A high precision optical fiber time-delay system

Time-delay technology is widely used in machine vision, optical communication, laser radar (LIDAR), photoelectric detection and other fields. Compared with electric time-delay technology, optical fiber time-delay technology has many advantages under the condition of large delay time, such as high delay accuracy, good delay stability, small jitter, strong anti-electromagnetic interference ability, and less environmental impact, etc. It has attracted much attention in related fields. In order to achieve a larger delay time and a higher delay accuracy, this paper focused on the high-precision CNC (computerized numerical control) optical fiber delay system applied to laser echo simulator. The system consisted of 16 delay fibers, 16 optical fiber jumpers and 17 optical switches. By using binary gated mode, the delay of 0-64553ns was achieved and the laser echo of 0-5km was simulated. Using 10kHz-100MHz modulated laser, the actual length of 16 delay optical fibers was accurately measured by phase method, and the measurement error was less than 28.6mm. Aiming at the problem that the accuracy of long optical fiber cutting was poor in engineering, a compensation method for changing the delay resolution of the system is proposed, so that the delay precision of the whole system is controlled within 0.984 ns. The effects of temperature changes on the refractive index of the fiber and the length of the fiber on the system delay time are analyzed. The experimental device developed can achieve a delay of 0-64553 ns, a delay resolution of 0.984 ns, and a delay measurement accuracy of 0.14 ns. The system has been successfully applied.