- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Fabrication and optical characterization of photonic crystal nanocavities with electrodes for gate-defined quantum dots
摘要： Among various solid-state systems, gate-defined quantum dots (QD) with high scalability and controllability for single electron spin qubits are promising candidates to realize quantum spin-photon interface. The efficiency of the spin-photon interface is expected to be significantly enhanced by optical coupling of gate-defined QDs with photonic crystal (PhC) nanocavities. As the first step towards this optical coupling, we designed and experimentally demonstrated a PhC nanocavity with electrodes. The electrodes, which can form a single QD, were introduced on the top surfaces of two-dimensional PhC nanocavities with a position accuracy of a few tens of nanometers. Despite the electrodes, a resonant mode was confirmed for the PhC nanocavities through micro-photoluminescence spectroscopy. This work marks a crucial step towards optical coupling between gate-defined QDs and PhC nanocavities.
关键词： optical coupling,quantum spin-photon interface,quantum dots,photonic crystal nanocavities
更新于2025-09-16 10:30:52
-
TE band structure in a photonic waveguide with triangular holes
摘要： This study determines the TE band structures in a two-dimensional photonic crystal waveguide with triangular dispersers in a hexagonal lattice in a GaAs background. Using the plane-wave expansion method and the supercell technique, a defective mode propagating in the direction of the linear defect was numerically identi?ed within the photonic band gap. In addition, this study reports that this defective mode may be tuned to higher frequencies by increasing the applied hydrostatic pressure. However, when the triangular dispersers are rotated, no noticeable change is observed in the defective mode within the photonic band gap.
关键词： Photonic crystal,TE band structures,Hexagonal lattice,Waveguide
更新于2025-09-16 10:30:52
-
Optical properties of fluidic defect states in one-dimensional graphene-based photonic crystal biosensors: visible and infrared Hall regime sensing
摘要： Advances in biotechnology are outpacing studies into the use of graphene in photonic biosensors due to its peculiar optical properties and the successful progress in the nanoscale integration of photonic crystals. Moreover, going beyond the usual Dirac cone approximation for graphene introduces nonlinear effects in graphene’s optics. In this work, by the use of the transfer matrix method, we investigate the effect of hopping parameter on the chemical and biosensing performance of a 1D defective photonic biosensor with a micro/nano?uidic channel as a central defect cavity for biological ?uids and gas molecules to ?ow while interacting with two graphene sheet deposited on silicon dioxide layers of the device. As low-weight molecules absorption on graphene’s surface could affect hopping energy of graphene which plays a signi?cant role in its optical conductivity obtained from the tight-binding model for the visible range, it will serve as a promising tool for the detection of gas and other analytes. We also examine the sensitivity of the defect modes to the changes of the refractive index of the biological ?uids under the in?uence of quantum Hall situation for graphene in terahertz (THz) regime. It is revealed that two defective modes with relatively different sensing properties are emerged within the band stop of the device. The results of this study are not reported elsewhere to the best of our knowledge.
关键词： photonic crystal,hopping parameter,terahertz,biosensor,optical conductivity,visible light,graphene,quantum Hall effect
更新于2025-09-16 10:30:52
-
Advance in photonic crystal solar cells
摘要： Photonic crystals have been widely used in solar cells in recent years because of their unique optical properties such as photonic band gap and “slow photon” effect. The introduction of photonic crystals can adjust the propagation and distribution of photons in solar cells. Therefore, a full understanding of the optical properties of photonic crystals and the correct use of photonic crystals are the key to improve the photoelectric conversion efficiency. At present, photonic crystal structures are widely used in dye sensitized solar cell (DSSC) and quantum dots sensitized solar cell (QDSSC), but relatively few in the field of perovskite solar cell (PSC). In this paper, the applications of different types of photonic crystals in silicon solar cells and sensitized solar cells are summarized, and the possible problems are analyzed and commented. It is pointed out that although photonic crystals have many excellent optical control properties, it is difficult to meet the thickness requirements of PSC due to the limitations of preparation technology and structure of photonic crystals. At present, the photoelectric conversion efficiency of photonic crystal PSC is generally low. Therefore, develop new technology for preparing the large area and high quality ultra-thin photonic crystals, make a profound study of photonic crystal light control mechanism, design new structures, and explore new functions of photonic crystals will become the future development direction of photonic crystal solar cells.
关键词： Silicon,Photonic crystal,Solar cells
更新于2025-09-16 10:30:52
-
Maximizing the quality factor to mode volume ratio for ultra-small photonic crystal cavities
摘要： Small manufacturing-tolerant photonic crystal cavities are systematically designed using topology optimization to enhance the ratio between the quality factor and mode volume, Q/V. For relaxed manufacturing tolerance, a cavity with a bow-tie shape is obtained which confines light beyond the diffraction limit into a deep-subwavelength volume. Imposition of a small manufacturing tolerance still results in efficient designs, however, with diffraction-limited confinement. Inspired by numerical results, an elliptic ring grating cavity concept is extracted via geometric fitting. Numerical evaluations demonstrate that for small sizes, topology-optimized cavities enhance the Q/V-ratio by up to two orders of magnitude relative to standard L1 cavities and more than one order of magnitude relative to shape-optimized L1 cavities. An increase in cavity size can enhance the Q/V-ratio by an increase in the Q-factor without a significant increase in V. Comparison between optimized and reference cavities illustrates that significant reduction of V requires big topological changes in the cavity.
