Lucent Technologies Inc.

At&t Bell Laboratories

American Telephone & Telegraph Co., At&t Bell Laboratories

Agere Systems Optoelectronics Guardian Corp.

William James Minford

John William Osenbach

Allan James Bruce

Edmond J Murphy

Henry Miles O'Bryan

Ofer Sneh

Wilbur Dexter Johnston, Jr

Ronald J Holmes

Trudie C Rice

Douglas A Herr

The invention is an optical waveguide device and a method for forming the device which provides enhanced stability. The device includes a pyroelectric substrate such as lithium niobate where the bulk resistivity of at least a portion of the substrate is reduced to 10,ohm cm or less by heating the substrate in a reducing atmosphere. This causes the substrate to be less susceptible to temperature variants which can otherwise result in dc bias drift and variation.

Optical waveguide device with enhanced stability

Optical devices using non-centric crystals, such as lithium niobate, and methods for making and using the devices, are provided. The devices provide improved temperature stability as compared to conventional devices using non-centric crystals. The improved temperature stability is provided by etching the surface of a non-centric crystal to a depth of less than about 300 angstroms. The devices and methods of the invention reduce the magnitude of change in bias voltage required to maintain an optical crystal at a pre-selected operating point.

Optical devices having improved temperature stability

Embodiments of the invention include an apparatus and method for stabilizing the operation of lithium niobate devices such as modulators due to charge accumulation caused by, e.g., pyroelectric and piezoelectride effects. The apparatus comprises a substrate having a waveguide formed therein, a buffer layer formed on the substrate, a Si.sub.2 Ti.sub.x N.sub.8/3+x charge dissipation layer (CDL) formed on the buffer layer and a set of electrodes formed on the charge dissipation layer. According to embodiments of the invention, the Si.sub.2 Ti.sub.x N.sub.8/3+x charge dissipation layer has a resistivity of approximately 15-150 k.OMEGA.cm. Alternatively, the apparatus includes a second charge dissipation layer formed on the opposing surface of the substrate. The charge dissipation layer according to embodiments of the invention is advantageous in that it provides a suitable resistivity and is a composition that is easily reproducible using conventional formation techniques such as sputtering.

Apparatus and method for dissipating charge from lithium niobate devices

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.

Method of improving waveguide uniformity in optical substrate and product

The specification describes a technique for etching titanium using EDTA compounds. It is especially useful for selective etch processes such as those used to form titanium diffused waveguides in lithium niobate crystals.

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Lehigh, PA, United States of America

William James Minford