Fiber-based ratiometric optical thermometry with silicon vacancy in microdiamonds

Fiber optic all-optical thermometry is a promising technology to track temperature at a microscale while designing efficient and reliable microelectronic devices and components. In this work, we demonstrate a real-time ratiometric fiber optic thermometry technique based on silicon-vacancy diamond that shows excellent temperature resolution and spatial resolution. Instead of analyzing the spectral features of the temperature-dependent SiV signal coming from the SiV microdiamond fixed on the fiber tip, an alternative parallel detection method based on filtering optics and photon counters is proposed to read out the sample temperature in real-time. The signal collection efficiency of the fiber is also investigated numerically with semianalytic ray-optical analysis and then compared with our experimental study. We finally demonstrate the performance of the thermosensor by monitoring the temperature at distinct locations in a lab-built graphite-based microheater device. Our work introduces a reconfigurable method for temperature monitoring in microelectronic, microfluidic devices, or biological environments and unlocks a direction for fiber-based all-optical thermometry research.