Open AccessTapered optical fiber waveguide coupling to whispering gallery modes of liquid crystal microdroplet for thermal sensing application
Author(s) -
Yan Wang,
Hanyang Li,
Lun Zhao,
Yongjun Liu,
Shuangqiang Liu,
Jun Yang
Publication year - 2017
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.25.000918
Subject(s) - materials science , whispering gallery wave , optics , waveguide , liquid crystal , coupling (piping) , optical fiber , optical power , optoelectronics , thermal , optical force , optical tweezers , resonator , laser , physics , meteorology , metallurgy
We demonstrate efficient coupling to the optical whispering gallery modes (WGMs) of nematic liquid crystal (NLC) microdroplets immersed in an immiscible aqueous environment. An individual NLC microdroplet, confined at the tip of a microcapillary, was coupled via a tapered optical fiber waveguide positioned correctly within its vicinity. Critical coupling of the taper-microdroplet system was facilitated by adjusting the gap between the taper and the microdroplet to change the overlap of the evanescent electromagnetic fields; efficient and controlled power transfer from the taper waveguide to the NLC microdroplet is indeed possible via the proposed technique. We also found that NLC microdroplets can function as highly sensitive thermal sensors: A maximum temperature sensitivity of 267.6 pm/°C and resolution of 7.5 × 10 -2 °C were achieved in a 78-μm-diameter NLC microdroplet.