Pulse on demand fiber laser with passive gain control

One of the hallmarks of a versatile laser is the ability to generate pulses on demand. In this work, we demonstrate a self-stabilizing pulse on demand fiber laser with passive gain control through an implemented gain-clamped oscillator that generates an idler beam that is filtered out from the amplifier output. The amplification gain is defined by the losses in the oscillator, while the pump power determines the maximum repetition rate for stable amplification. The temporal dynamics of the system are analyzed in the context of gain switching theory to determine the maximum frequency at which the stable amplified pulses can be obtained at the output. As a proof of principle, the range from single pulses to repetition rates over 100 kHz is demonstrated with constant pulse energies. For arbitrary seeding of gain clamping oscillator, a laser diode-based seeder with a pulse duration down to 60 ps and repetition rates of up to 200 MHz is used. The high temporal resolution of the seed is also used to investigate the temporal dynamics of the population inversion in the gain clamped amplifying fiber after a single pulse passage. The presented approach is suitable for fiber preamplifier systems where low power signals consisting of arbitrarily spaced pulses need to be amplified to an appropriate level prior to high power amplification.