Tapered Thickness Quantum Well Semiconductor Laser
Original Publication Date: 1988-Dec-01
Included in the Prior Art Database: 2005-Feb-15
In the proposed quantum well (QW) GaAs laser the peak optical power output is increased in that the optical absorption near the mirror facets is greatly reduced by increasing the effective bandgap. This is accomplished by growing the structure on a varying-width ridge. The resulting tapered-thickness quantum well provides the desired effective bandgap increase in the mirror regions. The design of the laser structure is based on the observation that, when growing GaAs or AlGaAs on a ridge-patterned substrate in a molecular beam epitaxy (MBE) system, Ga preferentially diffuses from the (m11A) edges of the ridge onto the top (100) plane of the ridge during growth. This increases the GaAs growth rate and reduces the AlGaAs mole fraction for structures grown on narrow ridges whereas the effect is much smaller on wide ridges.