Optical properties of mesoporous one-dimensional photonic crystals

The systematic features in the reflectance spectra of broadband optical radiation from the surface of one-dimensional photonic crystals based on mesoporous structures are presented. The dispersion dependence for electromagnetic waves in the mesoporous one-dimensional photonic crystal is established. On its basis, reflectance and transmittance spectra are calculated for particular structures, and the microscopic parameters of the samples under study are determined. The developed theory is used to explain the shape of reflectance spectra in mesoporous photonic crystals based on silicon, quartz, and aluminum oxide.     

Tunable double-channel filter based on two-dimensional ferroelectric photonic crystals

A tunable double-channel filter is presented, which is based on a two-dimensional nonlinear ferroelectric photonic crystal made of cerium doped barium titanate. The filtering properties of the photonic crystal filter can be tuned by adjusting the defect structure or by a pump light. The influences of the structure disorders caused by the perturbations in the radius or the position of air holes on the filtering properties are also analyzed.     

一维磁化等离子体光子晶体非互易特性研究

在理想条件下,为了研究等离子体回旋频率、等离子体频率、等离子体层厚度、周期常数和入射角在TM模式下对一维磁化等离子体光子晶体的非互易特性的影响,用利用传输矩阵法计算得到的TM波正向和反向传播的透射率来研究其非互易特性。研究结果表明,增加等离子体回旋频率和入射角度能够改善非互易特性;而一味地增加等离子体频率和等离子体层厚度将会使得非互易传播特性变得恶化;增加周期常数不能明显地改善非互易传播特性,但是通过改变外加磁场的施加方式能够改善其非互易特性。     

Transmission properties of Fibonacci quasi-periodic one-dimensional superconducting photonic crystals

The transmission properties of Fibonacci quasi-periodic one-dimensional photonic crystals (1DPCs) containing superconducting material are theoretically investigated based on the transfer matrix method. It is shown that the 1DPCs can possess a same photonic band gap property as the periodic structure superconducting PC. The results of transmittance spectra show that the cutoff frequency can be manipulated through the thicknesses of the superconductor and dielectric layers as well as the ambient temperature of the system. It is observed that the shift of cutoff frequency becomes more noticeable by adjusting the thickness of the superconductor layer than that of the dielectric one. Furthermore, the cutoff frequency becomes very sensitive when the system temperature is tuned to close vicinity of the critical temperature of the superconductor.     

Optical properties of one-dimensional photonic crystals containing graded materials

The optical properties of an one-dimensional photonic crystal containing graded materials are studied theoretically. The graded layers have space dispersive permittivity and magnetic permeability which vary along the direction perpendicular to the surface of the layer. The gradation profiles of permittivity are studied in detail. We show that the structure possesses forbidden band gaps in its transmission spectra and the gradation profiles of permittivity affect the band gaps significantly. For the exponential gradation profile ε₁(x) = α e^βx, the number of the band gaps increases and the total frequency region corresponding to the gaps becomes large with increasing parameter β. On the other hand, the position of band gaps can be changed by the adjustment of the gradation profiles even if possessing same volume-average permittivity in the graded layers. Therefore, we can achieve suitable photonic band gaps by choosing gradation profiles of permittivity.     

Eigenstate statistics and optical properties of one-dimensional disordered photonic crystals

Optical eigenstates in one-dimensional disordered photonic crystals were studied. The threshold disorder level was established below which the probability of appearance of an eigenstate at the photonic bandgap center is negligible. The threshold is reached when the relative fluctuation in the optical lengths of the structure periods becomes equal to the square root of one-third of the relative bandgap width. The dependence of the ensemble-averaged structure transmission coefficient on the fluctuation of the period optical length has a break corresponding to the threshold fluctuation.     

