the structure from the propagation direction will cause decrease of TE-mode and TM-mode LEE. TE and TM mode are enhanced by 60% and 40% in cylindrical-PhC LED, in which the single nanorod act as light waveguide. Finally, a multi-layer-compound-PhC-LED is proposed. Results show that the TM-mode LEE based on this structure is increased by 1.45 times at a wavelength of 532 nm, and the TM-mode illuminous intensity will be larger than that of TE mode, and then polarization inversion occurs.
关键词： GaN-based LED,Polarization,Photonic crystals,Light extraction efficiency
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Collective Laser Emission in Coupled Hybrid InP-on-SOI Nanocavities
摘要： Coupled optical micro/nanocavities have raised large attention over the last decades as their use has triggered breakthroughs in photonics such as the exploitation of electromagnetically induced transparency (EIT) effect for delaying or storing light [1]. More recently, research was initiated on the coupling between micro/nano cavities including an active medium, in order to develop optical memories [2] or to study more fundamental physical effects such as spontaneous mirror-symmetry breaking [3]. This work is focused on coupled nanolasers made of photonic crystals onto a silicon optical platform. The development of ultra-compact and power efficient laser sources on this type of platform is crucial to enable the deployment of on chip optical interconnects. We already demonstrated an electrically powered single nanolaser integrated on SOI (Silicon-On-Insulator) [4]. To go beyond, we present here the study of the collective laser emission arising from the coupling of two identical photonic crystal nanobeam cavities made of InP materials through a SOI wire. The coupled system is fabricated by bonding a III-V semiconductor heterostructure onto a SOI optical waveguide circuitry. The InP-based slab is then patterned using electron beam lithography followed by inductively coupled plasma etching [Fig. 1]. We show that this hybrid platform is very versatile to change at will, both the coupling strength and phase. Indeed, the coupling strength can easily be tuned by changing the SOI wire width. Regarding the coupling phase, it is controlled by varying the relative distance of the 2 cavities made atop the SOI waveguides [Fig. 2]. We demonstrate that collective laser emission is obtained at 1.55μm at room temperature by CW optically pumping at 1180nm. It is obtained when the coupling phase is near a multiple of π. Compared to stand alone structures, this coupled configuration results in a drastic reduction of the laser threshold and an improvement of the slope efficiency [Fig. 3], due to the control of the coupling phase to reduce the losses in the coupled system. This is an unprecedented manner to achieve simultaneously low threshold and high coupling efficiency to the SOI waveguide circuitry. In the same time, this configuration allows to investigate interesting fundamental physical effects, such as superradiance, lasing effect without inversion of population [5], but also to study the existence of exceptional points [6] and dark modes [7] in this kind of coupled system.
关键词： silicon optical platform,coupled optical micro/nanocavities,collective laser emission,photonic crystals,SOI waveguide circuitry
更新于2025-09-12 10:27:22
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Reflection Spectra of Composite Photonic Crystals Based on Anodic Alumina Filled with Ferroelectric Sodium Nitrite
摘要： Re?ection spectra of a composite one-dimensional photonic crystal (PC) based on porous anodic alumina ?lled with ferroelectric sodium nitrite have been recorded in the wavelength range of 400 to 1200 nm. Signi?cant spectral shifts of the ?rst and second stopbands are revealed for the composite PC. The stopband spectral half-width is found to decrease by a factor of four to ?ve. The possibility of applying composite alumina-based photonic crystals as selective narrowband mirrors is discussed.
关键词： reflection spectra,ferroelectric sodium nitrite,photonic crystals,anodic alumina,stopbands
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Anisotropic Fluorescence Emission at the Surface of 1D-Photonic Crystal Biochips
摘要： Novel disposable optical biochips based on one-dimensional photonic crystals (1DPC) sustaining Bloch surface waves (BSW) are a desirable tool for the detection of several disease-related biomarkers. In particular, cancer biomarkers have gained considerable attention, due to the increasing demand for cancer treatment. Within this framework, the herein proposed optical biochips can quantify low concentration (sub ng/mL) of the ERBB2 breast cancer biomarker in biological complex matrices. To discriminate ERBB2 levels in several different cell lysate samples, we made use of a biosensing platform based on 1DPC biochips and on a reading instrument that can work in both a label-free and a fluorescence detection mode. Such combined configuration provides the advantage of complementary information and lower limit of detection (LoD) in the fluorescence mode [1]. In the label-free configuration the BSW excitation is achieved by a prism coupling system (Kretschmann-Raether configuration), like in the surface plasmon resonance (SPR) technique, resulting in a dip in the angular reflectance spectrum, shifting its position due to the refractive index changes [2]. The fluorescence mode is carried out by making use of dye labeled antibodies bound at the 1DPC surface. Coupling between the dye labels and a BSW results in strongly directional fluorescence emission. The advantages brought by the 1DPC, when compared to metal structures, are smaller energy dissipation and narrower resonances [3]. Presently, there is no study about photobleaching in experiments with BSW sustained by 1DPC, while it is evident that such phenomenon cannot be neglected in biosensing assays carried out close to the LoD, where quantitative and accurate information is needed. Here we report for the first time on cancer detection assays carried out with our platform, in which the trustworthiness of the output is put in doubt by photobleaching, which not only affects the overall emission intensity but also its polarization distribution via the TE and TM BSW modes provided by the 1DPC. The experimental data is interpreted by means of a theoretical model for the orientational distribution of dye labels over time, taking into account the density of the optical states of the 1DPC, photobleaching and rotational diffusion of surface bound emitters. The approach permits to model anisotropic fluorescence emission and to manage photobleaching effects in biosensing assays, leading to their correct interpretation.
关键词： one-dimensional photonic crystals,optical biochips,Bloch surface waves,cancer biomarkers,fluorescence emission,photobleaching
更新于2025-09-12 10:27:22
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Quantitative Analysis of Photon Density of States for One-Dimensional Photonic Crystals in a Rectangular Waveguide
摘要： Light propagation in one-dimensional (1D) photonic crystals (PCs) enclosed in a rectangular waveguide is investigated in order to achieve a complete photonic band gap (PBG) while avoiding the difficulty in fabricating 3D PCs. This work complements our two previous articles (Phys. Rev. E) that quantitatively analyzed omnidirectional light propagation in 1D and 2D PCs, respectively, both showing that a complete PBG cannot exist if an evanescent wave propagation is involved. Here, we present a quantitative analysis of the transmission functions, the band structures, and the photon density of states (PDOS) for both the transverse electric (TE) and transverse magnetic (TM) polarization modes of the periodic multilayer heterostructure confined in a rectangular waveguide. The PDOS of the quasi-1D photonic crystal for both the TE and TM modes are obtained, respectively. It is demonstrated that a “complete PBG” can be obtained for some frequency ranges and categorized into three types: (1) below the cutoff frequency of the fundamental TE mode, (2) within the PBG of the fundamental TE mode but below the cutoff frequency of the next higher order mode, and (3) within an overlap of the PBGs of either TE modes, TM modes, or both. These results are of general importance and relevance to the dipole radiation or spontaneous emission by an atom in quasi-1D periodic structures and may have applications in future photonic quantum technologies.
关键词： TE,PDOS,photonic crystals,waveguide,photonic band gap,TM,complete PBG
更新于2025-09-11 14:15:04