Method of precision fabrication by light exposure and structure of tunable waveguide bragg grating

A method of forming a Bragg grating in an operative portion of a first waveguide in a substrate that has a top surface and that has a second waveguide disposed such that an operative portion of the second waveguide is within a separation distance to the operative portion of the first waveguide that is less than or equal to the UV spot size, the method comprising:

• depositing a first metallic layer on the top surface;
• etching the first metallic layer to form a passive metallic structure over the operative portion of the second waveguide and to expose the operative portion of the first waveguide;
• and
• exposing the top surface to an UV exposure to form the Bragg grating in the operative portion of the first waveguide.

An optical device comprising:

• a first waveguide having an operative portion;
• a second waveguide having a Bragg grating formed in an operative portion of the second waveguide, the Bragg grating being formed by exposing the operative portion of the second waveguide to an UV exposure, the operative portion of the second waveguide being within a separation distance to the operative portion of the first waveguide that is less than or equal to an UV spot size;
• and
• a passive metallic structure formed over the operative portion of the first waveguide to protect the operative portion of the first waveguide during the exposing of the operative portion of the second waveguide to the UV exposure.

A planar lightwave circuit comprising:

• a first waveguide disposed in a substrate, the first waveguide having an operative portion and a temperature tuned region extending from the operative portion of the first waveguide into the substrate;
• a Bragg grating formed in the operative portion of the first waveguide and having a resonant frequency, the Bragg grating being formed using an UV exposure process;
• and
• a metallic heater disposed above the temperature tuned region and having interconnects to drive the metallic heater to tune the resonant frequency, the metallic heater being formed by depositing and etching a metallic layer above the substrate, where said depositing and etching occurs before the UV exposure process, the metallic heater being positioned so as to expose a top surface of the operative portion of the first waveguide to the UV exposure process.

In a planar lightwave circuit, an optical device comprising:

• a first waveguide having an operative portion;
• a second waveguide having an operative portion within a separation distance to the operative portion of the first waveguide, the separation distance being within an UV spot size;
• a Bragg grating formed in the operative portion of the first waveguide, the Bragg grating having a resonant frequency;
• a metallic heater disposed over a temperature tuned region adjacent to the operative portion of the first waveguide to controllably tune the resonant frequency in response to changes to a driving voltage applied to the metallic heater;
• and
• a passive metallic structure disposed over the operative portion of the second waveguide.

A planar lightwave circuit optical coupler comprising:

• a first waveguide having an operative portion;
• a second waveguide evanescently coupled to the first waveguide and having an operative portion;
• a first Bragg grating formed in the operative portion of the first waveguide, the first Bragg grating having a first resonant frequency;
• and
• a first metallic heater disposed over a first temperature tuned region adjacent to the operative portion of the first waveguide to controllably tune the first resonant frequency in response to changes to a driving voltage applied to the first metallic heater, the first metallic heater disposed such that a top surface of the first waveguide is exposed.