Multi-channel and sharp angular spatial filters based on one-dimensional photonic crystals

A photonic heterostructure with multi-channel and sharp angular defect modes by combining two different one-dimensional defective photonic crystals is proposed. The filters designed on the basis of this heterostructure possess both functions of multi-channel narrow band filtering and sharp angular filtering.The channels, channel interval, and number of channels can be tuned by adjusting the geometric and physical parameters of the heterostuctures. This kind of filters will benefit the development of multi-channel interstellar or atmosphere optical communication.     

Multi-channel and sharp angular spatial filters based on one-dimensional photonic crystals

A photonic heterostructure with multi-channel and sharp angular defect modes by combining two different one-dimensional defective photonic crystals is proposed. The filters designed on the basis of this heterostructure possess both functions of multi-channel narrow band filtering and sharp angular filtering. The channels, channel interval, and number of channels can be tuned by adjusting the geometric and physical parameters of the heterostuctures. This kind of filters will benefit the development of multi-channel interstellar or atmosphere optical communication.     

Tunable phase compensator based on one-dimensional photonic crystals with single-negative materials

The reflection phase difference between TE and TM waves in one-dimensional photonic crystals composed of single-negative (SNG) (permittivity- or permeability-negative) materials is investigated by transfer matrix method. Within two omni-directional gaps the reflection phase difference changes smoothly and increases with the increasing of the incident angle. In the center of the second omni-directional gap the reflection phase difference remains almost unchanged in a broad frequency band. Especially, at both the edges of the second omni-directional gap the reflection phase difference keeps zero in spite of the change of incident angle. Based on these properties, a continuously tunable phase compensators and an omni-directionally synchronous reflector for TE and TM waves can be designed. The working frequencies for the phase compensators and synchronous reflector are tunable.     

基于一维耦合腔光子晶体的声光可调谐平顶滤波器的研究

本文利用一维耦合腔光子晶体,提出了一种声光可调谐平顶滤波器.该滤波器利用声光效应,通过改变超声波频率使一维耦合腔光子晶体透射谱的平顶滤波器的中心波长产生漂移,从而实现可调谐的滤波功能.基于传输矩阵法和声光效应理论,建立了这种平顶滤波器的理论模型;利用COMSOL软件,对平顶滤波器的矩形度、通带带宽、插入损耗、可调谐特性...     

Optical and electro-optical properties of photonic crystals based on polymer-dispersed liquid crystals

Two-dimensional (2-D) square lattice (SL) photonic crystals (PCs) are fabricated, and their optical/electro-optical properties are studied. The PCs are based on polymer-dispersed liquid crystals (PDLC) that are formed using two-beam interference with double exposures. The PC structure that is observed using a scanning electron microscope matches with the calculated interference pattern. The results of optical/electro-optical studies demonstrate that superprism and negative refraction effects occur at certain incident angles over a range of frequencies and are consistent with the simulated ones. Moreover, the negative refraction efficiency is electrically controllable.     

Tunable photonic crystals based on ferroelectric and ferromagnetic materials by focused ion beam

By making photonic crystals in ferroelectric and ferromagnetic materials, field-provoked tunability of photonic crystals is broadening the interest in new applications of on-chip photonic devices. We report a nano-precise fabrication of various designs of photonic crystals in these non-conventional materials using the focused ion beam milling technique. Standard methods are developed and parameters for different materials are calibrated. Optical responses such as bandgaps and polarization status changing from planar film waveguide system with these patterns have been examined on ferromagnetic materials.     

Transmission properties of Fibonacci quasi-periodic one-dimensional photonic crystals containing indefinite metamaterials

The transmission properties of Fibonacci quasi-periodic one-dimensional photonic crystals (1DPCs) containing indefinite metamaterials are theoretically studied. It is found that 1DPCs can possess an omnidirectional zero average index (zero-n?) gap which exists in all Fibonacci sequences. In contrast to Bragg gaps, such zero-n? gap is less sensitive to the incidence angle, the scale length and the polarizations of electromagnetic waves. When an impurity is introduced, a defect mode appears inside the zero-n? gap with a very weak dependence on the incidence angle and scaling.     

