Heterostructure CdS/sub 1-x/Se/sub x/--CdS surface lasers for integrated optics

Heterostructure CdS1−xSex−CdS surface lasers which have a larger refractive index and a smaller band gap than CdS substrates were fabricated by vapor phase epitaxy and their laser characteristics at 80 K were studied by using a nitrogen gas laser excitation. The Se profiles which were deduced from the fluorescence wavelength were steplike but graded due to diffusion. The optical gain of the epitaxially grown surface layer was larger than that of CdS single crystal owing to optical confinement. By stripe geometry excitation, an intense axial single−mode output was observed up to the excitation intensity three times as high as the threshold 70 kW/cm2. Optical coupling between the active and passive layers was observed in the samples which have a double epitaxial layer.