Phase-coded microwave waveform generation based on a tunable optoelectronic oscillator

Photonic generation of an arbitrary phase-coded microwave waveform with a tunable microwave carrier frequency using a frequency-tunable optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. The tunable OEO has two functions: to generate a frequency-tunable microwave signal and to output one optical sideband. The optical sideband is injected into a polarization modulator (PolM) jointly with part of the light wave from the OEO laser source, with their polarization directions alighted, respectively, with the principal axes of the PolM. An electrical phase coding signal is applied to the PolM, to generate two complementarily phase-coded light waves which are converted to an electrical signal by the two signals at a highspeed photodetector (PD). The key significance of the technique is that a phase-coded signal with a tunable microwave carrier frequency and a reconfigurable coding pattern can be generated without using a separate microwave source. The technique is experimentally verified. The generation of a binary and quadratic phase-coded microwave waveform with a microwave carrier frequency at 10 and 15 GHz is demonstrated.