High temperature stable fiber grating sensor and method for producing same

US8402789B2 · kind B2 · utility

Assignee

• Her Majesty the Queen in the Right of Canada, as represented by the Minister Industry, through the Communications Research Center Canada · CA

Inventors

• Christopher W. Smelser · Ottawa, CA
• Stephen J. Mihailov · Gatineau, CA
• Dan Grobnic · Ottawa, CA
• Ping Lu · Ottawa, CA
• Robert B. Walker · Paradise, US
• Gino Cuglietta · Gatineau, CA
• Huimin Ding · Ottawa, CA
• Xiaoli Dai · Ottawa, CA

Key dates

• Filing date: Aug 23, 2012
• Grant date: Mar 26, 2013
• Expiry date: Aug 23, 2032

Classification

• Technology area (CPC G): Physics
• CPC primary: G02B6/02138
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A method of producing a thermally stable grating allows the grating to be placed in environments where temperatures reach 1000° C. These gratings may be concatenated so as to form a sensor array. The method requires a step of lowering the characteristic intensity threshold of a waveguide by at least 25%, followed by irradiating the waveguide with femtosecond pulses of light having a sufficient intensity and for a sufficient duration to write the grating so that at least 60% of the grating remains after exposures of at least 10 hours at a temperature of at least 1000° C. Pre-writing a Type I grating before writing a minimal damage Type II grating lowers the characteristic threshold of the waveguide so that a stable low damage type II grating can be written; alternatively providing a hydrogen or deuterium loaded waveguide before writing the grating lowers the characteristic threshold of the waveguide.