Filaments as optical waveguides in gallium-arsenide lasers

Experimental evidence is given in support of a dielectric-waveguide model for filaments in gallium-arsenide lasers. Measurements of the variation with current of the spectral-mode frequencies of a single-heterojunction gallium-arsenide laser have been carried out both below and above threshold. It is suggested that the frequency shifts above threshold are due to the formation of filaments in the laser. Changes in the far-field pattern support this theory.