High-quality pulse compressor for WDM/OTDM applications

The paper reports the results of a high-quality pulse source incorporating a gain-switched laser diode followed by a novel compact two-cascade fibre compression scheme. The pulse compression scheme incorporates a dispersive delay line and a nonlinear pulse compressor based on a dispersion-imbalanced fibre loop mirror (DILM). We analyse and demonstrate for the first time significant improvement of the loop performance by means of the chirped pulse switching. As a result, the DILM provides high-quality nonlinear pulse compression as well as rejection of the nonsoliton component. In the experiment, 20ps pulses from a gain switched laser diode are compressed to a duration of 300fs at a repetition rate in range 70MHz-10GHz. The pulses are pedestal free and transform-limited. Spectral filtering of the output signal by means of a bandpass filter results in generation of wavelength-tuneable picosecond pulses with a duration defined by the filter bandwidth. Alternatively, signal filtering by an arrayed waveguide grating (AWG) results in multichannel picosecond pulse generation for WDM and OTDM applications. The pulse source is built of standard components and is of compact and potentially robust design.