Stabilizing Laser Output Light Intensity in Optical Communication Systems in Order to Reduce Source Errors

Nowadays, most optical communication systems use semiconductor lasers as optical sources, but in FSO systems, due to high transmission channel loss, optimum usage of this kind of laser is essential. Increase of bit error rate is not only due to transmission channel losses, but, in some cases it could be due to instability of laser power or drifting of laser characteristics due to aging. Driving semiconductor lasers, monitoring and controlling power and temperature are important aspects of FSO systems. In this paper, a system able to stabilize output light power intensity of semiconductor laser (0.1 percent maximum error) for variable environmental temperature (0 to 50 ̊C) is designed and built.