Temperature sensing by using whispering gallery modes with hollow core fibers

Abstract

We describe temperature sensing by hollow core fibers using whispering gallery modes of a spherical microresonator. Light from a tunable laser was coupled into the input end of the hollow core fiber. Optical resonances were excited in a microsphere inserted in the modified output end. Part of the light was coupled back from the resonator into the hollow core fiber and transported back to the input end. This light was recorded via a beam splitter by a diode. The sensing principle is based on the shift of the optical resonances by changing the temperature of the resonator. This shift is monitored and leads to the temperature of the resonator and surrounding respectively.

WGM microresonators: sensing, lasing and fundamental optics with microspheres

“…This device did not rely on monitoring the microspheres WGM, instead the intensity ratio of the green emission at 522 nm and 547 nm and Boltzmann statistics were used to determine the temperature [57,104]. Another thermal point sensor was made by putting a microsphere inside the tip of a hollow-core optical fiber [105], see Fig. 12.…”

Highly Sensitive Temperature Measurements With Liquid-Core Microbubble Resonators

“…This is a large improvement in sensitivity for thermal sensing using WGRs compared to earlier work [7]- [11]. Using FEM simulations, it was also shown that, if the microbubble is in the quasidroplet regime, the fundamental TE mode in a bubble with a 500 nm wall is estimated to experience a shift of 35 GHz/K, while the effective index is still high enough to allow efficient coupling to a tapered optical fiber.…”

“…Whispering gallery resonators are demonstrated as effective sensors for a wide range of physical effects such as changes in temperature [6]- [11], pressure [12], force [13], and refractive index [14], [15], to name just a few. With regards to temperature, typically, this is done by measuring the shift in the wavelength of the WGMs due to the thermal expansion of the resonators circumference and the change in the refractive index of the glass.…”

“…This setup used an alignment-free, fiber-coupled microsphere resonator. A thermal point sensor was made by placing a microsphere inside the tip of a hollow-core optical fiber [11]. Using this configuration enabled thermal sensing where the span of the device was quoted as 1000°C.…”

Mathematical Model for Electric Field Sensor Based on Whispering Gallery Modes Using Navier’s Equation for Linear Elasticity

“…These applications include wall shear stress calculation [3,4]; temperature measurement [5][6][7]; biosensing [8][9][10][11][12][13]; hemozoin nanocrystals detection in aquatic environment [14]; nanoparticle detection [15]; and acceleration measurement [16][17][18]. In this paper, WGM based optical cavities are used to detect and measure the applied electric field.…”