300 attosecond active synchronization of passively mode locked lasers using balanced cross-correlation

Abstract

A balanced cross-correlator, the optical equivalent of a balanced microwave phase-detector, is demonstrated. Its use in synchronization of a sub-10 fs Ti:sapphire laser and a 40 fs Cr:forsterite laser yields 300 attoseconds timing jitter measured from 10 mHz to 2.3 MHz.