All-optical digital 4 × 2 encoder based on 2D photonic crystal ring resonators

The photonic crystals draw significant attention to build all-optical logic devices and are considered one of the solutions for the opto-electronic bottleneck via speed and size. The paper presents a novel optical 4 × 2 encoder based on 2D square lattice photonic crystals of silicon rods. The main realization of optical encoder is based on the photonic crystal ring resonator NOR gates. The proposed structure has four logic input ports, two output ports, and two bias input port. The photonic crystal structure has a square lattice of silicon rods with a refractive index of 3.39 in air. The structure has lattice constant ‘a’ equal to 630 nm and bandgap range from 0.32 to 044. The total size of the proposed 4 × 2 encoder is equal to 35 μm × 35 μm. The simulation results using the dimensional finite difference time domain and Plane Wave Expansion methods confirm the operation and the feasibility of the proposed optical encoder for ultrafast optical digital circuits.     

Biomaterial‐Based “Structured Opals” with Programmable Combination of Diffractive Optical Elements and Photonic Bandgap Effects

Naturally occurring iridescent systems produce brilliant color displays through multiscale, hierarchical assembly of structures that combine reflective, diffractive, diffusive, or absorbing domains. The fabrication of biopolymer‐based, hierarchical 3D photonic crystals through the use of a topographical templating strategy that allows combined optical effects derived from the interplay of predesigned 2D and 3D geometries is reported here. This biomaterials‐based approach generates 2D diffractive optics composed of 3D nanophotonic lattices that allow simultaneous control over the reflection (through the 3D photonic bandgap) and the transmission (through 2D diffractive structuring) of light with the additional utility of being constituted by a biocompatible, implantable, edible commodity textile material. The use of biopolymers allows additional degrees of freedom in photonic bandgap design through directed protein conformation modulation. Demonstrator structures are presented to illustrate the lattice multifunctionality, including tunable diffractive properties, increased angle of view of photonic crystals, color‐mixing, and sensing applications.     

All optical active high decoder using integrated 2D square lattice photonic crystals

The paper introduces a novel all optical active high 2 × 4 decoder based on 2D photonic crystals (PhC) of silicon rods with permittivity of ε = 10.1 × 10^?11 farad/m. The main structure of optical decoder is designed using a combination of five nonlinear photonic crystal ring resonator, set of T-type waveguide, and line defect of Y and T branch splitters. The proposed structure has two logic input ports, four output ports, and one bias input port. The total size of the proposed 2 × 4 decoder is equal to 40 μm × 38 μm. The PhC structure has a square lattice of silicon rod with refractive index of 3.39 in air. The overall design and the results are discussed through the realization and the numerically simulation to confirm its operation and feasibility.     

3D photonic crystals with a hierarchical pore structure

Perfect 3D film photonic crystals are synthesized from submicron spherical silica particles consisting of a nonporous core and a mesoporous shell. The obtained photonic crystals with a hierarchical pore arrangement—transport macropores between particles and mesopores inside the shell—are promising for application in optical gas sensors.     

Fabrication and characterisation of CdSe photonic structures from self-assembled templates

We demonstrate here a method to fabricate CdSe photonic crystal from a very cheap fabrication route of templated self-assembly. The hexagonal close-packed photonic crystals are formed by the electrochemical growth of CdSe through the interstitial spaces between polymer nano/micro sphere templates. The confocal voids containing photonic crystals can be made either interconnected or well separated, with high uniformity. Structural and optical characterisation confirms the good quality of electrochemically grown CdSe. These cheaply fabricated 2D photonic crystals provide a wide range of opportunities for optoelectronic devices.     

Polymer‐Based Photonic Crystals

In this report, we highlight the development of polymers as 1D photonic crystals and subsequently place special emphasis on the activities in self‐assembled block copolymers as a promising platform material for new photonic crystals. We review recent progress, including the use of plasticizer and homopolymer blends of diblock copolymers to increase periodicity and the role of self‐assembly in producing 2D and 3D photonic crystals. The employment of inorganic nanoparticles to increase the dielectric contrast and the application of a biasing field during self‐assembly to control the long‐range domain order and orientation are examined, as well as in‐situ tunable materials via a mechanochromic materials system. Finally, the inherent optical anisotropy of extruded polymer films and side‐chain liquid‐crystalline polymers is shown to provide greater degrees of freedom for further novel optical designs.     

Getting effective permittivity and permeability equal to −1 in 1D dielectric photonic crystals

J.B. Pendry (Phys. Rev. Lett., 86 3966 (2000)) mentioned the possibility of making perfect lenses using a slab of left-handed material with relative permeability, permittivity and optical index equal to ?1. This kind of metamaterial has been made in the microwaves domain, using metal and dielectric materials. On the other hand, it has been shown that lenses made using 2D dielectric photonic crystals can generate similar imaging properties, but until now, the image contains only a small part of the incident light. The paper shows, using a very simple analytical model, that 1D dielectric photonic crystals can generate left-handed materials with relative permeability, permittivity and optical index rigorously equal to ?1. Of course, such photonic crystals cannot be used to make perfect lenses, but this conclusion leads to the conjecture that 2D or 3D dielectric photonic crystals could be used in the visible region to realize superlenses.     

