Semiconductor laser

Abstract

A semiconductor laser includes an n type GaAs semiconductor substrate, an n type AlGaAs cladding layer, an active layer producing light having a wavelength equal to or larger than 900 nm, a p type AlGaAs cladding layer, and an n type AlGaAs current blocking layer having a current concentrating structure. The n type AlGaAs current blocking layer comprises Al.sub.x Ga.sub.1-x As having an Al composition ratio x smaller than an Al composition ratio of the p type AlGaAs cladding layer, and is doped with Si to a concentration equal to or larger than 1.times.10.sup.19 cm.sup.-3. Therefore, since more V.sub.III -Si.sub.Ga complexes C are produced in the AlGaAs current blocking layer than those produced when the current blocking layer is GaAs and absorption of light having a wavelength of 0.9.about.1.2 .mu.m is promoted, generation of higher-order modes is reliably suppressed and laser light having a fundamental mode is stably produced. Consequently, a semiconductor laser for exciting a fiber amplifier and excellent as a pumping light source of an optical fiber is realized.

Dependencies are inferred from the claim text.