Surface plasmon polaritons generated magneto–optical Kerr reversal in nanograting

Controlling the phase of light in magnetoplasmonic structures is receiving increasing attention because of its already shown capability in ultrasensitive and label-free molecular-level detection.Magneto-optical Kerr reversal has been achieved and well explained in nanodisks by using the phase of localized plasmons.In this paper,we report that the Kerr reversal can also be produced by surface plasmon polaritons independently.We experimentally confirm this in Co and Ag/Co/Ag metal nanogratings,and can give a qualitative explanation that it is the charge accumulation at the interface between the grating surface and air that acts as the electromagnetic restoring force to contribute necessary additional phase for Kerr reversal.Our finding can enrich the means of designing and fabricating magneto-optical-based biochemical sensors.

Magnetically controllable metasurface and its application

The dynamic control of the metasurface opens up a vital technological approach for the development of multifunctional integrated optical devices.The magnetic field manipulation has the advantages of sub-nanosecond ultra-fast response,non-contact,and continuous adjustment.Thus,the magnetically controllable metasurface has attracted significant attention in recent years.This study introduces the basic principles of the Faraday and Kerr effect of magneto-optical(MO)materials.It classifies the typical MO materials according to their properties.It also summarizes the physical mechanism of different MO metasurfaces that combine the MO effect with plasmonic or dielectric resonance.Besides,their applications in the nonreciprocal device and MO sensing are demonstrated.The future perspectives and challenges of the research on MO metasurfaces are discussed.

Enhanced magneto-optical Kerr effect and index sensitivity in Au/Fe_xCo_(1-x) magnetoplasmonic transducers

Magnetoplasmonic sensors are attractive candidates for ultrasensitive chemical and biomedical sensor applications.A variety of ferromagnetic metal thin films have been used for magnetoplasmonic device applications, yet the dependence of sensor performance on the optical and magneto-optical properties of ferromagnetic metal materials has been rarely studied. In this work, we report the study of enhanced magneto-optical Kerr effect(MOKE) and sensing performance in Au∕Fe_xCo_(1-x)bilayer magneto-optical surface plasmon resonance(MOSPR) transducers.The optical constants of Fe_xCo_(1-x)(x = 0, 0.29, 0.47, 0.65, and 1) in a sputter-deposited Au∕Fe_xCo_(1-x)device are characterized by the attenuated total internal reflection(ATR) method. Fe_xCo_(1-x)thin films show different MOKEs as a function of the chemical concentration, with the highest transverse MOKE signal observed in Fe_0.7Co_0.3.Index sensing performance is closely related to the material's optical and magneto-optical constants. By studying the sensing performance in the parameter space of the Au∕Fe_xCo_(1-x)bilayer thicknesses, the highest sensitivity is found to be 0.385(theoretical) and 0.306 RIU^(-1)(experimental) in the Au∕Fe_0.7Co_0.3 MOSPR devices. Our research highlights the influence of the optical properties of ferromagnetic material to device sensitivity in MOSPR transducers. The high sensitivity in Au∕Fe_xCo_(1-x)MOSPR devices make these structures attractivecandidates for chemical and biomedical sensing applications.