Fiber optic carbon dioxide purity sensor package and system

A carbon dioxide (CO2) purity sensor package 80 includes a fiber core 82, a periodic refractive index modulated fiber grating structure 86 within the fiber core 82 and a fiber cladding 90. A thermally conductive sensing layer 92 is positioned about a portion of the fiber cladding 90 surrounding the periodic refractive index modulated fiber grating structure 86. A gas chamber 94 encloses the fiber cladding 90 with the thermally conductive sensing layer 92. A system includes such a CO2 purity sensor, with the gas chamber being thermally insulated and cylindrical, together with a light source, a photodetector and processing circuitry. A system for measuring multi-point CO2 purity incorporates a plurality of such CO2 purity sensor packages, each including an apodized fibre Bragg grating, together with an optical splitter, a photodetector array and processing circuitry.