Glass manufacturing – Processes – With chemically reactive treatment of glass preform
Patent
1987-01-16
1988-11-01
Lindsay, Robert L.
Glass manufacturing
Processes
With chemically reactive treatment of glass preform
65 311, 65 6053, 65117, 350 9612, 350 9634, 427164, C03B 2500, G02B 514, C03C 2100
Patent
active
047817437
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.
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Holmes Ronald J.
Minford William J.
American Telephone and Telegraph Company AT&T Bell Laboratories
Koba Wendy W.
Lindsay Robert L.
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