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:
Dec. 07, 2004
Filed:
Jul. 15, 2002
The Furukawa Electric Co., Ltd., Tokyo, JP;
Abstract
Disclosed is a distributed feedback semiconductor laser device having a resonator for oscillating a laser beam and a laser module which is provided with the semiconductor laser device. The semiconductor laser device comprises a diffraction grating, formed inside the resonator, for periodically changing only an extinction coefficient k or both a real refractive index n and the extinction coefficient k in a complex refractive index N expressed by N=n−ik where i is an imaginary unit. The resonator has a first facet having a first reflectance and a second facet opposite to the first facet and having a second reflectance. The first reflectance is smaller than the second reflectance and equal to or larger than 10%, preferably equal to or smaller than 20%.