Pressure-isolated Bragg grating temperature sensor

Abstract

A pressure-isolated Bragg grating temperature sensor includes an optical element 20,600 which includes an optical fiber 10 having at least one Bragg grating 12 disposed therein which is encased within and fused to at least a portion of an inner glass capillary tube 20 and/or a large diameter waveguide grating 600 having a core and a wide cladding and having the grating 12 disposed therein, which is encased within an outer tube 40 to form a chamber 44. An extended portion 58 of the sensing element that has the grating 12 therein extends inwardly into the chamber 44 which allows the grating 12 to sense temperature changes but isolates the grating 12 from external pressure. An end tube 42 may be attached to the tube 40 and the fiber 10 fed therethrough to form the chamber 44 and a pass-through for the fiber 10. As the external pressure P increases, the outer tube 40 compresses or deflects, the sensing element 20,600 moves closer to the end tube 42 and/or the outer tube 40 move toward each other. More than one grating or pair of gratings may be used and more than one fiber or optical core may be used. Also, at least a portion of the sensing element may be doped between a pair of gratings 150,152, to form a temperature tuned laser or the grating 12 or gratings 150,152 may be configured as a tunable DFB laser disposed in the sensing element.

Dependencies are inferred from the claim text.