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:
Nov. 16, 2004
Filed:
Jul. 17, 2002
Applicant:
Inventors:
Hitoshi Hatayama, Yokohama, JP;
Chisai Hirose, Yokohama, JP;
Assignee:
Sumitomo Electric Industries, Ltd., Osaka, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G02B 6/00 ;
U.S. Cl.
CPC ...
G02B 6/00 ;
Abstract
The invention provides a planar lightwave circuit type variable optical attenuator in which a small PDL is maintained even when an attenuation is large. The variable optical attenuator is constituted by a Mach-Zehnder interferometer comprising a substrate, two optical waveguide arms buried in a clad formed on the substrate, and thin-film heaters disposed on the surface of the clad and adjusting optical lengths of the optical waveguide arms. The optical waveguide arms are each made of a silica-based glass material, and a difference &Dgr;L between arm lengths is set to be in the range of 0.38 &mgr;m to 0.52 &mgr;m.