关键词： topology optimization,mode volume,light-matter interaction,photonic crystal cavities,quality factor
更新于2025-09-16 10:30:52
-
All-Optical Ultra-Fast Graphene-Photonic Crystal Switch
摘要： In this paper, an all-optical photonic crystal-based switch containing a graphene resonant ring has been presented. The structure has been composed of 15 × 15 silicon rods for a fundamental lattice. Then, a resonant ring including 9 thick silicon rods and 24 graphene-SiO2 rods was placed between two waveguides. The thick rods with a radius of 0.41a in the form of a 3 × 3 lattice were placed at the center of the ring. Graphene-SiO2 rods with a radius of 0.2a were assumed around the thick rods. These rods were made of the graphene monolayers which were separated by SiO2 disks. The size of the structure was about 70 μm2 that was more compact than other works. Furthermore, the rise and fall times were obtained by 0.3 ps and 0.4 ps, respectively, which were less than other reports. Besides, the amount of the contrast ratio (the di?erence between the margin values for logics 1 and 0) for the proposed structure was calculated by about 82%. The correct switching operation, compactness, and ultra-fast response, as well as the high contrast ratio, make the presented switch for optical integrated circuits.
关键词： optical switch,photonic crystal,graphene,photonic band gap,kerr e?ect
更新于2025-09-12 10:27:22
-
III–V nanowire array telecom lasers on (001) silicon-on-insulator photonic platforms
摘要： III–V nanowires have recently gained attention as a promising approach to enable monolithic integration of ultracompact lasers on silicon. However, III–V nanowires typically grow only along h111i directions, and thus, it is challenging to integrate nanowire lasers on standard silicon photonic platforms that utilize (001) silicon-on-insulator (SOI) substrates. Here, we propose III–V nanowire lasers on (001) silicon photonic platforms, which are enabled by forming one-dimensional nanowire arrays on (111) sidewalls. The one-dimensional photonic crystal laser cavity has a high Q factor >70 000 with a small footprint of (cid:2)7.2 (cid:3) 1.0 lm2, and the lasing wavelengths can be tuned to cover the entire telecom bands by adjusting the nanowire geometry. These nanowire lasers can be coupled to SOI waveguides with a coupling ef?ciency > 40% while maintaining a suf?ciently high Q factor (cid:2)18 000, which will be bene?cial for low-threshold and energy-ef?cient operations. Therefore, the proposed nanowire lasers could be a stepping stone for ultracompact lasers compatible with standard silicon photonic platforms.
关键词： monolithic integration,III–V nanowires,telecom lasers,photonic crystal laser cavity,silicon photonic platforms
更新于2025-09-12 10:27:22
-
Modulated photonic-crystal surface-emitting laser with elliptical lattice points for two-dimensional coupling enhancement
摘要： Modulated photonic-crystal surface-emitting lasers (M-PCSELs) are new semiconductor lasers that can emit a laser beam in arbitrary directions. Therefore, they can be regarded as a next-generation light source for light detection and ranging. In this manuscript, we numerically investigate the characteristics of M-PCSELs, including one- and two-dimensional optical coupling constants and radiation constants, by using three-dimensional coupled wave theory. We also carry out lattice point designs and show that the two-dimensional optical coupling can be enhanced by more than four times over our previous M-PCSEL devices by employing elliptical lattice points. Moreover, we find that two-dimensional optical coupling can be maintained even when large lattice point position modulations are introduced for large radiation constants. These results indicate that more stable two-dimensional oscillation and a higher slope efficiency are expected in M-PCSELs with elliptical lattice points.
关键词： elliptical lattice points,M-PCSELs,radiation constants,Modulated photonic-crystal surface-emitting lasers,two-dimensional optical coupling
更新于2025-09-12 10:27:22
-
Low cross-talk waveguide intersections for TE polarization using photonic crystals
摘要： In this paper, two low cross-talk and wide bandwidth waveguide intersections are proposed based on novel types of resonators which are created using rotated photonic crystal lattices. A lattice of the air holes in a GaAs substrate is used to realize the waveguides. By inserting a second lattice of holes which resembles the main lattice, with a particular amount of scaling and rotation, we have created a resonator which can diminish the cross-talk in waveguide intersections. Two new topologies have been proposed based on the mentioned resonators, one with two sets of waveguides (four arms) and the other one with three sets of the waveguides (six arms). Plane wave expansion (PWE) and finite difference time domain (FDTD) methods are used for numerical simulation of the intersections. Simulation results indicate that a bandwidth of 49.1 nm and a cross-talk level of -40 dB can be obtained for the intersection of two waveguides using the configuration proposed in this paper.
关键词： Cross-talk,Optical waveguide,Photonic crystal,Integrated optics,Waveguide intersection
更新于2025-09-12 10:27:22
-
Embedded waveguide band: New localized states from parity-time symmetric photonic crystal waveguide
摘要： Using conventional photonic crystal waveguides combined with the Parity-Time (PT) symmetry configuration, we study the evolution of the waveguide mode bands, and the mechanism of the band merging and the exceptional point forming. A special waveguide mode band occurs in the band evolution with a part of the band embedded in the bulky bands. The embedded band takes on a new localized state with its mode field is mainly localized in the waveguide. The frequency on the bottom of the embedded band excites a huge localized field. The exceptional point on the special band excites an asymmetric mode field in the waveguide and an amplified transmission.
关键词： Localized state,Exceptional point,Parity-time symmetry,Photonic crystal waveguides
更新于2025-09-12 10:27:22