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

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.