Silica-Polymer Heterogeneous Hybrid Integrated Mach-Zehnder Interferometer Optical Waveguide Temperature Sensor

Area of Science:

• Photonics and Optical Engineering
• Materials Science
• Integrated Optics

Background:

• Traditional temperature sensors often lack the sensitivity and integration capabilities required for advanced applications.
• Mach-Zehnder interferometers (MZIs) are sensitive optical devices, but their performance can be limited by material properties.

Purpose of the Study:

• To propose and analyze a novel polymer-silica heterogeneous integrated Mach-Zehnder interferometer (MZI) for enhanced temperature sensing.
• To investigate the impact of hybrid integration on temperature sensing characteristics.
• To compare different coupling methods and polymer materials for optimal device performance.

Main Methods:

• Fabrication of a hybrid MZI structure combining polymer and doped silica waveguide arms.
• Utilizing opposite thermal optical coefficients of polymers and silica to enhance temperature sensitivity.
• Implementing and simulating direct and side coupling methods to minimize optical loss.
• Evaluating the performance of devices using PMMA, NOA, and SU-8 polymer materials.

Main Results:

• The hybrid integrated MZI structure demonstrates significantly enhanced temperature sensing characteristics.
• Side coupling method shows lower coupling loss (0.104–0.618 dB) and greater manufacturing tolerance compared to direct coupling.
• Achieved sensitivity values of -6.85 nm/K (PMMA), -6.48 nm/K (NOA), and -2.30 nm/K (SU-8), an order of magnitude higher than all-polymer sensors.
• Calculated temperature responsivity (R_T) values range from 13.16 × 10^-5 K to 32.20 × 10^-5 K.

Conclusions:

• The polymer-silica heterogeneous integrated MZI offers superior temperature sensing performance.
• High thermo-optic coefficient polymers combined with hybrid integration are promising for on-chip temperature sensing.
• The side coupling method is advantageous for reducing loss and improving manufacturability.