Wide-bandwidth phase lock between a CW laser and a frequency comb based on a feed-forward configuration

Wide-bandwidth phase lock between the tooth of a frequency comb and a CW extended-cavity diode laser at 1.55 mu m is achieved by the use of an acousto-optical frequency shifter in a feed-forward configuration. The coherence properties of the comb are efficiently transferred to the CW laser, whose linewidth is narrowed down to the similar to 10 KHz comb level. A maximum control bandwidth of similar to 0.6 MHz has been experimentally achieved, limited by the transit time of the acoustic wave inside the frequency shifter. (C) 2012 Optical Society of America