UC Davis

ABSTRACTOptical phased arrays (OPAs), by controlling the phase and/or amplitude of optical emitter structure (e.g., grating coupler, 45-degree vertical coupler), have been widely used in applications such as light detection and ranging (LIDAR), imaging, and free-space communication systems. OPAs in the mid-wave infrared (MWIR) and long-wave infrared (LWIR) regime, therefore, will be a good candidate for realizing thermal or gas-sensing, LIDAR with a lower level of turbulence. Here, based on our previous work, we propose an integrated non-mechanical OPAs-based beam steering system using a germanium-silicon optical platform. In the functional device part, we utilize vertical germanium via emitter and grating emitter arrays at MWIR and LWIR, respectively. Also, considering the fabrication complexity, we are now demonstrating a phase-change-material (PCM) assisted grating emitter to realize MWIR beam steering. Besides, we collaborated with AIM Photonics, demonstrating a large-scale lateral emitter array by foundry-based fabrication. For the light source part, Quantum Cascade Lasers (QCLs) are the only electrically pumped semiconductor light sources that can operate at room temperature over the entire MWIR/LWIR spectral range. We collaborate with other research groups and a commercial company to grow QCL wafers We design the III-V material QCL laser integration part with the germanium-silicon platform, to guarantee the good mode transition between III-V mesa and germanium waveguide. The integrated process will rely on the emerging micro-transfer-printing technology. We have already made some testing preparation work for this fabrication process.