Harsh environments minimally invasive optical sensor using free-space targeted single-crystal silicon carbide

To the best of our knowledge, for the first time, a single-crystal silicon carbide (SiC)-based minimally invasive smart optical sensor suited for harsh environments has been designed and demonstrated. The novel sensor design is based on an agile wavelength source, instantaneous single-wavelength strong two-beam interferometry, full optical power cycle data acquisition, free-space targeted laser beams, multiple single-crystal-thick SiC optical front-end chips, and multiwavelength signal processing for unambiguous temperature measurements to form a fast and distributed smart optical sensor system. Experiments conducted using a 1550-nm eye-safe band-tunable laser and a 300-μm coating-free thick SiC chip demonstrate temperature sensing from room temperature to 1000°C with an estimated average 1.3°C resolution. Applications for the proposed sensor include use in fossil fuel-based power systems, aerospace/aircraft systems, satellite systems, deep-space exploration systems, and drilling and oil mining industries.