Femtosecond harmonic mode locking of a fiber laser at 3.27 GHz using a bulk like, MoSe2 based saturable absorber.
We experimentally demonstrate the use of a bulk like, MoSe2 based saturable absorber (SA) as a passive harmonic mode locker for the production of femtosecond pulses from a fiber laser at a repetition rate of 3.27 GHz. By incorporating a bulk like, MoSe2/PVA composite deposited side polished fiber as an SA within an erbium doped fiber ring cavity, mode locked pulses with a temporal width of 737 fs to 798 fs can be readily obtained at various harmonic frequencies. The fundamental resonance frequency and the maximum harmonic resonance frequency are 15.38 MHz and 3.27 GHz (212th harmonic) respectively. The temporal and spectral characteristics of the output pulses are systematically investigated as a function of the pump power. The output pulses exhibited Gaussian temporal shapes irrespective of the harmonic order, and even when their spectra possessed hyperbolic secant shapes. The saturable absorption and harmonic mode locking performance of our prepared SA are compared with those of previously demonstrated SAs that are based on other transition metal dichalcogenides (TMDs) To the best of the authors' knowledge, the repetition rate of 3.27 GHz is the highest frequency that has ever been demonstrated regarding the production of femtosecond pulses from a fiber laser that is based on SA induced passive harmonic mode locking.
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