Whispering-gallery mode lasing from polymer microsphere for humidity sensing
Wei Xu1, Chunxiang Xu1,*, Feifei Qin1, Yaqi Shan2, Zhu Zhu1, and Ye Zhu1
- 1State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
- 2School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, China
Microlasers based on high quality (Q) whispering-gallery mode (WGM) resonance are promising low threshold laser sources for bio-sensing and imaging applications. In this Letter, dye-doped polymer microspheres were fabricated by a controlling emulsion solvent evaporation method. WGM lasing with low threshold and high Q factors was realized in an individual microsphere under femtosecond laser pumping. The slight change of environmental relative humidity (RH) can be monitored by measuring the shift of the lasing modes at the exposure of water molecules, which demonstrates the sensitivity is as high as 6 pm/RH%. The results would offer an insight into employing microlasers as sensors.