Advancing the sensitivity of integrated epoxy-based Bragg grating refractometry by high-index nanolayers

Area of Science:

• Materials Science
• Optoelectronics
• Sensor Technology

Background:

• Waveguide Bragg gratings are crucial for sensing applications.
• Improving the sensitivity of these sensors is an ongoing challenge.
• Epoxy polymer waveguides offer a versatile platform for sensor development.

Purpose of the Study:

• To enhance the surrounding refractive index (RI) sensitivity of epoxy polymer waveguide Bragg grating sensors.
• To investigate the effect of titanium dioxide nanolayer deposition on sensor performance.

Main Methods:

• Fabrication of uniform Bragg gratings in epoxy waveguides using excimer laser writing.
• Deposition of titanium dioxide (TiO2) nanolayers on waveguide surfaces via reactive sputter deposition.
• Characterization of Bragg wavelength shifts and sensitivity under varying RI conditions.

Main Results:

• Achieved significant improvements in surrounding RI sensitivity.
• Observed maximum Bragg wavelength shifts up to 74.22 nm.
• Attained a maximum sensitivity of 523 nm/RI unit with a TiO2 coating of ~75 nm.
• Demonstrated a minimum RI resolution of 1.9 x 10^-6.

Conclusions:

• The developed epoxy polymer waveguide Bragg grating sensors exhibit significantly enhanced RI sensitivity.
• Titanium dioxide nanocoatings are effective in boosting the performance of waveguide sensors.
• The sensor design shows promise for high-resolution RI sensing applications.