Two-dimensional (2D) optical field distribution and the far-field patterns are analyzed for semiconductor lasers with small vertical beam divergence. The discrete spectral index method is used for the analysis and compared with other methods such as the effective index method. The discrete spectral index method is found to be much better in terms of accuracy and computation efficiency for the laser structures studied. Two laser structures with experimental counterparts are studied. The best beam aspect ratio ( <1.5) is achieved using the conventional ridge waveguide process. The calculated results compare very favorably with the experimental results. Simulations also reveal the guidelines for design of symmetric optical beam.