Ultra-stable multi-frequency source injection locked to a spectral-mode-filtered fiber laser comb for terahertz generation

We present a discretely tunable multi-frequency source injection locked to an optical frequency comb (OFC) based on the spectral-mode-filtered femtosecond fiber laser (FSFL). The spectral-mode-filtered OFC (SMFD-OFC) with 1.5 GHz mode spacing was achieved using the spectral-mode-filtering (SMFG) method with a Fabry-Pérot cavity. With the SMFD-OFC as the master laser and two distributed-feedback (DFB) lasers as the slave lasers, we simultaneously selected and amplified the desired modes of the OFC using the injection locking (IL) technique. We then generated a widely separated coherent multi-frequency optical source (CMFOS) that can synthesize in the frequency range from gigahertz to terahertz.