Semiconductor laser device which makes it possible to realize high-speed

Abstract

In a laser device in which a first cladding layer (11b) of InP of p-type, an active layer (12) of InGaAsP, and a second cladding layer (13) of InP of n-type are successively formed on a predetermined area of a base layer (10, 11a) of InP of p-type, a current confining structure includes, to confine a current in the active layer, a pair of first buried layers (14) of InP of p-type on a remaining area of the base layer, a pair of first current blocking layers (15) of InP of n-type on the pair of first buried layers, a pair of second current blocking layers (16) of a semi-insulating InP on the pair of first current blocking layers, and a second buried layer (17) of InP of n-type on the pair of second current blocking layers. The pair of first buried layers have a pair of projecting portions (14a) projecting over inner edge portions of the pair of first buried layers with the first cladding, the active, and the second cladding layers interposed between the pair of projecting portions and with the pair of projecting portions brought into contact with side surfaces of the active layer and with inner edge portions of the pair of second current blocking layers so that the pair of first current blocking layers are electrically isolated from the active layer. Instead of the pair of second current blocking layers, a pair of low carrier concentration layers (22) of InP of n-type (or p-type) and a pair of current blocking layers (23) of p-type may be successively formed on the pair of first current blocking layers.