提出并实验研究了一种基于铌酸锂薄膜光波导的电光调谐的光栅辅助定向耦合器。该耦合器由单模与双模脊形波导及制作于双模波导侧壁的长周期光栅构成。长周期光栅的引入补偿了单模与双模波导中基模的相位失配，可在共振波长实现两波导中基模的高效耦合。进一步地，在双模脊形波导两侧制作调谐电极实现了高速、低驱动电压的电光调谐功能。优化了器件的制作工艺，并采用单次干法刻蚀将耦合器的光栅与波导同步制作于X切铌酸锂薄膜上。测试结果表明所制作的器件在1 595.3 nm波长处实现了14.8 dB的隔离度，其电光调谐效率为0.38 nm/V（1 595.3 nm~1 599.0 nm），热光调谐效率为0.14 nm/℃（25 ℃~50 ℃）。该器件可用于实现可调谐滤波、滤模、电光调制及高灵敏度温度传感等功能。

为实现模块化相对论速调管放大器功率、频率和相位的在线测量，对紧凑型高定向性高带宽的定向耦合器进行了仿真和实验研究。利用小孔耦合理论和相位叠加原理进行理论分析，设计了一种双孔紧凑型定向耦合器，在此基础上采用主、副波导正交连接，耦合孔沿轴向和角向二维分布的方法，进一步缩短了耦合器的长度。通过电磁仿真对耦合器各参数进行优化，模拟结果表明：当中心频率为10 GHz时，普通双孔定向耦合器对TM₀₁模式的耦合度为−60.68 dB，在250 MHz的带宽内定向性大于20 dB，此时耦合区长度为3.49 cm。改进型定向耦合器对TM₀₁模式的耦合度为−58.1 dB，在300 MHz的带宽内定向性大于20 dB，此时耦合区长度仅为1.8 cm（约0.6λ）。耦合器的冷腔实验测量结果与仿真结果符合较好。

Flexible strain sensors play an important role in electronic skins, wearable medical devices, and advanced robots. Herein, a highly sensitive and fast response optical strain sensor with two evanescently coupled optical micro/nanofibers (MNFs) embedded in a polydimethylsiloxane (PDMS) film is proposed. The strain sensor exhibits a gauge factor as high as 64.5 for strain ≤ 0.5% and a strain resolution of 0.0012% which corresponds to elongation of 120 nm on a 1 cm long device. As a proof-of-concept, highly sensitive fingertip pulse measurement is realized. The properties of fast temporal frequency response up to 30 kHz and a pressure sensitivity of 102 kPa^?1 enable the sensor for sound detection. Such versatile sensor could be of great use in physiological signal monitoring, voice recognition and micro-displacement detection.Flexible strain sensors play an important role in electronic skins, wearable medical devices, and advanced robots. Herein, a highly sensitive and fast response optical strain sensor with two evanescently coupled optical micro/nanofibers (MNFs) embedded in a polydimethylsiloxane (PDMS) film is proposed. The strain sensor exhibits a gauge factor as high as 64.5 for strain ≤ 0.5% and a strain resolution of 0.0012% which corresponds to elongation of 120 nm on a 1 cm long device. As a proof-of-concept, highly sensitive fingertip pulse measurement is realized. The properties of fast temporal frequency response up to 30 kHz and a pressure sensitivity of 102 kPa^?1 enable the sensor for sound detection. Such versatile sensor could be of great use in physiological signal monitoring, voice recognition and micro-displacement detection.

提出了一种小型化双枝节加载的L波段微带线定向耦合器。使用功率相消技术提高定向耦合器的隔离度，并且采用两根长度不同的加载枝节分别在两个相近的频点上反射信号，从而实现耦合器的带宽扩展；同时采用缺陷地结构的慢波特性减小该定向耦合器的物理尺寸，并利用缺陷地结构产生的陷波，合并上述两根枝节反射抵消产生的的两个陷波，进一步提高定向耦合器的带宽和隔离度。该耦合器工作在L波段，耦合度约为10 dB，在整个L波段内的隔离度均优于−20 dB，最大约为−52.81 dB，相对带宽为60%。最后对设计的定向耦合器进行加工和测试，测试与仿真结果一致性较好，证明了该电路的可行性。

High-performance ultra-compact polarization splitter-rotators (PSRs) are designed and experimentally demonstrated, using dual etching and a tapered asymmetrical directional coupler. First, two novel PSRs are designed with nanowire and subwavelength grating cross-port waveguides and verified in simulations. Then, one of the two PSRs is fabricated. Experiment results reveal that the extinction ratio is higher than 28 dB or 32 dB at 1550 nm for the launched fundamental transverse magnetic or the transverse electric modes, while the corresponding insertion loss and polarization conversion loss are 0.33 dB and 0.18 dB, respectively.