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:
May. 11, 1999
Filed:
Jul. 22, 1997
Yasufumi Yamada, Ibaraki, JP;
Masahiro Yanagisawa, Ibaraki, JP;
Hiroaki Okano, Ibaraki, JP;
Keiichi Higuchi, Ibaraki, JP;
Hisato Uetsuka, Ibaraki, JP;
Tatsuo Teraoka, Ibaraki, JP;
Satoshi Aoki, Kanagawa, JP;
Yasunori Iwafuji, Kanagawa, JP;
Hitachi Ltd., Tokyo, JP;
Hitachi Cable, Ltd., Tokyo, JP;
Nippon Telegraph and Telephone Corporation, Tokyo, JP;
Abstract
An optical waveguide 3 comprises a substrate like a Si substrate having a projection with a flat surface and inclined side surfaces thereon, a buffer layer having a refractive index of n.sub.0 formed on lower surfaces of the substrate, a secondary buffer layer having a refractive index of n.sub.0 formed on the buffer layer, a core waveguide having a refractive index of n.sub.1 formed on the secondary buffer layer and a cladding layer having a refractive index of n.sub.0 covering the core waveguide. The flat surface of the projection 31 is exposed through an opening. The secondary buffer layer controls a transmission loss increase caused by partial thickness differences of the ground buffer layer or scattering by scratches or strains created by the grind.