The Current Dependence of the Intensity of Spontaneous Emission of GaAs Injection Lasers to Full Operating Power

Abstract

The current dependence of the intensity of the spontaneous emission from GaAs injection lasers operated at 300 °K to five times threshold is reported. The long-wavelength emission saturates before threshold, while the spontaneous intensity for wavelengths shorter than the lasing emission grows smoothly with no indication of the transit of threshold. At five times threshold the intensity is 2.4 times the threshold value and still growing. Similar behavior was observed with double-heterojunction lasers exhibiting five stripes parallel to the junction in the near field, and with single-heterojunction lasers with a single stripe. It is argued that the behavior of the spontaneous emission is in fundamental disagreement with the linear theory of lasing and that its explanation will require introduction into the rate equations of a strong nonlinearity which controls the lasing region.