Multi-beam semiconductor laser with separated contacts characterized by

Abstract

This semiconductor laser includes resistors as heating means through insulation films for generating pre-heat of substantially the same calorie as oscillation heat generated when the laser resonator are driven. When the light emitting regions as the light source are driven, first the heating means is actuated to give pre-heat to the laser resonators. After the laser resonators are driven, the heating means is stopped to decrease a calories of the pre-heat. It is preferable that the pre-heat has substantially the same calories as the above-described generated heat, but may be below the generated heat. Specifically, when all of the two laser resonators are driven, the heating means may generate a calories for one laser beam so as to suppress the heat crosstalks due to the mutual influence of the heat generation of the laser beams. In this case, the heating means stops heating only while both laser resonators are being driven, and continues heating in other cases. Thus, whether or not one and/or the other of the light emitting regions is driven, the laser chip has a substantially constant temperature, and temperature changes before and after an actuation is suppressed. As a result, laser beams of uniform output levels can be supplied to the printing unit of a laser printer.