Optimization of MQW structure in 630 nm AlGaInP laser diodes for high-temperature operation

In recent years there has been intensive study on shortening the lasing wavelength of AlGaInP laser diodes by introducing a quaternary active layerl or a ternary quantum well (QW) structure. CW operation at the lasing wavelength of 633 nm, which corresponds to that of a He-Ne gas laser, has been attained by adopting a multiquantum well (MQW) structure with very thin QWs. However, the performance at high temperatures was not good enough to allow an operating temperature higher than 50/spl deg/C. This is thought to be caused by significant carrier overflow from the active layer, which tends to increase with shorter lasing wavelength as the bandgap difference between the active layer and the cladding layers becomes smaller. We first evaluate the effect of the number of QWs on the carrier confinement and the high-temperature characteristics, and then use the results to optimize the structure of an MQW made on misoriented substrates.