One-dimensional Magnetophotonic Crystals Research Articles

High performance reflection-type 1D magnetophotonic crystals with flat-top responses

In this paper, a theoretical study on the case of reflection-type one-dimensional magnetophotonic crystals (MPCs) has been carried out to establish high performance structures having concurrent high reflectance and large Kerr rotation with flat-top responses. The introduced MPCs are able to maintain their flat-top responses in a wide range of incident angle. For practical purposes, we have also inquired the influence of the error in the thickness of individual layers on the operational parameters of the MPCs. The reflectance flatness and bandwidth of the MPCs are appreciably stable against the imposed thickness errors.

Influence of arrangement order ratio on the magneto-optical properties of one-dimensional microcavity structures

The dependence of the optical responses of microcavity-type one-dimensional (1D) photonic crystals and 1D magnetophotonic crystals (1D-MPCs) on the arrangement order ratio (AOR), which is the ratio of the first and second layers' refractive indexes of Bragg reflectors, is studied. It is demonstrated that the optical properties of two microcavity structures resulting from exchanging the order of Bragg reflector layers so that they have the same optical contrast ratios and different AORs would be different. This difference will be more noticeable in the case of microcavity type 1D-MPCs. Regarding the arrangement-dependent magneto-optical properties of the structures, we can propose the efficient Bragg reflectors with high transmittance enhanced Faraday rotation.

Adjustable magneto-optical isolators with flat-top responses

In order to construct flat-top magneto-optical isolators (MOIs), we have performed a theoretical study on the case of transmission-type one-dimensional magnetophotonic crystals (MPCs). We have introduced high performance MPC structures with flat-top responses and with the capability of adjusting to perfect MOIs. The adjustment is carried out by tuning the applied magnetic field. All introduced MOIs are sufficiently thin with acceptable transmission bandwidth. In the best case, we have achieved a 19.42 μm-thick perfect MOI with the flat-top width of 7.2 nm. For practical purposes, we have also considered the influence of the error in thickness of individual layers on the operational parameters of the MOIs and investigated the possibility of compensating the deviations by the magnetic adjustment.

Influence of thickness error on the operation of adjustable magneto-optical isolators

We have performed a theoretical study on the case of transmission-type one-dimensional magnetophotonic crystals (MPCs) to establish a practical magneto-optical isolator (MOI) that operates properly even in the presence of construction errors. We have introduced a very thin MPC structure with high transmittance and a large Faraday rotation, with the capability of adjusting to a perfect MOI. A minor thickness error for the individual layers of this MOI may take it from being a perfect MOI; however, its adjustability can provide a stable operation against fabrication errors.

Interplay of surface resonances in one-dimensional plasmonic magnetophotonic crystal slabs

Responses from one-dimensional magnetophotonic crystals terminated by gold layers have been studied experimentally. Such a plasmonic magnetophotonic crystal slab supported an optical resonance (optical Tamm state) originating from the periodicity of the magnetophotonic crystal and a surface plasmon resonance on a gold film's interface. Parameters of the slab and experimental conditions were chosen such that the optical Tamm state and the surface plasmon resonance were excited simultaneously and overlapped in a selected spectral range. Significant alteration of the magneto-optical response together with the change of its sign was observed when tuning the overlap between the resonances.

Polarization switching and nonreciprocity in symmetric and asymmetric magnetophotonic multilayers with nonlinear defect

A one-dimensional magnetophotonic crystal with a nonlinear defect placed either symmetrically or asymmetrically inside the structure is considered. Simultaneous effects of time-reversal nonreciprocity and nonlinear spatial asymmetry in the structure are studied. Bistable response is demonstrated in a such system, accompanied by abrupt polarization switching between two circular or elliptical polarizations for transmitted and reflected waves. The effect is explained in terms of field localization at defect-mode spectral resonances and can be used in the design of thin-film optical isolators and polarization transformation devices.

