Investigation of the width of the emission line of single-frequency GaAlAs injection lasers

An investigation was made of the width of the emission line of single-frequency GaAlAs heterojunction lasers of various types. It was found that the absence of lateral optical confinement resulted in considerable broadening of the emission line. The observed broadening of the emission line of lasers exhibiting a gain-induced waveguiding effect was attributed to an increase in the level of spontaneous background of the modes generated in such lasers.