Stable CdSe/ZnS QDs Fiber Temperature Sensor Fabricated With Precise Fusion-Spliced Encapsulation

Quantum dots (QDs) exhibit photoluminescence that is highly sensitive to temperature, but their stability degrades rapidly in high-temperature environments. This study introduces an innovative sensor preparation method: CdSe/ZnS QDs are encapsulated in the optical fiber by the precision fusion splicing of concave fiber. This method provides robust protection, enabling the QDs to retain nearly 100% fluorescence after 30 min of continuous laser irradiation, compared with unprotected QDs, which lose 95% of their fluorescence. The sensor exhibits a linear temperature response up to $105~^{\circ }$ C, with repeated measurements showing deviations of less than $0.5~^{\circ }$ C. By comparison, unprotected QDs showed a $6.7~^{\circ }$ C fluctuation during three measurements at a sample temperature of $80~^{\circ }$ C. Furthermore, in situ testing on a device with a 100 s operating period and a 50% duty cycle revealed that the device’s temperature increased by up to $33.6~^{\circ }$ C within 50 s, with temperature changes correlating closely to the operating cycle. These findings highlight the sensor’s durability in high-temperature environments and suggest its broader industrial application potential.