Widely tunable parity-time symmetric optoelectronic oscillator based on a polarization modulator

We here propose a parity-time (PT) symmetric optoelectronic oscillator (OEO) with a wide tunable frequency range. Inside the parity-time symmetric OEO, a polarization modulator (PolM) and a polarization control are incorporated to form a reconfigurable dispersion-induced power fading in a fiber link, due to the adjustable ratio between intensity modulation (IM) and phase modulation (PM). The PT-symmetry breaking further enables a fine mode selection, when following the power fading. Thus, a widely tunable PT-OEO is achieved in the absence of a widely tunable, fine-resolution filter. The frequency of the generated signal can be tuned over a wide frequency range from 16 to 30 GHz, when using a 190-m dispersion compensating fiber. The phase noise is estimated as - 116 dBc/Hz @ 10-kHz offset for the generated signal.