Non-Linear Fiber Amplifier for Shaping the Optical Pulses Emitted by a Gain-Switch Laser Diode

Gain-switch (GS) laser diode can emit ultra-short pulses ranging from few picoseconds to few nanoseconds. The coupling with fibre amplifiers leads to monolithic configurations able to deliver high energy pulses [1]. Compared to mode-lock lasers, GS-based lasers can operate in a wide range of repetition rate not limited by the length of the cavity resonator. Nevertheless, compared with mode-lock lasers the emitted pulses are not as well defined with symmetric Gaussian shapes which is an issue for the subsequent amplifiers and optical modules. The pulses emitted by a GS laser diode are commonly composed of a first spike and a trailing edge Different ways have been proposed to circumvent this drawback based on spectral filtering [2] or by tailoring the electrical pulse driving the laser diode emission [3] or adding a nonlinear loop composed of a SOA and PCF fibre [4]. Here we propose to use the nonlinear properties of an all-fibre Non-linear Amplifying Loop Mirror (NALM) used in transmission to shape the optical pulses of a GS laser complementary to its amplification.