Long-term stable balanced optical-microwave phase detector with sub-femtosecond residual timing jitter capability for optical-to-RF extraction

Balanced optical-microwave phase detectors (BOMPD) based on fiber Sagnac interferometers and single-ended heterodyne detection are capable of optical-to-RF conversion with sub-femtosecond residual timing jitter. By increasing the BOMPD phase sensitivity and reducing its internal noise down to the thermal noise limit, we achieve an integrated noise floor in the sub-fs regime. Second, we demonstrate long-term stable optical-RF conversion by phase-locking an RF oscillator to a mode-locked laser using a BOMPD with <;1 fs RMS drift and <;7 fs pk-pk for over 10 hours.