Adjustable Faraday rotation by using engineered one-dimensional magneto photonic crystals

Enhancing the Faraday rotation in the monolayer phosphorus base of magneto-photonic crystals

Large enhancement of Faraday rotation by localized surface plasmon resonance in Au nanoparticles embedded in Bi:YIG film

The transmission and Faraday rotation characteristics of one-dimensional photonic crystals in certain-substituted yttrium iron garnet (Ce:YIG) with multiple defects in the optical bandgap are studied theoretically at λ = 1.55 μm. It is found that the interdefect spacing can be adjusted to yield a flat top response, with close to 100% transmission and 45° Faraday rotation, for film structures as thin as 30 to 35 μm. This is better than a three-fold reduction in thickness compared to the best Ce:YIG films for comparable rotations, and may allow a considerable reduction in size in manufactured optical isolators. Transmission bands as wide as 7 nm are predicted, which constitutes a considerable improvement over previously reported bandwidths for magnetic photonic crystals. Diffraction across the structure corresponds to a longer optical path length than the thickness of the film, calling for the use of guided optics to minimize insertion losses in integrated devices. The basis for the flat-top transmission in ferrite photonic crystals is presented and discussed.

We fabricated new one-dimensional magnetophotonic crystal (1D-MPC) utilizing the second and third photonic band gaps where localized modes existed. Structure of the 1D-MPC was <TEX>$(Ta_{2}O_{5}/SiO_{2})_{5}/Bi:YIG/(SiO_{2}/Ta_{2}O_{5})_{5}$</TEX> with optical thicknesses of 3<TEX>$\lambda$</TEX> /4 for <TEX>$Ta_{2}O_{5}</TEX> and <TEX>$SiO_2$</TEX> dielectric layers and <TEX>$\lambda$</TEX> /2 for Bi:YIG defect layer, where <TEX>$\lambda$</TEX> is a wavelength of a localized mode in the second photonic band gap. Faraday rotation at the localized mode in the second photonic band gap was enhanced, which was confirmed by calculation using 4<TEX>${\times}$</TEX>4 matrix method.

The study of magnetophotonic crystals is usually based on its reflection and transmission of light waves, but its absorption properties are rarely studied. Considering the current high absorptivity of one-way absorbers has one absorption peak, and the optical constants of magnetophotonic crystals are all ideal approximation, we introduce the practical optical constants of silicon carbide (SiC) into the magnetophotonic crystals model. The optical properties are investigated in visible wavelength based on the transformation matrix method, and some parameter effects are also discussed in detail, such as the incidence angle and the thickness of defect layer. The one-dimensional (1-D) magnetophotonic crystal structure was systematically optimized. Then a multipeak one-way light absorber composed of real semiconductor and metal based on 1-D magnetophotonic crystal is further proposed, which makes the channel position of perfect nonreciprocal absorption controllable and the number increased; the influence of incident conditions on the absorption efficiency is greatly weakened and the universality and flexibility of one-way absorber in practice are greatly enhanced. The achievement provides new ideas for the study of nonreciprocal absorbers.

In this paper, a one-dimensional photonic crystal with dielectric defect layer was studied in near-infrared band. For photonic crystal with only one defect layer, the effects of refractive index and thickness of defect layer, photonic crystal structure and incident angle on defect mode were discussed in detail. A photonic crystal structure with two defect layers was proposed, which had two defect modes in the forbidden band. The position of the two defect modes could be regulated by adjusting the number of photon periods and the thickness of the defect layer. Based on this structure, a twochannel narrow band filter was designed. The calculation results showed that the transmittance at the two defect modes of 1310 nm and 1550 nm reached 92.16% and 95.44%, respectively, while the full width at half maximum was only 5.5 nm and 9.7 nm. The simulation of the electric field distribution in the defect mode further proved the correctness of the design results. The research results had important value in the field of optical communication.

In present study, the effect of different defect layer refractive indices and thicknesses on group velocity has been studied in one-dimensional photonic crystal. It is found that the increase of refractive index, number of defects and defect layer thickness will induce the decrease of group velocity. Taking advantage of these results, a novel technique has been introduced to tune and control the slowing light in photonic crystal

Transverse Kerr effect in one-dimensional magnetophotonic crystals: Experiment and theory

We present a two-step homogenization method for studying the Faraday magneto-optical effect in graded metal-dielectric composite films of width W, in which the volume fraction of metal particles in a slice varies along the direction perpendicular to the film surface. First, we adopt the effective-medium theory to formulate the equivalent (local) dielectric permittivity tensor for a z slice. Second, the graded composite films are homogenized with an effective (overall) dielectric permittivity tensor including the diagonal and off-diagonal elements. Faraday rotation is studied as a function of the graded profile p(z) with the same total volume fraction. For a power-law form p(z)=a(z/W)m with different m, it is found that with increasing m, the magnitude of Faraday rotation becomes weak near the surface plasmon resonant band, accompanied with the redshift of the resonant center. Interestingly, it is possible to achieve strongly enhanced Faraday rotation in the high-frequency region, and to change the direction of rotation in the low-frequency one. Moreover, the magnitude can be further enhanced for needle-like particles. In the dilute limit, we show that Faraday rotation is indeed independent of m within Maxwell-Garnett theory.

