Spectrally tunable liquid resonator based on electrowetting

Wei Yang Lim, Mo Zohrabi, Jiangang Zhu, Tomer Ur Soco, Tal Carmon, Juliet T. Gopinath, Victor M. Bright

Research output: Contribution to journalArticlepeer-review


We present a tunable on-chip liquid resonator in conjunction with a tapered fiber coupling scheme. The resonator consists of a glycerol droplet submerged within an immiscible liquid bath, which mitigates the effects of environmental fluctuations. The platform is fabricated using standard semiconductor techniques, which enable the future integration of photonic components for an on-chip liquid resonator device. The liquid resonator maintains its high Q-factor on chip (105) due to surface tension forming an atomically smooth liquid-liquid interface. Higher Q-factor resonance modes experienced linewidth broadening due to the random excitation of thermal capillary vibrations. Spectral tuning is demonstrated using the electrowetting effect, increasing the surface's wettability and an expansion in the droplet diameter. A maximum spectral tuning of 1.44 nm } 5 pm is observed by applying 35 V. The tuning range is twice the free spectral range (FSR) of 0.679 nm measured at a pumping wavelength range of 770-775 nm. A 2D axisymmetric finite-element simulation shows resonance modes in good agreement with experimentally measured spectra and with predicted tuning speeds of 20 nm/s.

Original languageEnglish
Pages (from-to)18949-18965
Number of pages17
JournalOptics Express
Issue number11
StatePublished - 23 May 2022


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