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:
Sep. 07, 1999
Filed:
Sep. 23, 1997
Masayoshi Ashida, Kyoto, JP;
Rohm Co., Ltd., Kyoto, JP;
Abstract
A semiconductor laser device is of a double-hetero structure having an active layer sandwiched between a first conductivity type cladding layer and a second conductivity type cladding layer, one of the first and second conductivity type cladding layers being formed by a first cladding layer and a second cladding layer. A current blocking layer is provided between the first cladding layer and the second cladding layer, and formed of a material having a forbidden band gap wider than that of the active layer and a refractive index lower than that of the one cladding layer, the current blocking layer being formed with a current injecting region having a conductivity type different from that of the one cladding layer. An over-saturation absorbing layer is formed in the current blocking layer, the over-saturation absorbing layer is formed of such a material that has approximately the same forbidden band gap as that of the active layer. It is possible to set independently the distance between the active layer and the over-saturation absorbing layer as well as the distance between the active layer and the current blocking layer, so as to provide device operation on a low operating current (lowered threshold value) with low noise and astigmatism in a multi mode instead of a longitudinal mode.