基于一维光子晶体微腔的全吸收器件

将具有高本征吸收的极化材料SiC引入到一维光子晶体中间,形成一维光子晶体微腔。利用传输矩阵方法,研究了这种含SiC材料的一维光子晶体微腔的光学特性:包括透射率、反射率和吸收率。研究结果表明该结构在波长λ=12.6μm处存在一个全吸收峰,该吸收峰在0°～50°的入射角度范围内不随角度和偏振模式的影响。该结构可以用来制作宽角度窄带全吸收器件,有望在热发射、太阳能光伏电池中得到应用。     

Study on modulation of near infrared radiation based on plasma photonic crystal

In this paper, a plasma photonic crystal (PPC) for infrared radiation modulation which is composed of indium tin oxide (ITO) and plasma is proposed. The performance of plasma photonic crystal in near infrared radiation modulation is researched by transfer matrix method (TMM). The simulation results show that the near infrared radiation pass band can be adjusted by the changing of plasma frequency of plasma. The reflection to near infrared radiation by plasma photonic crystal increases with plasma frequency and that of absorption decreases. In addition, the modulation performance of the plasma photonic crystal at different incidence wave angles is also studied. The results show that the incident wave angles have little effect on the transmission of plasma photonic crystal in near infrared band. The reflection of the plasma photonic crystal to near infrared radiation decreases with increasing of the incident wave angle, but that of the absorption increases with the incident wave angle. Therefore, the proposed plasma photonic crystal has a potential application in tunable near infrared filter devices.     

Dipole-induced grating in a waveguide-coupled photonic crystal microcavity embedding a driven three-level emitter

We study optical transmission characteristics of a waveguide-coupled photonic crystal microcavity embedding a driven three-level dipole emitter. By spatially modulating the control field, alternating regions of high transmission and absorption can be produced in two waveguide channels which can be used for an amplitude grating.     

Isotropic photonic bandgap in Penrose textured metallic mircocavity

Photonic microcavity has modified photonic modes that have intense localized electric field, which can couple strongly with the embedded emission centers. In this work, we fabricated 2D photonic microcavities with Penrose quasicrystal pattern with 10-fold symmetry. Organic luminescence material tris(8-hydroxyquinoline) aluminum (Alq₃) was embedded into the microcavity and the angle resolved transmission (ART) and photoluminescence (ARPL) spectra of the microcavity were measured. The results showed that the normal Gaussian photoluminescence spectrum of Alq₃ has been strongly modified by the microcavity dispersion characteristic. In addition, omni-directional photonic band gap exists in the microcavity. The higher symmetry of Penrose quasicrystal pattern means that there was minimal difference in the directional dispersion characteristics.     

Optical third-harmonic generation in one-dimensional photonic crystals and microcavities

The formalism of nonlinear transfer matrices is used to develop a phenomenological model of a cubic nonlinear-optical response of one-dimensional photonic crystals and microcavities. It is shown that third-harmonic generation can be resonantly enhanced by frequency-angular tuning of the fundamental wave to the photonic band-gap edges and the microcavity mode. The positions and amplitudes of third-harmonic resonances at the edges of a photonic band gap strongly depend on the value and sign of the dispersion of refractive indexes of the layers that constitute the photonic crystal. Model calculations elucidate the role played by phase matching and spatial localization of the fundamental and third-harmonic fields inside a photonic crystal as the main mechanisms of enhancement of third-harmonic generation. The experimental spectrum of third-harmonic intensity of a porous silicon microcavity agrees with the calculated results.     

Thermal emission properties of 2D and 3D silicon photonic crystals

We present measurements of the thermal emission properties of 2D and 3D silicon photonic crystals with and without substrate heated resistively as well as passively with an aluminium hotplate. The out-of-plane and in-plane emission properties were recorded and compared to numerical simulation. It turned out that for the in-plane 2D photonic crystal and out-of-plane 3D photonic crystal emission a photonic stop gap effect is visible. For the out-of-plane 2D photonic crystal emission, no photonic bandgap effect is observable but instead strong silicon oxide emission from native oxide inside the pores of silicon are observable. A model for the modified thermal emission is presented.     

