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Collinear holography has been good candidate for a volumetric recording technology of holographic data storage system (HDSS), because of there are not only large storage capacities, high transfer rates, but also the unique configuration, in which the information and reference beams are modulated co-axially by the same spatial light modulator, as a new read/write method for HDSS are very promising. The optical pickup can be designed as small as DVDs, and can be placed on one side of the recording media (disc). In the disc structure, the preformatted reflective layer is used for the focus/tracking servo and reading address information, and a dichroic mirror layer is used for detecting holographic recording information without interfering with the preformatted information. A 2-dimensional digital page data format is used and the shift-multiplexing method is employed to increase recording density. As servo technologies are being introduced to control the objective lens to be maintained precisely to the disc in the recording and reconstructing process, a vibration isolator is no longer necessary. In this paper, we introduced the principle of the collinear holography and its media structure of disc. Some results of experimental and theoretical studies suggest that it is a very effective method. We also discussed some methods to increase the recording density and data transfer rates of collinear holography using phase modulated page data format.

We have demonstrated remarkable enhancement of longitudinal and transverse magneto-optical Kerr effects in magnetoplasmonic crystals based on thin nanostructured films of nickel and iron due to resonant excitation of magnetoplasmonic waves in Faraday and Voight configurations . Manifestations of ultrafast time-dependent transverse magneto-optical Kerr effect are experimentally demonstrated in femtosecond laser pulses reflected from a one-dimensional magnetoplasmonic crystal. We show that exciting surface plasmon-polaritons with magnetization-dependent dispersion law allows one to control the shape of the refected pulse.

A compact optical correlator applicable to the retrieval of colour and texture as well as shape information was developed. A new technique for retrieving colour and texture information by using a slot-in-type compact joint-transform correlator (JTC) with minimum size (140 (W) × 220 (L) × 40 mm (H)) was developed. The developed techniques were used to retrieve images of fruits and vegetables, taken by the digital camera. The developed technique can retrieve images of certain fruits, such as an apple, from images of many different fruits and vegetables. It will open up a new area of retrieval techniques for ambiguous images based on shape, colour and texture information.

We present a new slot-in type of optical correlator that is more compact than the previous types. The correlator can fit inside the cabinet of commercial personal computers and is fully controllable with windows-based software. The correlator is a Joint Transform type (JTC) and its optical system fits inside a metal box measuring 140 mm (W) x 220 mm (L) x 40 mm (H). The optical source is a 650-nm-band laser diode of the kind used in DVD systems. A spatial light modulator and a CMOS camera are installed in the metal box with the passive optical components required for the JTC. The collimated light from the laser diode is illuminated on the spatial light modulator displaying reference and data to be examined. The light reflected from the modulator is Fourier-transformed by a lens on the plane of the CMOS camera. The computer reads the power spectrum recorded by the camera and modulates the spatial light modulator. This process is repeated. We found that these JTC processes could be performed with the prototype developed in this study.

We propose a new technique for retrieving color information. The color data taken by a digital camera is transferred to two-dimensional data on the color chart and displayed on a spatial light modulator. This modulation technique is combined with a retrieval technique using a joint transform correlator. The color data, e.g., photograph of a flower, are retrieved by this system, and the same color data (photograph) can be perfectly selected from the many reference data. This technique will open a new area of retrieval techniques for ambiguous images based on shape and color information.

We have studied magneto-optical responses of gold-bismuth-substituted yttrium iron garnet (Au-Bi:YIG) composite films in which Au particles are embedded into Bi:YIG in two different ways. First type were samples in which planar arrays of Au particles were introduced into the middle of Bi:YIG films using a step-by-step sputtering technique. Second type were granular films fabricated using simultaneous co-sputtering of Au and Bi:YIG; in these films Au particles occupy positions inside composite films in a random way. Absorption bands associated with localized surface plasmon resonances (LSPRs) were observed in transmission spectra of films of both types. In the spectral range of LSPRs, samples of Au-array type exhibited larger Faraday rotation angles as compared with that for reference Bi:YIG films of the same thickness. However, given that the volume fraction of Au particles was nearly the same for both types, the enhancement of Faraday rotation for samples of Au-granular type was insignificantly altered. Experiments showed that of the primary importance is the role of the interfaces between Au particles and Bi:YIG. Theoretical estimations showed that, in samples of Au-granular type, air shells appeared between Au particles and Bi:YIG during fabrication. In fact, annealing needed for crystallization of Bi:YIG films is always accompanied with an expansion of their thicknesses.

