Asymmetric Russian-doll model for semiconductor lasers

We demonstrate that the asymmetry of a high-power laser diode spectrum with its typical blue tail is related to frequency-dependent diffraction losses. A two-dimensional differential near-field analysis shows that the red longitudinal modes exhibit more self-focusing than the blue ones, reducing their diffraction losses, leading to as much as 20% variation of measured filament sizes in the plane parallel to the junction. The topological analysis of the far-field allows us to isolate the higher losses experienced by the blue modes, in agreement with a wavelength-dependent Kerr-lens model.