高下路空气孔型光子晶体环形谐振腔的设计

提出一种基于二维正方晶格光子晶体空气孔型高下路效率的环形谐振腔,通过压缩线缺陷波导的宽度实现单模有效控制,同时讨论内围光子晶体列数对传输场的影响,然后运用二维时域有限差分方法数值分析了耦合强度及环区局部折射率调制对下路效率、品质因子以及下路波长等参量的影响.结果表明:当波导宽度为0.7个晶格常量,耦合强度为0个晶格常量,在信道波长为1 528.1nm时,下路效率为99%,品质因子Q为379;当耦合强度提高到1个晶格常量,下路波长稍微漂移为1 524.3nm,品质因子显著提高到1 397,而下路效率下降为89%.同时,下路波长会随着环区折射率的增加呈线性红移.     

高下路空气孔型光子晶体环形谐振腔的设计

提出一种基于二维正方晶格光子晶体空气孔型高下路效率的环形谐振腔,通过压缩线缺陷波导的宽度实现单模有效控制,同时讨论内围光子晶体列数对传输场的影响,然后运用二维时域有限差分方法数值分析了耦合强度及环区局部折射率调制对下路效率、品质因子以及下路波长等参量的影响.结果表明:当波导宽度为0.7个晶格常量,耦合强度为0个晶格常量,在信道波长为1 528.1 nm时,下路效率为99%,品质因子Q为379;当耦合强度提高到1个晶格常量,下路波长稍微漂移为1 524.3 nm,品质因子显著提高到1 397,而下路效率下降为89%.同时,下路波长会随着环区折射率的增加呈线性红移.     

Two dimensional Photonic Crystal Ring Resonator based Add Drop Filter for CWDM systems

In this paper, two-dimensional circular Photonic Crystal Ring Resonator (2D PCRR) based Add Drop Filter (ADF) using circular rods is designed for ITU-T G.694.2 eight channel Coarse Wavelength Division Multiplexing (CWDM) systems to add/drop a channel centered at a resonant wavelength of 1491 nm. The Plane Wave Expansion (PWE) method and 2D Finite Difference Time Domain (FDTD) method are employed to obtain the Photonic Band Gap (PBG) range and output spectra of the ADF. Close to 100% of coupling and dropping efficiencies, 13 nm of passband width and 114.69 of quality factor are observed for the designed filter at 1491 nm which is highly sufficient and fulfill the requirement of ITU-T G.694.2 CWDM system. Further, the resonant wavelength tuning possibilities of ADF are theoretically studied to cover the lower channels of CWDM systems. The structural parameters such as refractive index, lattice constant and radius of the rod in the structure are considered for resonant wavelength tuning.     

Investigation on parameters affecting the performance of two dimensional photonic crystal based bandpass filter

A two dimensional Photonic Crystal based Bandpass Filter is designed by exploiting coupling between the quasi waveguides and the circular Photonic Crystal Ring Resonator (PCRR). The output efficiency, resonant wavelength and bandwidth of PCBPF are investigated by varying the dielectric constant of the structure. The normalized transmission spectra of circular PCRR are taken using 2D Finite Difference Time Domain method. The Photonic Band Gap is calculated by Plane Wave Expansion method. Close to 100% (Band II) output efficiency is observed over the wavelength range from 1,504 to 1,521?nm and 85% (Band I) is obtained at 1,420?nm through simulation. The full width half maximum bandwidth of these bands is 35 and 20?nm, respectively. Further, the parameters that affect the resonant wavelength, output efficiency and bandwidth of the filter such as size of the reflector, radius of the coupling rods, lattice constant, rod radius and number of rods in the structure are analyzed. The overall size of the proposed filter is 11.4?μm ×?10.2?μm, which is smaller than the filters already reported in the literature and highly desirable for Photonic Integrated Circuits.     

Realization of tunable optical filter by photonic crystal ring resonators

We have designed a tunable two dimensional (2D) channel drop filter (CDF) based on photonic crystal ring resonators (PCRR). Dropping efficiency and Q factor of single improved ring are 100% and 842, respectively. In this filter the quality factor is significantly improved with respect to other published reports. We investigate parameters which have an effect on resonant wavelength in this CDF, such as dielectric constant of inner, coupling, adjacent and whole rods of the structure and radius of inner rods. The transmission spectrum for our proposed configuration has been investigated using the 2D finite difference time domain (FDTD) method. The area of the proposed structure is about 117 μm².     

Optical channel drop filters based on photonic crystal ring resonators

A new optical channel drop filters (CDFs) configuration based on photonic crystals ring resonators (PCRRs) is provided. The transmission characteristics for single-ring and multiple-ring configurations have been investigated by using the two-dimensional (2D) finite-difference time-domain (FDTD) technique in triangular lattice photonic crystal (PC) silicon rods. Both forward and backward dropping were achieved in dual-ring PCRR structures. In this filter, 100% drop efficiency and acceptable quality factor can be obtained at 1550 nm. The present device can be used in the future photonic integrated circuits.     

