Frequency comb generation using femtosecond pulses and cross-phase modulation in optical fiber at arbitrary center frequencies

A technique is presented for generating optical frequency combs centered at arbitrary wavelengths by use of cross-phase modulation (XPM) between a fem tosecond pulse train and a cw laser beam by copropagating these signals thr ough an optical fiber. We report results from use of this method to place a 90-MHz frequency comb on an iodine-stabilized Nd:YAG laser at 1064 nm and on a frequency-doubled Nd:YVO4 laser at 532 nm. XPM is verified to be the c omb-generating process, and the width of the frequency comb is measured and compared with theory. The spacing of the frequency comb is compared with t he femtosecond source, and a frequency measurement with this comb is demons trated. (C) 2000 Optical Society of America OCIS codes: 120.4800, 120.3940, 060.4370, 060.7140, 120.0120.