Spectral characteristics of multimode semiconductor lasers with a high-order surface diffraction grating

We have studied the spectral characteristics of multimode semiconductor lasers with high-order surface diffraction gratings based on asymmetric separate-confinement heterostructures grown by metalorganic vapour phase epitaxy (λ = 1070 nm). Experimental data demonstrate that, in the temperature range ±50 °C, the laser emission spectrum is ~5 Å in width and contains a fine structure of longitudinal and transverse modes. A high-order (m = 15) surface diffraction grating is shown to ensure a temperature stability of the lasing spectrum dλ/dT = 0.9 Å K^-1 in this temperature range. From analysis of the fine structure of the lasing spectrum, we have evaluated the mode spacing and, thus, experimentally determined the effective length of the Bragg diffraction grating, which was ~400 μm in our samples.