Bi-substituted yttrium iron garnet, Y3-xBixFe5O12 (Bi:YIG, x = 1, 1.5), films were prepared on Gd3Ga5O12 (111) substrates by metal-organic decomposition (MOD) method to use as MO indicator films. Those films had the in-plane magnetic anisotropy and Faraday rotation as large as that of the single crystal and do not show prominent magnetic domain structure, which is often observed in single crystalline garnet films grown by liquid phase epitaxy method. Disappearance o magnetic domain structure can be attributed to a granular structure with a grain size of ∼ 50 nm in Bi:YIG thin films. The characteristics are suitable for MO indicator films to visualize a stray magnetic field strayed from a specimen. In this paper, MO imaging of Nb films with groove patterns is demonstrated.

Microwave-assisted synthesis and characterization of Bi-substituted yttrium garnet nanoparticles

Three-dimensional magnetoplasmonic nanostructures possess more novel and richer optical and magneto-optical (MO) behaviors compared with planar nanostructures, and exhibit attractive potential applications in micro-nano non-reciprocal photonic devices. However, fabrication of three-dimensional magnetoplasmonic nanostructures is difficult using the usual nanofabrication methods. This work constructs three-dimensional substrate-free Au/Co/Au structures prepared using focused ion beam (FIB) technology. In the three-dimensional split-ring structure, with y-polarized light normal incidence, a three-dimensional coupling current is formed between the vertical split-ring and the bottom square hole, which causes excitation of the Fano resonance. The Fano resonance causes a significant enhancement of the local magnetic field, resulting in a larger Faraday rotation (FR). The resonance also brings about a sign reversal of FR, which is related to the direction of the Lorentz force on electrons. Similar effects also exist in the three-dimensional nanopillar structure and the three-dimensional nanoring structure in the simulation results. Due to the high flexibility of FIB machining, the height and shape of the three-dimensional split-ring can be arbitrarily changed, which means the FR intensity and the position of the FR null point are tunable. The designed three-dimensional structures provide a new route to regulate the Faraday effect, and broaden the possibilities for the design and construction of MO devices.

In this paper, the properties of the right circular polarized (RCP) waves in the three-dimensional (3D) dispersive photonic crystals (PCs) consisting of the magnetized plasma and uniaxial material with face-centered-cubic (fcc) lattices are theoretically investigated by the plane wave expansion method, which the homogeneous anisotropic dielectric spheres (the uniaxial material) immersed in the magnetized plasma background, as the Faraday effects of magnetized plasma are considered (the incidence electromagnetic wave vector is parallel to the external magnetic field at any time). The equations for calculating the anisotropic photonic band gaps (PBGs) for the RCP waves in the first irreducible Brillouin zone are theoretically deduced. The anisotropic PBGs and a flatbands region can be obtained. The effects of the ordinary-refractive index, extraordinary-refractive index, anisotropic dielectric filling factor, plasma frequency, and plasma cyclotron frequency (the external magnetic field) on the properties of first two anisotropic PBGs for the RCP waves are investigated in detail, respectively. The numerical results show that the anisotropy can open partial band gaps in fcc lattices at U and W points, and the complete PBGs for the RCP waves can be achieved compared to the conventional 3D dispersive PCs composed of the magnetized plasma and isotropic material. It is also shown that the first two anisotropic PBGs can be tuned by those parameters as mentioned above. Those PBGs can be enlarged by introducing the uniaxial material into such 3D PCs as the Faraday effects are considered.

Summary form only given. In recent years, Inoue and Fujii have studied theoretically and experimentally, the one-dimensional magnetophotonic crystal (1-D MPC) multilayer films composed of magneto-optical and dielectric materials. This 1-D MPC film exhibits an extremely large magneto-optical Faraday rotation due to the weak localization of light Such 1-D MPC film offers the possibility of realizing a rotation of 45/spl deg/ with a thickness of only several microns. The application from showing high transmittance (T) and large Faraday rotation (/sup /spl Theta///sub F/) to a variety of magneto-optical devices for optical communication (ex. film-based optical isolator) is expected. Therefore, we investigated on the possibility of the application to optical isolator (T>95%, /sup /spl Theta///sub F/=45/spl deg/) for the optical communication of 1-D MPC from the theory.

This paper has focused on the potential of the negative refractive index materials in order to improve the optical and magneto-optical characteristics of one-dimensional magnetophotonic crystals (MPCs). We have investigated the capability of such double-negative materials (DNGs) in comparison with conventional materials in MPCs. As a result, we found that the flat-top resonance peak bandwidth of the MPCs comprising DNGs can be expanded. The broadening of the flat-top response occurs simultaneously for transmittance and Faraday rotation, as well as ellipticity.