Bi-substituted iron garnet films for one-dimensional magneto-photonic crystals: Synthesis and properties

The crystallization processes in Bi2.8Y0.2Fe5O12, Bi2.5Gd0.5Fe3.8Al1.2O12, Bi1.5Gd1.5Fe4.5Al0.5O12 and Bi1.0Y0.5Gd1.5Fe4.2Al0.8O12 garnet films deposited by reactive ion beam sputtering on (111) gadolinium–gallium garnet substrates, optical glass-ceramic and SiO2 films have been studied. Films were annealed at low pressure in oxygen atmosphere and in the air. The possibility of preparation of crystalline garnet films with high concentration of bismuth on the SiO2 films using a buffer layer with low concentration of Bi has been shown. This allows to produce one-dimensional magneto-photonic crystals with high effective Faraday rotation (several tens of°/μm for the visible optical spectrum).

Compact one-dimensional magnetophotonic crystals with simultaneous large Faraday rotation and high transmittance

We have investigated the case of transmission-type one-dimensional magnetophotonic crystals (MPCs) in order to achieve simultaneous high transmittance and large Faraday rotation utilizing few magnetic layers. In a MPC that includes two Ce:YIG magnetic layers, we have achieved a Faraday rotation as large as 85.82° and a transmittance of 95.66%. In addition, another structure in the form of a triple-cavity MPC with a transmittance of 100% and a Faraday rotation as huge as 87.72° has been achieved through precise selection of layer thicknesses and positions. Both of these high-performance structures are very compact and thin, which makes them excellent candidates for application in integrated MO devices.

Microcavity One-Dimensional Magnetophotonic Crystals with Double Layer Iron Garnet

In this work the results of investigation of microcavity one-dimensional magnetophotonic crystals GGG (111)/[TiO2/SiO2]5/M/[SiO2/TiO2]5 are presented, where M is single (Bi1,0Y0,5Gd1,5Fe4,2Al0,8O12) or double(Bi1,0Y0,5Gd1,5Fe4,2Al0,8O12/Bi2,8Y0,2Fe5O12 or Bi1,0Y0,5Gd1,5Fe4,2Al0,8O12/Bi1,5Gd1,5Fe4,5Al0,5O12) magnetoactive layers. Theoretical calculations and experiments showed that magnetooptical properties of microcavity one-dimensional magnetophotonic crystals can be improved using double layer iron garnet. In particular, the Faraday rotation can be significantly increased. It was determined, that depending on the crystal structure and magnetic layers composition magnetophotonic crystals with different types of magnetic anisotropy can be realized.

Adjustable magneto-optical isolators with high transmittance and large Faraday rotation

In order to construct perfect magneto-optical isolators (MOIs), we have performed a theoretical study on the case of transmission-type one-dimensional magnetophotonic crystals (MPCs). We have introduced high performance MPC structures with high transmittance and large Faraday rotation, and with the capability of adjusting to perfect MOIs. The adjustment is carried out by tuning the applied magnetic field. All of the MOIs are very thin and, hence, have high potential for application in integrated optical systems.

Elliptical normal modes and stop band reconfiguration in multimode birefringent one-dimensional magnetophotonic crystals

This study examines photonic stop band reconfiguration upon magnetization reversal in multimode elliptically birefringent Bragg filter waveguides. Magnetization reversal in longitudinally magnetized magneto-optic waveguides affects the character of the local orthogonal elliptically polarized normal modes, impacting the filter's stop band configuration. Unlike the standard case of circular birefringence in magneto-optic media, opposite helicity states do not transform into each other upon magnetization reversal for a given propagation direction. Rather, helicity reversals yield new and different normal modes with perpendicularly oriented semimajor axes, corresponding to a north-south mirror reflection through the equatorial plane of the Poincar\'e sphere. For asymmetric contradirectional coupling between different-order waveguide modes in multimode magnetophotonic crystals, this symmetry breaking, namely, the obliteration of normal modes upon magnetization reversal, allows for strongly reconfigured stop bands, through the hybridization of the elliptically polarized states. The effect of Bloch mode reconfiguration on the stop band spectral profile contributes to the magnetic response of the filter. In such elliptically birefringent media, input polarization helicity reversal also becomes a powerful tool for optical transmittance control. Both magnetization and helicity reversals can thus serve as useful tools for the fabrication of on-chip magnetophotonic crystal switches.

