Micro-ball and micro-bottle resonators for relative humidity sensing

U. U.M. Ali, B. A. Ahmad, M. A.M. Johari, Z. Jusoh, S. W. Harun, M. Yasin

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


We compare the performance of two whispering gallery mode optical resonators; optical micro-ball (MBaR) and micro-bottle resonators (MBR) as a relative humidity (RH) sensor. The MBaR and MBR are fabricated via the so-called "soften-and-compress" method to create a ball or bulge structure. The MBaR and MBR is then optically excited by using a 8μm optical microfiber and was found to have a Q-factor of >105. The MBaR and MBR was then employed as a humidity sensor with a RH range of between 40% to 100% and the performance is compared for both resonator. The MBR RH sensor was found to have a sensitivity of 0.2973 dB/%, linearity >90% and is superior to the MBaR microfiber in all measured parameters. The MBR RH sensor was also found to have good repeatability and stability compare to MBaR.

Original languageEnglish
Pages (from-to)567-571
Number of pages5
JournalOptoelectronics and Advanced Materials, Rapid Communications
Issue number11-12
Publication statusPublished - 1 Nov 2019


  • Humidity sensor
  • Optical resonator
  • Whispering gallery mode


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