Monolithic integration of quantum cascade laser, quantum cascade detector, and subwavelength waveguides for mid-infrared integrated gas sensing
Monolithic integration of quantum cascade laser, quantum cascade detector, and subwavelength waveguides for mid-infrared integrated gas sensing
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DOI：
10.1117/12.2508873
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发表时间：
2019-02
期刊：
影响因子：
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通讯作者：
S. Chakravarty;J. Midkiff;K. Yoo;A. Rostamian;Ray T. Chen
中科院分区：
文献类型：
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作者：
S. Chakravarty;J. Midkiff;K. Yoo;A. Rostamian;Ray T. Chen
中红外痕量气体传感是一个发展迅速、应用广泛的领域。尽管CRDS、TDLAS、FTIR等可以提供十亿分之一的灵敏度，并且在某些情况下，可以提供万亿分之一的灵敏度，但是这些系统需要庞大且昂贵的光学元件，并且此外，对光束对准非常敏感，并且具有显著的尺寸和重量，这限制了它们在现场的应用，特别是对于机载或手持平台。需要光源和检测器与光学透明的无源光子平台的单片集成，以实现对振动和物理应力鲁棒的紧凑的痕量气体感测系统。由于所展示的最高效的量子级联激光器（QCL）是在InP平台中，因此选择InGaAs-InP用于无源光子学消除了对昂贵的晶片键合的需要，而硅、锗或GaAs则需要光学吸收键合界面。InGaAs-InP材料平台可以潜在地覆盖整个λ=3-15μm的分子指纹区域。在本文中，我们实验证明单片集成QCL，量子级联探测器（QCD）和悬浮膜亚波长波导在一个完全单片InGaAs/InP材料系统。横向磁极化QCL发射被有效地耦合到下面的InGaAs悬浮膜亚波长波导。除了低损耗紧凑的波导弯曲，悬浮膜架构提供了一个高的分析物重叠与分析物整合。传播的光在所选分析物气体的峰值吸收波长处被吸收，并且转换的信号由集成QCD检测。气体传感将被证明。
Mid-infrared trace gas sensing is a rapidly developing field with wide range of applications. Although CRDS, TDLAS, FTIR and others, can provide parts per billion and in some cases, parts per trillion sensitivities, these systems require bulky and expensive optical elements and, furthermore, are very sensitive to beam alignment and have significant size and weight that place constrains on their applications in the field, particularly for airborne or handheld platforms. Monolithic integration of light sources and detectors with an optically transparent passive photonics platform is required to enable a compact trace gas sensing system that is robust to vibrations and physical stress. Since the most efficient quantum cascade lasers (QCLs) demonstrated are in the InP platform, the choice of InGaAs-InP for passive photonics eliminates the need for costly wafer bonding versus silicon, germanium of GaAs, that would require optically absorbing bonding interfaces. The InGaAs-InP material platform can potentially cover the entire λ=3-15μm molecular fingerprint region. In this paper, we experimentally demonstrate monolithic integration of QCL, quantum cascade detector (QCD) and suspended membrane sub-wavelength waveguides in a fully monolithic InGaAs/InP material system. The transverse magnetic polarized QCL emission is efficiently coupled into an underlying InGaAs suspended membrane subwavelength waveguide. In addition to low-loss compact waveguide bends, the suspended membrane architecture offers a high analyte overlap integral with the analyte. The propagating light is absorbed at the peak absorbance wavelength of the selected analyte gas and the transduced signal is detected by the integrated QCD. Gas sensing will be demonstrated.