Point Defect Micro-cavities Research Articles

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.

Neural network-based prediction and optimization of optical properties of two-dimensional GaAs dielectric background photonic crystal point-defect microcavities

Neural network-based prediction and optimization of optical properties of two-dimensional GaAs dielectric background photonic crystal point-defect microcavities

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.

Electrically pumped photonic crystal laser constructed with organic semiconductors

We experimentally demonstrate the lasing action of electrically pumped octagonal quasi-crystal microcavities formed in a layer of conjugated polymer poly[2-methoxy- 5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) sandwiched between two electrodes. Lasing from a point-defect microcavity is observed at a wavelength of 606 nm with a narrow linewidth of 0.5 nm, limited by the spectrometer resolution. Due to the properties of the photonic bandgap and localization in photonic crystals, the threshold current for lasing is low at 0.8 mA. The ion injection in the luminescent polymer layer by focused ion beam (FIB) etching technology also contributes to enhancement of the carrier density as well as the mobility, resulting in an increase of MEH-PPV conductivity and a decrease of turn-on voltage.

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

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

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.

Photonic crystal ring resonator channel drop filter

Photonic crystal channel drop filters (CDFs) with a ring resonator have been reported and have shown good optical properties to drop the light. Photonic crystal ring resonators (PCRRs) offer scalability in size and flexibility in mode design due to their multi-mode nature [1] compared to point-defect or line-defect photonic crystal (PhC) cavities. It is far smaller in size than other corresponding devices. In this paper, we proposed several channel drop filters combination of ring resonators and point defect micro-cavities. These ring resonators work as energy couplers. They capture the electromagnetic energy propagated in the input waveguide and send it to the output waveguide at its resonant frequencies. But ring resonators have too many resonant frequencies because of their multi-mode nature. So, point defect micro-cavities are used to further filter the original light wave. In our designed CDFs, close to 100% drop efficiency has been achieved at their center normalized frequencies, respectively.

基于二维六角晶格光子晶体的微型三重波分复用器

We design a compact triplexer based on two-dimensional (2D) hexagonal lattice photonic crystals (PCs). A folded directional coupler (FDC) is introduced in the triplexer beside the point-defect micro-cavities and line-defect waveguides. Because of the reflection feedback of the FDC, high channel drop efficiency can be realized and a compact size with the order of micrometers can be maintained. The proposed device is analyzed using the plane wave expansion method, and its transmission characteristics are calculated using the finite-difference time-domain method. The footprint of the triplexer is about 12×9 µm, and its extinction ratios are less than -20 dB for 1310 nm, approximately -20 dB for 1490 nm, and under -40 dB for 1550 nm, making it a potentially essential device in future fiber-to-the-home networks.

A novel polarization channel drop filter based on two-dimensional photonic crystals

A novel polarization channel drop filter (PCDF) based on two-dimensional (2D) photonic crystals (PCs) is presented. It consists of two line defect waveguides and two point defect micro-cavities. In the line-defect waveguides, the transverse-electric (TE) and transverse-magnetic (TM) polarization lights are guided using photonic band-gap and total internal reflection effect, respectively. The light at the resonant frequency for TE polarization can be transferred from one waveguide to the other using the proposed system. Compared with the existing four-port PCDF based on PCs, the three-port structure can realize a multi-channel wavelength system of PCDF more easily and can be an essential device in future polarization wavelength division multiplexing (PWDM) systems.

Photonic crystal channel drop filters with mirror cavities

In this paper, a new channel drop filter in two dimensional photonic crystals with mirror cavities is proposed. In the structure, three cavities are used. One is used for a resonant tunneling-based channel drop filter. The others are used to realize reflection feedback in the bus waveguide, which consists of a point defect micro-cavity side-coupled to a waveguide. The simulation results by using the finite-difference time-domain method conclude 98% output efficiency.

Photonic crystal channel drop filter with a wavelength-selective reflection micro-cavity

In the paper, a novel three-port channel drop filter in two dimensional photonic crystals (2D PCs) with a wavelength-selective reflection micro-cavity is proposed. In the structure, two micro-cavities are used. One is used for a resonant tunneling-based channel drop filter. The other is used to realize wavelength-selective reflection feedback in the bus wave-guide, which consists of a point defect micro-cavity side-coupled to a line defect waveguide based on photonic crystals. Using coupled mode theory in time, the conditions to achieve 100% drop efficiency are derived thoroughly. The simulation results by using the finite-difference time-domain (FDTD) method imply that the design is feasible.

A three-dimensional optical photonic crystal with designed point defects.

Photonic crystals offer unprecedented opportunities for miniaturization and integration of optical devices. They also exhibit a variety of new physical phenomena, including suppression or enhancement of spontaneous emission, low-threshold lasing, and quantum information processing. Various techniques for the fabrication of three-dimensional (3D) photonic crystals--such as silicon micromachining, wafer fusion bonding, holographic lithography, self-assembly, angled-etching, micromanipulation, glancing-angle deposition and auto-cloning--have been proposed and demonstrated with different levels of success. However, a critical step towards the fabrication of functional 3D devices, that is, the incorporation of microcavities or waveguides in a controllable way, has not been achieved at optical wavelengths. Here we present the fabrication of 3D photonic crystals that are particularly suited for optical device integration using a lithographic layer-by-layer approach. Point-defect microcavities are introduced during the fabrication process and optical measurements show they have resonant signatures around telecommunications wavelengths (1.3-1.5 microm). Measurements of reflectance and transmittance at near-infrared are in good agreement with numerical simulations.

Coupling of point-defect microcavities in two-dimensional photonic-crystal slabs

We investigate the coupling of two single point-defect microcavities formed in a two-dimensional photonic-crystal slab. The mode structure is probed using photoluminescence spectroscopy of self-assembled InGaAs quantum dots embedded in GaAs/AlGaAs membrane-based, photonic-crystal microcavities. As a baseline, we start from single defect cavities: We observe defect states originating from both the ground and the first-excited slab waveguide mode, depending on the photonic-crystal lattice period. This is explained using three-dimensional, plane-wave-expansion calculations. In the case of coupling between two such single defects, a splitting of the mode energies into binding and antibinding states controlled by the coupling strength is observed. These photonic-defect–molecule states are identified by a comparison of their expected far-field distributions with polarization-dependent measurements.