Coherence of the radiation emitted from single-frequency injection lasers

An experimental investigation was made of the dependence of the coherence length of the radiation emitted from single-frequency GaAs injection lasers on the radiation power and intensity. For intensities of ~0.5×10⁵ W/cm² the emission line became considerably broader. The dependence of the coherence length on the radiation power in the weak-field regime, i.e., for intensities I≪10⁵ W/cm², was used to estimate the upper value of the saturation parameter. The results were in good agreement with the corresponding theoretical predictions.