Mode-locked ring lasers and their application in an all-optical flip-flop memory

We demonstrate the generation of picosecond and sub-picosecond optical pulses source by using a semiconductor optical amplifier (SOA) placed in a ring cavity. Sub-picosecond optical pulses are generated by using an SOA and a linear polarizer placed in a passively mode-locked ring-laser configuration. Nonlinear polarization rotation in the SOA serves as the mode-locking mechanism. The ring cavity generates pulses with duration below 800 fs (FWHM) at a repetition rate of 14 MHz. We also demonstrate an all-optical flip-flop based on two coupled identical actively mode-locked lasers. Each ring-laser outputs optical pulses with duration of 3 ps (FWHM) at a repetition rate of 10 GHz. We demonstrate flip-flop operation and regular toggling between the states.