Magneto-optical plasmonic heterostructure with ultranarrow resonance for sensing applications

Abstract

Currently, sensors invade into our everyday life to bring higher life standards, excellent medical diagnostic and efficient security. Plasmonic biosensors demonstrate an outstanding performance ranking themselves among best candidates for different applications. However, their sensitivity is still limited that prevents further expansion. Here we present a novel concept of magnetoplasmonic sensor with ultranarrow resonances and high sensitivity. Our approach is based on the combination of a specially designed one-dimensional photonic crystal and a ferromagnetic layer to realize ultralong-range propagating magnetoplasmons and to detect alteration of the environment refractive index via observation of the modifications in the Transversal Magnetooptical Kerr Effect spectrum. The fabrication of such a structure is relatively easy in comparison with e.g. nanopatterned samples. The fabricated heterostructure shows extremely sharp (angular width of 0.06°) surface plasmon resonance and even sharper magnetoplasmonic resonance (angular width is 0.02°). It corresponds to the propagation length as large as 106 μm which is record for magnetoplasmons and promising for magneto-optical interferometry and plasmonic circuitry as well as magnetic field sensing. The magnitude of the Kerr effect of 11% is achieved which allows for detection limit of 1∙10−6. The prospects of further increase of the sensitivity of this approach are discussed.

Photonic Crystal-Supported Long-Range Surface Plasmon-Polaritons Propagating Along High-Quality Silver Nanofilms

“…Indeed, comparable LRSPP propagation lengths have been observed also in experiments with Pd [10] and Co [12] nanofilms deposited onto the properly designed PC. The common characteristic feature here is that in all of these cases, the experimentally measured values, although are impressively large enough and much exceed the propagation lengths for simple metal-dielectric interfaces, turn out to be substantially smaller than those which could be achieved according to the theoretical predictions.…”

“…This value is quite large, and enables the practical use of similar structures as sensors, cf. [9][10][11][12][13], and the corresponding possibilities will be considered in the course of subsequent work.…”

“…This enabled the launch and use of surface plasmons (in the red spectral region) for such "non-plasmonic" materials as palladium [9][10][11] and cobalt [12], as well as launch and use blue (at 405 nm [13]) surface plasmons for gold. Note, that in all of the above cases, without the properly designed Photonic Crystal supporting LRSPP, there is simply no point in speaking about surface plasmons at all: their propagation distances would then be just of the order of the wavelength.…”

Microstructure and magneto-optical surface plasmon resonance of Co/Au multilayers

“…Co/Au multilayers (MLs) are of great interest not only due to their magnetic and magneto-optic properties, but also due to the plasmonic enhancement that is associated with Au, making them attractive for application in magnetic-recording and ultra-sensitive biosensors. If deposited and annealed under controlled conditions their microstructural, optical, and magneto-optical (MO) properties can be changed and tuned substantially [1][2][3][4][5]. From the prospective of designing more efficient MO devices, these MLs offer the possibility of carefully tuning the plasmonic properties of the diamagnetic layer, in this case Au, with the MO effect of the ferromagnetic layer, in this case Co.…”

Horizontal Plasmonic Ruler Based on the Scattering Far-Field Pattern

“…SPR is an optical phenomenon that results from strong light-matter interaction, thus leading to resonance oscillation of electron charges excited by the incident light at the interface between two materials with different permittivity values. These different positive and negative permittivity values are mostly associated with dielectric and metallic materials [3,4,5,6,7]. At the resonance wavelength, the amplitude of the near-field is enhanced owing to the strong confinement at the interface.…”