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US4781743A Expired / Lapsed US ⏱️ 0.0 years remaining

Method of improving waveguide uniformity in optical substrate and product

Assignee: BELL TELEPHONE AND TELEGRAPH COMPANY A CORP OF NY
•
Filing: 1987-01-16
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Granted: 1988-11-01
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Expires: 2007-01-16
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Abstract

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 2 O-rich phase boundary in a two-phase (LiNbO 3 , Li 3 NbO 4 ) powder bed.

Inventors

  • 👤 Ronald J. Holmes
  • 👤 William J. Minford

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-06 08:58
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/10; G02B6/12; G02B6/13; G02B6/134; G02B6/1342

Claims Analysis

Total Claims: 10
Claim 1
Independent Claim 90 words
A method of forming optical waveguides in an optical substrate for providing improv ed diffusion uniformity of said optical waveguides , said method comprising the steps of: (a) providing an optical substrate consisting of LiNbO 3 ; (b) pre-annealing said optical substrate provided in step (a) to form a surface layer with a predetermined congruent composition, said surface layer formed to comprise a depth at least equal to the depth of the optical waveguides; and (c) forming said optical waveguides in said congruent composition surface layer formed in step (b).
Claim 2
Independent Claim 90 words
A method of forming optical waveguides in an optical substrate for providing improv ed diffusion uniformity of said optical waveguides , said method comprising the steps of: (a) providing an optical substrate consisting of LiNbO 3 ; (b) pre-annealing said optical substrate provided in step (a) to form a surface layer with a predetermined congruent composition, said surface layer formed to comprise a depth at least equal to the depth of the optical waveguides; and (c) forming said optical waveguides in said congruent composition surface layer formed in step (b).
Claim 3
Dependent Claim 31 words
The method according to claim 1 wherein in performing step (b), the optical substrate is pre-equilibrated in a vapor-phase equilibration crucible containing pre-reacted optical substrate material of the predetermined congruent composition.
Claim 4
Dependent Claim 31 words
The method according to claim 1 wherein in performing step (a), the optical substrate material provided is lithium niobate having a congruent composition defined as 48.60 mole % Li 2 O.
Claim 5
Dependent Claim 29 words
The method according to claim 3 wherein in performing step (b), the optical substrate material is pre-equilibrated to the Li 2 O-rich phase boundary in a two-phase powder bed.
Claim 6
Dependent Claim 19 words
The method according to claim 4 wherein the two phases are LiNbO 3 and Li 3 NbO 4 .
Claim 7
Dependent Claim 16 words
The method according to claim 1 wherein in performing step (c), titanium-diffused optical waveguides are formed.
Claim 8
Dependent Claim 27 words
An optical device including optical waveguides formed in a surface layer having a predetermined congruent composition, said surface layer formed according to the method of claim 1.
Claim 9
Dependent Claim 25 words
The method according to claim 2, where in performing step (b) the pre-annealing is performed at a temperature of 1050° C. for approximately 100 hours.
Claim 10
Dependent Claim 25 words
The method according to claim 4, wherein in performing step (b) the pre-annealing is performed at a temperature of 1050° C. for approximately 500 hours.

References Cited (Backward Citations)

US3486963A Cited
US3665205A Cited
US4284663A Cited
US4196963A Cited
US4206251A Cited
US4329016A Cited
US4370158A Cited
US4312660A Cited
US4375312A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1991-11-01 1992-05-02 1992-11-01 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1995-11-01 1996-05-02 1996-11-01 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1999-11-01 2000-05-02 2000-11-01 $7700.00 Window Closed / Lapsed

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