Thermo-Optical Sensitivity of Whispering Gallery Modes in As2S3 Chalcogenide Glass Microresonators

Abstract

Glass microresonators with whispering gallery modes (WGMs) have a lot of diversified applications, including applications for sensing based on thermo-optical effects. Chalcogenide glass microresonators have a noticeably higher temperature sensitivity compared to silica ones, but only a few works have been devoted to the study of their thermo-optical properties. We present experimental and theoretical studies of thermo-optical effects in microspheres made of an As2S3 chalcogenide glass fiber. We investigated the steady-state and transient temperature distributions caused by heating due to the partial thermalization of the pump power and found the corresponding wavelength shifts of the WGMs. The experimental measurements of the thermal response time, thermo-optical shifts of the WGMs, and heat power sensitivity in microspheres with diameters of 80–380 µm are in a good agreement with the theoretically predicted dependences. The calculated temperature sensitivity of 42 pm/K does not depend on diameter for microspheres made of commercially available chalcogenide fiber, which may play an important role in the development of temperature sensors.

Comprehensive Numerical Analysis of Temperature Sensitivity of Spherical Microresonators Based on Silica and Soft Glasses

“…A regular telecommunication fiber splicer may also be used to make fused silica microspheres [ 33 ], and a microheater to make soft glass microspheres [ 22 , 34 ]. Earlier, we successfully employed the latter method to produce different-sized spherical microresonators from commercially available chalcogenide and customized tellurite fibers [ 35 , 36 ].…”

Thermo-Optical Control of Raman Solitons in a Functionalized Silica Microsphere

“…Steady-state temperature fields were found numerically by the finite element method using COMSOL Multiphysics software. The obtained data were imported into specially developed software simulating frequency shifts of WGMs due to refractive index changes ( dn / dT ) and thermal expansion [ 29 ]. The temperature was calculated using an axially symmetric model, taking into account the geometric parameters of the functionalized microsphere.…”

“…We also considered partial thermalization of pump power in the region corresponding to the effective WGM volume near the microsphere equator, which also affects the temperature distribution and WGM shifts. We previously developed the model describing WGM frequency shifts due to pump thermalization and experimentally verified its performance [ 29 ]. Thermo-optical control of the WGM frequency shifts achieved due to microsphere functionalizing allows us to control pump frequency detuning from exact resonance in the experiment, which greatly affects the intracavity nonlinear dynamics of radiation and the regimes of pump conversion.…”

Comprehensive review of advances in the field of chalcogenide glass microresonators

“…66 They have also experimentally and theoretically investigated the thermo-optics properties of the As 2 S 3 microspheres of 80-380 µm diameter range. 67 They demonstrated singlemode Raman lasing at 1620 nm from a 40 µm diameter As 2 S 3 microsphere of Q factor 10 6 using a CW C-band laser at 1530 nm of power 50 mW as the pump. A red laser diode at 650 nm of power 2 mW is used for the thermal control of WGMs to pull the modes and start Raman lasing.…”

“…On increasing pump power beyond the threshold, cascaded Raman lasing is observed up to fourth (1.66, 1.76, 1.88, and 2.01 µm) and third (1.62, 1.72, and 1.83 µm) order for pump wavelengths of 1.57 and 1.53 µm, respectively 66 . They have also experimentally and theoretically investigated the thermo‐optics properties of the As 2 S 3 microspheres of 80–380 µm diameter range 67 . They demonstrated single‐mode Raman lasing at 1620 nm from a 40 µm diameter As 2 S 3 microsphere of Q factor 10 6 using a CW C‐band laser at 1530 nm of power 50 mW as the pump.…”