Wideband Dual-Channel Photonic RF Repeater Based on Polarization Division Multiplexing Modulation and Polarization Control

Radio frequency (RF) repeaters are often used in satellite communication, wireless wideband communication, and electronic warfare systems for signal receiving, forwarding, and processing. Due to frequency-dependent microwave devices, conventional electrical RF repeaters have limited bandwidth and are susceptible to electromagnetic interference. In this article, a dual-channel photonic RF repeater using a polarization-division multiplexing dual-parallel Mach-Zehnder modulator is proposed. The RF repeater is built entirely using optical methods and does not require any frequency-dependent equipment, thus enabling high operating frequency and large operating bandwidth. The modulator is used to perform frequency conversion on the received uplink/downlink RF signals, and the followed polarization controller and the balanced photodetector realize switching of the uplink and downlink RF channels. In the experiment, wide operating bandwidth (1-20 GHz), low channel crosstalk (>33 dB), and a large spurious-free dynamic range (106 dB·Hz^2/3) for the RF repeater are obtained. Also, the channel switching of 16 quadrature amplitude modulation (QAM) RF signals with 200 Mbps data rate is demonstrated, while the adjacent channel power ratio (ACPR), demodulated constellation diagrams, and the error vector magnitude (EVM) are evaluated.