Whispering gallery modes in a glass microsphere as a function of temperature

Area of Science:

• Materials Science
• Optical Physics
• Nanotechnology

Background:

• Whispering gallery mode (WGM) resonances in microspheres offer unique optical properties.
• Rare-earth doped glasses are promising for optical sensing applications.
• Accurate temperature sensing is crucial in various scientific and industrial fields.

Purpose of the Study:

• To prepare Nd3+ doped barium titano silicate glass microspheres.
• To investigate the potential of these microspheres as temperature sensors.
• To compare the performance of WGM resonance shifts with the fluorescence intensity ratio (FIR) technique for temperature sensing.

Main Methods:

• Fabrication of Nd3+ doped barium titano silicate glass microspheres.
• Observation of WGM resonances using a modified confocal microscope.
• Calibration of a bulk glass sample using the FIR technique.
• In-situ temperature measurement of microspheres via laser irradiation and FIR.
• Correlation of WGM peak displacement with temperature.

Main Results:

• WGM resonances were successfully observed in the prepared microspheres.
• A bulk sample was calibrated as a temperature sensor using FIR.
• The surface temperature of microspheres was estimated using FIR during laser heating.
• A red-shift of WGM peaks was observed with increasing temperature, averaging 10 pm/K from 300 K to 950 K.
• Temperature resolution using WGM displacement was an order of magnitude better than the FIR method.

Conclusions:

• Nd3+ doped barium titano silicate glass microspheres exhibit temperature-dependent WGM shifts.
• WGM displacement offers a highly sensitive method for temperature sensing in microspheres.
• This technique provides an order of magnitude improvement in temperature resolution compared to FIR.