A novel pulse source for low-jitter optical sampling: a rugged alternative to mode-locked lasers

Abstract

A novel low jitter optical pulse source for applications including optical sampling has been modelled and experimentally verified using commercially available photonic components. Dispersion and non-linear fibre effects were utilised to compress a periodic optical waveform to generate pulses of the order of 10-15 picoseconds, via soliton-effect compression. Modelling of variable dispersion fibre indicates that future work will enable pulse compression to sub-picosecond durations. Attractive features of this new pulse source include electronically tuneable repetition rates over a continuous range at frequencies above ~1.5 GHz, ultra-short pulse duration (10-15 ps now, 100's fs planned), and low timing jitter as consistently measured by both harmonic analysis and single-sideband (SSB) phase noise measurements. In addition, the system is inherently robust to thermal effects unlike some low jitter pulse source alternatives, and does not require precise optical alignment. Timing jitter analysis reveals that the optical pulse timing jitter is currently limited by the mid-range specification microwave source used to create the initial periodic waveform. In order to overcome stimulated Brillouin scattering at high launch powers into the compression fibre, phase modulation was applied to the pulse train, and the timing jitter implications of this are discussed. It is believed that this is the first time that detailed timing jitter analysis has been performed on a soliton-effect compression scheme.