TY - JOUR AU - R. Shelton AU - L.-S. Ma AU - Henry Kapteyn AU - Margaret Murnane AU - John Hall AU - Jun Ye AB - Two independent mode-locked femtosecond lasers are synchronized to an unprecedented precision. The rms timing jitter between the lasers is 4.3 fs observed within a 160Hz bandwidth over tens of seconds, or 26 fs within a 50 kHz bandwidth. Novel multi-stage phase-locked loops help to preserve this ultrahigh timing resolution while setting on arbitrary delay between the two pulse trains (0±5 ns). Under such synchronization, phase locking between the carrier frequencies of the two femtosecond lasers has been achieved. It is also demonstrated that the same level of synchronization can be achieved with two lasers at di€ erent repetition frequencies. BT - Journal of Modern Optics DA - 2002-03 DO - 10.1080/09500340110088533 N2 - Two independent mode-locked femtosecond lasers are synchronized to an unprecedented precision. The rms timing jitter between the lasers is 4.3 fs observed within a 160Hz bandwidth over tens of seconds, or 26 fs within a 50 kHz bandwidth. Novel multi-stage phase-locked loops help to preserve this ultrahigh timing resolution while setting on arbitrary delay between the two pulse trains (0±5 ns). Under such synchronization, phase locking between the carrier frequencies of the two femtosecond lasers has been achieved. It is also demonstrated that the same level of synchronization can be achieved with two lasers at di€ erent repetition frequencies. PY - 2002 SP - 401 EP - 409 T2 - Journal of Modern Optics TI - Active synchronization and carrier phase locking of two separate mode-locked femtosecond lasers VL - 49 SN - 0950-0340 ER -