The angular beam divergence in double-heterojunction lasers with very thin active regions

An analytical expression is found for the angular beam divergence from a double-heterojunction (DH) laser in the limit of an infinitely thin active region. In this limit the beam divergence is proportional to the thickness of the active region and to the index of refraction difference between the active and confining layers. A simple expression combining the limiting expressions for thin and thick active regions gives a very accurate fit to the numerical calculations of the beam divergence for intermediate active region thicknesses.