Measurement of spatial modes of broad-area diode lasers with 1-GHz resolution grating spectrometer

A 1-GHz resolution double-pass grating spectroscopy of broad-area diode lasers is performed. Measurements of spatial and spectral distribution of emitting power are performed as a function of pumping current. Results are confronted with the mode structure of gain-guided waveguide. Nonlinear coupling of lateral modes has been observed and quantified.