Patent ID: 8542955

Claim:
A gas detection system for identifying at least one of a plurality of gases, comprising: at least one sensing module including: a hollow chamber enclosed by a chamber housing; an optical sensing fiber positioned within the hollow chamber, said optical sensing fiber comprising a plurality of fiber gas sensors including, a plurality of fiber Bragg gratings which are spaced apart at a plurality of respective grating locations along the fiber, and a respective sensing layer affixed to an exterior surface of the optical fiber at each respective grating location, wherein at least one sensing layer of at least one fiber gas sensor is configured with a thermal sensitivity tuned to detect a first gas and a second gas having respective first and second heat transfer coefficients, said first heat transfer coefficient being greater than said second heat transfer coefficient, wherein a first material is selected for the at least one sensing layer of a first fiber Bragg grating at a first grating location and a second material is selected for the sensing layer of a second fiber Bragg grating at a second grating location, the first and second materials have respective first and second thermal expansion characteristics and respective first and second thicknesses, where the first thermal expansion characteristic is greater than the second thermal expansion characteristic and the first thickness is greater than the second thickness, wherein the first material is configured to dissipate heat energy to the second gas when said second gas is directed into the hollow chamber based at least in part on the second heat transfer coefficient of the second gas, said dissipation of heat energy to induce strain in said at least one sensing layer and in the first fiber Bragg grating sufficient to induce a shift in the Bragg resonant wavelength of the first fiber Bragg grating which is greater than a threshold shift required for detection of the second gas, said strain is based on at least one of the first thermal expansion characteristic and the first thickness of the first material, wherein the second material is configured to dissipate heat energy to the first gas when said first gas is directed into the hollow chamber based at least in part on the first heat transfer coefficient of the first gas, said dissipation of heat energy to induce strain in said sensing layer and in the second fiber Bragg grating sufficient to induce a shift in the Bragg resonant wavelength of the second fiber Bragg grating which is greater than a threshold shift required for detection of the first gas, said strain is based on at least one of the second thermal expansion characteristic and the second thickness of the second material; and a photodetector configured to detect said respective shift in the Bragg resonant wavelength for each fiber gas sensor.