General conditions of polarization-independent transmissions in one-dimensional magnetic photonic crystals

Abstract

Based on the transfer matrix theory, general conditions of polarization-independent transmissions in one-dimensional photonic crystals are derived. It is shown that the polarization-independent transmissions are obtained in photonic crystals consisting of two alternating layers with the same refraction index and optical thickness as well as the mutually reciprocal wave impedance. By using two different photonic crystals satisfying the above relation to constitute the light quantum-well structures, the structures have polarization-independent transmission properties. When a defective layer with wave impedance of 1 is introduced in the photonic crystals, the defective photonic crystals also have the polarization-independent transmission properties. In addition, polarization-independent low-pass spatial filters are achieved based on these photonic crystal structures.     

Hybrid colloidal plasmonic-photonic crystals

We review the recently emerged class of hybrid metal-dielectric colloidal photonic crystals. The hybrid approach is understood as the combination of a dielectric photonic crystal with a continuous metal film. It allows to achieve a strong modification of the optical properties of photonic crystals by involving the light scattering at electronic excitations in the metal component into moulding of the light flow in series to the diffraction resonances occurring in the body of the photonic crystal. We consider different realizations of hybrid plasmonic-photonic crystals based on two- and three-dimensional colloidal photonic crystals in association with flat and corrugated metal films. In agreement with model calculations, different resonance phenomena determine the optical response of hybrid crystals leading to a broadly tuneable functionality of these crystals.     

硅槽内自组装二氧化硅光子晶体

采用溶剂蒸发法在硅片上微槽内对不同粒径的SiO2微球进行组装,尝试利用刻有微槽的硅片与平坦衬底间形成的毛细管池限制胶体晶体的生长厚度,获得了具有显著光子带隙特征的光子晶体线形阵列,并在此基础上比较了不同实验条件如微球直径、毛细管池物理限制作用等对微球排列方式及规整度的影响.     

基于金属有机框架的光子晶体制备与应用研究进展

近年来,基于光子晶体优异的光学性能和金属有机框架(MOFs)特殊的多孔结构,使基于MOFs的光子晶体研究备受研究者们的关注。本文综述了近年来MOFs材料及其在光子晶体中的应用研究进展。首先简单介绍了MOFs和光子晶体的基本概况及MOFs与光子晶体相结合的优势,然后阐述了基于MOFs的光子晶体的制备方法,进一步概括了其应用现状,并总结了当前基于MOFs的光子晶体研究所存在的困境,最后展望了其未来的发展方向。这些工作为MOFs材料在光子晶体中的实际应用提供了策略支撑。      

Microassembly of semiconductor three-dimensional photonic crystals

Electronic devices and their highly integrated components formed from semiconductor crystals contain complex three-dimensional (3D) arrangements of elements and wiring. Photonic crystals, being analogous to semiconductor crystals, are expected to require a 3D structure to form successful optoelectronic devices. Here, we report a novel fabrication technology for a semiconductor 3D photonic crystal by uniting integrated circuit processing technology with micromanipulation. Four- to twenty-layered (five periods) crystals, including one with a controlled defect, for infrared wavelengths of 3-4.5 microm, were integrated at predetermined positions on a chip (structural error <50 nm). Numerical calculations revealed that a transmission peak observed at the upper frequency edge of the bandgap originated from the excitation of a resonant guided mode in the defective layers. Despite their importance, detailed discussions on the defective modes of 3D photonic crystals for such short wavelengths have not been reported before. This technology offers great potential for the production of optical wavelength photonic crystal devices.     

Silicon Inverse Opal—A Platform for Photonic Bandgap Research

This article focuses attention on recent research on the silicon inverse opal, the first self‐assembled or bottom–up synthetic photonic crystal to exhibit a complete photonic bandgap (PBG) at 1.5 μm^[1] in accordance with theoretical predictions.^[2] The silicon inverse opal has since proven to be a useful platform for assembling on‐chip films^[3] and in‐chip patterns,^[4] engineering extrinsic defects,^[5] mapping photon density of states,^[6] switching light with light, and inhibiting spontaneous emission.^[7] Also, new and exciting colloidal‐crystal‐based structures are being developed based on experimental and theoretical knowledge acquired for the synthesis of inverted silicon photonic crystals.^[8–10] It has also inspired the idea of the silicon inverse opal heterostructure, a theoretical construct that could enable an all‐optical microchip for single mode diffractionless waveguiding of light in air throughout a bandwidth of more than 70 nm at 1.5 μm.^[11]     

机械力致变色光子晶体材料研究进展

目的 总结光子晶体材料在机械力致变色方面的研究现状,基于机械力致变色光子晶体的特点进行展望,为进一步研究和应用提供参考.方法 基于机械力的施加方式,从拉伸变色和压缩变色两个方面系统介绍了机械力致变色光子晶体的制备方法、光学性能以及机械性能,并分析比较了这两种光子晶体材料的应用现状和前景.结论 机械力致变色光子晶体在结构上有多种形式,包括嵌入胶体阵列的弹性体光子晶体、胶体交联光子晶体、层状光子晶体、链状光子晶体等,近些年这些光子晶体已经可以达到明亮的结构色和应变能力.机械力致变色光子晶体因其形式的多样性和良好的光学、机械性能,使其在应力检测、人体运动状态监测、防伪、显示等方面得以应用,具有很大的实际应用潜力.     