Engineered one-dimensional magneto-photonic crystals for wavelength division multiplexing systems

We have investigated the behaviour of an engineered one-dimensional magneto-photonic crystal with a (TiO2/SiO2)6/Bi : YIG/(SiO2/TiO2)6 structure for use in wavelength division multiplexing. The magnetic defect layer was fabricated using the pulsed laser deposition technique between two dielectric mirrors. The optical and magneto-optical properties of the sample were studied in detail so as to corroborate, or otherwise, the hypotheses formulated to achieve sufficient Faraday rotation of the media originating in the localized peak of light. Results indicate that this magneto-photonic crystal can be considered as a candidate for a multichannel isolator in wavelength division multiplexing systems. Also, the low-temperature behaviour of this sample indicates five order of magnitude enhancements in the magneto-optical Faraday rotation.

Compact 1-D magnetophotonic crystals with simultaneous large magnetooptical Kerr rotation and high reflectance

We have investigated the case of reflection-type one-dimensional magnetophotonic crystals (MPCs) in order to achieve high reflectance and high magnetooptical Kerr effect, simultaneously, utilizing a low number of magnetic layers. In a MPC structure including only one Bi:YIG magnetic layer, we have achieved a Kerr rotation as huge as θ k ≈ 90° with a reflectance of R > 97%. In addition, we have introduced a thinner structure having three Bi:YIG layers and with approximately the same Kerr rotation and reflectance. Both the structures are very compact with lengths of less than 9 μm.

Spatial light phase modulators with one-dimensional magnetophotonic crystals driven by piezoelectric films

We demonstrate a novel spatial light phase modulator composed of a one-dimensional magnetophotonic crystal driven by a piezoelectric film. With the application of a constant magnetic bias field perpendicular to the film plane, the magneto-optic Kerr rotation angle of the modulator was subject to continuous change from 3.8–2.4° with the voltage up to 50 V and hence a continuous phase modulation for rays with circular polarization. Surprisingly, the magneto-optical response of the modulator showed nonvolatile behavior and the light phase was maintained at a designated value without applying any stress. Based upon the above experimental results, magneto-optic spatial light phase modulators with a 64 × 64 array of magnetic pixels were constructed. The fabricated device had a dimension of 15 μm2 and demonstrated two-dimensional optical modulation of the phase of reflected rays.

Defect modes and magnetooptical activity of a one-dimensional magnetophotonic crystal

The reflection spectrum of a periodic transverse-magnetized structure containing a finite number of ferromagnet-dielectric periods has been obtained. The influence of a substitutional defect on the reflection spectrum is analyzed for normal incidence of light on the structure. It is shown that the intensity and position of the defect miniband in the bad gap of the spectrum depend on the location of the defect layer in the structure and on its type (magnetic or nonmagnetic). It is found that magnetooptical activity of the defect structure is higher than in a defect-free structure.

Artificial Periodic Magnetic Structures for Photonic and High Frequency Micro-magnetic Devices

Magnetophotonic crystals and magnonic crystals having periodic structures formed band gaps by interference of waves. A one-dimensional magnetophotonic crystal (1D-MPC), which exhibits optical Tamm state at the interface between magnetic and nonmagnetic photonic crystals (PCs), shows resonant transmissivity and large enhancement of Faraday rotation at the localized mode inside the photonic band gap. We developed two-dimensional magnetophotonic crystals (2D-MPCs) on various types of templates with periodical structures. A 2D-MPC with multi-layers formed on a periodic 1D line resist template has several photonic band gaps with enhanced magneto-optical (MO) effects. In a structural garnet film formed on the opal template, a significant enhancement of MO response was obtained at edges of band gaps. Magnonic crystal with Cu metal strips formed on YIG surface showed high sensitivity of 11400 %/Oe as a magnetic sensor. In addition, enhanced MO effect was demonstrated by plasmonic composite films with noble metal particles and magnetic garnet.

