Semiconductor laser device having a semiconductor region for creating a depletion layer in a laser active layer for controlling current flow therethrough

Claim 1

A semiconductor laser device comprising: a substrate; a first semiconductor layer, a laser active layer and a second semiconductor layer, said three layers being laminated in the named order on said substrate and said first and second semiconductor layers having a higher resistance than said laser active layer; a first semiconductor region formed in said second semiconductor layer being joined to said laser active layer and having a first conductivity type which is common to said laser active layer; a second semiconductor region formed in said second semiconductor layer being joined to said laser active layer and being spaced form said first semiconductor region, and having a second conductivity type; first and second electrodes connected to said first and second semiconductor regions, respectively, wherein light emission is effected by a current flowing between said first and second electrodes through said laser active layer; a third semiconductor region formed between said first and second semiconductor regions in said second semiconductor layer, and having the second conductivity type; and a third electrode connected to said third semiconductor region, a depletion layer for controlling the current flow through said laser active layer being formed in said laser active layer by applying a reverse biased voltage between said third semiconductor region and said laser active layer through said third electrode.