孔型硅光子晶体中折叠式马赫-曾德尔干涉仪(英文)

设计了基于孔型硅光子晶体的折叠式马赫-曾德尔干涉仪.它由一个光反射器和几个光分束器构成.在干涉仪中,窄光束依赖自准直效应进行传输.利用时域有限差分法研究了折叠式马赫-曾德尔干涉仪的特性.结果表明,在0.255～0.270c/a的归一化频率范围内,干涉仪的两个透射谱均为正弦形且强度互补,透射谱的透射峰间距随着干涉仪两臂的光程差的增大而减小.该折叠式干涉仪结构紧凑,尺寸比非折叠式光子晶体马赫-曾德尔干涉仪要小许多,有望作为信道解复用器应用于光子芯片中.     

二维光子晶体全光异或门的设计及研究

分析了二维光子晶体马赫-曾德尔干涉仪的传输特性,将二维光子晶体波导、环形腔和马赫-曾德尔干涉仪有效结合,提出了一种基于二维光子晶体马赫-曾德尔干涉仪的异或门设计。用平面波展开法分析二维光子晶体能带结构,并用时域有限差分法验证光信号在该器件中的电场稳态分布。结果表明,该结构能够实现异或逻辑,且具有高逻辑对比度7.88 dB,快速响应周期0.388 ps和高传输速率7.87 Tbit/s;并且该器件结构尺寸仅为13 μm×14 μm,易于集成。该异或逻辑结构中引入了二维光子晶体马赫-曾德尔干涉仪,使得光子晶体逻辑门结构的设计更加多样,并为二维光子晶体半加器与全加器的设计提供了基础,具有重要的研究意义。     

多普勒测风激光雷达中马赫-曾德尔干涉仪的视场展宽技术研究

火星大气风速廓线探测对研究火星大气环境具有重要意义,基于马赫-曾德尔干涉仪的多普勒测风激光雷达相对于一般的相干/非相干多普勒测风激光雷达更适合于火星地基探测。为使马赫-曾德尔干涉仪对激光雷达中望远镜接收到的大视场角回波光信号进行频移检测,需要对马赫-曾德尔干涉仪进行视场展宽。对马赫-曾德尔干涉仪中棱镜式视场展宽技术与"猫眼"光学系统的视场展宽技术进行研究后发现,棱镜式视场展宽技术更具优势。设计并搭建了一套光程差为219 mm的马赫-曾德尔干涉仪,使用压电晶体扫描反射镜片的方式测量其对以11 mrad视场角入射的准平行光束的透射谱,得到干涉仪最大的干涉对比度为0.87,满足多普勒测风激光雷达的使用需求。结合地球大气环境分析了干涉仪干涉对比度随高度的变化,结果表明:虽然大光程差马赫-曾德尔干涉仪的干涉对比度在5 km以下低空大气中随高度增加有小幅下降,但仍可使用这种干涉仪进行大气风速探测。     

基于光子晶体自准直和带隙效应的马赫-曾德尔干涉仪设计

结合能带图和等频图分析,基于光子晶体自准直和光子带隙效应,设计了一种紧凑、高效的全光子晶体马赫-曾德尔(MZ)干涉仪.相应的光分束器和反射镜均由缺陷结构的光子晶体实现.讨论了干涉仪的输出机理,并与时域有限差分法(FDTD)模拟结果进行了比较.结果分析表明可以把MZ干涉仪作为一种气体、液体微型探测器.可在集成光学中起到重要的作用. 关键词： 光子晶体 自准直 MZ干涉仪     

高消光比双通马赫-曾德尔干涉仪梳状滤波器

提出了一种新颖结构的高消光比双通马赫-曾德尔干涉仪梳状滤波器，将常规单通马赫-曾德尔干涉仪的两个输出端与光隔离器连接，构成一个双通马赫-曾德尔干涉仪梳妆滤波器，对滤波器的输出特性进行了理论分析和实验研究。数值模拟表明，与常规的单通马赫-曾德尔干涉仪相比，在相同参量的情况下该双通马赫-曾德尔干涉仪梳妆滤器的消光比得到了大大改善，消光比的提高取决于干涉仪的臂长差，当干涉仪的臂长差为0．7366mm时，消光比提高了20dB。实验结果表明，双通马赫-曾德尔干涉仪梳妆滤器的消光比为25．8dB，消光比提高了13dB。     