One‐dimensional magnetophotonic crystals based on double‐layer Bi‐substituted iron garnet films

AbstractIn the present work the fabrication process and properties of periodic one‐dimensional magnetophotonic crystal GGG (111)/M1/SiO2/[M2/M1/SiO2]4 in which as magnetic active layers were used double‐layer Bi‐substituted iron garnet films with high (Bi2.8Y0.2Fe5O12 : M1) and low (Bi1.0Y0.5Gd1.5Fe4.2.Al0.8O12 : M2) bismuth content were described. The Faraday effect and the parameters of ferromagnetic resonance were measured at different stages of magnetophotonic crystal formation. The theoretical and experimental magnetophotonic crystal transmission spectra displayed three photonic band gaps in the wavelength range of 450–1800 nm. The Faraday effect enhancement at the vicinity of the second photonic band gap at wavelength 710 nm was 2.6 times in comparison with combined (M1 + M2) layer and the effective value of Faraday rotation at the same wavelength reached –6.7°/μm.Diese Arbeit beschreibt das Herstellungsverfahren und die Eigenschaften von periodischen eindimensionalen magnetophotonischen Kristallen GGG (111)/M1/SiO2/[M2/M1/SiO2]4 mit einer magnetoaktiven Schicht aus Doppelschicht‐Bismut‐substituierten Ferritgranat‐Filmen mit niedrigem (Bi1.0Y0.5Gd1.5Fe4.2.Al0.8O12 : M2) und hohen (Bi2.8Y0.2Fe5O12 : M1) Gehalt an Bismut. Der Faraday‐Effekt und die Parameter der ferromagnetischen Resonanz wurden in verschiedenen Stadien der Magnetophotonenkristallbildung gemessen. Theoretische und experimentelle Transmissionsspektren des Magnetophotonenkristalle zeigen drei photonische Bandlücken im Wellenlängenbereich von 450–1800 nm. Der Faraday‐Effekt in der zweiten photonische Bandlücke bei einer Wellenlänge von 750 nm ist 2,6 mal größer als in der kombinierten (M1 + M2) Schicht. Der spezifische Wert der Faraday‐Rotation auf der gleichen Wellenlänge erreicht –6,7°/μm.

Dual-cavity magnetophotonic crystals when applying bounding: An analysis by the matrix approach

Optical responses of one-dimensional magnetophotonic crystals (1D MPCs) with a dual-cavity structure were analyzed by the transfer matrix method. The analysis implied that such dual cavities are fabricated when bounding two identical single microcavities. While keeping sameness of the cavities, we analyzed the influence of a synchronous layers' thickness deviation in both cavities. High transmittance and large Faraday rotation of the dual cavities were shown to be robust to the thickness deviation of the layers within the cavities and that of their interface layer.

Magneto-optical enhancement in magnetophotonic crystals based on cholesteric liquid crystals

The magneto-optical features in a one-dimensional magnetophotonic crystal based on cholesteric liquid crystals are explored theoretically by employing the Muller matrix method. It is unveiled that the intrinsic nonreciprocity-derived magneto-optical effect exhibits an enhancement, which origins from the strong photonic localization in the defect layers. Meanwhile, the oscillation behavior in the transmission spectrum with the linearly polarized angle indicates its polarization-dependent characteristic due to the breaking of time reversal symmetry in the magnetic materials. This novel scheme presents an opportunity of developing new hybrid structures for technological applications.

The Kerr effect enhancement in non-quarter-wave lossy magnetophotonic crystals

Lossy one-dimensional (1-D) magnetophotonic crystals (MPCs) consisting of a highly absorptive magnetic layer and two types of dielectric layers are assumed. Magnetic medium is a TbFeCo alloy mostly used for application in magneto-optical data storage disks. Bringing to account the problematic effects of optical loss on the photonic band gap of MPC, two compensative approaches are introduced to attain proper modified PBGs regarding operational wavelength of the structure. Both approaches, gap-shift and resonance-tuning, utilize non-quarter-wave design of MPC structures, and although each one is non-conventional in the realm of MPC design, they offer well suited solutions for the problem. Having applied these approaches, we obtained enhanced magneto optic Kerr effect accompanied with desired optical response.