High-frequency noise in the output of DH (AlGa)As injection lasers with different structures and waveguiding mechanisms

High-frequency (0.02-1.8 GHz) noise power measurements of both index- and gain-guided DH (AlGa)As injection lasers were carried out by means of single detector equipment. The index-guided structures include a new diffused index-guided type and some channeled substrate planar (CSP) structures, whereas the gain-guided lasers all have a stripe defined by proton bombardment, but they differ in the width of their stripe ( m) and the depth of the bombardment. From the measurements it was concluded ihat although, generally speaking, index-guided lasers show the lowest intensity noise level, the gain-guided lasers can approach this level, provided that their structure is optimized. The results of some of the various types of lasers studied are compared qualitatively with predictions of McCumber\´s theory.