A new design of tunable four-port wavelength demultiplexer by photonic crystal ring resonators

A four-channel wavelength demultiplexer based on photonic crystal ring resonators (PCRR), which can be used for photonic integrated circuits, is designed. Dropping efficiency and Q factor of single improved ring are 100% and 842, respectively. In order to achieve the structure of demultiplexer, three improved rings have been used, that every ring has an individual inner rod radius; it means that each ring has a varying resonant wavelength. The results of simulation using finite-difference time-domain (FDTD) method in our proposed structure reveals an average transmitted power higher than 90% for each output port, Channel spacing is about 8 nm and bandwidth for each individual channel is about 2.8 nm. The mean value of the crosstalk between output channels and the area of the proposed structure are about −29 dB and 317 μm², respectively. By changing the radius of inner rods, various wavelengths can be chosen, therefore this device is tunable.     

Improving the performance of a photonic crystal ring-resonator-based channel drop filter using particle swarm optimization method

The optical channel drop filters (CDFs) based on photonic crystals (PCs) are believed to be the essential components for compact photonic integrated circuits and WDM systems. One of the promising designs for a PC-CDF is based on the photonic crystal ring resonators (PCRRs). In this study, different parameters of a PCRR based CDF is optimized by using the particle swarm optimization (PSO) method in conjunction with the numerical method of two-dimensional (2D) finite-difference time-domain (FDTD) in a square lattice dielectric-rod 2D-PC. Hence a PC-CDF with ideal drop efficiency, large free spectral range (FSR) and acceptable quality factor will be proposed.     

可调谐光子晶体微环腔型光分叉复用器的设计

提出了一种基于二维光子晶体微环腔的新型光分叉复用器,并可以通过改变环区的硅介质柱的折射率实现波长调谐.运用经典的微环自由光谱范围FSR和微环半径R的关系,证实新型的光子晶体微环腔也满足该关系.利用二维时域有限差分法系统分析了下路信号波长及相应效率随折射率的变化关系.结果表明,只需改变环区折射率0.005,下路波长就可以漂移1 nm,而有效微环半径还不足1.4 μm.     

Channel drop filter using photonic crystal ring resonators for CWDM communication systems

In this paper, a new optical channel drop filter (CDF) using photonic crystal ring resonators (PCRRs) is presented. Using the two-dimensional (2D) finite-difference time-domain (FDTD) method in triangular lattice photonic crystal (PC) silicon rods, 100% forward dropping efficiency and a quality factor of more than 1000 can be achieved in third communication window while the resonant wavelength is 1550 nm. Through this novel (CDF), a multi-CDF operation with 100% drop efficiencies across all channels can be obtained. The proposed device could be used in future coarse wavelength division multiplexing (CWDM) communication systems.     

可调谐光子晶体微环腔型光分叉复用器的设计*

提出了一种基于二维光子晶体微环腔的新型光分叉复用器,并可以通过改变环区的硅介质柱的折射率实现波长调谐.运用经典的微环自由光谱范围FSR和微环半径R的关系,证实新型的光子晶体微环腔也满足该关系.利用二维时域有限差分法系统分析了下路信号波长及相应效率随折射率的变化关系.结果表明,只需改变环区折射率0.005,下路波长就可以漂移1 nm,而有效微环半径还不足1.4 μm.     

Investigation of cavity modes and direct observation of Purcell enhancement in 2D photonic crystal defect microcavities

We demonstrate our ability to control and manipulate the optical modes in 2D Photonic Crystal Defect cavities and investigate their coupling to InGaAs self-assembled quantum dots. Our results enable us to probe the nature of individual cavity modes and directly investigate cavity QED phenomena. For the lowest mode volume cavities investigated, consisting of a single missing air hole within a hexagonal lattice, we have measured a clear Purcell enhancement of the light-matter interaction in the weak coupling regime. For QDs on-resonance with localized cavity modes this translates to a shortening of the quantum dot spontaneous emission lifetime by a factor 2 when compared to off-resonance dots.     

宽带光子晶体插分滤波器

 通过使用正方格介质柱二维光子晶体设计了带有环形谐振器的一种插分滤波器ADF(add drop filter)结构,该结构具有1个输入端口和2个输出端口,采用时域有限差分法研究了带有1个环形谐振器和2个环形谐振器的ADF结构传输性能。结果表明：该ADF结构在第三通信窗口具有优良的滤波作用,能够根据需要将电磁波信号沿着波导向前后上下4个方向传输,ADF结构还具有可调性开关波长、宽频带、高传输率等特点,在光子晶体集成化、光器件制作等方面具有潜在价值。     

A new proposal for PCRR-based channel drop filter using elliptical rings

In this paper using elliptical resonant ring we proposed a channel drop filter based on photonic crystal structures suitable for optical communication applications. The drop efficiency and the quality factor of our proposed filter is 100% and 647. We also investigated the optical properties of different configurations of the proposed photonic crystal ring resonator such as vertical ring, dual ring and triple ring structures. According to the results different configurations show different optical properties, so for vertical, double and triple ring configurations the quality factor will be 387, 865 and 1559, respectively.     

