Defect Microcavities Research Articles

Temporal mode switching during polariton condensation

Multimode behavior plays a key role in a wide range of nonlinear optical phenomena. Multiple exciton-polariton modes can attain macroscopic population as observed in time-integrated measurements. Recent theory work has shown that, rather than being simultaneously in many modes, the population may temporally switch between the modes. However, the origin and the dynamics of multimode condensation has not been experimentally addressed. Here, we study the dynamics of exciton-polariton condensation into multiple modes of Gaussian defect microcavities filled with ladder type polymer gain material methyl-substituted ladder-type poly(p-phenylene) MeLPPP. We deploy a second-order cumulant model to simulate the dynamics of the system and find picosecond-timescale switching between condensate modes. By interferometric measurements we reveal the experimental signatures of such mode competition behaviour.

Design of a Neural Network Model for Point-Defect Microcavities in Two-Dimensional Silicon-Based Dielectric Column Photonic Crystals

Currently, circuits are becoming more and more highly integrated, but current electronic chip technology has difficulty in meeting the requirements for increased data transmission speed and capacity because of its characteristics of increased energy loss due to interactions between electronic components. In contrast, photonic technology is a promising solution due to its characteristics of high speed, wide bandwidth, and low interaction. Photonic crystals are materials with an artificial periodic dielectric structure, with photonic bandgap and localization properties that are critical to their performance. Photonic crystals, which use photons as an information transfer medium, allow flexible control of photon propagation, just as electrons are controlled in semiconductors, and the study of multifunctional photonic crystals is important for the construction of integrated optical circuits. This paper proposes a neural network-based model to analyze and predict the optical properties of point defect microcavities in 2D silicon-based dielectric column photonic crystals. By modeling the complex relationship between the structural parameters of the photonic crystal and its optical response, a theoretical approach for the design of 2D silicon dielectric column photonic crystals can be provided.

A neural network model for point defect microcavities of two-dimensional GaAs media background photonic crystals

This paper aims to address the challenge of constructing, training, and optimizing a neural network model for the point defect microcavity of a two-dimensional GaAs media background photonic crystal. The objective is to achieve more accurate predictions and analyses of photon modes, thereby enhancing the performance of the microcavity. Due to the structural complexity and multi-parameter nature of point defect microcavities, traditional analysis methods often fail to capture their optical behavior adequately. Consequently, there is a need for a novel approach to establishing an optical model for point defect microcavities, enabling precise predictions of their optical properties and optimal design. In this study, the MPB computing tool developed by MIT, in conjunction with the programming language Scheme, MATLAB, and the Ubuntu virtual machine platform, was utilized for data acquisition. The neural network model was employed to process the input data of the photonic crystal point defect microcavity, leading to predictions and analyses. This interdisciplinary approach results in a high-precision model of the microcavity. The neural network model is capable of nonlinear mapping and prediction by learning the patterns and features of the data. Additionally, this combination holds the promise of enabling more efficient optical information processing and increased data transfer rates. The relationship between the energy band data and the structure of photonic crystals exhibits a high degree of nonlinearity. The neural network model proposed in this paper can infer the structure of photonic crystals based on the photon energy band (dispersion relation ω-K) of micro-cavity structures with point defects in different photonic crystals. This provides a valuable reference for more accurate predictions and analyses of photon modes in complex photonic crystal micro-cavities, ultimately leading to improved micro-cavity performance.

Two-dimensional silicon-based dielectric column photonic crystal point defect microcavity Neural network modelling

In order to solve the problem that it is difficult to predict the microcavity photonic energy bands of point defects in two-dimensional silicon-based dielectric column photonic crystals, this paper proposes a method to predict the microcavity photonic energy bands of point defects in two-dimensional silicon-based photonic crystals by using an artificial neural network model. In this paper, the energy band structure of triangular lattice point defects at different radii is calculated using MPB, and a neural network model is established based on this data and the accuracy of the established model is verified.

