Abstract: A photoinduced refractive-index changing region is formed by irradiating while focusing a single beam of pulse laser light having an energy amount to cause a photoinduced change in refractive index onto a light guide of an optical element such as a lens, a mirror, a diffraction grating, a polarizer, or a wavelength filter. In the photoinduced refractive-index changing region, since the refractive index is periodically changed in one direction, of the light propagating through the optical element, only a polarized light penetrates through this photoinduced refractive-index changing region. Accordingly, the photoinduced refractive-index changing region can be functioned as a polarizer.

Abstract: A method of modifying liquid crystal polymers, which involves a step of irradiating a liquid crystal polymer with the laser beam having a pulse width of 10?12 seconds or less. Using the invention method, the physical strength of the liquid crystal polymers can be improved as compared with the conventional liquid crystal polymers.

Abstract: A single pulse laser beam of linear polarization is irradiated to a glass region such that the condensing point is located inside of the glass region, thereby to form, at the condensing point, a periodic structure region in which high refractive-index zones and low refractive-index zones are repeatedly being generated at pitches of 1 ?m or less. Planes in which the high refractive-index zones or the low refractive-index zones are being joined to one another, are formed in parallel to the polarized magnetic field direction of the pulse laser. It is therefore possible to prepare an optical structural body having a submicron-order fine periodic structure which can readily be produced.

Abstract: A photoinduced refractive-index changing region is formed by irradiating while focusing a single beam of pulse laser light having an energy amount to cause a photoinduced change in refractive index onto a light guide of an optical element such as a lens, a mirror, a diffraction grating, a polarizer, or a wavelength filter. In the photoinduced refractive-index changing region, since the refractive index is periodically changed in one direction, of the light propagating through the optical element, only a polarized light penetrates through this photoinduced refractive-index changing region. Accordingly, the photoinduced refractive-index changing region can be functioned as a polarizer.

Abstract: There is provided a multi-cored fiber array for optical communication which has high dimensional accuracy, can easily be prepared by machining, and is low in cost. There is also provided a fiber array for optical communication which can reduce the necessary amount of an adhesive used for fixing optical fibers to a substrate. The fiber array for optical communication comprises: a substrate for inserting optical fibers therein; and a press plate for pressing and fixing the inserted optical fibers. The substrate has a plurality of grooves into which the optical fibers are to be inserted. The accuracy of the center-to-center dimension between the grooves adjacent to each other is within ±0.5 ?m, and the degree of parallelization in the groove length direction between the grooves adjacent to each other is within ±0.1 degree.

Abstract: The aggregation and phase separation of inorganic particles are performed in a sol containing the inorganic particles and a solvent to produce a porous body having open pores. Preferably, the inorganic particles are particles of one or more inorganic material selected from the group consisting of titania, silica, alumina, zinc oxide and zirconia. Further, the sol may have strong acidity and the pH of the sol is elevated to perform the aggregation and phase separation of the inorganic particles. Alternatively, the sol may have strong basicity and the pH of the sol is lowered to perform the aggregation and phase separation of the inorganic particles. The present invention provides a novel method of producing a porous body and sintered body having co-continuous structure, applicable to a wide variety of inorganic materials.

Abstract: A titania nanotube suitable as an optical sensor or gas sensor is provided. The titania nanotube has a length of 1 ?m or more; preferably a diameter of 0.1 ?m or less and an aspect ratio of 100 or more.

Abstract: There is provided a multi-cored fiber array for optical communication which has high dimensional accuracy, can easily be prepared by machining, and is low in cost. There is also provided a fiber array for optical communication which can reduce the necessary amount of an adhesive used for fixing optical fibers to a substrate. The fiber array for optical communication comprises: a substrate for inserting optical fibers therein; and a press plate for pressing and fixing the inserted optical fibers. The substrate has a plurality of grooves into which the optical fibers are to be inserted. The accuracy of the center-to-center dimension between the grooves adjacent to each other is within ±0.5 ?m, and the degree of parallelization in the groove length direction between the grooves adjacent to each other is within ±0.1 degree.

Abstract: An optical connector capable of providing a multicore ferrule for optical communication or a fiber array for optical communication having a high dimensional accuracy and easily manufactured at a low cost, comprising a plurality of insert holes for inserting optical fibers therein arranged at specified intervals, characterized in that the accuracy of the center-to-center distances between the adjacent insert holes is within ±0.5 ?m and a parallelism between the adjacent insert holes in hole axial direction is within ±0.1°.

Abstract: A photoinduced refractive-index changing region is formed by irradiating while focusing a single beam of pulse laser light having an energy amount to cause a photoinduced change in refractive index onto a light guide of an optical element such as a lens, a mirror, a diffraction grating, a polarizer, or a wavelength filter. In the photoinduced refractive-index changing region, since the refractive index is periodically changed in one direction, of the light propagating through the optical element, only a polarized light penetrates through this photoinduced refractive-index changing region. Accordingly, the photoinduced refractive-index changing region can be functioned as a polarizer.

