Optical flip-flop based on two-coupled mode-locked ring lasers

We report an all-optical flip-flop that is based on two coupled actively mode-locked fiber ring lasers. The lasers are coupled so that when one of the lasers lases, it quenches lasing in the other laser. The state of the flip-flop is determined by the wavelength of the laser that is currently lasing. The concept of the flip-flop is explained and experimental results are presented that indicate a flip-flop operation over 25-dB contrast ratio and less than 0.3-mW switching power.