Low phase noise microwave extraction from mode-locked Er-fiber laser

In this paper we demonstrated 9.978-GHz microwave extraction from a mode-locked Er-fiber laser with -113 dBc/Hz phase noise at 10 kHz offset frequency. Instead of phase locking loop or direct detection, the extraction was achieved by a delay-matched frequency conversion pair and IF-domain opto-electronic conversion and narrowband filtering. Phase noise suppression as large as 32 dB, compared with the LO, was achieved. Future advantage may include the simple carrier tuning by the external LO.