Wavelength-selective filter based on a hollow optical waveguide

In this paper, we describe a theoretical and experimental study of a wavelength-selective filter derived from hollow optical waveguides composed of Bragg reflectors with defect layers on a silicon substrate. The defect states of the transmission filter at wavelengths of 1519 and 1571 nm were realized using one-dimensional photonic crystals (1D PCs) formed from a-Si and SiO(2). The transmission spectra of the filter waveguides and the band structure of the defect 1D PCs were calculated using the two-dimensional finite-difference time-domain and transfer matrix methods, respectively. The device exhibited the narrow bandwidths of 0.5 and 1.1 nm for wavelengths of 1571 and 1519 nm, respectively.     

Large-area 2D periodic crystalline silicon nanodome arrays on nanoimprinted glass exhibiting photonic band structure effects

Two-dimensional silicon nanodome arrays are prepared on large areas up to 50 cm2 exhibiting photonic band structure effects in the near-infrared and visible wavelength region by downscaling a recently developed fabrication method based on nanoimprint-patterned glass, high-rate electron-beam evaporation of silicon, self-organized solid phase crystallization and wet-chemical etching. The silicon nanodomes, arranged in square lattice geometry with 300 nm lattice constant, are optically characterized by angular resolved reflection measurements, allowing the partial determination of the photonic band structure. This experimentally determined band structure agrees well with the outcome of three-dimensional optical finite-element simulations. A 16% photonic bandgap is predicted for an optimized geometry of the silicon nanodome arrays. By variation of the duration of the selective etching step, the geometry as well as the optical properties of the periodic silicon nanodome arrays can be controlled systematically.     

三维光子晶体的制备技术研究进展

光子晶体是周期性介电结构．它能象周期性原子结构中的电子禁带一样．产生光子禁带。自从1987年Yablonovitch提出光子晶体的概念以来，有关光子晶体的各种研究非常活跃。本文回顾了三维光子晶体的制备技术研究现状，旨在激发不同学科领域研究人员的想象力和创造力．使他们从一些可能的光子晶体制造途径中有所裨益．并将这种可能性转变为现实。     

Creation of line defects in holographic photonic crystals by a double-exposure thresholding method

Recording of periodic variations of amplitude and phase by the interference of coherent laser beams in a hologram offers a natural means for creating one-, two-, and three-dimensional photonic crystals. For device applications such as waveguides in optical communications, one usually needs to create defects in photonic crystals. We present an analysis and an experimental demonstration of a double-exposure method for creating photonic crystals with line defects. The idea is based on the principle of superposition of holographic grating patterns of different spatial periods while the recording medium is held stationary and on the application of a threshold to the recording medium. We use the same symmetrical optical architecture to achieve nondefective and defective holographic photonic crystals. The technique may be extended to the creation of defects based on functional synthesis by means of Fourier series, by use of light sources of other wavelengths with an appropriate high-contrast recording material.     

Planar waveguide photonic crystals as an alternative for refractive index optical sensors design: theoretical evaluation

In this paper, the possibilities of designing refraction index optical sensors in planar waveguide photonic crystals are demonstrated for the first time. Photonic crystals obtained by connecting in cascade planar optical waveguides with high index contrast are analyzed. Photonic band gaps (PBGs) and photonic windows (PWs) were obtained. If a local defect is introduced in the PBG structure, the optical path length is modified and on states can be created in the gap. Besides, the on states wavelengths can be tuned if the optical path of the defect is modified: changing the physical length and/or the refraction index of the defect. In this way, planar waveguide photonic crystals could be used for sensing applications when a specimen modifies the refraction index lattice site. Sensing properties of planar waveguide photonic crystals, with one, two and three sensing channels, are demonstrated.     

Multidirectional lateral gradient films with position-dependent photonic signatures made from porous silicon

We describe here the fabrication of laterally graded porous silicon films which display gradients of photonic reflectance peaks spanning the optical spectrum. We demonstrate that up to three of these gradients can be overlayed to produce multidirectional photonic gradients with position-dependent spectral bar-codes. Each gradient is generated by asymmetric anodisation of silicon using temporal variations (sinusoidal or square-wave) in current density affording rugate and Bragg reflectors, respectively. The fabricated optical structures and the quality of the photonic resonances are characterised by optical reflectivity measurements and scanning electron microscopy. We finally remove the pSi gradient layers from the silicon substrate by applying an electropolishing current and embed the free-standing pSi membranes in polydimethylsiloxane to form flexible and foldable photonic films.