High-energy square pulses operating in dissipative soliton resonance region are experimentally observed in an erbium-doped figure-of-eight fiber laser with large net-normal dispersion for the first time to our knowledge. The dissipative soliton resonance is achieved by using the nonlinear-amplifying-loop-mirror mode-locked technique. The output pulse duration broadens linearly with the increase of pump power, while the peak power maintains a constant value. At the maximum pump power of 620 mW, the intracavity pulse energy is up to 379.2 nJ, and the average output power is 14.02 mW.

A high power picosecond pulsed Yb fiber amplifier with a pulse repetition rate of 3.7 GHz is experimentally demonstrated. The seed is a gain switched distributed Bragg reflection (DBR) structured laser diode (LD) with a pulse duration of 130 ps and a repetition rate of 460 MHz. The pulse repetition rate is increased to 3.7 GHz by introducing an all-fiber multiplier, which is composed of four 2  ×  2 structured fiber couplers. The multiplied pulse train is amplified to 81 W through two stage Yb fiber amplifiers.

A fiber laser-pumped high-power burst-mode-operated picosecond midinfrared (IR) laser at 3.8 m is reported. A gain-switched distributed Bragg reflector laser diode with a pulse repetition rate (PRR) of 138 MHz and pulse duration around 200 ps was applied as the seed laser of a master oscillator power amplifier (MOPA)-structured Yb fiber laser. The PRR of the MOPA was increased to about 1.1 GHz through a pulse multiplier consisting of four cascaded 2 Â 2 fiber couplers. A fiberpigtailed acousto-optic modulator was used to carve the pulse train into pulse bursts so that the peak power of the final linearly polarized fiber laser output could be optimized by adjusting the duty cycle of the pulse bursts correspondingly. The output of the fiber laser was directed to pump a periodically poled magnesium-oxide-doped lithium niobate-based optical parametric oscillator through the quasi-synchronized pump scheme. Efficient parametric conversion was realized with a maximum average power output of 7.3 W at 3.8 m under pump power of 45 W at 1.064 m with pump-to-idler conversion efficiency exceeding 16%.Index Terms: Optical fiber lasers, optical parametric oscillators (OPOs), periodically poled magnesium-oxide-doped lithium niobate (PPMgLN), quasi-synchronously pumping.

A master oscillator power amplification (MOPA) structured high power sub-nanosecond fiber laser with pulse bunch output is experimentally demonstrated. The seed was a figure-of-eight structured mode-locked fiber laser with a pulse duration of 700 ps and a repetition rate of 2.67 MHz. The seed pulse via two cascaded fiber couplers was multiplied to a pulse bunch, which was composed of 6 sub-pulses. The multiplied pulses were pre-amplified to an average power of 1.5 W through a cladding-pumping fiber amplifier. The pre-amplified laser was further amplified using a 20/125 μm large mode area (LMA) Yb-doped fiber. The laser emitted from the power-amplifier had an average power of 36 W, and a slope efficiency of 72%.