High repetition rate gain switched Ho doped fiber laser at 2.103 mm pumped by h shaped mode locked Tm doped fiber laser at 1.985 mm.
We present a MHz level high repetition rate gain switched Ho doped fiber laser at 2.103 mm using a h shaped mode locked Tm doped fiber laser as the pump, for the first time. A NPR mode locked Tm doped ring cavity was designed as the seed, which could generate h shaped pulses at 1.985 mm with a fundamental repetition rate of 1.435 MHz. It had a pump dependent ns scale pulse duration with an almost unchanged peak amplitude. Then its output power and pulse energy were significantly scaled to 3.92W and 2.71 mJ, respectively based on a one stage Tm doped fiber based amplifier. After that, the amplified pulses were fed to a linear cavity Ho doped fiber laser formed by a HR FBG and a perpendicularly cleaved fiber end, resulting in stable gain switched pulses at 2.103 mm with a repetition rate of 1.435 MHz, which marks the record of gain switched fiber lasers in this spectral region. At this repetition rate, the maximum output power of 1.13 W and pulse energy of 0.79 mJ were achieved at a high slope efficiency of 75.4% with respect to its absorbed pump power, giving the shortest pulse duration of 10.8 ns. The results indicated that the h shaped pulses were an alternative choice for high repetition rate gain switching in an all fiber configuration.
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