An expression for the far field of the fundamental TE0mode in an asymmetrical dielectric slab waveguide is derived. By using normalized waveguide parameters, universal plots of the beamwidth are presented. These plots include the obliquity factor correction. Experimental results for symmetrical GaInAsP lasers at wavelengths near 1.3 μm are compared with theoretical predictions by Buus and Adams. Calculated results for the 1.55 μm wavelength are presented. A numerical method for the calculation of the far field for structures where four or more layers must be included is outlined.