基于多芯光纤级联布喇格光纤光栅的横向压力与温度同时测量

提出并制作了一种基于多芯光纤与单模光纤错位构成的马赫-曾德尔干涉仪,将其与光纤布喇格光栅级联,形成的全光纤传感系统可实现横向压力和温度双参量同时测量.马赫-曾德尔干涉仪是利用多芯光纤和单模光纤的模场不匹配而发生模间干涉,当外界横向压力直接作用在多芯光纤内部光场,干涉仪具有较高的灵敏度.实验结果表明:马赫-曾德尔干涉仪压力灵敏度为28.57nm/(N·mm~(-1)),线性度为0.997,而光纤布喇格光栅在一定范围内对压力变化不敏感;马赫-曾德干涉仪和光纤布喇格光栅对温度变化都具有较高的线性度,温度灵敏度分别为56.1pm/℃和11.3pm/℃.对于分辨率为0.02nm的光谱仪,传感器可实现的压力和温度测量分辨率分别为7.0×10~(-4)N/mm和0.03℃.马赫-曾德尔干涉仪的透射谱和光纤布拉光栅的谐振峰对横向压力和温度的变化有不同的光谱响应,利用光谱仪对传感器的透射谱实时监测,方便地实现了压力与温度双参量的测量.该传感器结构简单,灵敏度高,可用于不同领域的压力传感.     

基于马赫-曾德尔干涉仪的单个光子操控

分别利用空间和光纤马赫—曾德尔干涉仪对空间和光纤传输中的单个光子的干涉现象进行了研究,干涉对比度可达到90％以上,实现了空间和光纤中的单个光子的路由操控。实验采用脉冲调制加衰减的方法产生单个光子,获得了每个脉冲中只包含0．1个光子的准单光子源。通过改变压电换能器的电压控制马赫—曾德尔干涉仪的单个光子在两个输出端的选择,实现了光子在节点上的路由。采用同步符合检测技术,利用重复频率为1kHz,脉冲宽度为100ns的同步信号对输出信号进行符合,实现了量子效率高于70％,暗计数小于0．2s^-1的单光子高灵敏度检测,观测到了单个光子在相位操控下出射到两个输出端的有序分配现象。验证了基于马赫—曾德尔干涉仪的单个光子路由操控实现的可能性。     

马赫-曾德尔光纤干涉仪型梳状滤波器优化计算

提出了一种具有方波形输出谱的级联马赫-曾德尔光纤干涉仪型梳状滤波器的优化计算方法。利用传输矩阵法将级联马赫-曾德尔光纤干涉仪的输出光谱表示为显式函数，采用独特的递推方法将理想的梳状滤波器的方波型输出函数展开，当这2个函数的系数对比时，有时候没有精确解，此时利用Matlab，通过特别的优化计算，可以得到级联马赫-曾德尔光纤干涉仪的近似结构参数，使其输出谱近似为方波。设计实例表明：此种优化计算方法非常方便、灵活和有效。     

同时测量温度和曲率的光纤传感器

提出了一种基于光纤布拉格光栅和马赫-曾德干涉仪相结合的同时测量曲率和温度的光纤传感器.该光纤传感器在马赫-曾德干涉仪中熔接一段布拉格光纤光栅,其中马赫-曾德干涉仪由两个花生形结构单模光纤熔接而成.实验结果表明,马赫-曾德干涉仪的透射谱中干涉峰和光纤布拉格光栅透射谱中谐振峰对曲率和温度有不同的响应灵敏度,因此可以利用矩阵实现对曲率和温度的同时测量.实验中测得马赫-曾德干涉仪曲率灵敏度为-27.58nm/m-1,光纤布拉格光栅在一定的测量范围内对曲率的变化不敏感,马赫-曾德干涉仪和光纤布拉格光栅的温度灵敏度分别为0.038 69nm/℃和0.012 17nm/℃.该系统采用全光纤结构,光纤布拉格光栅嵌入到马赫-曾德干涉仪中,因而结构紧凑和简单,且易于实现.     

马赫-曾德尔干涉仪消光比和单通道光开关

对马赫-曾德尔(M—Z)干涉仪的滤光消光比特性进行了研究，提出了一种在其一端加上光纤全反镜的方法，大大改善了马赫一曾德尔干涉仪的输出谱特性，由此提出并设计了一种单通道光开关，实验得到了约37．4dB的开关动态范围。     

Slow Light by Two-Dimensional Photonic Crystal Waveguides

A simple and effective way to measure the group velocity ofphotonic crystal waveguides （PCWGs） is developed by using a fiber Mach-Zehnder interferometer. A PCWG with perfect air-bridge structure is fabricated and slow light with group velocity slower than c/80 is demonstrated.     

