Ultra-flat multicarrier light source based on recirculating frequency shift loop driven by a parity–time symmetric optoelectronic oscillator

Abstract

A multicarrier light source based on a recirculating frequency shift loop (RFSL) driven by a parity–time (PT)-symmetric optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. The impact of the side-mode suppression ratio (SMSR) of the radio frequency (RF) signal on the multicarrier is studied for the first time, to our knowledge. The RFSL driven by PT-symmetric OEO significantly optimizes the phase noise and flatness of the multicarrier, facilitating the system miniaturization. In the experiment, a 10.019 GHz RF signal with a SMSR of 42 dB is generated with −98.63dBc/Hz measured phase noise at 10 kHz offset frequency (actual phase noise should be lower than −122.87dBc/Hz). Up to 120 subcarriers with 2.32 dB flatness are obtained successfully, covering the overall bandwidth of approximately 1.2 THz.