Journal article

Publication year: 2014

Journal: Journal of Optics

Volume number: 16

Issue number: 9

ISSN: 2040-8978

eISSN: 2040-8986

DOI Link: https://doi.org/10.1088/2040-8978/16/9/094015

Publisher: IOP Publishing

Abstract: 
The frequency of the Rayleigh anomaly of a metallic grating varies with the refractive index of the surrounding medium. To employ this phenomenon in optical sensors it is essential that the feature, due to the Raleigh anomaly in the sensor's optical response, is very distinct and stable. We study the reflectance of optical structures consisting of a metallic grating with a thin dielectric film on highly reflective silicon substrates in the terahertz (THz) range between 0.6 and 2 THz. A distinct reflectance peak due to the Rayleigh anomaly can only be observed if a dielectric spacer layer is inserted between the metallic grating and silicon substrate. The dielectric layer between the grating and substrate acts as a Fabry-Perot resonator with a low quality factor. Thus, the corresponding Fabry-Perot modes only couple weakly to the Rayleigh anomaly. At the frequency of the Rayleigh anomaly, the combined structure exhibits a distinct peak due to the Rayleigh anomaly, no matter whether there is a Fabry-Perot low or high reflection band at this frequency. In particular, the reflection background in the vicinity of the frequency of the Rayleigh anomaly is suppressed when the Rayleigh anomaly is in resonance with a Fabry-Perot low reflection band, whilst the Rayleigh reflectance peak itself is retained. The underlying physics is confirmed by a simple analytic model and by numerical calculations. This approach of optimizing the optical response of metallic gratings is important for the design of THz sensing devices based on Rayleigh anomalies.

Harvard Citation style: Deng, L., Henning, T., Klar, P., Feng, S., Xie, Z., Wang, X., et al. (2014) Optimization of the Rayleigh anomaly of metallic gratings for terahertz sensor applications, Journal of Optics, 16(9), Article 094015. https://doi.org/10.1088/2040-8978/16/9/094015

APA Citation style: Deng, L., Henning, T., Klar, P., Feng, S., Xie, Z., Wang, X., Sun, W., Ye, J., Han, P., & Zhang, Y. (2014). Optimization of the Rayleigh anomaly of metallic gratings for terahertz sensor applications. Journal of Optics. 16(9), Article 094015. https://doi.org/10.1088/2040-8978/16/9/094015