Related Experiment Video
Updated: Jun 22, 2026
08:12
Synthesis and Operation of Fluorescent-core Microcavities for Refractometric Sensing
Published on: March 13, 2013
Refractometric sensor based on whispering-gallery modes of thin capillarie
Optics Express
|June 24, 2009
Summary
Submicron capillaries with whispering-gallery modes show high sensitivity to refractive index changes. This optical sensor technology enables measurements beyond the capillary material
Area of Science:
- Optics and Photonics
- Materials Science
- Sensor Technology
Background:
- Whispering-gallery mode (WGM) resonances in optical microcavities are sensitive to changes in the surrounding medium's refractive index.
- Existing microcavities like microspheres, microdisks, and microrings have limitations in sensitivity and measurement range.
- Submicron wall thickness capillaries offer a unique geometry for optical sensing applications.
Purpose of the Study:
- To investigate the refractive index sensing capabilities of submicron wall thickness capillaries utilizing whispering-gallery modes.
- To demonstrate a novel optical microcavity sensor with enhanced sensitivity and measurement range.
- To develop a fabrication technique for submicron wall thickness capillaries suitable for sensing.
Main Methods:
- Excitation and detection of whispering-gallery modes in submicron wall thickness capillaries.
- Systematic variation of the internal medium's refractive index and measurement of corresponding wavelength shifts.
- Development and application of a specialized fabrication technique for creating submicron wall thickness capillaries.
Main Results:
- Observed very large wavelength shifts of WGM resonances as a function of the internal medium's refractive index.
- Demonstrated higher sensitivity to refractive index changes compared to conventional microcavities.
- Achieved a refractometer response exceeding 390 nm per refractive index unit.
- Enabled measurement of refractive index values higher than the capillary material's refractive index due to air-clad outer surface.
Conclusions:
- Submicron wall thickness capillaries are highly effective optical microcavity sensors for refractive index measurements.
- The developed sensor technology offers superior sensitivity and a broader measurement range than existing optical microcavities.
- These capillary-based sensors are compatible with microfluidic systems, paving the way for integrated sensing solutions.
