Abstract: An optical device includes a small and low-cost variable polarization plane rotator that can control a rotation angle of the polarization plane easily. A variable polarization plane rotator is provided with a ?/4 phase plate having an optical axis in the same direction as, or at a 90 degree angle relative to, a polarization direction of an input light beam. A phase difference variable element has an optical axis at a ±45 degree angle relative to the optical axis of the ?/4 phase plate, to apply a variable phase difference between the polarization components parallel to and perpendicular to the optical axis thereof. A phase difference adjustment section adjusts the variable phase difference of the phase difference variable element, wherein the input light beam after being transmitted through the phase difference variable element to form elliptically polarized light or circularly polarized light, is transmitted through the ?/4 phase plate to form linearly polarized light.

Abstract: In a method for producing an SOI wafer comprising steps of implanting hydrogen ions etc. from a surface of a bond wafer 21 to form an ion-implanted layer 24 inside the wafer, bonding the ion-implanted surface of the bond wafer and a surface of a base wafer 22 via an oxide film 23 or directly, and forming an SOI wafer by delaminating a part of the bond wafer at the ion-implanted layer by heat treatment, wherein a silicon wafer consisting of silicon single crystal grown by Chochralski method, which is occupied by N region outside OSF generated in a ring shape and has no defect region detected by Cu deposition method, is used as the bond wafer. Thereby, even in the case of forming an extremely thin SOI layer 27 such that, for example, its thickness is 200 nm or less, there is provided an SOI wafer which has an excellent electric property without causing micro pits by cleaning with hydrofluoric acid etc., and in addition, can be produced without increasing the number of process.

Abstract: A spectroscopic apparatus which is compact in size and performs high-precision light-splitting with a large angular dispersion. An optical input-processing section outputs a filtered transmitted light, using a bandpass filter that transmits only wavelength bands at one period of an input light, and collects the filtered transmitted light to generate a collected beam. An optic includes a first reflection surface and a second reflection surface which are high but asymmetric in reflectivity, and causes the collected beam incident thereon to undergo multiple reflections within an inner region between the first reflection surface and the second reflection surface, to thereby cause split beams to be emitted via the second reflection surface. A received light-processing section performs received light processing of the beams emitted from the optic. A control section variably controls at least one of a filter characteristic of the bandpass filter and an optical length through the optic.

Abstract: The present invention aims at providing a transmission wavelength characteristics variable optical element which can actively equalize changes of the wavelength characteristics due to temperature changes, and providing a wavelength characteristics variable apparatus, an optical amplifier, an optical transmission system, and a control method of the transmission wavelength characteristics, which use such an optical element.

Abstract: An airgap type etalon has a higher degree of design freedom of a wavelength-temperature characteristic so that such a wavelength-temperature characteristic can be freely adjusted. The airgap type etalon includes a fixing block having one flat surface, and a transparent parallel flat plate having parallel flat surfaces formed with an antireflection coating and a reflection augmenting coating thereon, respectively. The flat surface at the antireflection coating side is joined to the flat surface of the fixing block. A parallel flat spacer has a thickness greater than that of the transparent parallel flat plate and an expansion coefficient different from that of the transparent parallel flat plate. One of the flat surfaces of the parallel flat spacer is joined to the flat surface of the fixing block. A transparent flat plate has opposite flat surfaces formed with an antireflection coating and a reflection augmenting coating thereon, respectively.

Abstract: An optical device includes a small and low-cost variable polarization plane rotator that can control a rotation angle of the polarization plane easily. A variable polarization plane rotator is provided with a &lgr;/4 phase plate having an optical axis in the same direction as, or at a 90 degree angle relative to, a polarization direction of an input light beam. A phase difference variable element has an optical axis at a ±45 degree angle relative to the optical axis of the &lgr;/4 phase plate, to apply a variable phase difference between the polarization components parallel to and perpendicular to the optical axis thereof. A phase difference adjustment section adjusts the variable phase difference of the phase difference variable element, wherein the input light beam after being transmitted through the phase difference variable element to form elliptically polarized light or circularly polarized light, is transmitted through the &lgr;/4 phase plate to form linearly polarized light.

Abstract: A movable mirror having a mirror surface reflecting a light input from an input fiber collimator is moved in an arrow (1) direction so that the reflection frequency of the input light reflected by an optical filter can be variable. The light is reflected plural times between the mirror surface and the optical filter, directed to a fixed mirror by the mirror surface, reflected by the fixed mirror, and is connected to an output fiber collimator. By moving the movable mirror in parallel, the reflection count of the light between the optical filter and the mirror surface is variable. Therefore, the wavelength characteristic of the light is obtained as an accumulated wavelength characteristic depending on the reflection count.

