Design and fabrication of high-efficiency photonic crystal power beam splitters

Efficient beam splitters in a planar photonic crystal waveguide with corrugated terminators were designed, fabricated, and characterized. Experimental results showed that these beam splitters have high splitting efficiency and power intensity in the propagation direction, an achievement made possible through a design method employing a genetic algorithm-based optimization method. High-efficiency power beam splitters are useful components in integrated optics, and the design implemented here is particularly suited for integration with other optical components.     

硅光子晶体TE模式光下路分束器设计

设计了基于自准直效应的硅光子晶体TE模式13和12光下路分束器。13光下路分束器由4个分束镜组成,而12下路分束器由3个分束镜和1个反射镜组成。利用多光束干涉原理推导出光下路分束器各个出口的透射谱理论公式。通过选择合适的分束镜,可以得到不同分束比例的光下路分束器。对于13光下路分束器,设计了1∶1∶1和1∶2∶3两种分束比例;对于12光下路分束器,设计了1∶1和1∶2两种分束比例。再利用时域有限差分软件数值模拟了透射谱,其结果与理论设计一致。当下路波长为1550 nm时,13和12两种光下路分束器的大小均约为10 m 10 m,自由光谱区为36 nm,覆盖了整个光通信C波段。     

硅光子晶体TE模式光下路分束器设计

设计了基于自准直效应的硅光子晶体TE模式13和12光下路分束器。13光下路分束器由4个分束镜组成,而12下路分束器由3个分束镜和1个反射镜组成。利用多光束干涉原理推导出光下路分束器各个出口的透射谱理论公式。通过选择合适的分束镜,可以得到不同分束比例的光下路分束器。对于13光下路分束器,设计了1∶1∶1和1∶2∶3两种分束比例;对于12光下路分束器,设计了1∶1和1∶2两种分束比例。再利用时域有限差分软件数值模拟了透射谱,其结果与理论设计一致。当下路波长为1550 nm时,13和12两种光下路分束器的大小均约为10 m 10 m,自由光谱区为36 nm,覆盖了整个光通信C波段。     

Photonic drop splitters based on self-collimation ring resonators in a silicon photonic crystal

We report here 1 × 3 and 1 × 2 photonic drop splitters (PDSs) with different splitting ratios based on self-collimation ring resonators (SCRRs) in an air-hole silicon photonic crystal. An 1 × 3 PDS consists of four beam splitters and an 1 × 2 PDS consists of three beam splitters and one mirror. Light propagates in the PDSs employing self-collimation effect. The theoretical transmission spectra at different drop ports in PDSs were analyzed with the multiple-beam interference theory. Then they were investigated with the finite-difference time-domain (FDTD) simulation technique. The simulation results agree well with the theoretical prediction. For the drop wavelength 1550 nm, the free spectral range of the PDSs is about 29 nm, which almost covers the whole optical communication C-band window. Because of small dimensions, air-hole structure and whole-silicon material, the proposed PDSs hold great potentials for applications in photonic integrated circuits.     

On use of ghost-less beam splitter in reversal shear interferometer for measurement of spatial coherence of large cross-section laser beam

A configuration of reversal shear interferometer suitable for measurement of spatial coherence of high average power, large cross-section laser beam has been discussed. Ghost-less beam splitters in which unwanted multiple reflections from the surfaces have been suppressed by total internal reflection are used for beam splitting and re-combination. Advantages and drawbacks of this configuration have been discussed.     

光子晶体定向耦合三波长功分器

以二维三角晶格光子晶体为研究对象,在该光子晶体中引入两行以一行耦合介质柱为间距的平行单模线缺陷波导.通过分析和研究光子晶体波导耦合结构的耦合和解耦合特性,发现在不同频率下耦合波导的耦合长度不同.利用平面波展开法和定向耦合原理计算了在不同入射光频率下,缺陷波导间耦合波导的耦合长度,设计了一种新型超微光子晶体波导耦合型三波长功分器,实现了归一化频率分别为0.369、0.394、0.435的光波的分束效果.采用时域有限差分法验证了该功分器具有很好的功率分配效果.本文结果有助于光子晶体新型滤波器、定向耦合器、波分复用器、偏振光分束器以及光开关等光子器件的研究.     

