Sensing response characterization of a micro-holographic sensor and its kinetics simulation

摘要

A photopolymer-based micro-holographic sensor was developed to improve the sensitivity in sensing environmental factors. The micro-holographic grating can be formed by interference of two counter-propagating beams. The response rate and sensitivity of the micro-grating based sensor were measured. The response rate reached 0.171 nm/s in sensing relative humidity and 0.03 nm/s in sensing ethanol vapor. The corresponding maximum of the peak wavelength shifted up to 51.2 nm and 8.9 nm, respectively, for 5 min of sensing. The minimum detectable ethanol vapor concentration was as low as 10 ppm, while the sensitivity approached up to 0.179 nm/ppm. Theoretically, relating the absorption and modulation along the thickness direction, a diffusion model with nonlocal response was proposed to describe the micro-grating formation and its sensing characterization. The numerical simulation provides a significant foundation for understanding the grating formation and sensing the physical mechanism inside the materials. These results can accelerate the development and practicality of novel holographic sensing elements. (C) 2019 Optical Society of America