Semiconductor laser device

摘要

A semiconductor laser device is capable of producing an increased optical output power with improved optical characteristics without being subjected to mode distortions in the output beam, while retaining advantageous features inherent to a semiconductor laser device of a buried heterostructure. The semiconductor laser device comprises an optical confinement region which is constituted by at least first, second, third and fourth semiconductor layers successively laminated on a predetemined semiconductor substrate. The second semiconductor layer has a relatively small refractive index and a relatively wide band gap as compared with those of the third semiconductor layer, while the first and the fourth semiconductor layers which are of the conductivity types opposite to each other have relatively small refractive indexes as compared with the second and the third semiconductor layers. The band gaps of the fourth and the second semiconductor layers are relatively large as compared with that of the third semiconductor layer. Difference in the band gap at least between the second and the third semiconductor layers is not smaller than 0.15 eV.