The effect of double heterojunction waveguide parameters on the far field emission patterns of lasers

A model of double-heterostructure lasers is developed which gives the far-field pattern of the laser in terms of such waveguide parameters as the active region width and the dielectric constants of the layers forming the waveguide. For symmetrical waveguides an explicit expression is given. Experimental results are presented which show a close agreement between the theory and the measured far-field patterns. By adding an extra passive layer to the conventional double heterostructure laser a structure is produced in which the measured half-power width of the far-field distribution is reduced from 55° to 32°. It is shown in this case that the model is useful for estimating the near-field pattern from the measured far-field pattern and hence determining the unknown waveguide parameters.