The disclosure relates to an optical method for temperature sensing utilizing a temperature sensing material. In an embodiment the gas stream, liquid, or solid has a temperature greater than about 500° C. The temperature sensing material is comprised of metallic nanoparticles dispersed in a dielectric matrix. The metallic nanoparticles have an electronic conductivity greater than approximately 10−1 S/cm at the temperature of the temperature sensing material. The dielectric matrix has an electronic conductivity at least two orders of magnitude less than the dispersed metallic nanoparticles at the temperature of the temperature sensing material. In some embodiments, the chemical composition of a gas stream or liquid is simultaneously monitored by optical signal shifts through multiple or broadband wavelength interrogation approaches. In some embodiments, the dielectric matrix provides additional functionality due to a temperature dependent band-edge, an optimized chemical sensing response, or an optimized refractive index of the temperature sensing material for integration with optical waveguides.