FMCW light source with a feedback optical phase-locked loop

Abstract

A scheme of frequency linearly swept light source with a feedback phase-locked loop is proposed and demonstrated, which the stability can be significantly improved. By applying the pre-distortion method, the offset phase lock servo generates a control signal to feedback the loop and adjust the frequency of semiconductor laser source, and the frequency-swept signal can be produced. By adjusting the parameters of the offset phase lock servo, a linearly swept light source is achieved with low-frequency noise and improved robustness. In the experiment, a microwave signals with a sweep excursion of 4 GHz and phase noise of 4.6557*10 -7 rad 2 /Hz at 1 kHz have been successfully generated.