Technique to generate equal amplitude, higher-order optical pulses in rational harmonically modelocked fibre ring lasers

A novel technique of pulse amplitude equalisation in higher-order optical p ulses in a rational harmonically modelocked fibre ring laser is proposed an d demonstrated. The combination of intracavity optical filtering, and even- order modulation sideband generation using nonlinear characteristics of a M ach-Zehnder intensity modulator can effectively eliminate pulse amplitude i nstability at higher-order rational harmonic modelocking. The generated opt ical pulse trains exhibit equal amplitudes with a high degree of spectral p urity in terms of a large suppression of supermode noise, low amplitude noi se, phase noise, and tin-ling jitter.