High-fidelity all-fiber amplification of a gain-switched laser diode.

We demonstrate a multistage erbium fiber amplifier seeded by a gain-switched laser diode operating at a wavelength of 1550 nm and a repetition rate of 1 MHz. The pulse energy is 0.5 μJ, and the pulse duration is 40 ps, resulting in a peak power of 11.4 kW. The three-stage all-fiber amplifier system is designed to avoid any spectral distortions induced by gain saturation or nonlinear effects and high levels of amplified spontaneous emission. The output pulses are close to transform limited with a Gaussian pulse envelope.