Browse Prior Art Database

Buried TI In-Diffused Waveguide On Lithium Niobate

IP.com Disclosure Number: IPCOM000101393D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 1 page(s) / 35K

Publishing Venue

IBM

Related People

Ewen, J: AUTHOR

Abstract

A circular cross-sectional lithium niobate waveguide may be formed by burying a stripe of titanium in a body of lithium niobate and then heating the structure until the titanium diffuses outwardly to form a waveguide.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Buried TI In-Diffused Waveguide On Lithium Niobate

       A circular cross-sectional lithium niobate waveguide may
be formed by burying a stripe of titanium in a body of lithium
niobate and then heating the structure until the titanium diffuses
outwardly to form a waveguide.

      A major practical drawback in using lithium niobate integrated
optical devices is the difficulty in efficiently coupling the output
of an optical fiber to the waveguide in the lithium niobate, due in
large part to the different cross sections of the fiber and the
lithium niobate waveguides.

      The standard Ti in-diffused waveguide configuration is shown in
Fig. 1.  The waveguide cross section 10 is at best semicircular, and
presents a poor match to the circular cross section of a fiber.  Fig.
2.1 illustrates a structure which eliminates this mismatch.  A Ti
stripe 12 is deposited on a lithium niobate substrate 14.  Then an
additional layer 16 of lithium niobate is deposited on top of the
substrate (which may be accomplished via sputtering deposition or LPE
techniques).  Next, the structure is heated to allow the Ti layer to
diffuse, forming the waveguide structure 18 shown in Fig. 2.2.  The
waveguide now more closely approximates the circular cross section of
an optical fiber, yielding lower coupling losses.