Pulse-repetition-frequency-variable mode-locked fiber laser

In this scheme, mode-locking operation was achieved under appropriate conditions. Using a fiber laser, it is easy to construct multiple laser cavities using fiber Bragg gratings (FBGs) for different wavelengths with a specific cavity length coaxially. Therefore, the PRF of the mode-lock pulse train can be changed by varying the acousto-optic tunable filter (AOTF) diffraction wavelength in the fiber laser. The laser diode pump power was 100 mW. Changing the RF frequency applied to the AOTF varied the output power and the wavelength. The wavelength was locked by the reflection spectrum of each FBG, while the broad diffraction bandwidth of the AOTF allowed laser emission other than the RF frequency of the diffraction peak of each FBG. We confirmed the possibility of applying a PRF-variable mode-lock laser with an AOTF to fiber lasers. The output power can be easily increased by constructing a master-oscillator power-amplifier.