TOPICAL REVIEW: Magnetophotonic crystals

In this paper we outline a new direction in the area of photonic crystals (PCs), or photonic band gap materials, i.e. one-, two-, or three-dimensional superstructures with periods that are comparable with the wavelengths of electromagnetic radiation. The main (and principal) characteristic of this new class of PCs is the presence of magnetically ordered components (or external magnetic field). The linear and nonlinear optical properties of such magnetic PCs are discussed.

Magnetic photonic crystals

Research on magneto-optical photonic crystals has so far been focused on theoretical investigations, because suitable multilayers of iron garnet, the most promising material, have not been readily available. We report the preparation and characterization of a one-dimensional magneto-optical photonic crystal composed of 17 heteroepitaxial layers of bismuth iron garnet and yttrium iron garnet. The magneto-optical Faraday rotation was increased by 140% while transmission decreased by just 16% at the design wavelength of 750 nm as compared with a single-layer bismuth iron garnet film of equivalent thickness. The sample is free of cracks, and good agreement of simulated and experimental spectra of optical transmission and Faraday rotation indicate high quality of the sample and robustness of the preparation technique.

Enhanced Faraday rotation in all-garnet magneto-optical photonic crystal

In much the same way that semiconductor crystals affect the propagation of electrons, photonic crystals (periodic composites of macroscopic dielectric media of different refractive index) affect the propagation of light, providing a new mechanism to control and manipulate the flow of light. When the constitutive material of PCs is magnetic, or even only a defect introduced into the periodic structure is magnetic, the resultant PCs (let us simply refer to as magnetophotonic crystals (MPCs) hereafter) exhibit unique optical and magneto-optical responses: The strong photon confinement associated with the magnetic defect can be exploited to enhance and optimize magneto-optical (MO) effects and optical non-linearity of existing materials.

http://ieeexplore.ieee.org/iel5/4261433/4261434/04261453.pdf

Magnetophotonic crystals

https://www.springer.com/cda/content/document/productFlyer/productFlyer_978-0-442-26262-4.pdf?SGWID=0-0-1297-36131341-0

Magnetic Recording Handbook

We present a procedure for analyzing the properties of multilayer structures with magnetic film. The magneto-optical effect in multilayer-structure magnetic films [e.g., bismuth-substituted yttrium iron garnet (YIG)] and dielectric films (e.g., SiO2 and Ta2O5) was investigated theoretically and experimentally to examine the correlation between the magneto-optical properties and the localization effect of light. The film structure of interest, which has symmetric periodicity, is the (Ta2O5/SiO2)n/Bi:YIG/(SiO2/Ta2O5)n structure, where n is the repetition number. We fabricated experimentally a one-dimensional magnetophotonic crystal film of (Ta2O5/SiO2)n/Bi:YIG/(SiO2/Ta2O5)n (n=2,6) structures. The theoretical calculation and the measured value for the Faraday rotation were in close agreement. Furthermore, the Faraday rotation of the multilayer structure with n=6 is 150 times larger than that of a Bi:YIG single-layer film. This is of interest from the point of view of actual magneto-optical device (e.g., opt...

Theoretical analysis of optical and magneto-optical properties of one-dimensional magnetophotonic crystals

A one-dimensional (1-D) magnetophotonic crystal (MPC) film made of a magneto-optical layer with nonmagnetic layers laminated thereon has an enhanced Faraday rotation. Theoretical studies about 1-D MPC films for use in magneto-optical (MO) applications of optical communication were carried out. The calculations revealed that required optical isolator performance (transmittance T>95% and Faraday rotation angle /spl theta//sub F/=45/spl deg/) can be fulfilled with the periodic multilayer films having only two or three magnetic layers. The structure of 1-D MPC films satisfying the optical isolator performance is very simple, which is very attractive for actual optical isolator fabrication.

Properties of one-dimensional magnetophotonic crystals for use in optical isolator devices

Effect of optical losses on optical and magneto-optical properties of one-dimensional magnetophotonic crystals for use in optical isolator devices

A magnetic head which can be miniaturized while maintaining the performance thereof includes a thin film conductor coil assembly having a magnetic core connected magnetically to magnetic substances and stepping across a non-magnetic substance located between the magnetic substances of a substrate and a thin film conductor coil formed with the magnetic core as a thin film magnetic core. This thin film conductor coil assembly is attached to a slider provided with a magnetic head core. The magnetic head core includes an I-core in which magnetic substances are formed on both sides of a non-magnetic substance, and a U-shaped core composed of a magnetic substance, formed together in one integral body with a magnetic gap provided therein. This magnetic head core is fitted into a slit in the slider, and the thin film conductor coil assembly is attached thereon. With this construction, it is possible to form the thin film conductor coil into a thin film and to enlarge the magnetic path area, thereby to miniaturize the magnetic head while maintaining the performance thereof.

Magnetic head having a thin film conductor coil assembly formed separate from a magnetic head core

A low inductance metal-in-gap (MIG) head for rigid disk drives using a single crystal ferrite core was developed. Side mounting of a core was adopted to reduce its thickness, thus improving the inductance, and to achieve the ease of controlling the narrow track width and small throat height. It was demonstrated that the side-core composite (SCC) head has several advantages over conventional monolithic and composite heads in terms of electrical performance and manufacturability. Testing methods called swept frequency and swept current were also developed to demonstrate different interpretations of magnetic recording phenomena. >

Motoji Egawa

Papers

Theoretical analysis of optical and magneto-optical properties of one-dimensional magnetophotonic crystals

Properties of one-dimensional magnetophotonic crystals for use in optical isolator devices

Effect of optical losses on optical and magneto-optical properties of one-dimensional magnetophotonic crystals for use in optical isolator devices

Magnetic head having a thin film conductor coil assembly formed separate from a magnetic head core

A low inductance metal-in-gap head using a side-core concept