Recently magneto-optic spatial light modulators (MOSLMs) using magnetic garnet materials have advantages of high switching speed. However, these materials are difficult to be used in short wavelength range, so that it appears huge light absorption by magneto optic effect of transmittance mode (Faraday effect). This problem can be solved by using the materials of metal magnetic films for magneto optic effect of reflection mode (Kerr effect). We suggest the new method, which is the switching of pixels by heating the pixels with semiconductor laser until Curie temperature and changing the direction of the driving current at the same time, for developing high speed MOSLM in broadband using amorphous TbFe films. TbFe films were fabricated by RF sputtering using the Tb 21 Fe 79 target, and we have confirmed Kerr rotation (over 0.4 degree from 400nm to 800 in wavelength), the curie temperature (130 degree Celsius), and the switching of pixels of 16μm × 16 µ m by heating the pixels with semiconductor laser and controlling magnetization from external bias magnetic field (15Oe) and driving current (20mA) of coil at 403, 532 and 633nm wavelength.

We report on an analytical study of the photonic band structure of 2D and 3D multi-component photonic crystals. It is found that both types of crystal demonstrate a quasiperiodic resonant behavior of (hkl) photonic stop-bands as a function of the reciprocal lattice vector, providing a selective ON/OFF switching of nonresonant (hkl) stop-bands. Our predictions are compared with the results of conventional numerical studies using the photonic Korringa-Kohn-Rostocker method. Experimental transmission spectra of a-SiO2 synthetic opals show the OFF-switching of the {111} stop-bands at the filler permittivity of ~1.82, the {200} bands at ~1.63, the {220} bands at ~1.93, and the {311} bands at ~1.75. The (222) photonic stop-band, which is due to the second order diffraction from the (111) planes, cannot be switched OFF in a wide range of filler permittivity values, thus indicating a resonant behavior. The experimental data demonstrate an excellent agreement with the theoretical predictions.

We develop a method to study the optical and magneto-optical response of perforated metallic films with magneto-optic media embedded within their holes. Due to the strong electromagnetic field confinement associated with the excitation of the transmission resonances appearing in this type of structures and nonreciprocal nature of the magneto-optical phenomena, strongly enhanced conversion of the polarization state in both reflected (magneto-optical Kerr effect) and transmitted (magneto-optical Faraday effect) waves was found. Possibility to reach huge rotation angles is demonstrated by increasing magneto-optic holes filler/background optical contrast, which appears to be responsible for the resonance quality.

Wood's anomaly is experimentally observed in 2D plasmon-assisted nickel magnetophotonic crystals. It is shown to be accompanied by s 2 times enhancement of longitudinal Kerr effect. Wood's anomaly appears only for p-polarization of incident light at any angle of incidence in the range between 10° and 70°. It vividly indicates surface plasmon-polariton inducing on nickel surface. The experimental results are proved by numerical calculations.

In this work, we investigated the possibility of application of magnetophotonic crystals to the optical magnetic field sensor. The structure of 1D-MPC was (Ta 2 O 5 /SiO 2 ) 5 /Bi:YIG/(Ta 2 O 5 /SiO 2 ) (magnetic material as a defect layer between two Bragg reflectors) on a fused quarts substrate using RF magnetron sputtering apparatus. We used Bismuth substituted yttrium iron garnet (Bi:YIG) polycrystal film as a defect la yer, because Bi:YIG is well known as the magnetic material with effective MO propertie s, even if it is polycrystal. Due to specially designed structure, the localized mode appeared at the wavelength of 880 nm, which is tunable by the thickness of multi layers or defect layer. At the wavelength of localized mode, Faraday rotation was shown large enhancement of 1.5 o , that is fifty times larger than for single Bi:YIG polycrystal film of the same thickness. Keywords: magnetic field sensor, magnetophotonic crystals, Bi:YIG, Faraday effect 1. INTRODUCTION

Optical properties of mesoporous three-dimensional photonic crystals (3D PCs) based on thin opal films were found to be extremely sensitive to a humidity of the surrounding air. It was manifested that the internal structure of a single SiO 2 sphere together with the net of voids between them in a thin opal film acts as a sponge for wet steams. Our experimental data have shown that hydrophilic internal structure of a mesoporous film sponges up (and lose) water (dry or wet steams) that influences dielectric permittivity, the latter causes significant changes in transmission spectra. High sensitivity, quick response and possibility of contactless measurements makes sensors based on optical effects in mesoporous PCs to be very promising. It concerns not only humidity sensors, but also sensors of various gases, temperature, deformation and other environmental impacts.

Spatial light modulators (SLMs) are key components of collinear holographic storage. Collinear holography utilizes coaxially aligned information and reference beams which are displayed simultaneously by a same SLM for writing process, and also employs reference beam for retrieving process. We developed magneto-optic spatial light modulators (MOSLMs) which have high-speed switching and applied them to transmission-type collinear holography. In this study, we investigate performance of collinear holography with magneto-optic spatial light modulator. The Bit error rate was 8.9×10 -3 for single hologram. To examine the performance of shift-multiplexing, reconstructed image was disappeared after 3 μm shift. MOSLMs is suitable for collinear holography in terms of transfer rate especially.