Silicon photonic MZI sensor array employing on-chip wavelength multiplexing

In this work, we present a novel wavelength multiplexing concept for an integrated label-free biosensor array employing silicon photonic Mach-Zehnder interferometers as sensors. Microring resonators act as wavelength selective elements in order to address the individual interferometers. Wire Bragg gratings terminate the interferometer arms and reflect the light back, which eliminates the risk of a wavelength mismatch between drop and add port. The characteristics of the device are discussed and the design based on FEM and 3D-FDTD simulations as well as measurements of the nanophotonic key components—micro ring resonators, Mach-Zehnder interferometers and photonic wire Bragg gratings—are presented. Measurements of combinations of the wire Bragg gratings with ring resonators and Mach-Zehnder interferometer sensors demonstrate the applicability of the reflectors in photonic circuits.     

Fiber in-line Mach-Zehnder interferometer constructed by selective infiltration of two air holes in photonic crystal fiber

A fiber in-line Mach-Zehnder interferometer is fabricated through selective infiltrating of two adjacent air holes of the innermost layer in the solid core photonic crystal fiber, assisted by femtosecond laser micromachining. The liquid infiltrated has higher refractive index than that of the background silica, and, hence, the two rods created can support a guide mode with lower effective refractive index than that of silica. The interference is produced by the fiber fundamental mode and the guide mode. The free spectral range (FSR) of the interferometer is found to be dependent on the photonic crystal fiber length, and a large FSR corresponds to a short photonic crystal fiber length. Such an interferometer device is robust and exhibits extremely high temperature sensitivity (～7.3?nm/°C for the photonic crystal fiber length of 3.4?cm) and flexible operation capability.     

Fabrication of a void array in dielectric materials by femtosecond laser micro-processing for compact photonic devices

We describe a systematic investigation on void structures fabricated by femtosecond laser irradiation inside dielectric materials for fabrication of a compact optical circuit. Void shapes fabricated in 5 different dielectric materials were compared and the physical constants determining the void shape were discussed. A long void array is obtainable in a material which has a low critical power for self-focusing. It was also indicated that the coefficient of thermal expansion is a dominant governing factor to fabricate a precise void which has a clear boundary. Furthermore, we propose and design a Mach-Zehnder interferometer in fused silica composed of optical waveguides and photonic crystals to verify practical application of a void array. Simulation results of the optical propagation in a Mach-Zehnder interferometer indicated that the photonic crystals using a void array have potential to fabricate compact optical circuits.     

二维光子晶体非对称Mach-Zehnder自准直传感器研究

基于自准直效应,通过在二维空气柱型光子晶体非对称Mach-Zehnder干涉仪长臂上设置传感区域,设计了一种自准直传感器.平面波展开法确定了入射光的自准直频率范围,时域有限差分法分析了传感器的灵敏度达到68 nm/RIU,采用单频光入射实现了传感模拟.该传感器完全依赖自准直导光,无需引入任何缺陷波导,大大降低了制作工艺要求,其大小只有十几个微米,能够满足超紧凑、高灵敏度、廉价和无标记的要求.     

Mach-Zehnder interferometer formed in a photonic crystal fiber based on a pair of long-period fiber gratings

We demonstrate implementation of an all-fiber Mach-Zehnder interferometer formed in a photonic crystal fiber (PCF). We formed the all-PCF Mach-Zehnder interferometer by mechanically inducing two identical long-period fiber gratings (LPGs) in the PCF. The spectral properties of a LPG and a LPG pair were investigated. The interference fringe formed within the stop band of the LPG pair varied with the period and the strength of the gratings, and the fringe spacing was decreased with increasing grating separation. From the fringe spacing measurement the differential effective group index of the PCF was calculated to be deltam approximately equal to 2.8 x 10(-3).     

Measurement of the photonic de broglie wavelength of entangled photon pairs generated by spontaneous parametric down-conversion

Using a basic Mach-Zehnder interferometer, we demonstrate experimentally the measurement of the photonic de Broglie wavelength of entangled photon pairs (biphotons) generated by spontaneous parametric down-conversion. The observed interference manifests the concept of the photonic de Broglie wavelength. We also discuss the phase uncertainty obtained from the experiment.