Effect of cavity length on stripe-geometry DH laser output linearity

We report here a strong correlation between cavity length and the severity of nonlinearities in light-output-vs-current (P-I) curves observed in oxide-stripe geometry (GaAl)As DH lasers. Cleaving kinky long (∼500 μm) lasers results in two or more shorter (150-250 μm) units, all of which show kinks with reduced severity shifted to higher optical power. When cleaved short enough, the lasers show no kinks up to 25 mW. A similar result is seen when comparing units originally cleaved with long or short cavities. An explanation is offered in terms of the difference in lateral mode stability in long versus short lasers.