System and method of improving intensity control of laser diodes using back facet photodiode

摘要

A system and method of controlling laser power output levels includes a laser (9) and a control circuit (27) for energizing the laser. A sensor (11) that measures power output from a back facet of a laser element (17) of the laser provides feedback to the control circuit so as to maintain power output from the laser constant. The back facet of the laser element is covered with a coating that has transmission and reflection characteristics that are relatively insensitive to minor changes in the wavelength of the laser. The coating is preferably a thin metallic layer which provides a constant and adequate reflectivity and low transmittance. With the specific metallic layer on the back facet, the transmittance remains relatively consistent even when there is a change in wavelength. This provides for consistent readings at the sensor.