An optical S-R latch is demonstrated using two injection locked single-mode (SM) Fabry-Perot laser diode (FP-LD). The S-R latch is based on the bi-stability and injection-locking properties of FP-LD. The latch performs simultaneous inverted and non-inverted outputs in set and reset states. The proposed latch performs very well both in set and reset conditions. The switching times of the latch both for inverted and non-inverted outputs in set and reset conditions were measured by oscilloscope and recorded as about 90 ps. For the latching function, very low powers of set and reset signal were required. Power of set signal was -17 dBm and that of reset signal was -7 dBm.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.