title: Laser frequency locking with second-harmonic demodulation.
abstract: An external-optical-cavity-based laser frequency-locking method with second-harmonic demodulation was proposed, analyzed, and demonstrated. The second-harmonic component of the cavity output was demodulated to feed back to the frequency-locking loop, resulting in a high sensitivity, great carrier suppression, and large modulation bandwidth. The experimental demodulation curve was consistent with the simulation result. A distributed feedback fiber laser was then locked using this technique. A carrier wave suppression ratio of -67  dB and a laser frequency noise floor of 1  Hz/Hz level above 1 Hz were achieved. This technique has great potential to be used in resonator optic gyroscopes.
authors.forename: Lishuang
authors.initials: L
authors.lastname: Feng
authors.forename: Haicheng
authors.initials: H
authors.lastname: Li
authors.forename: Junjie
authors.initials: J
authors.lastname: Wang
authors.forename: Yinzhou
authors.initials: Y
authors.lastname: Zhi
authors.forename: Yichuang
authors.initials: Y
authors.lastname: Tang
authors.forename: Chenglong
authors.initials: C
authors.lastname: Li