All-optical functions based on semiconductor ring lasers

Semiconductor ring laser (SRL) has been shown to possess robust bistability between its two possible directions, i.e., clockwise (cw) and counter-clockwise (ccw) lasing, routinely demonstrating directional extinction ratio (DER) of 25 dB. In this paper, experimental schemes and results using the SRL as a universal photonic digital element to form all-optical logic, memory, and signal processing circuits are summarized. It is demonstrated that the SRL can be used for both combinatorial and sequential logic functions, and as all-optical regeneration devices. Furthermore, it is shown that a SRL logic circuit can be all-optically reconfigured to perform different all-optical logic functions.