Kazuo Kuroda

Angular multiplex recording of data pages by dual-channel polarization holography

Simultaneous recording of two data pages by dual-channel polarization holography is experimentally demonstrated. Two data pages are transferred as two orthogonal scalar wave components of a vector wave. The signal vector wave and reference beam are superposed on a polarization-sensitive medium. The two recorded data pages are simultaneously and independently reconstructed. Furthermore, holographic angular multiplex recording is performed.

Dual-channel polarization holography: a technique for recording two complex amplitude components of a vector wave

In this Letter, the principle of polarization holography for recording an arbitrary vector wave on a thin polarization-sensitive recording medium is proposed. It is analytically shown that the complex amplitudes of p- and s-polarization components are simultaneously recorded and independently reconstructed by using an s-polarized reference beam. The characteristics are experimentally verified.

Calculation of the Pixel Spread Function with a Simple Numerical Model for the Collinear Holographic Storage System

A numerical simulation method to evaluate the collinear holographic memory is proposed. A pixel spread function is defined and the resolving power of the page data image increases with the increase of the media thickness.

All solid state laser image amplifier system with polymer dye

An all-optical image brightness amplifier is a key device in parallel optical data processing systems. It works like an Er-doped fiber amplifier in optical fiber communication systems. The laser image amplifier can recover the energy loss of the spatially two-dimensional and temporally one-dimensional optical signal without losing the phase information of the light. Recently, solid dye laser materials have improved steadily, and the dye doped polymer amplifier is now commercially available. Also, diode-pumped Nd:YAG laser systems also become very popular. Thus, the reality of a compact all solid state laser image amplifier system is growing. In the paper, we show the basic performance of the polymer dye laser amplifier system for an image amplification system.

Femtosecond measurement of nonlinear refraction in periodically poled lithium tantalate

We present femtosecond measurements of nonlinear refraction in periodically poled lithium tantalate by using spectrally resolved two-beam coupling. The sign and magnitude of nonlinear phase shifts induced by cascade quadratic nonlinearity and intrinsic Kerr nonlinearity are measured.

Research of circular polarized holography with a large crossing angle under a common condition (Conference Presentation)

Polarization holography is the coherent interference of the beams that can have the different polarized states. The early-stage theory of polarization holography is based on Jones matrix, where the paraxial approximation is assumed, while the theory of polarization holography represented by dielectric tensor can describe the case with a large crossing angle. And it also depicts the relationship between diffraction light and interference light. During the research people find some extraordinary phenomenon, such as null reconstruction and inverse polarizing effect. But there is a disadvantage in this new polarization holography theory, where only under a peculiar circumstance can we get a faithful reconstruction. The circumstance can be expressed as “A+B=0”, where A and B refer to the coefficients for intensity and polarization holograms respectively. In this research, we calculate the formula of diffraction light’s polarization, and extract the A+B factor in it. Then we establish a series of equations which can let the diffraction light faithfully reconstruct, no matter what value of A plus B is. From the result, we can use an artificial reference beam which is corresponding to the signal beam to generate the hologram. Under this condition, the polarization of the diffraction light is similar to the signal. For simplification, we only discuss the signal wave with circular polarization and experimentally verify the result.

Color speckle in laser displays

At the beginning of this century, lighting technology has been shifted from discharge lamps, fluorescent lamps and electric bulbs to solid-state lighting. Current solid-state lighting is based on the light emitting diodes (LED) technology, but the laser lighting technology is developing rapidly, such as, laser cinema projectors, laser TVs, laser head-up displays, laser head mounted displays, and laser headlamps for motor vehicles. One of the main issues of laser displays is the reduction of speckle noise1). For the monochromatic laser light, speckle is random interference pattern on the image plane (retina for human observer). For laser displays, RGB (red-green-blue) lasers form speckle patterns independently, which results in random distribution of chromaticity, called color speckle2).

Laser display technologies: Light sources and systems

This presentation reviews the important issues on laser display including the requirement for lasers (lasing wavelength, power), some examples of laser display systems, and the issues on image quality especially speckle noise reduction technique.

Multilevel logic polarization coded holographic memory

A polarization coded holographic memory is demonstrated. Writing and reading characteristics are examined through numerical calculations and experiments. The polarization state of the readout signal is influenced by the ratio of intensity and polarization gratings.

Temporally coded collinear holographic memory

A collinear holographic memory system recording multichannel time sequential signal is proposed and demonstrated. Higher recording density and data transfer rate comparing to the page-oriented system are expected because Run-Length Limited code can be used.