A Packaged Whispering Gallery Mode Strain Sensor Based on a Polymer-Wire Cylindrical Micro Resonator

Abstract

Abstract-We propose a whispering gallery mode (WGM) strain sensor formed by a polymer-wire cylindrical micro resonator for strain measurement applications. WGMs are generated by evanescently coupling light into the polymer-wire resonator from a silica fiber taper fabricated by the micro heater brushing technique. Accurate and repeatable measurements of a strains up to one free spectral range (FSR) shift of the WGMs (corresponding to 0.33 % of the polymer-wire elongation, 3250 μɛ) are demonstrated experimentally with the proposed sensor. Practical packaging method for the proposed strain sensor on a glass microscope slide has also been realized making the sensor portable and easy to handle. The robustness of the packaged coupling system is confirmed by vibration tests. The performance of the packaged strain sensor is evaluated and compared with that for an unpackaged sensor.

Packaged inline cascaded optical micro-resonators for multi- parameter sensing

“…Figure 1 (c) is a schematic of a packaged triple-cylindrical resonator array. The robustness of the packaged system was confirmed by testing the device in the presence of strong vibrations by placing it on a mechanical vibration generator as explained in [20]. Figure 2 shows the photograph of an ICOMR formed by three cylindrical microresonators.…”

“…The PDMS coated silica micro-resonator and the tapered POF micro-resonator served for temperature and strain measurements respectively. PDMS material was chosen for the coating of the silica micro-cylinder due to its low attenuation loss, good chemical stability and large thermo-optic coefficient [21], while a POF micro-cylinder was chosen for strain sensing because of its large elastic modulus compared to silica fibers [20,22,23]. The PDMS coating was prepared as a solution with a base to curing agent ratio of 5:1.…”

“…The Q-factor of the resonant modes due the tapered POF cylindrical microresonator was 7×10². Packaging of the strain sensor based on the POF tapered micro-cylinder was achieved as explained in [20]. Figure 5 shows the WGM spectra excited by the individual resonators (PDMS-coated and POF) as well as the resulting combined ICOMR spectrum.…”

Whispering Gallery Mode Optical Microresonators: Structures and Sensing Applications

“…The results showed that the axial strain of the device can reach 3250 με and the sensitivity of axial tension strain was respectively −0.68 pm με −1 (no package) and −0.58 pm με −1 (package). In addition, external vibration had little effect on the performance of the sensor …”

“…With the continuous improvement of WGMRs in optical sensing, many novel geometric structures have appeared in recent years, such as: microdisk, [17,[116][117][118][119][120][121][122][123][124][125] microbubble, [126][127][128][129][130][131][132] microbottle, [133][134][135][136][137][138][139][140][141][142][143][144][145][146][147] microtube, [148][149][150][151][152][153][154][155][156][157][158][159][160] microcylinder, [161][162][163] etc. These new resonators are widely used in the field of phy...…”