Compact Low-Noise Photonic Microwave Generation From Commercial Low-Noise Lasers

Abstract : We demonstrate how phase-locking a whispering gallery mode-stabilized semiconductor laser to a high-stability Erbium-based distributed feedback fiber laser makes an outstanding optical reference for photonic microwave generation using an optical frequency comb. Using only commercially available compact lasers, it allows generation of a 12 GHz microwave signal with absolute levels of phase noise below-47 dBc/Hz at 1 Hz and-170 dBc/Hz at 50 kHz from the carrier. Index Terms-Phase noise, microwave source, optical frequency comb, distributed feedback laser, whispering gallery mode resonator (WGMR).