New class of gain guiding laser with a tapered-stripe structure

A new class of gain guiding laser with a tapered‐stripe structure has been developed which exhibits a linear dependence of light output on cw current, a stable single‐lobe far‐field pattern along the junction at the power level of more than 10 mW, and an amount of astigmatism below 20 μm. It is also shown that a thin active layer thickness is desirable to achieve a stable lateral mode. The main feature of the tapered‐stripe structure is that it offers an additional degree of freedom in controlling the beam spot size and the radius of curvature of the phase front separately, by varying the widths as well as the length of the tapered stripe.