Generation of optical frequency combs in optically injected integrated gain-switched semiconductor lasers and their applications in Doppler LIDAR

This paper introduces an optical frequency comb (OFC) source. It is constructed using a monolithically integrated gain-switched semiconductor laser with the optical injection technique. The theoretical analysis of the working principle of this integrated OFC source based on optical injection is carried out. Fabricated <i>via</i> micro-nano processing technology, the proposed OFC source has been experimentally investigated. The results clearly show that the optical injection method can notably increase the number of comb teeth with a higher carrier-to-noise ratio. The measured phase noise of the beat-frequency signal between comb teeth is less than -102 dBc Hz^-1 @ 10 kHz. Moreover, a Doppler velocity-measuring LIDAR system is designed based on this OFC source, and the velocity of a moving target is measured. Compared with single-frequency speed measurement, using multi-comb teeth for speed measurement can significantly reduce the error.