title: Microwave signal extraction from femtosecond mode-locked lasers with attosecond relative timing drift.
abstract: We present a feedback-control method for suppression of excess phase noise in the optical-to-electronic conversion process involved in the extraction of microwave signals from femtosecond mode-locked lasers. A delay-locked loop based on drift-free phase detection with a differentially biased Sagnac loop is employed to eliminate low-frequency (e.g., <1 kHz) excess phase noise and drift in the regenerated microwave signals. A 10 GHz microwave signal is extracted from a 200 MHz repetition rate mode-locked laser with a relative rms timing jitter of 2.4 fs (integrated from 1 mHz to 1 MHz) and a relative rms timing drift of 0.84 fs (integrated over 8 h with 1 Hz bandwidth) between the optical pulse train and the extracted microwave signal.
authors.affiliation: Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. jungwon.kim@kaist.ac.kr
authors.forename: Jungwon
authors.initials: J
authors.lastname: Kim
authors.forename: Franz X
authors.initials: FX
authors.lastname: Kärtner