Abstract: A fiber gas sensor includes a fiber core with first and second refractive index periodic modulated grating structures having different amplitude modulation profiles positioned about the fiber core. A fiber cladding is positioned about the first and second refractive index periodic modulated grating structures. A sensing layer is positioned about the fiber cladding of one of the refractive index periodic modulated grating structures. The sensing layer includes a sensing material made of a Pd-based alloy, such as nano-PdOx, nano-Pd(x)Au(y)Ni(1-x-y) or nano-Pd/Au/WOx. The fiber gas sensor provides a measurement of localized, temperature-corrected gas concentration and composition from a combustion environment. A reflection-based or a transmission-based sensing system with an array of one or more fiber gas sensors is also described.

Abstract: A sensing module positioned about an optical fiber cable having a long axis. The optical fiber includes a core that transmits light through the optical fiber cable. The sensing module includes a first short-period fiber grating positioned about the core. A second short-period fiber grating is positioned about the core and at a distance along the long axis with respect to the first short-period fiber grating. At least one of a long-aperiod fiber grating and a long-period fiber grating is positioned between the first short-period fiber grating and the second short-period fiber grating. A fiber cladding is positioned around the long-period grating and/or the long-aperiod grating of the sensing module. A sensing skin is positioned about the fiber cladding and includes a chemical gas active material.

Abstract: In accordance with one exemplary embodiment the invention provides a multi-parameter fiber optic sensing system with an aperiodic sapphire fiber grating as sensing element for simultaneous temperature, strain, NOx, CO, O2 and H2 gas detection. The exemplary sensing system includes an aperiodic fiber grating with an alternative refractive index modulation for such multi-function sensing and determination. Fabrication of such quasiperiodic grating structures can be made with point-by-point UV laser inscribing, diamond saw micromachining, and phase mask-based coating and chemical etching methods. In the exemplary embodiment, simultaneous detections on multi-parameter can be distributed, but not limited, in gas/steam turbine exhaust, in combustion and compressor, and in coal fired boilers etc.

Abstract: A sensing module positioned about an optical fiber cable having a long axis. The optical fiber includes a core that transmits light through the optical fiber cable. The sensing module includes a first short-period fiber grating positioned about the core. A second short-period fiber grating is positioned about the core and at a distance along the long axis with respect to the first short-period fiber grating. At least one of a long-aperiod fiber grating and a long-period fiber grating is positioned between the first short-period fiber grating and the second short-period fiber grating. A fiber cladding is positioned around the long-period grating and/or the long-aperiod grating of the sensing module. A sensing skin is positioned about the fiber cladding and includes a chemical gas active material.

Abstract: In accordance with one exemplary embodiment the invention provides a multi-parameter fiber optic sensing system with an aperiodic sapphire fiber grating as sensing element for simultaneous temperature, strain, NOx, CO, O2 and H2 gas detection. The exemplary sensing system includes an aperiodic fiber grating with an alternative refractive index modulation for such multi-function sensing and determination. Fabrication of such quasiperiodic grating structures can be made with point-by-point UV laser inscribing, diamond saw micromachining, and phase mask-based coating and chemical etching methods. In the exemplary embodiment, simultaneous detections on multi-parameter can be distributed, but not limited, in gas/steam turbine exhaust, in combustion and compressor, and in coal fired boilers etc.

Abstract: A sensing module positioned about an optical fiber cable having a long axis. The optical fiber includes a core that transmits light through the optical fiber cable. The sensing module includes a first short-period fiber grating positioned about the core. A second short-period fiber grating is positioned about the core and at a distance along the long axis with respect to the first short-period fiber grating. At least one of a long-aperiod fiber grating and a long-period fiber grating is positioned between the first short-period fiber grating and the second short-period fiber grating. A fiber cladding is positioned around the long-period grating and/or the long-aperiod grating of the sensing module. A sensing skin is positioned about the fiber cladding and includes a chemical gas active material.

Abstract: A fiber optic sensor is provided. The fiber optic sensor includes a fiber core having a plurality of Bragg grating elements wherein, the grating elements comprise a periodic or a quasiperiodic modulated microcrystalline and rigid silicon dioxide tetrahedral structure and a cladding disposed about the fiber core.

Abstract: A sensing module positioned about an optical fiber cable having a long axis. The optical fiber includes a core that transmits light through the optical fiber cable. The sensing module includes a first short-period fiber grating positioned about the core. A second short-period fiber grating is positioned about the core and at a distance along the long axis with respect to the first short-period fiber grating. At least one of a long-aperiod fiber grating and a long-period fiber grating is positioned between the first short-period fiber grating and the second short-period fiber grating. A fiber cladding is positioned around the long-period grating and/or the long-aperiod grating of the sensing module. A sensing skin is positioned about the fiber cladding and includes a chemical gas active material.