We present the results of a comprehensive experimental study of the modal behavior of electrically pumped circular grating-coupled surface-emitting lasers with resonant second-order gratings. Our results show stable cylindrical mode operation with azimuthal orders <i>m</i> = 1 and <i>m</i> = 52. We have found that, when a passive, unpumped 0.7-μm-deep indentation is included at the center of the circular resonator contact, the modal behavior becomes more stable with respect to increasing current. This result manifests itself in the lasing of two orthogonal <i>m</i> = 1 modes along with one higher-order mode from threshold to 2.2 times threshold or more. The spatial coherence of the cylindrical modes over the area of the resonator leads to better beam quality. Lasers without passive central indentations exhibit mode hopping between quasi-linear modes and higher-order cylindrical modes as the current is increased.
© 2000 Optical Society of America
(050.1950) Diffraction and gratings : Diffraction gratings
(130.2790) Integrated optics : Guided waves
(140.3300) Lasers and laser optics : Laser beam shaping
(140.3410) Lasers and laser optics : Laser resonators
(140.5960) Lasers and laser optics : Semiconductor lasers
Sigurgeir Kristjánsson, Niklas Eriksson, Anders Larsson, R. Scott Penner, and Mahmoud Fallahi, "Observation of Stable Cylindrical Modes in Electrically Pumped Circular Grating-Coupled Surface-Emitting Lasers," Appl. Opt. 39, 1946-1953 (2000)