Thermo-Optic Sensor Based on Resonance Waveguide Grating for Infrared/Thermal Imaging

The development of high resolution, low cost, infrared/thermal imaging systems is one of the critical challenges in infrared photonics. This paper highlights the design, simulation, fabrication, and characterization of a thermo-optic sensor based on a resonance waveguide grating structure. The sensor has been realized using polymer materials on a glass substrate. Detailed characterization of the thermal response of the structure has been performed and the experimental results show close correspondence with the simulations. The thermal response of the sensor was measured within the temperature range of 25 °C-45 °C and the measured sensitivity was found to be 0.268 nm/°C. The resonance of the structure undergoes a blue shift with respect to applied temperature. This observed displacement of the resonance is due to the thermo-optic properties of the sensor's waveguide material. Based on 2-D structure, the sensor can be implemented as a thermal imaging sensor array. The simplicity of fabrication and high thermal sensitivity of the resonance structure enable low cost, infrared/thermal imaging applications.