The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 23, 1999
Filed:
Feb. 18, 1997
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A semiconductor laser includes a first conductivity type GaAs substrate; a AlGaAs double heterojunction structure disposed on the GaAs substrate and including an upper cladding layer having a mesa ridge stripe with a side surface that makes an angle larger than 90.degree. with a front surface of the upper cladding layer; a first current blocking layer of first conductivity type AlGaAs; and a second current blocking layer of first conductivity type AlGaAs, the first and second current blocking layers covering the mesa ridge stripe. The Al compositions of the first and second current blocking layers are larger than that of the upper cladding layer, maintaining an equivalent refractive index of an active region higher than that of other portions of the semiconductor laser. As a result, the differences between the lattice constant of the second current blocking layer and the GaAs substrate or the AlGaAs upper cladding layer are smaller than in prior art semiconductor lasers. Since the second current blocking layer is in the vicinity of the active region in the mesa ridge stripe, stress applied to the active region is reduced, thereby producing a semiconductor laser that facilitates ridge width control and burying layer growth, and with improved reliability.