Strain-compensated multiple quantum well laser structures

摘要

Semiconductor laser structures utilize strain-compensated multiple quantum wells as the laser gain medium to greatly increase the gain and substantially reduce mirror reflectivity constraints in long wavelength (1.3 and 1.55 mu m) surface emitting, and other, lasers. The strain-compensated multiple quantum well structures include a plurality of quantum well barrier layer pairs with each quantum well layer being placed under strain and each barrier layer being placed under an equal and opposite strain so that the net overall strain on the quantum well structure is zero. As a result, it can be made as thick as necessary for the lasers to operate efficiently at long wavelengths. Each of the quantum well layers are also preferably p-doped to further increase the optical gain. Another embodiment of the present invention employs the strain-compensated multiple quantum wells in combination with grating-coupling in a surface or edge emitting laser. The gratings are formed on top of the multiple quantum well structure to simplify the fabrication process, and are provided with strong light coupling characteristics to reduce the overall width of the laser structure to as low as 10 microns.