熔锥型光纤耦合器的扭转响应

对熔锥型光纤耦合器进行了扭转响应研究.通过放置在耦合器一端的旋转装置对未封装的熔锥型光纤耦合器耦合区施加扭转作用.实验表明:耦合器的耦合比不但对扭转作用敏感,而且变化呈单调性;同时耦合器的附加损耗和工作波长不受扭转作用影响,并且这种扭转操作具有可重复性.通过扭转操作能够对生产出来偏离预定耦合比的耦合器进行调整,使之符合产品要求,提高生产效率.     

一种硅基SiO2波导耦合器的设计与分析

波导耦合器是组成光纤传感系统和光纤通信系统光收发组件及模块的重要元器件,是实现光收发模块一体化光电集成的基础。给出了一种用光纤陀螺系统的X型四端口波导耦合器的工作原理,采用有效折射率法和BPM(Beam propagation method)法建立了耦合器的数学模型,计算并分析了耦合器尺寸在尽可能小的情况下和在满足单模传输的条件下耦合器的耦合系数、有效耦合长度、分光比以及回波损耗等参数之间的关系,并对其关键技术进行了系统的研究。仿真结果表明,所设计的波导耦合器在低损耗情况下分光比可达到50%∶50%,耦合器全长为33.5mm,输入输出波导间距为410μm,芯层截面积为6μm×6μm。     

用于光纤光栅解调的波长敏感光纤耦合器

为了拓宽光纤耦合器的使用范围,开发光纤耦合器的新功能,采用熔锥技术制作波长敏感耦合器,该耦合器在分光的同时对波长敏感。通过耦合理论验证实验结果,实验数据与理论值相符合。实验中得到波长灵敏度最大值为17.86%/nm的耦合器。采用拉锥工艺制作波长敏感耦合器工艺简单,耦合比峰值对应波长控制易于实现。该耦合器可用于光纤光栅布拉格波长漂移解调。令待解调光纤光栅布拉格波长与耦合器波长灵敏度最大值对应的波长一致,当波长发生漂移时,耦合器输出耦合比发生变化。自制的波长敏感耦合器实现了对布拉格波长为1566.71 nm光纤光栅波长漂移的解调,波长漂移1.80 nm,耦合比变化20.34%。此种解调方式具有光路简单,易于与光纤匹配的优点,可以应用在大型建筑中光纤光栅的健康监测。     

基于光纤环形腔光数据包循环复制的实验研究

通过实验研究了利用不同分光比耦合器构成的光纤环形腔实现光数据包循环复制的效果，并理论分析了影响复制效果的结构因素。耦合器分光比、光纤环形腔中的损耗和噪声对复制效果有不同的影响。光纤环形腔中光放大器、滤波器的加入，以及光脉冲直流基座的降低，可以明显改善输出的幅值和复制序列长度。但实验显示，接近等幅复制的光放大会引起光纤环形腔的自激。在这一情况下，在输出端增加饱和半导体光放大器（SOA）可提高复制信号的识别效果。     

匹配液的折射率对光纤定向耦合器分光比的影响

本文从理论和实验二个方面研究了光纤定向耦合器中使用不同折射率的匹配液对其分光比的影响。做出了分光比在1/1～1/30之间变化的光纤定向耦合器。     

耦合器分光比的精确控制

利用矩形近似理论对用熔锥法制作的耦合器分光比进行了分析。结果表明,影响分光比的主要因素为耦合区长度。给出了两者间变化的理论公式,并在实验中得到了证实。CorningSMF28光纤耦合器分光比随耦合区长度变化的实验值为0 04%/μm,实验值与理论值基本一致。通过调节耦合区长度,得到了精确的50∶50分光比的光纤耦合器。     

Y型熔锥光纤耦合器的应变响应

本文对已广泛应用于光纤通信或作为光纤传感系统中处理元件的Y型单模熔锥光纤耦合器对应变的响应进行了研究.在悬臂梁上进行的应变实验表明,该型耦合器的耦合比不但对应变敏感,而且有单调性.其中,值得注意的是Y型耦合器的应变响应灵敏度高于结构检测中常用的电阻应变片对应变的响应灵敏度.     

熔锥型保偏光纤耦合器分光比的偏振依赖研究

实验研究了熔锥型保偏光纤耦合器分光比随入射单色线偏振光偏振方向的旋转所呈现的周期性,验证了保偏光纤耦合器分光比的偏振依赖特性.借鉴已成熟的单模光纤耦合器的倏逝场耦合模理论,对这一偏振依赖分光比的周期性规律提出了一种理论解释.在实验结果的规律性基础上,经验拟合出了分光比与单色线偏振光输入偏振角的函数关系.     

