Multimode regime of red laser diodes

Multimode lasing regime of red laser diodes with Fabry-Perot resonator (FP-laser diodes) is considered in the paper. This regime is usual between the areas of single-frequency generation and it is not acceptable for many practical applications. Interest in this issue is associated with the possibility to determine the boundaries of the single-frequency generation regime. It is shown that multimode regime can be realized in differently for different types of lasers. It is found that there are at least two different types of realization of multimode generation. In one case there was a switching of two competing longitudinal modes, in the other case - switching of three modes. Short-time switches of generating mode with following return of lasing regime may occur for a short (about 1 µs) time at almost steady single frequency regime.