A Theoretical Proposal for a Refractive Index and Angle Sensor Based on One-Dimensional Photonic Crystals

In this article, a structure based on one-dimensional photonic crystals that can be used for both angle sensing and refractive index sensing is proposed, which is achieved by optical Tamm state. Under Bragg scattering, its features are investigated by the transfer matrix method. This sensing structure is based on a multi-frequency absorption structure, which can achieve an absorption rate higher than 0.9 for three to four frequency points at the same time. The studied results demonstrate that the absorption peaks of such an absorption structure can be changed from three to four by adjusting the number of periods and silver layer thickness. Absorption peaks can occur red and blue shifts employing tailoring the thickness of defect and the angle of the incident light. By altering the thickness of the defect and the number of periods, the interval between the absorption peaks can be dominated. They are all with high-quality factors and can be used to bring about a high absorption sensor for the refractive index or angle. When it acts as a refractive index sensor, the operating range can cover from 2 to 2.7, whose sensitivity and average figure of merit are 32.3 THz/RIU and 100. If the presented device is used as an angle sensor, those values will become 0.5 THz/degree and 1.2, and its measuring range is from 25 degrees to 70 degrees. It can be said that the emergence of this special sensing structure will be possible to have a broad application prospect in the field of measurement.

Automated summary

A structure based on one-dimensional photonic crystals is proposed for angle sensing and refractive index sensing through optical Tamm state. It demonstrates high absorption rates at multiple frequency points and the ability to adjust absorption peaks through period adjustments. This special sensing structure shows promising application prospects in the field of measurement.