Self‐Aligned Photonic Defect Microcavity Lasers with Site‐Controlled Quantum Dots

AbstractSelf‐assembled semiconductor quantum dots face challenges in terms of scalable device integration because of their random growth positions, originating from the Stranski–Krastanov growth mode. Even with existing site‐controlled growth techniques, for example, nanohole or buried stressor concepts, a further lithography and etching step with high spatial alignment requirements is necessary to accurately integrate quantum dots into the nanophotonic devices. Here, the fabrication and characterization of strain‐induced site‐controlled microcavities are reported, where site‐controlled quantum dots are positioned at the antinode of the optical mode field in a self‐aligned manner without the need of any further nano‐processing. It is shown that the cavity properties such as Q‐factor, mode volume, and mode splitting can be tailored by the geometry of the integrated buried stressor, with an opening <4 µm. The experimental results are complemented with theory calculations based on continuum elasticity. Lasing signatures, including super‐linear input‐output response and linewidth narrowing, are observed for a 3.6‐µm self‐aligned cavity with a Q‐factor of 18 000. Furthermore, the quasi‐planar site‐controlled cavities exhibit no detrimental thermal effects. This approach integrates seamlessly with the industrial‐matured manufacturing process and the buried‐stressor technique, paving the way for exceptional scalability and straightforward manufacturing of high‐β microlasers and bright quantum light sources.

One-dimensional defect micro-cavity optical Bragg reflector biosensor for the detection of CHIKV virus

One-dimensional defect micro-cavity optical Bragg reflector biosensor for the detection of CHIKV virus

Organic copolymer lasing from single defect microcavity fabricated using laser patterning

This study uses a laser patterning setup to write defect structures into a conjugated polymer microcavity. We show that the defect enhances optical confinement and reduces the lasing threshold.

Photonic coherent perfect transmission, absorption, and synthesis in a bimodal cavity quantum electrodynamics system

In this paper, we investigate an optical hybrid system in which a single quantum emitter is coupled to both modes of a bimodal optical microcavity, and propose a scheme for coherent perfect transmission, coherent perfect absorption, and coherent perfect synthesis of optical photons by utilizing such a bimodal cavity quantum electrodynamics (QED) system. In the present scheme, each mode of the bimodal microcavity can be coherently driven by an external monochromatic continuous-wave driving laser and the two cavity modes are not directly coupled to each other due to their orthogonal polarizations. It is found that three important phenomena, i.e., photonic coherent perfect transmission, absorption, and synthesis can be achieved in the optical hybrid system under appropriate conditions. We discuss in detail the theoretical model and present results of numerical simulation of the system in the steady state with experimentally achievable system parameters. Also, the possible experimental realization of the scheme in a solid-state approach is analyzed based on the semiconductor quantum dot and the photonic crystal defect microcavity. This study may provide further insight into the understanding of bimodal cavity QED system and find potential applications in quantum information processing and future quantum networks.

High figure of merit ultra-compact 3-channel parallel-connected photonic crystal mini-hexagonal-H1 defect microcavity sensor array

In this paper, a photonic crystal (PhC) butt-coupled mini-hexagonal-H1 defect (MHHD) microcavity sensor is proposed. The MHHD microcavity is designed by introducing six mini-holes into the initial H1 defect region. Further, based on a well-designed 1 ×3 PhC Beam Splitter and three optimal MHHD microcavity sensors with different lattice constants (a), a 3-channel parallel-connected PhC sensor array on monolithic silicon on insulator (SOI) is proposed. Finite-difference time-domain (FDTD) simulations method is performed to demonstrate the high performance of our structures. As statistics show, the quality factor (Q) of our optimal MHHD microcavity attains higher than 7×104, while the sensitivity (S) reaches up to 233nm/RIU(RIU = refractive index unit). Thus, the figure of merit (FOM) >104 of the sensor is obtained, which is enhanced by two orders of magnitude compared to the previous butt-coupled sensors [1–4]. As for the 3-channel parallel-connected PhC MHHD microcavity sensor array, the FOMs of three independent MHHD microcavity sensors are 8071, 8250 and 8250, respectively. In addition, the total footprint of the proposed 3-channel parallel-connected PhC sensor array is ultra-compactness of 12.5µm ×31µm (width × length). Therefore, the proposed high FOM sensor array is an ideal platform for realizing ultra-compact highly parallel refractive index (RI) sensing.

