针对水下高速无线激光通信发射功率较低，通信距离受限的问题，该研究采用非线性光学中二次谐波理论，将1064 nm的高速外调制与放大技术和非线性晶体的准相位匹配技术相结合，通过光学设计和系统参数研究，设计了一种532 nm的高速大功率无线激光调制发射系统，并建立了基于温度和角度变换的波长转换效率模型。然后通过仿真分析的方法得到了不同温度下，最大转换效率对应的角度范围。最后对系统的性能进行了系统搭建和实验分析，验证了该系统在常温下可实现1 W大功率532 nm绿光无线输出，且频率大于1 GHz的模拟信号和速率大于500 Mbps的数字信号调制。实验结果表明：常温下，该系统输出的光斑光强分布均匀，光束质量显著好于调制后的基频光模式。系统输出的方波信号上升沿宽度和下降沿宽度会发生压缩，但随着脉冲宽度的减小压缩现象会发生收敛，上升沿宽度收敛于0.27，下降沿宽度收敛于0.06，系统输出的正弦信号随着频率的增加没有发生明显的畸变。研究结果可以为未来水下长距离高速无线光通信应用提供理论和技术支撑。

Ⅲ-Ⅴ族半导体波导平台在实现主动和被动器件单片集成上有自身的优势，同时基于Ⅲ-Ⅴ族材料的波长转换器可以通过非线性效应扩展波长范围。设计了一种基于InP/In_1-xGa_xAs_yP_1-y半导体波导平台的加载条状波导，并研究了基于该波导的有效波长转换。通过完美匹配层边界条件下的频域有限元仿真法分析了该波导最佳结构的TE模有效模式面积、非线性系数、有效模式折射率、波导损耗和波导色散。优化InP/In_1-xGa_xAs_yP_1-y加载条状波导的色散，使其满足零相位失配条件，实现了3 dB带宽为35 nm的波长转换，最高转换效率为-26.7 dB。同时，还分析了掺杂系数y、泵浦功率、泵浦波长、波导长度等因素对波长转换中转换带宽和转换效率的影响。InP/In_1-xGa_xAs_yP_1-y加载条状波导展现了优良的波长转换性能，可为全光波长转换的实现提供设计参考。

Modern information networks are built on hybrid systems working at disparate optical wavelengths. Coherent interconnects for converting photons between different wavelengths are highly desired. Although coherent interconnects have conventionally been realized with nonlinear optical effects, those systems require demanding experimental conditions, such as phase matching and/or cavity enhancement, which not only bring difficulties in experimental implementation but also set a narrow tuning bandwidth (typically in the MHz to GHz range as determined by the cavity linewidth). Here, we propose and experimentally demonstrate coherent information transfer between two orthogonally propagating light beams of disparate wavelengths in a fiber-based optomechanical system, which does not require phase matching or cavity enhancement of the pump beam. The coherent process is demonstrated by interference phenomena similar to optomechanically induced transparency and absorption. Our scheme not only significantly simplifies the experimental implementation of coherent wavelength conversion but also extends the tuning bandwidth to that of an optical fiber (tens of THz), which will enable a broad range of coherent-optics-based applications, such as optical sensing, spectroscopy, and communication.

We fully demonstrate the special requirements of a mid-infrared all-optical wavelength converter. The construction mechanism of a 2.05 µm all-optical wavelength converter based on the single-wall carbon nanotube (SWCNT) is proposed. Systematic experiments are carried out, and the converter device is successfully developed. With the assistance of SWCNT-coated microfiber, the conversion efficiency up to -45.57dB is realized, and the tuning range can reach 9.72 nm. The experimental results verify the correctness of the proposed mechanism and the feasibility of the converter device so that it can be a new technical approach for all-optical wavelength conversion beyond 2 µm. We believe the research can extend the application of this composite waveguide in the field of all-optical communication.

Femtosecond laser inscription or writing has been recognized as a powerful technique to engineer various materials toward a number of applications. By efficient modification of refractive indices of dielectric crystals, optical waveguides with diverse configurations have been produced by femtosecond laser writing. The waveguiding properties depend not only on the parameters of the laser writing but also on the nature of the crystals. The mode profile tailoring and polarization engineering are realizable by selecting appropriate fabrication conditions. In addition, regardless of the complexity of crystal refractive index changes induced by ultrafast pulses, several three-dimensional geometries have been designed and implemented that are useful for the fabrication of laser-written photonic chips. Some intriguing devices, e.g., waveguide lasers, wavelength converters, and quantum memories, have been made, exhibiting potential for applications in various areas. Our work gives a concise review of the femtosecond laser-inscribed waveguides in dielectric crystals and focuses on the recent advances of this research area, including the fundamentals, fabrication, and selected photonic applications.

针对当前日盲紫外光通信系统接收端半导体光电探测器对日盲紫外波段不灵敏、响应度较低等问题，提出了一种基于光谱转换以提高信号探测响应度的紫外光通信接收方案。该方案利用二种波长下转化材料（掺Sn-硅酸盐荧光玻璃1和掺荧光染料聚苯乙烯2），通过LED@270 nm激励实现了450~650 nm的可见光探测。实验结果表明，在接收端的雪崩光电二极管窗口前贴附荧光下转化材料后，它对270 nm发射光的探测响应度明显增强；在1 kHz频率调制下，掺杂Sn-硅酸盐玻璃可使探测器的接收响应度提高1.5倍；当光源调制速率低于1.8 MHz时，掺荧光染料聚苯乙烯使得雪崩光电二极管探测器的接收灵敏度提高2倍。本工作在保留紫外光通信特点的情况下，为提高其探测灵敏度提供了一个全新的研究思路和方法。