Thermal Sensor Based on Polydimethylsiloxane Polymer Deposited on Low-Index-Contrast Dielectric Photonic Crystal Structure

In this work, a dielectric photonic crystal-based thermal sensor is numerically investigated for the near-infrared spectral range. An easy-to-fabricate design is chosen with a waveguide layer deposited on a silicon dioxide substrate with air holes drilled across it. To sense the ambient temperature, a functional layer of polydimethylsiloxane biguanide polymer is deposited on the top, the optical properties of which vary with changes in the temperature. An open-source finite-difference time-domain-based software, MEEP, is used for design and numerical simulation. The design of the sensor, spectral properties, and proposed fabrication method are part of the discussion. The performance of the sensor is investigated for an ambient temperature range of 10 to 90 °C, for which the device offers a sensitivity value in the range of 0.109 nm/°C and a figure-of-merit of 0.045 °C⁻¹. Keeping in mind the high-temperature tolerance, inert chemical properties, low material cost, and easy integration with optical fiber, the device can be proposed for a wide range of thermal sensing applications.