光子晶体二元缺陷微腔的光传输特性

光子晶体二元缺陷微腔的光传输特性

Zero-Dimensional Organic Exciton–Polaritons in Tunable Coupled Gaussian Defect Microcavities at Room Temperature

We demonstrate strong light-matter interaction at ambient conditions between a ladder-type conjugated polymer and the individual modes of a vertical microcavity with tunable resonance frequencies. Zero-dimensional wavelength-scale confinement for the polaritons is achieved through a sub-micron sized Gaussian defect, resulting in a vacuum Rabi splitting of the polariton branches of 2g = 166 meV. By placing a second Gaussian defect nearby, we create a polaritonic molecule with tunnel coupling strength of up to 2J ~ 50 meV. This platform enables the creation of tailor-made potential landscapes with wavelength-scale dimensions and tunable coupling strengths beyond the thermal energy, opening a route towards room-temperature polariton-based quantum simulators.

Zero-Dimensional Organic Exciton?Polaritons in Tunable Coupled Gaussian Defect Microcavities at Room Temperature

Zero-Dimensional Organic Exciton?Polaritons in Tunable Coupled Gaussian Defect Microcavities at Room Temperature

Wavelength routers with low crosstalk using photonic crystal point defect micro-cavities

Abstract A broadband photonic crystal (PhC) waveguide crossing is proposed with low crosstalk. On the basis of the structure, two 1 × 2 PhC λ-routers are constructed by exploiting several PhC point-defect micro-cavities. By means of the interference coupling between the point-defect modes in micro-cavities, the incidence light with the resonant wavelength can be routed to the designed output port in the router. To achieve the high routing efficiency with narrow pass-band width, the micro-cavity structure is elaborately engineered to satisfy the condition of the quality factor ratio, which consists of these rods with the gradual radii. Their performances are demonstrated by the numerical results calculated by the finite difference time domain (FDTD) and the plane wave expansion (PWE) methods. Furthermore, the analysis of the 4 × 4 λ -router configuration, obtained by assembling these basic wavelength routing elements, is reported to highlight its performances with a theoretical maximum crosstalk between the ports equal to −27.23 dB.

Design of dual‐mode dual‐band photonic crystal bandpass filters for terahertz communication applications

ABSTRACTIn this study, Photonic Crystal (PhC) dual‐mode dual‐band bandpass filter is designed and its transmission characteristics are investigated for various configurations. PhC resonator structure is formed by a point defect microcavity that is equipped with one large and three smaller auxiliary perturbation rods. Degenerate modes at each band may also be excited by changing the structure properties of the perturbation. Plane wave expansion method and Finite Difference Time‐Domain method are used to analyze the device characteristics. Proposed dual‐band dual‐mode PhC filter structure can effectively be used for terahertz communication applications. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1806–1810, 2015

Theoretical study of light localization in photonic bandgaps of organic octagonal quasiperiodic photonic crystal slabs

Based on the polystyrene material of low refractive index, light localization in photonic bandgaps of two kinds of 2D octagonal quasiperiodic photonic crystal slabs are investigated in theory, including the air-rod polystyrene slab and polystyrene-rod slab. The properties of bandgaps and localized modes in both two defect-free patterns are analyzed in detail. When a single-point defect is introduced into two quasiperiodic structures, the position of emerging defect modes and the red-shifting of resonant modes in wavelength are observed quite differently when the defect microcavity is increased in size. This difference is caused by the competition of two physical mechanisms, which are the effect of defect energy levels caused by defects introduced into photonic crystals and the resonance of modes in the defect cavity. These results will provide theoretical support for experimental fabrication of organic light-emitting quasiperiodic photonic crystal devices.