光纤环形腔激光器输出特性的研究

对由不同长度的掺饵光纤、不同分光比的耦合器构成的光纤环形腔激光器的输出特性进行了实验研究。通过理论与实验分析,得出了激光器的输出功率、斜率效率与掺铒光纤的长度、耦合器的分光比有关,而且存在最佳值的结论。     

分光比可调的光子晶体光纤耦合器

实验研究了一种磁流体包覆的光子晶体光纤耦合器,其分光比可由磁场在线调节。实验结果表明,耦合器耦合区的尺寸越小,其分光比随磁场的变化越敏感。在外磁场强度为0~14mT时,耦合区尺寸为27μm的耦合器分光比随磁场强度线性变化的灵敏度为0.0289mT~(-1)。耦合器耦合区尺寸越小,环境温度对分光比的影响越强。对于实际应用的耦合器,应综合考虑分光比的磁场调谐特性及温度响应特性,选择合适参数的光子晶体光纤耦合器。     

Tunable photonic crystal fiber coupler based on a side-polishing technique

A tunable photonic crystal fiber (PCF) coupler, which couples part of the optical power in one PCF with that in another PCF, has been made by side polishing. We fabricated the PCF coupler by mating two side-polished PCFs. We achieved evanescent field coupling between the core modes of the two PCFs by using side polishing to bring the cores close to each other. By adjusting the mating angle between the two side-polished PCFs we obtained as much as 90% tunability in the coupling ratio. The spectrum of the coupling ratio was almost flat, with small ripples, over a 400-nm wavelength range.     

Fabrication of an optical fiber reflective notch coupler

A method of fabricating a reflective notch coupler in an optical fiber has been developed. The coupler consists of a 45° microprism that penetrates into the core of a multimode optical fiber. One face, at 90° to the fiber axis, is nonreflective, and one face, at 45° to the fiber axis, is reflective. Our method of fabricating a notch and selectively mirroring only the 45° face is low-cost, precise, and easily scalable. The coupler allows near-100% coupling of light into an optical fiber from the side, while allowing coupling of any desired fraction of light out from the core at a 90° angle on the opposite side of the fiber.     

Fabrication of all-solid photonic bandgap fiber coupler

We report the fabrication of a tunable all-solid photonic bandgap fiber coupler based on the side-polishing technique. This device is believed to be the first demonstration of a photonic bandgap fiber coupler to eliminate the contamination of the open air holes. By adjusting the length of the interaction section, the tunable coupling ratio as much as 92.5% at 1550 nm is achieved. The investigation of the spectrum properties shows that the coupler has excellent tunability properties, for which the coupling ratio can be smoothly and continuously controlled.     

Fiber grating couplers for silicon nanophotonic circuits: Design modeling methodology and fabrication tolerances

Silicon nanophotonic circuits can exhibit a very high level of functional integration due to the very small cross sections of the silicon waveguides. However, to be implemented in data transmission networks, such circuits still must be interfaced with optical fibers having much larger dimensions. Due to this mismatch in size, a coupling structure is required in order to minimize the coupling loss. Diffraction grating coupler structures are one of the best candidates to perform this mode size conversion with good performances. However, they are also very sensitive to fabrication tolerances that may require an adaptation of the coupling conditions. In this paper, we present an iterative numerical method to optimize the design of a grating coupler by analyzing the out coupled beam from the waveguide towards the fiber. Using this method we show in details the sensitivity of the grating couplers to the principal fabrication variabilities in order to maximize the robustness of the design. A grating with 53% fiber to waveguide coupling efficiency is designed. Considering the dispersion of the modern CMOS fabrication processing, it appears that the optimal fiber coupling ratio remains rather constant but the optimal coupling angle at a given wavelength may vary by as much as ±10°.     

Development of single mode fiber coupling coefficient using kinetic model

We propose a simple kinetic model that can be used to improve the coupling coefficient value of a single mode fiber coupler in the fabrication process. The proposed model is time independent, where the internal and external parametric functions are included. The simulation is integrated over the coupling ratio range for the various fiber separations. The coupling coefficient value of the device is examined by using the coupling ratio range from 1% to 75%. The result obtained is compared with the experimental results, where it is noted that the separation of fiber cores significantly affects the coupling coefficient, exhibiting exponential behavior. We also found that the coupling coefficient gradient is significantly changed with respect to the coupling ratio. This model can be used to determine power losses of the fiber coupler at the coupled region, while the fabrication of the fiber coupler is operated.