Investigation of 2D-photonic crystal resonant cavity based WDM demultiplexer

In this attempt, Two Dimensional Photonic Crystal (2DPC) Quasi Square Ring Resonator (QSRR) based four channel demultiplexer is proposed and designed for Wavelength Division Multiplexing systems. The performance parameters of the demultiplexer such as transmission efficiency, passband width, line spacing, Q factor and crosstalk are investigated. The proposed demultiplexer is composed of bus waveguide, drop waveguide and QSRR. In the proposed demultiplexer, the output ports are arranged separately in odd and even number, where an odd number of ports are located on the right side and even number of ports are located on the left side of the bus waveguide that are used to reduce the channel interference or crosstalk. Further, the refractive index of rods around the center rod is increased linearly one to another in order to improve the signal quality. The resonant wavelengths of the proposed demultiplexer are of 1521.1?nm, 1522.0?nm, 1523.2?nm and 1524.3?nm, respectively. The footprint of the device is of 180.96?μm². Then, a four channel point to point network is designed and the proposed four channel demultiplexer is implemented by replacing a conventional demultiplexer. Finally, functional parameters of the network, namely, BER, receiver sensitivity and Q factor are estimated by varying the link distance. This attempt could create new dimensions of research in the domain of photonic networks.     

Photonic crystal bends and power splitters based on ring resonators

In this paper, theoretical and numerical analysis of low-loss right angle waveguide bends and T-junctions based on ultra-compact photonic crystal ring resonators (PCRR) is presented. Desirable characteristics are obtained by designing the waveguide bends and T-junctions as low-Q resonant cavities with certain symmetries and small radiation loss. A simple analysis, based on coupled mode theory (CMT) in time, is used to explain the operation principles which agree qualitatively with the numerical results. These structures have high transmission efficiency over a large bandwidth in third communication window. Also effects of changing the ring size on power splitter transmission characteristics are discussed. The perfect transmission and zero reflection conditions are discussed by applying coupled mode theory. Results obtained by the finite difference time domain (FDTD) simulations are consistent with those from the coupled mode theory.     

Low threshold laser cavities of two-dimensional photonic crystal line defect mode

Two-dimensional (2D) rod-type photonic crystal (PC) line defect waveguide (LDW) laser cavities based on three types of line defect modes with zero group velocity are studied by using finite-difference time-domain (FDTD) method. These laser cavities have high quality (Q) factor, better localization of light, non-uniform gain distribution and small overlap between gain medium and light field. Therefore, they have the advantages over conventional and air-bridge PC cavities with uniform gain, such as low threshold, single mode lasing and effectively avoiding thermal effect. From their comparison, one can find the mode at middle Brillouin zones (BZ) is the best one to be used as lasing mode. Its dynamic lasing process and lasing features are demonstrated by the numerical experiment where the FDTD method coupling Maxwell's equations with the rate equations of electronic population is used.     

高效多信道光子晶体滤波器的设计与仿真

利用二维光子晶体仿真设计了四信道光滤波器.首先根据时域耦合模理论导出了实现100％信道耦合的条件;然后根据该条件设计了四信道滤波器,并利用时域有限差分法进行了仿真.仿真结果显示,四信道耦合效率均超过96％,当晶格常量取570 nm时,四信道的中心频率在1 520 nm到1 580 nm之间,信道间隔均小于20 nm,信道间窜扰很小.     

构成环形谐振腔的光子晶体微镜设计

研究了光子晶体作为陀螺谐振腔空间微镜的应用,基于平面波展开法计算了光子晶体能带结构和带隙分布图,利用时域有限差分方法对三角晶格介质柱结构微反射镜的传输特性进行了研究,讨论介质柱半径和晶格周期对反射率的影响,并给出优化结果和参量.对输入输出镜进行了初步探索设计,初步给出优化结构.基于介质柱光子晶体微镜的环形谐振腔不仅能实现单片集成还能实现光在空气中传输来大幅度减小克尔和法拉第效应,以及背向散射等影响,这对于研究高准确度谐振陀螺提供了新思路.     

硅基孔状光子晶体高选择性滤波器设计

通过平面波展开法研究了三角孔状光子晶体晶格的能带结构,并考虑了该过程的辐射损耗.用时域有限差分的方法模拟计算了对应六边形环行腔结构的光谱透射特性,得出优化的晶格周期和占空比.在C波段上,优化的结构达到了98.8%的光学选择比和32.9 nm的半高全宽.用光刻和反应离子刻蚀的方法对样片的加工过程进行了尝试并给出加工参量.搭建相应的系统测试了样片的光谱性能,结果表明:实际样片孔状的样片较之柱状样片更为稳定,而基于环行谐振腔的结构在未来有应用于滤波器、波分复用系统、微陀螺等领域.