Broad emission direction with two lobes is analyzed in a spiral-shaped microcavity laser. By pumping the boundary of the InGaAsP semiconductor laser with dc current injection, whispering-gallery-type modes emitting through a notch are obtained. By classifying the lasing modes into mode groups based on the equidistant mode spacing, it is shown that each mode group has its own emission direction with a narrow divergence angle and that a superposition of emission direction of dominant mode groups reproduces a far-field pattern of total intensity with two lobes, which is contrary to theoretical results.
© 2011 Optical Society of America
Lasers and Laser Optics
Original Manuscript: September 9, 2011
Revised Manuscript: October 15, 2011
Manuscript Accepted: October 15, 2011
Published: November 22, 2011
Myung-Woon Kim, Kyu-Won Park, Chang-Hwan Yi, and Chil-Min Kim, "Analysis of broad emission direction in a spiral-shaped microcavity laser," Opt. Lett. 36, 4503-4505 (2011)