Abstract

For dual comb spectroscopy or asynchronous optical sampling, a signal optical frequency comb (FC) is probed by a second FC serving as a local oscillator [1 2]. The repetition rate of the local oscillator comb, f_rep,1, is slightly offset from that of the signal comb f_rep,2, and the beat between them constitutes a radio frequency (RF) frequency comb, with a repetition rate of Δ = f_rep,1 f_rep,2. In a lab environment, the repetition rate drift can be very slow, so, some early experiments were implemented with non stabilized FCs [2]. However, more accurate measurement requires FCs with stabilized relative repetition rates. The repetition rates of the two FCs can be controlled independently, by locking directly to a microwave oscillator or locking two teeth of each individual FC to two stable continuous wave lasers [1][3]. Here, we report a simplified locking scheme, in which the repetition rate difference, Δ, of two FCs was directly stabilized.

© 2011 Optical Society of America