ИСТИНА

The PC nanostructure composed of two Bragg mirrors and a subwavelength layer between them allows one to support an optical analogue of Tamm state. The sharp resonance peak appears in the bandgap of the transmittance spectrum. The spectral position and amplitude of the peak in the transmittance spectrum depends on the thickness of the microcavity between the Bragg mirrors. The optical Tamm state is also accompanied by the strong localization of light in the microcavity. If the layer between the Bragg mirrors has magnetic properties, the magneto-optical (MO) effects can be observed there. Among a variety of such effects we would like to focus on the inverse Faraday effect (IFE). It denotes the effect when the magnetization occurs in a transparent medium exposed to a circularly polarized high-frequency electromagnetic wave. The strong localization of light inside the magnetic layer of the MPC leads to an enhancement of the IFE in the nanostructure. It is proposed a design of the photonic crystal (PC) nanostructure with the magnetic layer of gradient thickness sandwiched between two non-magnetic Bragg mirrors. The spectral position of the optical Tamm state of the magneto-photonic crystal (MPC) nanostructure depends on the spatial position of the input light spot on the sample surface. Therefore, the resonant enhancement of the IFE associated with the peak in transmittance band gap also changes with the input light spot position. Thus, illuminating the proposed MPC nanostructure by the circularly polarized light at the normal incidence the observation of the broadband inverse Faraday effect can be achieved. The numerical simulations revealed that an increase of the magnetic layer thickness from 120nm to 180nm leads to the resonance spectral position detuning from 0.6um to 0.675um, correspondingly. Besides the smooth gradient magnetic layer, the PC nanostructure with the magnetic layer with etched discs is proposed. In the magnetic layer with the constant thickness the disks with diameter of dozen microns are etched. The etching depth is different for various disks. As a result, the thickness of the magnetic layer is smaller in the area of such disks. Therefore, the enhanced IFE occurs at the different frequencies for each disk. This idea allows us to achieve spatial localization of the IFE limited just by the disk diameter that is of several microns. To sum up, two designs of the MPC nanostructures with gradient of the magnetic layer thickness for tunable inverse Faraday effect are proposed. The spectral position and amplitude of the transmittance peak and resonant IFE depend on the thickness of the magnetic layer. The first design of the MPC nanostructure has smooth magnetic layer with thickness gradient that allows to tune the spectral position of peak in transmittance spectra and the IFE gradually. The second design has perforated magnetic layer and provide spatially localized emergence of the IFE in the spots of several microns. The sample fabrication and the experimental verification of the reported results is expected.