New gratingless wavelength-stabilized laser

Abstract

Described is a novel structure that may overcome problems of standard semiconductor lasers. The laser, is composed of two coupled waveguides, a thick low index waveguide and a lower semiconductor waveguide made with quarter-wave mirrors. The lower waveguide resembles a vertical-cavity structure, however it is optimized at an angle away from normal. At this angle the propagation constant of the semiconductor waveguide matches that of the polymer waveguide at a single wavelength. By pumping only half of the structure only this coupled wavelength can lase. Other wavelengths remain in the semiconductor and are absorbed in the unpumped section. Feedback is provided by a mirror on the polymer on the passive side of the device, and on the semiconductor on the pumped side. The wavelength selectivity of such an asymmetric directional coupler is sufficient to distinguish between longitudinal modes and results in single-mode emission. Furthermore, light can be extracted from the device on the polymer side, where the mode is compatible with an optical fiber. The device should also be capable of high-power operation because the exit aperture can withstand high optical fields.