Omnidirectional reflection in one-dimensional ternary photonic crystals and photonic heterostructures

Designing dielectric systems to create omnidirectional band gaps (OBGs) is an attractive topic in the field of photonic band gap (PBG) structures. In this Letter, we propose a new approach to create OBGs by ternary photonic heterostructures (TPHs) composed of three kinds of materials with different refractive indices and obtain the formulae of the structures of TPHs, i.e., those of the thicknesses of materials and the number of sub-ternary photonic crystals. It may provide a powerful technique for designing the structures being able to produce OBGs by use of usual materials, lowcost materials, and materials with low refractive indices, etc.     

Control of photonic band gaps in one-dimensional photonic crystals

The photonic band gaps in one-dimensional photonic crystals (PCs) are theoretically investigated. A new method to broaden the photonic band gaps is introduced. Based on the similar method, a kind of photonic crystals is constructed to generate photonic band gaps with proportioned central frequencies. This technology can be used for designing nonlinear PCs for harmonic generation.     

Design of broad omnidirectional total reflectors based on one-dimensional dielectric and magnetic photonic crystals

Omnidirectional total reflectors based on one-dimensional dielectric and magnetic photonic crystals are investigated in this paper. We adopt the transmission matrix method to analyze the transmission properties of such reflectors and use the decimal genetic algorithm to obtain broad omnidirectional total reflection (ODTR) bandwidth. Finally, an omnidirectional total reflector with very broad ODTR bandwidth of 1.34ω₀ is achieved.     

A comb frequency filter based on one-dimensional photonic crystals composed of single-negative-refractive materials

A new type of comb frequency filter based on one-dimensional photonic crystals (1DPC) containing two kinds of single-negative-refractive media is presented. The filter is a multichannel one with the number of channels being dependent on the number of 1DPC periods. The position of each channel and its Q value can be adjusted varying the thickness of the material layers.     

Optical spectra of one-dimensional defect photonic crystals

The effect exerted by defects that represent a local disturbance of the structural periodicity on the band spectrum of a one-dimensional photonic crystal has been investigated. A classification of single defects has been proposed. It has been demonstrated that the position of defect minibands in the band gap of the spectrum of the crystal can be controlled by varying the type of a defect and its location in the crystal structure. The presence of two defects in the structure leads to the formation of two minibands, so that the spacing between the minibands and their intensity depend on the type of defects and on the distance between them.     

一维磁光子晶体的法拉第效应

由于一维磁光子晶体能同时展示出很好的光透射率和法拉第旋转,故可用于实现小尺度的磁光隔离器。采用传输矩阵法研究了由磁光膜(Bi∶YIG)和电介质膜(Ta2O5,SiO2)构成的一维磁光子晶体,分别讨论了在垂直入射和斜入射条件下的法拉第效应,并给出了几种可行性结构,对磁光隔离器件的进一步改进设计具有一定的参考价值。     

Optical properties of one-dimensional photonic crystals fabricated by photo-electrochemical etching of silicon

The optical properties of one-dimensional photonic crystals (1D PCs), fabricated by electrochemical etching of periodic wall arrays on n-type (100) Si substrates, are investigated in this study. Several 1D PCs were fabricated with lattice periods varying from 4 to 7 μm and with trench depths in the range 160–210 μm. In-plane reflection spectra of the photonic structures at different depths were registered over a wide spectral range of 1.5–15 μm using Fourier Transform Infra-Red (FTIR) micro-spectroscopy. Some of the features observed in the reflection spectra of the structures investigated are believed to be as a result of interface roughness. A corrugated side-wall surface, an artifact of the fabrication technique, results in the degradation of optical reflection characteristics, principally mainly in the near IR spectral range, and the emergence of optical anisotropy. As a result of the periodicity, modulation of the reflection spectra, that is, the difference between the maxima and minima of the interference fringes, reached a value of 95% in the mid-infrared. The optical properties of the structures investigated indicate that they show promise for microphotonics applications.