Shun-ichi Tanaka

Grating lenses for integrated optics.

Lenses made of Bragg-type gratings and used for integrated optics are fabricated by the technique of electron-beam pattern generation, chemical etching, and printing. They consist of straight lines of varying inclination and spacing. Focusing action is demonstrated experimentally.

Optical Waveguide Lenses

The development of optical waveguide lenses, i.e. mode-index (including Luneburg), geodesic, Fresnel and Bragg grating lenses is briefly reviewed chronologically. A Bragg lens and a Luneburg lens, fabricated by electron lithography and vacuum deposition respectively, are described. A nearly diffraction-limited lens of the latter type can be obtained by using the shadow mask process.

Longitudinal Kerr Magneto-Optic Effect in Permalloy Film

The longitudinal Kerr effect in an evaporated film of nickel (80%) and iron (20%) alloy is investigated by the use of a photoelectric polarization spectrometer. The Kerr rotation of the film is measured as a function of the angle of incidence for several wavelengths of light ranging from 400 mµ to 650 mµ. The compensation of the phase angle of the rotation with which the reflected beam of elliptically polarized light degenerates into a linear polarized light is also made with a Babinet Soleil compensator. When the values of the magneto-optic quantity and the refractive index of the film are chosen as 1.48×10-2exp {i(32^°)} and 1.76(1-1.84i), respectively, at the wavelength 592 mµ, the calculated values of the rotation given by the theory of Voigt agree well with the experimental results.

Electronic Properties of High Tc Superconducting Oxides

The normal-state electronic properties of (La,A)2CuO4 and LnBa2Cu3O7-y are investigated to have an insight into the electronic states of these high Tc superconductors. The experimental results suggest that the states may be modified strongly due possibly to the Fermi surface instability and/or to some excitations extending to higher energies.

Noncollinearly Phase Matched Second Harmonic Generation in LiIO3

A formulation of the theory on the noncollinearly phase matched second harmonic generation is given. The theory treats the effects of phase mismatching and of the interaction volume of two differently directed fundamental laser beams. When the crystal is rotated from the matching angle, the second harmonic power decreases more rapidly with the enlargement of the interaction volume. The experimental results suggest the validity of the theory. Comparison with the collinear case indicates that higher power can be obtained in the noncollinear case.

Measurement of an arbitrary parallel displacement of a rigid body by using polychromatic speckle patterns

Abstract A novel speckle method for measuring the parallel displacement of a rigid body in an arbitrary direction is presented. The amount of displacement as well as its angle made with the optical axis is to be measured from the Fourier transform patterns of a doubly exposed photographic plate.

Longitudinal magneto-optical effect in Ni and nickel-rich Ni-Fe films in visible and near infrared regions

Abstract Magneto-optical properties of Ni and Ni-Fe films are studied experimentally for the spectral range 0.4 to 2.2 μ. From the measurement of longitudinal Kerr rotation and of optical constant of these evaporated films, the diagonal and off-diagonal components of the gyroelectric tensor are determined. The magneto-optical resonance is observed at a frequency of about 1 eV.

Unstable Phase-Conjugate Resonator

A fundamental Gaussian mode in a phase-conjugate resonator consisting of conventional optical elements and a phase-conjugate mirror constructed by means of degenerate four-wave mixing is analyzed. A ray matrix method is used for the analysis by taking the finite radii of wavefront curvature and the finite beam radii of pump waves into account. It is suggested that the phase-conjugate resonator is generally an unstable resonator.

Noncollinearly phase‐matched second‐harmonic generation in LilO3

Efficient second‐harmonic generation of light, where the wave‐vector‐matching condition is satisfied noncollinearly or two‐dimensionally, has been observed using a Nd:YAG laser as a fundamental and LiIO3 as a nonlinear crystal. The phase‐matching condition has been found to be satisfied in a wide range of the angle around the optic axis of the crystal.

Optical logic operations using three-beam phase-conjugate interferometry

An experimental arrangement of the three-beam phase conjugate interferometer is proposed in which a phase of any of the three signal beams is easily and independently controlled by the small rotation of a mirror set in each optical path, and its performance is reported. Using this arrangement, several optical logic operations of two binary patterns, such as XOR, OR, overlineXOR and NAND, are demonstrated.