Biograph: Dr. Wangzhe Li is currently the head of the National Key Lab of Microwave Imaging Technology, Aerospace Information Research Institute (AIR). He graduated from University of Ottawa as a PhD in 2013. Dr. Li did his postdoctoral research in Prof. Jianping Yao’s group in University of Ottawa and in Prof. Larry Coldren’s group in UCSB until the end of 2015. Then Dr. Li joined IECAS with the support of the “100 Talent Project of Chinese Academy of Sciences” and was entitled to "1000 Plan Program for Young Talents" (2017). Dr. Li’s major research interests include microwave photonics, photonic integrated circuits, photonic-assisted radar and its applications. Dr. Li has published over 60 papers in peer-reviewed journals. In 2017, Dr. Li’s group develop the first prototype of a microwave photonic radar of China and successfully obtained the ISAR and SAR imaging through a series of field trials.

Title: Microwave photonic radar

Abstract: In the past few decades, photonic techniques have been intensively studied to improve the capabilities of modern radar systems, such as large bandwidth, low loss transmission and electromagnetic immunity. In our previous works, a microwave photonic synthetic aperture radar (SAR) is developed and experimentally demonstrated. In the transmitter, microwave photonic frequency multiplication is used to generate a linearly-frequency-modulated (LFM) radar signal; while in the receiver, photonic stretch processing is employed to receive the reflection signal. The presented system operates in Ku band with an instantaneous bandwidth up to 5 GHz, and is vehicle-mounted for a series of SAR and inverse SAR imaging tests in the field trial. A SAR image of the ground surface is obtained through motion compensation and imaging algorithms, achieving a high two-dimensional resolution of 3 cm (range) × 4 cm (cross-range). Furthermore, a microwave photonic dual-band radar operating in C-band and Ku-band is proposed with photonic-assisted stretch receiving. In the receiver, the echoes and reference signals of C-band and Ku-band are applied to two parallel pairs of sub-modulators, which are biased at the peak points and null points respectively, resulting in two stretched signals with different frequencies. Thus operation in dual-band based on a unified system is achieved. An experimental demonstration in C-band and Ku-band with a bandwidth of 850 MHz and 3600 MHz is conducted. The above works show the potential of photonic technique to overcome the conventional radar bandwidth bottleneck and promote the performance of modern radar systems, which can be further applied in target recognition and earth observation.