共轴环光子晶体的缺陷微腔特性

 采用数值计算方法,模拟了共轴环光子晶体缺陷微腔的谐振模式场分布,计算了此微腔的品质因数和功率损耗,并分析其几何参数对谐振特性的影响。以此缺陷微腔为基础构建周期性慢波系统,讨论了该系统的色散特性。结果表明,微腔中能够存在单一的谐振模式,微腔的纵向长度和介质环介电常数对谐振特性影响较大。所构建的慢波系统有较宽的慢波频域,且慢波比曲线较为平坦。增大电子注开孔半径和减小周期长度对于提高工作频率及增加带宽较为有效。     

Simplified design of low-loss and flat dispersion photonic crystal waveguide on SOI

A low-loss and flat dispersion line-defect photonic crystal waveguide is proposed with a simplified waveguide-design on silicon-on-insulator (SOI) based on hexagonal lattice of 2D photonic crystals. A propagation loss of 3.6 dB/mm and flat dispersion over a large wavelength band is reported with an easy-to-implement design without disturbing the periodicity (keeping lattice constant and hole diameter fixed) in the line-defect photonic crystals. The combined effect of photonic crystals (in-plane periodicity) and the vertical layers on SOI results in efficient waveguiding and dispersion characteristics.     

Dispersion characteristics of two-dimensional unmagnetized dielectric plasma photonic crystal

This paper studies dispersion characteristics of the transverse magnetic (TM) mode for two-dimensional unmagnetized dielectric plasma photonic crystal by a modified plane wave method. First, the cutoff behaviour is made clear by using the Maxwell--Garnett effective medium theory, and the influences of dielectric filling factor and dielectric constant on effective plasma frequency are analysed. Moreover, the occurence of large gaps in dielectric plasma photonic crystal is demonstrated by comparing the skin depth with the lattice constant, and the influence of plasma frequency on the first three gaps is also studied. Finally, by using the particle-in-cell simulation method, a transmission curve in the \Gamma -X direction is obtained in dielectric plasma photonic crystal, which is in accordance with the dispersion curves calculated by the modified plane wave method, and the large gap between the transmission points of 27~GHz and 47~GHz is explained by comparing the electric field patterns in particle-in-cell simulation.     

高品质因子和高传输效率的二维光子晶体耦合腔波导研究

基于时域有限差分方法,通过仿真计算设计了一种具有较高品质因子和传输效率的二维光子晶体耦合腔波导结构。通过改变二维光子晶体波导微腔结构中隔绝波导与微腔的空气孔的半径和数量,在获得近似90%的传输效率的同时,使得品质因子达到了8.20×104。为了使品质因子在大幅度提高的同时,传输效率只有小幅度的降低,在波导微腔结构中引入了链式微腔。将链式微腔结构与传统的波导微腔结构相结合,使这种新形式的耦合腔结构的品质因子提高了1个数量级,传输效率仅下降了约40%。     

Electrically injected quantum-dot photonic crystal microcavity light sources

The design, fabrication, and characterization of an electrically injected quantum-dot photonic crystal microcavity light source are described. The optical gain in the GaAs/AlGaAs-based device is provided by self-organized InGaAs quantum dots with ground-state room-temperature emission at 1.1 microm. The carriers are injected directly into the photonic crystal microcavity, which contains approximately 50 dots, avoiding surface state recombination in the photonic crystal pattern. The spectral characteristics of a single-defect photonic crystal microcavity show a single 2 nm broad microcavity resonance. The output power is of the order of a few tens of nanowatts.     

All-optical tunable photonic bandgap microcavities with a femtosecond time response

An all-optical tunable photonic bandgap microcavity made from a two-dimensional polystyrene photonic crystal is fabricated by focused ion beam etching. The pump and probe scheme is adopted to measure tunability based on the femtosecond optical Kerr effect. An ultrafast response time of less than 120 fs is achieved for the tunable photonic bandgap microcavity. The microcavity resonant wavelength shifts 3.1 nm under excitation of 9.4 GW/cm2 pump intensity, which is in agreement with the theoretical prediction.     

Engineering photonic density of states using metamaterials

The photonic density of states (PDOS), like its electronic counterpart, is one of the key physical quantities governing a variety of phenomena and hence PDOS manipulation is the route to new photonic devices. The PDOS is conventionally altered by exploiting the resonance within a device such as a microcavity or a bandgap structure like a photonic crystal. Here we show that nanostructured metamaterials with hyperbolic dispersion can dramatically enhance the photonic density of states paving the way for metamaterial-based PDOS engineering.     

