OPTIC VARIABLE DELAY CIRCUIT

摘要

PURPOSE:To enable the emission of laser light by a semiconductor laser to be delayed by a variable period of time by utilizing the fact that the delayed time depends on bias current applied thereto, and to provide an optical variable delaying circuit having decreased dimensions and capable of setting the delay time easily at any desired value by utilizing a laser array. CONSTITUTION:An optical signal entering into a photo detector PD 1-1 in a channel 1 is converted into an electric current. This current is applied as bias current to a semiconductor layer LD 2-1, and the laser initiates emission of light after a delay of time required for the injected carrier density to exceed a threshold value. Light outputted from the back of the laser is inputted to a photodetector PD 1-2 in the next channel by means of a photocoupler 3-1. That channel is thereby caused to initiate laser oscillation after a certain delay of time given by a semiconductor laser LD 2-2. In this manner, the channels in a laser array successively output laser light by each channel, while laser light outputted from each channel is given a delay of time accumulatively by each semiconductor laser LD.