Abstract: When separated phases are formed in a glass by a nucleation and growth mechanism, a phase separation region only in a small desired area is difficult to form by a conventional method, in which the entire glass is heated. Thus, an optical waveguide structure, or a photonic crystal, which requires an orderly arrangement of high-refractive-index regions, cannot be manufactured. The present invention provides a method for forming a phase separation region by converging a laser pulse in a glass containing a metastable immiscible phase to separate only an area at a focal point of the laser or in the vicinity of the focal point into phases. The focal point of the laser is moved continuously or intermittently relative to the glass to form a linear phase separation region or a dotted phase separation region in two or three dimensions in the glass. The pulse width of the laser is preferably between 10 femtoseconds and 10 picoseconds.

Abstract: A single pulse laser beam of linear polarization is irradiated to a glass region such that the condensing point is located inside of the glass region, thereby to form, at the condensing point, a periodic structure region in which high refractive-index zones and low refractive-index zones are repeatedly being generated at pitches of 1 &mgr;m or less. Planes in which the high refractive-index zones or the low refractive-index zones are being joined to one another, are formed in parallel to the polarized magnetic field direction of the pulse laser. It is therefore possible to prepare an optical structural body having a submicron-order fine periodic structure which can readily be produced.

Abstract: An inorganic body containing rare earth and/or transition metal ions that has been irradiated with a pulsed laser beam in the manner such that a focal point of the pulsed laser beam is adjusted to an inner part of the inorganic body is disclosed. The inorganic body may be a glass or crystal containing one or more of oxide, halide and chalcogenide. The rare earth ion may be one or more of Ce, Nd, Pr, Sm, Eu, Tb, Dy, Tm, Tb. The transition metal ion may be one or more of Ti, Mn, Cr, V, Fe, Cu, Mo and Ru. When the focal point is relatively shifted with respect to the inorganic body, an ionic valence-changed domain is formed with a predetermined pattern at the inner part of the inorganic body. The pulsed laser beam preferably has a pulse width under a picosecond. The ionic valence change occurs at the focal point and its vicinity, but the rare earth or transition metal ion keeps its original valence at all other parts, so as to form a reformed domain with a predetermined pattern in the inorganic body.

Abstract: A glass containing one or more of metal microparticles, semiconductor microparticles, transition metal ion, rare earth ion and anion with characteristic absorption in a wavelength region longer than 360 nm is irradiated with a pulsed laser beam condensed at a focal point preset in an inner part of the glass. The condensed irradiation induces change of a refractive index as well as decrease of characteristic absorption in the wavelength region longer than 360 nm at the focal point. Such the domain is continuously formed by relatively shifting the focal point with respect to the glass. The continuous domains serve as optical waveguides, since optical properties are greatly different between the irradiated part and the non-irradiated part.

Abstract: A glass 1 is irradiated with a focused pulsed laser beam 2 having a peak power density of 10.sup.5 W/cm.sup.2 or more and a repetition rate of 10 KHz or more. The glass 1 irradiated with the laser beam 2 changes its refractive index at the focal point 4. During the laser beam irradiation, the glass 1 is continuously moved with respect to the focal point of the pulsed laser beam 2 or continuously scanned with the focused laser beam 2, so as to form the refractive index changed region (i.e. an optical waveguide 5) with a predetermined pattern. The glass 1 in which the optical waveguide 5 will be formed may be any kind of glass having high transparency.

Abstract: A glass is irradiated with a focused pulsed laser beam having a peak power density of 10.sup.5 W/cm.sup.2 or more and a repetition rate of 10 KHz or more. The glass irradiated with the laser beam changes its refractive index at the focal point. During the laser beam irradiation, the glass is continuously moved with respect to the focal point of the pulsed laser beam or continuously scanned with the focused laser beam, so as to form the refractive index changed region (i.e. an optical waveguide) with a predetermined pattern. The glass in which the optical waveguide is formed may be any kind of glass having high transparency.

Abstract: A radiation imaging device including a photostimulable phosphor which is a glass including active cations that release light having a wavelength in the blue colour or ultra-violet region when those parts of the glass which have been stimulated by radiation, and a radiation source to irradiate the phosphor and an excitation light source to photostimulate the phosphor. The radiation source may be X-rays, .gamma.-rays, .alpha.-rays, .beta.-rays, electron beams, neutron beams, ion beams, ultra-violet rays having an energy equal to or greater than the band gap of the glass are excited by visible or infra-red light. Ce.sup.3+, Eu.sup.2+ can be used as the active cation, and are preferably included in an amount of 10 mole % or less of all the cations, and particularly preferably in an amount in the range of 0.001 to 2 mole %.

Abstract: A disordered fluorite-type photochemical hole burning crystal contains Sm.sup.2+ as active ions, and a composition except Sm.sup.2+ is represented by a general formula .alpha.-(MALn)F.sub.6-v X.sub.v where 0.ltoreq.v.ltoreq.1, and M is an element selected from Ca, Sr and Ba, A is an element selected from Na, K, Rb and Cs, Ln is an element selected from Y, La, Gd and Ce, and X is an element selected from Cl, Br and I. Stable hole burning occurs at the room temperature to create narrow holes. The crystal can be used as a superior optical recording material for a room temperature operation.