The ~ffect of lateral carrier diffusion on the modulation response of a semiconductor laser

The e_ff~ct of l_ateral carrier diffusion upon the modulation characteristics of the semiconductor laser ts mvest~gated. ~ self-consistent analysis of the spatially dependent rate equations is performed usmg a fim~e ele_ment model. The transverse junction stripe laser is treated as an exam~le and a co~panson ts made between lateral carrier diffusion and spontaneous emission as dampmg ~echamsms for the resonance peak. Experimental results bear out the conclusion that t?e relaxation_ resonan~e in this device ~s d~mped mainly by lateral carrier diffusion. In addition, a st_mpl~ analyttc result IS presented whtch Illustrates qualitatively the effect of lateral carrier dtffus10n upon such _devices. The conclusion from this result is that lateral carrier diffusion serves to damp_ the relaxatiOn reso~a~ce in the semiconductor laser quite well, but probably will not serve to Improve the upper hmtt on modulation frequency as might have been suspected.