We report a comparison between measured and calculated far field data for an optically pumpedIn0.15Ga0.85N/In0.05Ga0.95Nmultiquantum well laser structure with AlGaN cladding layers. Optical pumping of the semiconductor device was performed with a pulsed 337 nmN2laser, whose beam was focused to a narrow stripe. A thin upper cladding layer allowed efficient pumping of theIn0.15Ga0.85N/In0.05Ga0.95Nlaser structure. Despite high distributed cavity losses of at least30 cm−1,and although gain occurred in the small active region only, the seventh order transverse mode was supported in a waveguide formed by the entire 5-&mgr;m-thick epitaxial layer structure. Excellent agreement is demonstrated between measured and calculated far field patterns of the lasing mode. ©1997 American Institute of Physics.