基于时域有限差分算法的光子晶体光分束器的设计

报道了一种基于空气孔型光子晶体自准直环形谐振腔1×4光分束器。其结构由4个改变空气孔半径的分光镜组成。首先运用多光束干涉原理分析光分束器各个端口的透射谱,通过分光镜的合适组合,自准直光就可以按照设定的比例从各出口出射。再利用编写的二维时域有限差分程序进行数值模拟计算,其结果和理论值很好地吻合。该结构具有尺寸小、自由光谱范围大、硅基等优点,有望应用于未来的高密度集成光路中。     

红外区二维光子晶体偏振分光镜透射谱分析

采用时域有限差分（Finite-Difference Time-Domain,FDTD）法模拟了垂直入射红外波段二维光子晶体偏振分光镜的透射谱,从而验证了用平面波展开方法计算的二维光子晶体能带结构.用电子束蒸发方法在光栅基板上制备了Ge/BaF2多层膜,实现了二维光子晶体偏振分光镜.实验初步证明了这种光子晶体在垂直入射时具有偏振特性,分析了实验结果与理论计算之间偏差的产生原因.     

Polarization beam splitters based on a two-dimensional photonic crystal of negative refraction

A two-dimensional metallo-dielectric photonic crystal of negative refraction was designed for the application of polarization beam splitters. To match the refractive index of air, the effective refractive index of the designed photonic crystal is -1 for TE polarization and +1 for TM polarization. Two types of polarization beam splitter are presented.     

Design of photonic crystal power couplers via gratinglike surfaces

This work deals with the inverse design in the field of photonic crystal based devices. We use the finite-difference time-domain method in conjunction with a genetic algorithm to design a power coupler between two photonic crystal waveguides. By optimizing the structure of gratinglike surfaces added near the photonic crystal waveguides, we have obtained several simple power couplers considering different coupling lengths. These couplers have high coupling efficiency as well as high power intensity in the propagation direction.     

基于圆柱型硅光子晶体的1×2光下路分束器

本文设计了一个基于圆柱型硅光子晶体自准直环形腔的1×2光下路分束器.该光下路分束器由三个分光镜和一个反射镜构成,其中窄光束依赖自准直效应进行传输.利用多光束干涉理论分析了光下路分束器中不同出口的理论透射谱,并且利用时域有限差分法对光下路分束器透射谱进行数值模拟计算,其结果与理论预测基本一致.当下路波长为1 550 nm时,光下路分束器的自由光谱范围约为30 nm,几乎涵盖了整个光通信C波段.由于其小尺寸和全硅材料,本文设计的1×2光下路分束器有望应用于未来的集成光路中.     

Tunable photonic crystal circuits: concepts and designs based on single-pore infiltration

We demonstrate that the infiltration of individual pores of certain two-dimensional photonic crystals with liquid crystals and (or) polymers provides an efficient platform for the realization of integrated photonic crystal circuitry. As an illustration of this principle, we present designs for monomode photonic crystal wave-guides and certain functional elements, such as waveguide bends, beam splitters, and waveguide intersections. These devices exhibit very low reflection over broad frequency ranges. In addition, we discuss the inherent tunability of these devices that originates in the tunability of the infiltrated material.     

基于圆柱型硅光子晶体的1×2光下路分束器(英文)

本文设计了一个基于圆柱型硅光子晶体自准直环形腔的1×2光下路分束器.该光下路分束器由三个分光镜和一个反射镜构成,其中窄光束依赖自准直效应进行传输.利用多光束干涉理论分析了光下路分束器中不同出口的理论透射谱,并且利用时域有限差分法对光下路分束器透射谱进行数值模拟计算,其结果与理论预测基本一致.当下路波长为1 550nm时,光下路分束器的自由光谱范围约为30nm,几乎涵盖了整个光通信C波段.由于其小尺寸和全硅材料,本文设计的1×2光下路分束器有望应用于未来的集成光路中.     

