Sensing of Surface and Bulk Refractive Index Using Magnetophotonic Crystal with Hybrid Magneto-Optical Response.

Daria Ignatyeva,Mohammad Nur-E-Alam,Sergey Sekatskii,Andrey Kalish,Pavel Kapralov,Polina Shilina,Polina Golovko,Vladimir Belotelov,Kamal Alameh,Anastasiya Khramova,Mikhail Vasiliev

doi:10.3390/s21061984

Abstract

We propose an all-dielectric magneto-photonic crystal with a hybrid magneto-optical response that allows for the simultaneous measurements of the surface and bulk refractive index of the analyzed substance. The approach is based on two different spectral features of the magneto-optical response corresponding to the resonances in p- and s-polarizations of the incident light. Angular spectra of p-polarized light have a step-like behavior near the total internal reflection angle which position is sensitive to the bulk refractive index. S-polarized light excites the TE-polarized optical Tamm surface mode localized in a submicron region near the photonic crystal surface and is sensitive to the refractive index of the near-surface analyte. We propose to measure a hybrid magneto-optical intensity modulation of p-polarized light obtained by switching the magnetic field between the transverse and polar configurations. The transversal component of the external magnetic field is responsible for the magneto-optical resonance near total internal reflection conditions, and the polar component reveals the resonance of the Tamm surface mode. Therefore, both surface- and bulk-associated features are present in the magneto-optical spectra of the p-polarized light.

Highlights

Optical sensors based on the surface waves are characterized by a very high sensitivity that is crucial for various practical applications, including biosensing, medical studies, detection of chemical species, food safety, and environmental control [1]
We focus on an all-dielectric magnetophotonic crystal (MPC)based structure with a hybrid magneto-optical response that allows us to overcome this limitation
The position of this spec tral feature is determined by the total internal reflection angle θ TIR = sin−1 n an /n prism between the prism material and the analyzed substance with n an refractive index

Summary

Introduction

Optical sensors based on the surface waves are characterized by a very high sensitivity that is crucial for various practical applications, including biosensing, medical studies, detection of chemical species, food safety, and environmental control [1]. It can be scaled down to construct nanosensors utilizing plasmonic nanoantennas [2,3], in the present study we focus on the planar structures that allow operating with the macroscopic measurement cells and utilize the flat sensing surfaces to attach and detect various biological species [4,5]. Alongside with these advantages, surface plasmon resonances are characterized by low quality factors Q~10 due to the high absorption in the metallic layers which limit the sensitivity of such sensors. Long-range propagating surface plasmon polaritons in thin metal films deposited on the top of a dielectric layer [6,7,8], multilayered plasmonic [9,10] structures or photonic crystals [11,12,13,14,15]

Methods

Results

Conclusion