Frequency-Doubled Phase-Coded Microwave Pulses Generation Based on an Optoelectronic Oscillator

This paper proposes an optoelectronic oscillator (OEO)-based scheme for generating frequency-doubled binary phase-coded microwave pulses. The architecture employs a cascaded dual-polarization quadrature phase shift keying modulator (DP-QPSK) and a polarization modulator (PolM) to generate carrier-suppressed ±2nd-order sidebands and an orthogonally polarized optical carrier. By applying opposite phase modulation to the two polarization components and subsequently converting them into the same polarization state using a polarization controller (PC) and a polarizer, frequency-doubled phase-coded microwave pulses are obtained after photodetection. The operating principle of the scheme is theoretically analyzed and experimentally validated. A 5 GHz OEO signal is successfully converted into a 10 GHz phase-coded microwave pulse without the use of an external electronic frequency multiplier or an additional intensity modulator for pulse carving. Binary phase-coded pulses with coding rates of 0.1 Gb/s and 0.25 Gb/s are experimentally demonstrated. The measured temporal waveforms, recovered phase information, and autocorrelation results agree well with theoretical predictions. The proposed scheme provides a structurally simple and frequency-doubling solution for OEO-based phase-coded microwave pulse generation with reduced system complexity.