Magneto-Optic Hologram

Abstract

In this paper the first experiment of thermomagnetic writing of a hologram on a thin film of EuO and the reconstruction of the hologram is reported. Writing of the hologram is achieved by using a giant pulsed ruby laser as a source for thermomagnetization. Erasing of the hologram is accomplished by a small applied magnetic field. The ruby laser is used because of its ability to provide the energy required for writing in a time that is short compared with the thermo-relaxation time. A hologram with shallow angle (10 μ resolution) was recorded and the reconstruction of the hologram was done using a He–Ne laser as a source. The formation of the hologram is based on the fact that the index of refraction of the material is a function of magnetization. Thus, the different state of magnetization induced by the laser pulse acts as a phase-hologram for polarized light. Polarizing elements were used to observe the reconstructed images from the magnetic holograms. Results were also obtained for the diffraction intensity in the different orders of a simple thermo-magnetic hologram. An analysis is presented to interpret the observed phenomena and gives the calculated efficiency that can be obtained under ideal conditions.

Magnetism and Faraday Rotation in Oxygen-Deficient Polycrystalline and Single-Crystal Iron-Substituted Strontium Titanate

“…The STF films on Si were polycrystalline but exhibited a magnetic moment and FR up to 65% higher than the single-crystal film deposited on an STO substrate. From the viewpoint of applications, the formation of polycrystalline magnetic perovskite films on silica or other nonepitaxial substrates allows the useful properties of STF to be easily introduced into complementary metal-oxide semiconductor devices and into optical devices such as isolators and magnetophotonic crystals [4,[35][36][37][38][39], spatial light modulators [40][41][42], or magneto-optical holographic memories [43][44][45][46]. First-principles calculations demonstrate the importance of oxygen defects and exchange interactions in determining the magnetic properties.…”

Magnetic Holography and Its Application to Data Storage

“…Contrastingly, a magnetic hologram that is formed as the difference in the magnetization direction of a recording magnetic material was proposed by Mezrich [18] in 1969. Magnetic holograms are recorded by a thermomagnetic recording (Curie point writing) method [18][19][20][21][22] and reconstructed using the rotation of the polarization plane through a magneto-optical effect [18,[20][21][22][23].…”

Reconstruction of non-error magnetic hologram data by magnetic assist recording

“…On the other hand, magnetic hologram media using magnetic garnets have shown rewritability and long-term stability. In the recording process, volumetric holograms formed by using thermomagnetic recording are recorded as the direction of magnetization in magnetic films, while reconstruction involves the use of the magneto-optical (MO) effect 7 , 8 . Magnetic garnet films such as Bi-substituted rare-earth iron garnet (Bi:RIG) can be used for rewritable magnetic hologram media, and we have demonstrated that a volumetric hologram can be written in these garnet films using collinear holographic recording 9 , 10 .…”