Research on optical sideband signal wavefront damage repair technology in optical fibers

Abstract

In response to the technical demands of integrated sensing and communication (ISAC) systems for the sixth generation (6G), this paper addresses the critical issue of optical sideband wavefront distortion in holographic radio receiver and proposes a wavefront self-repair technique based on sawtooth voltage modulation. By using a single-bit analog-to-digital converter (ADC) to capture phase information in real time and constructing a low-complexity closed-loop system with field-programmable gate array (FPGA) and an 8-channel serial digital-to-analog converter (DAC), dynamic monitoring and compensation of inter-channel relative phase errors are achieved. Experimental results show that the $3\sigma$ value of phase error after repair is 6.61°, with a root mean square (RMS) error of 2.20°, meeting the phase control precision standard of $\lambda /10$. By analyzing the phase correlation between the carrier and first-order sideband, we propose an innovative passive control method that enables static phase offset correction between channels without additional components, while reducing reliance on radio frequency (RF) wave control systems. This technique provides an effective solution for wavefront repair and optical beam control in large-scale holographic radio receiver of the future.