Coated fiber pressure sensors utilizing pressure release coating material

An optical pressure sensor comprising a coherent optical source;

• a first optical path connected to said optical source, wherein said optical path is a glass fiber comprising a core and a cladding surrounding said core, refractive index of said core is greater than refractive index of said cladding;
• a first coupler connected to said first optical path;
• a second and a third optical paths connected to said first coupler;
• said third optical path includes a single mode optical fiber surrounded by a cellular pressure release material which has Young's modulus of 120-170 dB re 1/Pa and bulk modulus of 110-170 dB re 1/Pa and develops an optical path length shift on exposure to a pressure measurand;
• and means for evaluating the optical path length shift;
• said sensor is operated by projecting an optical signal from said optical source into said first optical path, projecting the optical signal from said first optical path into said first coupler where the optical signal is split and conveyed to said second and said third optical paths, and processing the signals from said second and said third optical paths to produce a signal relative to the pressure measurand.

An optical pressure sensor comprising an optical source selected from the group consisting of broadband optical sources, narrowband optical sources, and mixtures thereof;

• a first optical path connected to said optical source;
• a coupler connected to said first optical path;
• a wavelength shift detector connected to said coupler;
• a second optical path connected to said coupler;
• an optical fiber having Young's modulus of 120-170 dB re 1/P and bulk modulus of 110-170 dB re 1/Pa in said second optical path;
• a grating in said fiber in association with said second optical path, said fiber and said grating being surrounded by said pressure release material;
• said sensor is operated by projecting an optical signal into said first optical path;
• then projecting the optical signal from said first optical path through said coupler and into said grating where the optical signal, or a portion thereof, is reflected into said coupler through said second optical path and then into said shift detector.