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. 10, 1998
Filed:
Aug. 30, 1995
Amaresh Mahapatra, Acton, MA (US);
S Anantha Narayanan, Lowell, MA (US);
Ramar Corporation, Northboro, MA (US);
Abstract
A method for co-diffusing titanium and aluminum into a single-crystal lithium niobate substrate and guided wave devices produced therefrom are provided. Titanium diffused into the substrate forms a light guiding region. A layer of aluminum deposited over the light guiding region and diffused into the substrate buries the light guiding region below the substrate surface. In an alternate embodiment, a layer of aluminum forms a mode shaping region which surrounds the light guiding region on two sides. The mode shaping region has ordinary and extraordinary indices of refraction less than the substrate such that mode mismatch between a device fabricated thereby and an externally coupled fiber is reduced. The aluminum can be diffused into LiNbO.sub.3 at a much lower temperature without affecting diffused titanium guides. Preferably, the titanium diffusion occurs at about 1000.degree. to about 1100.degree. C. while further aluminum diffusion occurs at a lower temperature in the range of about 900.degree. to 950.degree. C.