Fabrication of Two-Dimensional Organic Photonic Crystal Microcavity

A two-dimensional polystyrene photonic crystal microcavity is fabricated by the method ot tocused ion Oeam etching. The scanning electron microscopy and the transmittance spectrum are used to characterize the properties of the photonic crystal microcavity. The quality factor and the transmittance of the photonic crystal microcavity is more than 530 and 90%, respectively. The measured results are in agreement with the theoretical predictions.     

Optical characteristics of one-dimensional photonic crystals composed of high-aspect-ratio Si walls fabricated on V-grooved wafer

We demonstrate optical properties of one-dimensional photonic crystals (PC), which are fabricated using high-aspect-ratio etching on a V-grooved silicon wafer. The measured transmission spectrum has an obvious band gap; the suppression is over 30 dB. The quite small insertion loss of 1.9 dB is achieved by induced coupled plasma (ICP) cryogenic etching and direct coupling to the optical fiber aligned in the V-groove. We also successfully observed peaks originating from a localized cavity mode. Such a microcavity enables control of the light, which qualifies photonic crystal as a fundamental structure of optical functional devices. These results lead to achievement of integrated Si-based photonic circuits.     

Terahertz pulse generation via optical rectification in photonic crystal microcavities

Using a three-dimensional fully vectorial nonlinear time-domain analysis, we numerically investigate generation of terahertz radiation by pumping a photonic crystal microcavity out of resonance. High quality factors and a quadratic susceptibility lead to few-cycle terahertz pulses via optical rectification. Material dispersion as well as linear and nonlinear anisotropy is fully accounted for.     

平板型光子晶体谐振腔性能分析

介绍了一种平板型光子晶体微谐振腔的结构.利用三维时域有限差分法(FDTD)分析了平板型光子晶体的结构参量及其对谐振腔性能的影响.平板型光子晶体微腔具有较小的模式体积和较大的品质因子(Q),可以有效的使光子局域化.该谐振腔可以用来制造单频发光二极管和零阈值微腔激光发射器.     

光子晶体光纤非线性光谱特性的理论与实验研究

光子晶体光纤具有特殊的导光机制和结构可调性,可以产生奇异的色散特性及高非线性,为非线性光纤光学领域的研究提供了新的条件。受多种非线性光学效应的共同作用,在不同泵浦光脉冲参数条件下,不同结构参数及传输特性的光子晶体光纤能产生丰富的非线性光谱。利用分步傅里叶方法求解非线性薛定谔方程,模拟飞秒激光脉冲在光子晶体光纤中的传输过程,获得输出光谱与入射光脉冲参数(泵浦光峰值功率P、泵浦光波长λ、光脉冲形状、光脉冲宽度T_FWHM)、光纤结构参数(孔间距Λ、空气填充比d/Λ、光纤长度z)、传输特性(色散、非线性系数)的关系,分析拉曼孤子、色散波、自相位调制等非线性效应产生的光谱特性。利用光子晶体光纤包层节区进行非线性光学实验研究,获得了孤子波和色散波的宽带光谱输出。理论分析与实验测量的光谱中都包括了波长0.5 μm附近可见光波段的蓝移色散波、0.82 μm波段的剩余泵浦光、1.1 μm波段的孤子波、2 μm附近的红移宽带色散波。理论分析与实验测量结果一致,阐明光子晶体光纤中非线性光谱产生的物理原理,实现了对宽带光谱的可控输出,为高非线性光子晶体光纤的结构设计、制备及非线性光谱的应用研究奠定基础。     

光子晶体光纤中自相位调制效应对超高斯脉冲传输的影响

为了研究光子晶体光纤的微结构对其非线性光传输特性的影响,利用超格子法和光子晶体光纤中的光传输方程,计算了光子晶体光纤中的高斯光脉冲和超高斯脉冲的自相位调制谱.计算结果表明：高斯光脉冲和超高斯光脉冲的高频端比低频端均有较大的频谱展宽,而高斯光脉冲的频谱比超高斯光脉冲的频谱具有更大的中心峰值;超高斯光脉冲较高斯光脉冲有较广的频谱范围,它们的自相位调制展宽范围均随着传输距离的增加而增大.这些现象均可以利用自陡峭效应的理论加以解释.与传统光纤相比,高斯光脉冲在传统光纤中所受自相位调制效应的影响较小.