A novel photonic crystal band-pass filter using degenerate modes of a point-defect microcavity for terahertz communication systems

Compact devices are important for the realization of terahertz communications systems. This article proposes a novel photonic crystal-based device for realizing microminiature, high-selectivity high Q band-pass filters (BPF) and the design of a dual-mode square lattice photonic crystal BPF that utilizes the degenerated modes of a point defect microcavity is presented. To design a high Q microcavity, the photonic band-gap is initially calculated using the plane wave expansion method. Second, the eigenfrequencies and modal fields of a point defect microcavity that generates localized states in the band-gap are calculated by a supercell method. Finally, the characteristics of mode splitting and the proposed dual-mode BPFs are numerically studied by a full-wave time-domain method. © 2014 The Authors. Microwave and Optical Technology Letters Published by Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:792–797, 2014

Graphene-based tunable plasmonic Bragg reflector with a broad bandwidth

We propose and numerically analyze a plasmonic Bragg reflector formed in a graphene waveguide. The results show that the graphene plasmonic Bragg reflector can produce a broadband stopband that can be tuned over a wide wavelength range by a small change in the Fermi energy level of graphene. By introducing a defect into the Bragg reflector, we can achieve a Fabry-Perot-like microcavity with a quality factor of 50 for the defect resonance mode formed in the stopband. The proposed Bragg reflector could be used as a broadband ultrafast tunable integrated filter and a broadband modulator. In addition, the defect microcavity may find applications in graphene-based resonators.

A New Two-Sided Coupling Channel Drop Filter Based on a Two-Dimensional Photonic Crystal

We design a new two-sided coupling channel drop filter (CDF) based on a two-dimensional (2D) photonic crystal (PC). Three channels formed by line defects for light propagation, two L4 resonators positioned at both sides of the input waveguide for light coupling, and one point defect micro-cavity in the bus waveguide for wavelength-selective reflection are introduced into the PC structure. The optical characteristics of this proposed structure are calculated by finite-difference time-domain (FDTD) method combined with the perfectly matched layers (PMLs) as the boundary conditions. Three wavelengths centered at 1550, 1575 and 1610 nm within the limit of communication windows are successfully separated in three channels by adjusting the size of coupling rods and the positions of L4 resonators and micro-cavity. High transmission efficiency and more than 20 nm channel spacing are achieved. These demonstrate that our proposed structure is suitable for photonic integrated circuits (PICs) and coarse wavelength division multiplexing (WDM) optical communication systems.

High-Sensitive Double-Hole Defect Refractive Index Sensor Based on 2-D Photonic Crystal

In this paper, we simulate a refractive index sensor based on the 2-D photonic crystal using finite difference time domain methods. The sensor which is called double-hole defect sensor, consists of two waveguides and two-point defect microcavities when the lattice constant is a = 440 nm. In the optimum structure, the sensitivity of the sensor is s = 500 nm/RIU (refractive index unit), whereas the refractive index resolution is very small and Δn = 0.0001 (i.e., resonance wavelength shifts up by 0.05 nm).

Characterization of Integrated Planar Photonic Crystal Circuits Fabricated by a CMOS Foundry

Integrated planar photonic crystal circuits in silicon on insulator were fabricated with a single-etch-step process by a foundry using complementary metal-oxide-semiconductor processing techniques. The devices studied integrate three key elements: i) input/output grating couplers consisting of 2D uniform arrays of holes, ii) single transverse electric (TE)/single transverse magnetic (TM) mode channel waveguides, and iii) a photonic crystal linear three hole defect (L3) microcavity. Experimentally measured s- and p-polarized transmission, both from grating-to-grating through a uniform silicon slab region, and through the channel waveguide/L3 cavity circuit, were quantitatively compared with finite-difference time-domain simulations. Excellent agreement is achieved assuming circular, vertical side-wall holes, but this requires accurate post-fabrication characterization of actual versus nominal device parameters, including especially the silicon device layer thickness. While s-polarized incident radiation excites TE modes that exhibit typical resonant cavity (filter-like) transmission, p-polarized incident radiation excites TM modes that non-resonantly propagate through the circuit with comparable transmission efficiency. The dependence of the grating coupler tuning range on hole diameter, and the addition of a photoresist covering is determined.