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:
Jul. 10, 2001
Filed:
Nov. 25, 1998
Tetsuro Okuda, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
A distributed feedback laser device comprises an optical waveguide having one end facet serving as a beam emission surface and the other end facet serving as a reflection surface, an active layer formed between the beam emission surface and the reflection surface, and a diffraction grating formed so as to extend along the active layer in the optical waveguide. The active layer has a first region located nearer to the beam emission surface than to the reflection surface and a second region located nearer to the reflection surface than to the beam emission surface. The first region is narrower in width than the second region. The diffraction grating has first and second portions located along the first and the second regions, respectively. The first portion is longer in pitch than the second portion.