Supermode behavior of coupled two-stripe AlxGa1−xAs-GaAs quantum-well heterostructure lasers

Abstract

Data are presented on the simplest form of multiple-stripe laser array, a gain-guided two-stripe configuration of wide spacing (∼15 μm, weak or moderate coupling), showing the effects of the two forms of supermode oscillation on the laser’s L-I characteristic, far-field emission pattern, and radiation spectrum. Measurements of the spatial dependence of the gain, at various currents, for a modified (antireflection-coated) two-stripe AlxGa1−xAs-GaAs quantum-well heterostucture laser diode provides a basis for explaining the onset of oscillations of both forms of supermodes (n=1, symmetric or ‘‘even,’’ and n=2, antisymmetric or ‘‘odd’’). These results agree with the significant band filling of the single quantum well and the supermode energy splitting of ∼15 meV in high-level laser operation. The data and results presented are obtained by operating antireflection-coated diodes in a tunable external grating cavity and by taking gain measurements on and between the stripes at the Fabry–Perot facets.