Control of astigmatism in proton isolated stripe aigaas double heterostructure lasers

Astigmatism was measured for proton isolated stripe geometry AIGaAs thin-active-layer (TAL) lasers, for which the proton implant depth was varied. Astigmatism was found to be smallest for deep implants close to the active layer. A semi-empirical model is presented which relates astigmatism to mode width, injected carrier distribution (gain width or spontaneous emission width), lateral dielectric constant variation across the laser stripe (determined from side lobe angle in far field) and active layer thickness. Comparison of experimental results with calculations are sufficiently precise to aid in practical laser design.