This paper represents fabrication and properties of an improved current-driven 128 by 128 magneto-optic spatial light modulator (MOSLM) consists of arrayed pixels patterned with 14 micrometers square of 16 micrometers pitch. It could be driven successively only drivelines without a bias field by external coil to saturate magnetization. The magnetic pixels were embedded into the nonmagnetic substrate both to avoid magnetic switching error and to make the pixels array surface smooth. The switching field of arrayed pixels was reduced to 145Oe by annealing them to decrease the growth induced magnetic anisotropy. This value was about half of the conventional 128 by 128 MOSLMs. Moreover, copper straight drivelines were used for decreasing electric power consumption and applying a homogeneous magnetic field to the pixel. This drivelines structure enabled to switch the individual pixels reversibly keeping a single domain state, therefore, the successive driving of writing and erasing various checker patterns could be possible without bias field by external coil. The electric power consumption was decreased about 70 %. The switching speed of one pixel was 25 nanoseconds. It is more than a thousand times faster than other types of SLM, for example, 10 to 30 milliseconds for liquid crystal (LC) type, and 10-20 microseconds for micro electro mechanical systems (MEMS) type.

We present a new method for calculation of optical and magneto-optical properties of three-dimensional magnetophotonic crystal heterostructures, composed from a sequence of homogeneous plates of a magneto-optical material and photonic crystal slabs. The algorithm is based on the layer KKR technique. As examples we consider the Bi:YIG (bismuth-substituted yttrium–iron–garnet) magneto-optical plate sandwiched by photonic crystal slabs consists of (i) simple cubic/face centered cubic lattices of SiO 2 spheres in the air; ( ii) air spheres in silicon background (inverse opals). The enhanced Faraday rotation appears at the resonant transmission frequency in analogy with one-dimensional structures with magneto-optical microcavity. However, the calculated spectral behavior of the Faraday rotation as well as its dependence on defect thickness is quite different and unusual. For instance, the Faraday rotation angle changes its sign within the photonic band gap that is due to complicated reflection of waves from 3D photonic crystal slabs. Keywords: photonic crystals, magneto-optics

Realization of enhancement of second-harmonic generation (SHG) in three-dimensional (3D) photonic crystals utilizing nonlinear diffraction is demonstrated. The samples are composed from close-packed silicon oxide spheres with diameter of 250 to 300 nm in each sample forming an ordered fcc opal matrix. The opal voids are filled by noncentrosymmetric gallium nitride and centrosymmetric silicon with filling factor close to unit. The photonic band gap (PBG) is obtained for light reflected from the (111) face and localized in the spectral region from 800 to 950 nm for different samples. SHG spectra show pronounced peaks as the fundamental radiation is tuned across the photonic band gap. The intensity enhancement in SHG is about 100 and the spectral width of the SHG resonances is approximately 15 nm. The SHG enhancement is attributed to combination of linear diffraction of the fundamental radiation from the (111) opal layers and nonlinear diffraction utilizing the 3D periodicity of the quadratic susceptibility of silicon and gallium nitride nanocrystals in opal voids. The spectral position of the SHG peak is slightly red-shifted in comparison with the PBG center and attributed to condition of the group velocity minima.

We demonstrated a magneto-optic spatial light modulator with one-step pattern formation of iron-garnet films on ion-milled substrates by LPE. The one-step pixel growth is based on the combination of a single-crystal epitaxial film growth (pixel area) by LPE and a impeded film growth (pixel gap area) on a substrate whose surface has been locally damaged and milled by ion bombardment before film deposition. This method overcomes the disadvantages associated with groove etching of the conventional MOSLM. The fabricated prototype MOSLM is switched by applying driving currents of 40 mA for the bottom conductor line and 80 mA for the top conductor line under external bias field of 20 Oe, which is over 2 times smaller than that of the conventional MOSLM. These results strongly suggest that the novel MOSLM can provide higher resolution, simpler fabrication process, more compact systems and lower driving current. Also, the selective-area LPE method offers new possibilities for the fabrication of integrated magneto-optic light switch arrays, magnetic waveguides and similar devices.

This work was aimed at fabrication of a three-dimensional magento-photonic crystal. In our experiments LATEX spheres with diameter of about 200 nm were coated with Fe 3 O4 fine particle. The diameter of Fe 3 O4 fine particles is about 30 nm when ration of Fe 3+ / Fe 2+ (r) = 3% and pH = 8.6. The diameter of these particles decreases about 10 nm by increasing up to r=20% in the same pH region. It was found that a decrease of the coated particles size can be made as low as the size of 5% of LATEX spheres diameter. Therefore, it may use these particles for preparation a three-dimensional magento-dielectric structure.

In this paper, results of the first observation of magnetization-induced second-harmonic generation (SHG) in one-dimensional magneto-photonic microcavities are described. Both significant magnetization-induced rotation of second-harmonic wave polarization and magnetization-induced variations of the SHG intensity are detected at the fundamental wavelengths in the vicinity of microcavity mode.