Nonlinear (self-focusing) limitations of output power in semiconductor lasers of various geometries

(Received 23 January 1992, revised 23 April 1992, accepted 19 May 1992)

Abstract
The influence of the configuration of the active region in the semiconductor laser on self-focusing (SF) is considered for bulk, waveguide and non-guide geometries. SF is assumed as the cause of the power limitation for obtaining a high quality laser beam, as it leads to a spatial beam instability and to a profile deformation. The power limits are estimated using one- and two-dimensional models. It is shown that the limit is rather low in the waveguide case but it may be enhanced by designing a non-guide geometry composite device with the active region sufficiently short as compared to a passive gap included in the cavity. A single-pass SF condition and small-scale disturbances are also discussed. For some non-guide geometries the output power is predicted in the multi-kilowatt range before SF occurrence.