Dispersion-based beam splitter in photonic crystals

A novel implementation of a dispersion-based beam splitter in a photonic crystal (PhC) is proposed. The beam splitter consists of two periodic structures: a nonchannel dispersion-guiding region and a splitting structure operating inside the photonic bandgap. The dispersion-guiding PhC structure is used to route the optical wave by exploiting the dispersion properties of the lattice. An arbitrary power ratio between the output beams can be achieved by varying the parameters of the splitting structure. Within the studied range of splitting structures, high output power was observed and verified experimentally.     

基于异质结界面优化的光子晶体二极管单向传输特性研究

基于光子晶体异质结结构的全光二极管是目前的一个研究热点,使其具有更好的单向传输特性是研究的一个目标.本文中通过改变异质结界面处的光子晶体结构,提出了不同的优化设计方案,在宽频带内实现了高对比度全光二极管的高效率单向传输,并且该结构还具有分束特性.     

Photonic crystal beam splitters

In this work, the beam splitter with two input ports and two output ports in two-dimensional photonic crystals is studied through the finite-difference time-domain method. The beam splitter consists of two orthogonally cross line defects. The diameter of the two diagonal air holes at the intersection of the two line defects was modified. The input light can be identically divided into the two output ports. The beam splitters can be applied in the photonic crystal Mach-Zehnder interferometers or photonic crystal optical switches.     

Waveguide circuits in three-dimensional photonic crystals

Waveguide circuits in three-dimensional photonic crystals with complete photonic band gaps are simulated with finite difference time domain (FDTD) simulations, and compared with measurements on microwave scale photonic crystals. The transmission through waveguide bends critically depends on the photonic crystal architecture in the bend region. We have found experimentally and theoretically, a new waveguide bend configuration consisting of overlapping rods in the bend region, that performs better than the simple waveguide bend of terminated rods, especially in the higher frequency portion of the band. Efficient beam splitters with this junction geometry are also simulated.     

Conditions for self-collimation in three-dimensional photonic crystals

We introduce the theoretical criterion for achieving three-dimensional self-collimation of light in a photonic crystal. Based on this criterion, we numerically demonstrate a body-center-cubic structure that supports wide-angle self-collimation and is directly compatible with the recently developed holographic fabrication technique. We further show that both bends and beam splitters can be introduced into this structure by the use of interfaces.     

基于波导间能量耦合效应的光子晶体频段选择与能量分束器

基于波导间能量耦合效应的光子晶体功率分束器具有结构紧凑、带宽较宽、弯曲损耗低、分光角度大和不受外界电磁场干扰等优点.本文利用时域有限差分方法,理论研究了二维三角晶格光子晶体耦合波导的功率分束特性,设计得出了一种能够在宽频谱范围内针对不同频率区间实现不同分光比的功能器件.在此基础上通过改变耦合区介质柱形状以及输出分支波导与能量耦合波导的连接位置,最终针对三个相邻频率范围内的入射光信号,较好地实现了三均分、二均分、单一输出通道这3种能量分配输出模式.该功能器件具有透过率对比度高、结构紧凑等特性,对于发展全光功能器件在大规模全光复杂集成领域内的实际应用具有一定的促进作用.     

All-optical analog-to-digital converters based on cascaded 3-dB power splitters in 2D photonic crystals

In this paper, a new design of a photonic crystal (PC) all-optical analog-to-digital converter (ADC), which is based on cascaded 3-dB power splitters, is presented. It has been shown that by choosing appropriate threshold values in the output ports of the 3-dB power splitters, a set of unique states corresponding to different power levels of input analog signal can be obtained. It has been demonstrated that based on the proposed approach, the design of 2 and 3-bit PC ADC can be achievable.