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. 01, 1988
Filed:
Jan. 16, 1987
Ronald J Holmes, Lowhill Township, Lehigh County, PA (US);
William J Minford, Lehigh Township, Northampton County, PA (US);
American Telephone and Telegraph Company AT&T Bell Laboratories, Murray Hill, NJ (US);
Abstract
A method of improving device performance of optical devices formed in optical substrates is disclosed. The method requires that the optical substrate material, for example, lithium niobate, be pre-annealed to form a surface layer with a known congruent composition before diffusing the waveguide material into the substrate. It has been determined that the composition of optical substrates can vary from boule-to-boule, or even along the length of a given boule. These variations affect the diffusion rate of the waveguide material and result in varying mode sizes (both width and depth of the mode). By pre-annealing all material, the diffusion rate will remain relatively constant, regardless of the particular boule. The pre-annealing can be accomplished either by pre-equilibrating the lithium niobate in a vapor-phase equilibrating crucible containing pre-reacted lithium niobate cullet with the desired composition, or pre-equilibrating the lithium niobate to the Li.sub.2 O-rich phase boundary in a two-phase (LiNbO.sub.3, Li.sub.3 NbO.sub.4) powder bed.