Analysis of beam properties in the neighbourhood of a double-heterostructure laser source

The power density distribution and beam characteristics of double-heterostructure lasers with very thin active layers in the neighbourhood of the light source are evaluated by using a plane wave spectrum approach and a second-moment order theory for diffracted scalar light beams. It is shown that the evanescent waves contribute to shape the power density when the distance is smaller than the emission wavelength lambda or of the order of lambda. It should be noted that the optical fields deeply penetrate into the cladding layers when the thickness of the active layer is much smaller than the emission wavelength lambda.