The optical phased array (OPA) chip is becoming the core component of all-solid-state lidars. In order to realize the wide-angle range beam scanning and rapid control of OPA-based solid-state lidars, we design and fabricate a 64-channel silicon-based OPA chip based on thermo-optical modulation. In accordance with the optical phase control characteristics of the multichannel thermo-optic OPA chip, we propose a parallel random access memory (RAM) array technique to realize high-speed phase control for the OPA chip and build the hardware system with a field-programmable logic gate array (FPGA). This system is used to test the main performance indicators of the OPA chip and realizes the high-speed scanning control of the wide-angle range of the OPA output beam. The test results show that the OPA chip we designed can achieve fast beam scanning within a large angle range between −32.5° and +32.5°, and the chip has high working reliability. Combined with the control system we build, it can meet the high-speed radar scanning requirements of all-solid-state lidars. This work lays a good foundation for the subsequential development of our thermo-optical and electrooptic OPA all-solid-state lidar prototypes.

Optical communication modulation technology and networking technology are two important technologies for constructing free-space optical (FSO) communication. In this paper, pulse width modulation (PWM) is used to realize free-space optical communication. The process of signal modulation and demodulation is implemented by means of a field programmable gate array (FPGA). An optical communication relay system is constructed to realize communication networking. The binary data bits in the communication process are converted into pulse signals of different widths, the data demodulation process is realized by sampling with a high-speed analog-to-digital converter (ADC), the data level is determined by counting the proportion of high and low voltages sampled in a pulse period. The relay system analyzes the routing target after receiving the pulse signal from the transmitter, and then sends the data to the target receiver. The experimental results show that the constructed system can achieve point-to-multipoint free-space optical communication. Additionally, using ADC to demodulate the received signal increases the stability of the free-space optical communication system. This system provides the design prototype system of FSO communication networking technology.

Traditional free-space laser communication systems use beacon and signal lights for target detection and alignment. However, these approaches are inaccurate owing to signal dispersion errors. To overcome this difficulty, we propose a new method using transient radio frequency (RF) signals to achieve highly accurate target detection and alignment. To validate the feasibility of our proposed method, we built an experimental multi-target space-laser communication system based on a rotating double prism and applied it to achieve multi-target space-laser communication. The results demonstrate the efficiency of the proposed method to capture multi-target positions in the field of view using wireless RF signals and a rotating double prism. In addition, we show that the system is capable of rapid scanning and accurate pointing as well as establishing a one-way stable communication with multiple targets. When the target is 36 cm away, the pointing accuracy of the system motor is less than 0.8°, the pointing time is 1.2 s, and the average pointing lateral error is 0.666 mm.

We propose a pulsed laser ranging method based on a multiecho delay trigger, which improves the precision of pulsed laser ranging. A signal delay unit is used to accurately delay the pulse-echo signal. In a fixed time window, the echo delay pulse triggers the laser transmitter to generate pulsed laser light; meanwhile, the counter records several echo pulses received, and then, the actual distance can be calculated. In terms of improving the ranging precision, this method overcomes the essential of higher time resolution time-to-digital converter (TDC) chip in traditional time-of-flight (TOF) pulsed laser ranging. The method can be realized by using a field-programmable logic gate array (FPGA) chip, a delay unit, and a set of laser transmitters and receivers, which makes the system structure simple and low cost. Experimental results show that this method can achieve more accurate distance measurement and significantly reduced error, to the best of our knowledge, which improves the pulsed laser ranging from centimeter- to millimeter-order precisions. We believe that this method has a promising application prospect in the field of high-precision pulsed laser ranging of fixed targets.