Quantum dot lasers with controllable spectral and modal characteristics

Simple analytical expressions for the shape and width of the multi-frequency lasing spectra of quantum dot lasers are derived by using a parabolic approximation of the gain spectrum. A giant nonlinear gain coefficient of 2.5 × 10^-15 cm³ was estimated from the experimental dependence of the lasing spectrum width on the output power. A monolithic diffraction optical filter was used to suppress lasing of higher-order transverse modes in a quantum dot laser with a relatively broad ridge waveguide. Stable lasing on a fundamental transverse mode is observed with the maximum continuous wave (CW) single-spatial-mode power of 700 mW.