Temperature Sensitivity Control of an Inkjet-Printed Optical Resonator on Pillar

Area of Science:

• Photonics and Materials Science
• Microfabrication and Sensor Technology

Background:

• Whispering gallery mode resonators are promising for sensing applications.
• Polymers used in sensors often exhibit sensitivity to multiple environmental stimuli, particularly temperature.
• Mitigating temperature sensitivity is crucial for reliable polymer-based sensor performance.

Purpose of the Study:

• To develop a whispering gallery mode resonator using inkjet printing and microfabrication.
• To investigate and mitigate the temperature sensitivity of polymer-based resonators.
• To achieve minimal temperature sensitivity in sensing devices fabricated with undercut microdroplets.

Main Methods:

• Fabrication of whispering gallery mode resonators on a pillar using a hybrid approach of inkjet printing and traditional microfabrication.
• Systematic tuning of the resonator's undercut-to-radius ratio to control temperature sensitivity.
• Characterization of temperature sensitivity across a range of design parameters.

Main Results:

• A linear dependence of temperature sensitivity on the undercut-to-radius ratio was achieved, ranging from -41.5 pm/°C to 23.4 pm/°C.
• A zero-crossing point for temperature sensitivity was identified at an undercut-to-radius ratio of 47.6%.
• The lowest measured temperature sensitivity was 5.9 pm/°C for a resonator with a 53% undercut-to-radius ratio.

Conclusions:

• Inkjet printing combined with microfabrication enables the creation of polymer-based whispering gallery mode resonators for sensing.
• Precise control over the undercut-to-radius ratio is an effective strategy to minimize temperature sensitivity in these resonators.
• The developed method allows for the fabrication of sensing devices with significantly reduced thermal cross-sensitivity, enhancing their reliability.