Whispering Gallery Mode Resonator Temperature Compensation and Refractive Index Sensing in Glucose Droplets

Abstract

Among the different types of photonic sensor devices, optical whispering gallery mode resonators (WGMRs) have attracted interest due to their high level of sensitivity, small size, and ability to perform real-time temperature measurements. Here we demonstrate the applicability of temperature measurements using WGMR in both air and liquid environments. We also show that WGMR allowed measurements of the refractive index variations in an evaporating glucose–water solution droplet. The thermal tuning of WGMR can be reduced by coating WGMRs with a thin layer of polymethyl methacrylate (PMMA). Dip-coating the silica microsphere multiple times significantly reduced the resonance shift, partially compensating for the positive thermo-optical coefficient of silica. The shift direction changed the sign eventually.

Noncontact optical device for measuring blood glucose in aqueous humor: a pilot clinical study investigating correlation with blood glucose levels

“…Biochemical assays measure changes in biochemical reactions using reagents sensitive to glucose, 34 and optical methods rely on glucose’s intrinsic molecular properties to determine its levels in tissue fluids. 35 – 40 The main challenge that NI glucose monitoring techniques face is achieving the required accuracy at an affordable cost without using blood samples for measurements. 41 The majority of NI glucose monitoring techniques utilized a single method to monitor physiological changes related to blood glucose levels.…”

COMSOL Simulations of the Main Properties of the Whispering Gallery Mode Resonators for Bio-Sensing Applications

“…WGMRs are tested experimentally mainly by monitoring light intensity that is transmitted through them via prism or tapered fiber coupling [13,14]. Linewidth scan of laser emission accompanied by time-domain plot of transmitted signal reveal the shape and the behavior of resonance signals of the WGMRs [15,16]. The full width at half maximum (FWHM) of the resonance peaks and their frequency positions are parameters that describe the interrelation between pumping laser light and the surrounding environment through these resonators.…”

“…Coating the WGMRs with a functionalizing layer to enhance optical proprieties impacts both the Q factor and the resonance peak location describes the ability to store energy inside a microcavity [16,17].…”

Whispering-Gallery Mode Micro-Ring Resonator Integrated with a Single-Core Fiber Tip for Refractive Index Sensing

“…One of the simplest structures proposed for RI sensing applications is a sphere on top of a fiber fabricated using a fiber-melting process [31]. However, the measurement setup requires aligning the structure with a prism to couple the WGMs.…”