Transverse mode selection in large area oxide-confined VCSELs using shallow surface reliefs

Presents results from a comparison between large area oxide-confined VCSELs with and without shallow surface reliefs of different diameters etched in the output mirror. The surface reliefs have diameters of 15.5 and 16.25 /spl mu/m. These are equal to the full width at l/e/sup 2/ and I/l0-intensity, respectively, of the calculated fundamental mode profile of the circular waveguide defined by the 20 /spl mu/m diameter Al-oxide current aperture. The 40 nm deep reliefs increase the cavity loss in the etched regions and introduce mode selective loss for transverse mode selection. To define the reliefs with high precision electron beam lithography and chemically assisted reactive ion beam etching were used.