An all fiber mid-IR pulse generator is disclosed that may be used to drive an external non-linear converter. The generator comprises fiber laser oscillator and fiber amplifier elements wherein diode lasers are used to cladding pump the different fiber elements depending on different configurations of the pulse generator. Gain switching of the fiber lasers precludes the need for discrete devices such as Q-switches to generate pulses. The fiber laser and fiber amplifier elements are all fused together, along with fiber isolators and reflective gratings, so there is no free space coupling, and there are no optical elements except as may be needed to couple the output of the generator to a non-linear converter. The all fiber implementation has a single transverse mode at the lowest order mode of operation which results in a nearly diffraction limited output which causes non-linear converters to operate more efficiently. To further increase the efficiency of the non-linear converters the fiber laser oscillator has Bragg gratings with a narrow spectral bandwidth of less than 0.5 nanometers.