JPS55107286A - Semiconductor laser modulation device - Google Patents

Abstract

PURPOSE:To obtain semiconductor laser output light which does not depend on temperature change, by making new addition of a distributor to a modulation device, distributing a modulation signal using this distributor and supplying thus distributed modulation signals to a controlling unit and a driving unit. CONSTITUTION:A part of output light 3 from a semiconductor laser 2 is received by a light-receiving unit 4, and this output light is converted into an electric signal of voltage or current. Thus converted output is sent over to a controlling unit 5, and an output from here is sent over through an input terminal 61 to a driving unit 6 which supplies the laser 2 with current, and at the same time, a modulation signal from a modulation signal input terminal 7 is impressed onto the controlling unit 5, at this time, the impression is to be made in the following manner, that is, the modulation signal is distributed by a distributor 8 instead of being impressed directly onto the controlling unit 5, and a signal from the 1st output terminal 81 on one side is impressed onto the controlling unit 5 and a signal from the 2nd output terminal 82 on the other side is impressed onto the driving unit 6. In this mechanism, if a time constant of the controlling unit 5 is made sufficiently smaller in value than a time constant of the light-receiving unit 4, all the lights ranging from DC to high frequency are put out the laser 2 irrespectively of ambient temperature.