Discretely Tunable Optical Frequency Synthesizer Utilizing a Femtosecond Fiber Laser Injection-Locking Technique

In this letter, we propose a discretely tunable optical frequency synthesizer (DTOFS) based on distributed-feedback (DFB) lasers that can be selectively injection locked to a desired single mode of the femtosecond fiber laser comb. The methods for the injection locking, the monitoring of the lock status, and the selection of the desired comb mode are given. We demonstrate the discrete tunability of the DTOFS by constructing two frequency-stabilized DFB lasers, both of which are injection locked to a respective single mode of the fiber laser comb with the frequency difference, which is an exact multiple of the comb repetition frequency.