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.

The optical properties of single crystals of tellurium (Te) are investigated in order to develop acousto-optic (AO) devices operating in the longwave infrared spectral region. The optical transparency of carefully cut and polished plates and large size samples of Te crystals was measured from 4 to 24 µm. The absorption of ordinary and extraordinary polarized optical beams was measured along various directions in the crystal with respect to the optic axis. Using a 10.6 µm CO2 laser the absorption coefficient for the best samples of Te was found to be 0.07 cm − 1 for the ordinary and between 0.07 and 4.0 cm − 1 for the extraordinary polarized optical beam. Here, we also discuss the possible application of Te crystals in fabricating AO imaging filters.

The acoustic, optic and acousto-optic properties of tellurium crystals have been examined in order to develop an acousto-optic tunable filter (AOTF) operating in the long-wave infrared (LWIR) region. The AOTF design is based on the wide-angle regime of light diffraction in the YZ plane of the birefringent crystal operating from 8.4 to 13.6 µm. Device characteristics were obtained from both theoretical and experimental investigations. Experiments were carried out using both a 10.6 µm pulsed CO2 laser as well as a tunable CO2 laser operating in a continuous wave mode from 9.2 to 10.7 µm. The AOTF was tuned over the acoustic frequency range of 81.5–94.7 MHz. The filtering performance in the tellurium device was provided by a pure shear elastic wave propagating at a 95.8° angle with respect to the positive direction of the optic axis, while an ordinary polarized optical beam was incident at the Bragg angle of 6.0° relative to the acoustic wavefront. At 10.6 µm, the measured spectral bandwidth of the filter was 127 nm and the optical transmission coefficient was around 8.8% with 2.0 W drive power. This paper presents detailed results from both the theoretical as well as experimental device characterization including the spectral images obtained with a 256 × 256 mercury cadmium telluride camera cooled to 77 K.

Magnetometry and visualization of very small magnetic fields are vital for a large variety of the areas ranging from magnetocardiography and encephalography to nondistractive defectoscopy and ultra-low-frequency communications. It is very advantageous to measure magnetic fields using exchange-coupled spins in magnetically ordered media (flux-gate magnetometry).Here we introduce and demonstrate a novel concept of a roomtemperature magnetoplasmonic magnetic field sensor with high sensitivity and spatial resolution. It is based on the advanced fluxgate technique in which magnetization of the fully saturated magnetic film is rotated in the film plane and the monitored magnetic field is measured by detecting variation of transmittance through the sensing element: a magnetoplasmonic crystal. The experimental study revealed that such an approach allows one to reach the nT sensitivity level, which was limited by the noise of the laser. Moreover, we propose an approach to improve the sensitivity up to fT/Hz 1/2 and reach micrometer spatial resolution. Therefore, the demonstrated magnetoplasmonic magnetometry method is promising for mapping and visualization of ultrasmall magnetic fields.