Multiple wavelength light source using an asymmetric waveguide coupler

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Abstract
We obtained multiple wavelength light emission from a coupled waveguide structure formed from a conventional waveguide and a vertical cavity resonator. The cavity and quarter-wave mirrors are optimized to act as another waveguide, thus forming an asymmetric directional coupler. This asymmetry between the waveguide and the vertical cavity causes wavelength selectivity in the cavity light emission. By tapering the cavity, the phase-matched wavelength becomes a function of position, and pumping different regions along the length of the waveguides causes different wavelengths to be emitted from the device. We obtained narrow-band luminescence with a minimum width of 1 nm using a 75-Å quantum well in a GaAs/AlGaAs vertical cavity structure coupled to a low index polymer waveguide.