近年来，中红外（波长范围2~20 μm）集成光子学因其潜在的应用场景如吸收光谱、热成像、自由空间光通信等而受到了广泛的关注。中红外波段包含了多个大气透明窗口，有着作为气体传感应用的先天优势，并且得益于近红外成熟的器件设计测试流程与微纳加工技术，一些近红外的应用也能够较快地拓展至中红外波段。此外，集成光子器件在一些传感应用中不仅可以做到媲美传统设备的灵敏度，同时还具有低功耗、低成本、结构紧凑，易于与其他设备集成的特点。因此，中红外集成光子传感器件在未来将会在工业检测、科学研究、医疗诊断、**安防、民用生活等领域中不断发挥出重要的作用。文中对中红外传感系统的三个主要部分：传感单元、光谱仪和探测器做出了简要介绍，展示了目前中红外集成光子传感器件的研究进展，并对其未来发展做出了展望。

Silicon has been the material of choice of the photonics industry over the last decade due to its easy integration with silicon electronics, high index contrast, small footprint, and low cost, as well as its optical transparency in the near-infrared and parts of mid-infrared (MIR) wavelengths (from 1.1 to 8 μm). While considerations of micro- and nano-fabrication-induced device parameter deviations and a higher-than-desirable propagation loss still serve as a bottleneck in many on-chip data communication applications, applications as sensors do not require similar stringent controls. Photonic devices on chips are increasingly being demonstrated for chemical and biological sensing with performance metrics rivaling benchtop instruments and thus promising the potential of portable, handheld, and wearable monitoring of various chemical and biological analytes. In this paper, we review recent advances in MIR silicon photonics research. We discuss the pros and cons of various platforms, the fabrication procedures for building such platforms, and the benchmarks demonstrated so far, together with their applications. Novel device architectures and improved fabrication techniques have paved a viable way for realizing low-cost, high-density, multi-function integrated devices in the MIR. These advances are expected to benefit several application domains in the years to come, including communication networks, sensing, and nonlinear systems.

A mode transformer based on the quasi-vertical taper is designed to enable high coupling efficiency for interboardlevel optical interconnects involving single-mode polymer waveguides and standard single-mode fibers. A triangular region fabricated above the waveguide is adopted to adiabatically transform the mode from the fiber into the polymer waveguide. The effects of the geometrical parameters of the taper, including width, height, tip width, etc., on the coupling efficiency are numerically investigated. Based on this, a quasi-vertical taper for the polymer rib waveguide system is designed, fabricated, and characterized. Coupling losses of 1.79 _ 0.30 and 2.23 _ 0.31 dB per coupler for the quasi-TM and quasi-TE mode, respectively, are measured across the optical communication C and L bands (1535 to 1610 nm). Low-cost packaging, leading to widespread utilization of polymeric photonic devices, is envisioned for optical interconnect applications.