Simultaneous Generation of Low-Phase-Noise LO and Reconfigurable Radar Waveforms in a Polarization-Multiplexed Optoelectronic Oscillator

We propose and experimentally demonstrate a polarization-multiplexed optoelectronic oscillator (OEO) that simultaneously generates a Ku-band low-phase-noise local oscillator (LO) signal and X-band high-quality, reconfigurable wideband radar waveforms. The architecture employs a commercial dual-polarization binary phase shift-keying Mach–Zehnder modulator (DP-BPSK MZM), and two orthogonally polarized loops are formed with independently tuned center frequencies defined by electrical bandpass filters. The x-polarized loop generates a Ku-band 14-GHz single-tone LO exhibiting −144-dBc/Hz single-sideband phase noise at a 10-kHz offset. In parallel, the y-polarized loop employs a wideband electrical bandpass filter to generate radar waveforms via either injection locking or active mode locking. Under injection locking, an X-band linear frequency-modulated (LFM) waveform centered at 8.5 GHz with a 2-GHz span (7.5–9.5 GHz) is obtained. Compared with the original LFM signal generated by the arbitrary waveform generator (AWG), the injected waveform benefits from the high-$Q$factor and filtering effect of the OEO loop, leading to a reduction of more than 40 dB in single-sideband phase noise and an improvement of about 20 dB in spectral signal-to-noise ratio (SNR). Active mode locking enables the generation of 9-GHz microwave pulse trains with repetition rates of 100 kHz, 500 kHz, and 1 MHz, exhibiting a phase noise of −144 dBc/Hz at a 10-kHz offset. Furthermore, staggered double- and triple-pulse sequences are realized by injecting position-encoded Gaussian-shaped waveforms from an AWG. These results confirm the potential of the proposed OEO for multifunctional applications in next-generation high-resolution and antijamming radar systems.