Impact of the effective refractive index in AlGaN-based mid-UV laser structures on waveguiding.

The effective refractive index in optically-pumped 265 nm AlGaN-based lasers is assessed from the spacing of the longitudinal cavity modes in short laser cavities. It is found that the effective refractive index is significantly higher than the value estimated from the Sellmeier equation (n = 2.5) and reaches values of 2.9 and 3.2 for structures with 3 and 15 quantum wells, respectively. These results indicate that the Sellmeier equation underestimates the effective refractive index in AlGaN-based laser structures and that a different approach is needed for successful mid-UV laser modeling and design. [ABSTRACT FROM AUTHOR]