Optofluidic conical microresonator for precise displacement sensing

In the present work we report fabrication of a compact optical displacement sensor based on whispering gallery mode with common materials on Polydimethylsiloxane (PDMS) medium with mold master technique. Conical and hollow geometry of microcavity filled with Rhodamine B-doped Glycerol as active medium. The fabricated device can be utilized for sensing applications. Coupling junction can be tuned so that moving the conical microcavity of about 100 mu m in the axial direction is equivalent to similar to 1.5 nm shift in resonant wavelength. Also, a small change in concentration of active medium results in a shift in the resonant wavelength which provides the feasibility of sensing the refractive index. The proposed structure demonstrates the ability of considerably high-resolution sensing for fine displacement steps which is limited by the resolution of the spectrometer (0.6 nm).

Automated summary

In this work, we fabricate a compact optical displacement sensor based on whispering gallery mode using common materials PDMS and mold master technique, and demonstrate its feasibility for sensing applications. The sensor structure allows for high-resolution sensing of micron-level displacement by adjusting the coupling junction, and sensing of refractive index by controlling the concentration of the active medium.