Hybrid LiDAR–radar at 9 μm wavelength with unipolar quantum optoelectronic devices

Unipolar quantum optoelectronics is emerging as a promising semiconductor platform for developing mid-infrared applications, particularly spectroscopy and free-space communications. In this work, we present a proof of principle of a unipolar quantum optoelectronic hybrid Lidar – Radar for the measurement of the position and speed of a moving target. The system operates at 9 µm wavelength and is composed of a quantum cascade laser, a Stark modulator and a metamaterial quantum well infrared photodetector. The laser amplitude is modulated with a chirped radio-frequency subcarrier, and the backscattered light is detected coherently on the metamaterial quadratic receiver. With our system we have measured a ranging distance of 150 cm with an intrinsic resolution of 15 cm. Our demonstration is a first milestone towards combined communication and ranging systems in a transparency window of the atmosphere.