Department of Physics2024-11-0920120740-322410.1364/JOSAB.29.0032402-s2.0-84870708817http://dx.doi.org/10.1364/JOSAB.29.003240https://hdl.handle.net/20.500.14288/10826We report measurements of ultrahigh quality factors (Q-factors) of the optical whispering-gallery modes excited via a tapered optical-fiber waveguide in single glycerol-water microdroplets standing on a superhydrophobic surface in air. Owing to the high contact angle of the glycerol-water mixture on the superhydrophobic surface (≥155°), microdroplets with the geometry of a truncated sphere minimally distorted by gravity and contact line pinning effects could be generated. Q-factors up to 2.3 × 106 were observed for such droplets with radii of 100-200 μm exposed to the ambient atmosphere in a closed chamber with controlled relative humidity. Placement of microdroplets in a constant humidity environment permitted prolonged characterization of Q-factors for individual microdroplets. We found that the Q-factors in air were stable over more than 1 h and their measured values were limited mostly by the thermally induced droplet shape fluctuations.PhysicsJournal Articlehttps://www.scopus.com/inward/record.uri?eid=2-s2.0-84870708817anddoi=10.1364%2fJOSAB.29.003240andpartnerID=40andmd5=cc34ac886f49f12b1b5e55d3c2aab4bd311990300005Q34771