Abstract: A mirror which reflects input light from a lens which focuses light emitted from a VIPA, and returns the light to the lens is constituted as a multi-faced mirror including multiple reflection surfaces in the traveling direction of the input light which individually reflect light with a different wavelength, and have a different shape. As a result, an apparatus which has a small optical loss, and generates a different wavelength dispersion depending on a channel signal wavelength of a WDM signal.

Abstract: A stress correction film is applied to one side of a VIPA optical element provided with a multi-layer fully reflective film and an anti-reflective film on one surface of a transparent plate, and a semi-transparent multi-layer reflective film on the other surface, in order to adjust the unbalance between the respective stress of the multi-layer films on each surface. In other words, by applying a stress correction film, the unbalance between the respective stress of the multi-layer films on each surface of the VIPA optical element is corrected, and accordingly a VIPA optical element with low profile irregularity can be realized.

Abstract: A cabinet provided with light input/output holes accommodates a VIPA optical element, a lens, a fixing material fixing the VIPA optical element. A temperature-controlled heater controls the temperature of and inside the cabinet. Both the light input and output holes of the cabinet are blocked by the fixing material and the lens, respectively, so that temperature inside the cabinet is not influenced by the outside air.

Abstract: An object of the invention is to provide a mirror fixing method capable of reducing stress distortion of a surface of a mirror which constitutes an optical system, with hardly deforming a surface shape of the mirror. To this end, the present mirror fixing method is characterized in that a mirror part including a base plate formed with a mirror on one face thereof, is provided with a boss on the other face of the base plate opposite to the face on which the mirror is formed, and only the boss is fixed, so that the mirror part excluding the boss is not in contact with other members.

Abstract: A mirror which reflects input light from a lens which focuses light emitted from a VIPA, and returns the light to the lens is constituted as a multi-faced mirror including multiple reflection surfaces in the traveling direction of the input light which individually reflect light with a different wavelength, and have a different shape. As a result, an apparatus which has a small optical loss, and generates a different wavelength dispersion depending on a channel signal wavelength of a WDM signal.

Abstract: A rolling bearing has the radius of curvature of the raceway on an inner ring and an outer ring is from not smaller than 50.1% to not greater than 51.9% of the diameter of the balls, and at least one of the compositions of the bearing is obtained by forming an alloy steel having a carbon (C) content of from not smaller than 0.50% to not greater than 0.90%, a chromium (Cr) content of from not smaller than 3.0% to not greater than 15.0%, a manganese (Mn) content of from not smaller than 0.10% to not greater than 2.0%, a silicon (Si) content of from not smaller than 0.10% to not greater than 2.0%, a molybdenum (Mo) content of zero or not greater than 2.0% by weight, and a vanadium (V) content of zero or not greater than 2.0%, by weight.

Abstract: An object of the invention is to easily realize an optical element using an etalon type structure, capable of changing a periodic transmission wavelength characteristic in an axial direction of transmissivity, and also capable of changing a periodic characteristic with respect to wavelength. To this end, a transmission wavelength characteristics variable optical element according to the invention comprises: a light interference section including a pair of wedge shape magneto-optic crystals arranged with taper faces thereof in close contact, that can change a distance between reflecting films formed on parallel planes of the magneto-optic crystals, by relatively moving the magneto-optic crystals by movable sections, permanent magnets for applying a fixed magnet field to the pair of magneto-optic crystals, an electromagnet for applying a variable magnetic field in a direction different to the fixed magnetic field, and a variable current source controlling the current flowing into the electromagnet.

Abstract: A rolling bearing for belt-type continuously variable transmission with a metal belt including pieces has an inner ring; an outer ring; and rolling elements, wherein at least one of the inner ring, the outer ring and the rolling element is made of an iron alloy having a chromium content of from 2.5 to 20.0% by weight.

Abstract: Rays of light having respective wavelengths angular-dispersed and output from a VIPA plate are collected by a lens, and diffracted by a grating pair which is an optical path shift generation unit and optical path shift amount variation unit, and have a shift in a path of rays having different wavelengths. When the rays are reflected by a dispersion leveling three-dimensional mirror and input into the VIPA plate again, they are received by portions having different dispersion compensation amount of the three-dimensional mirror, thereby realizing different amounts of wavelength dispersion for respective wavelengths, and independently adjusting an amount of wavelength dispersion of the entire wavelengths of the WDM rays and the wavelength dispersion slope.

Abstract: A dispersion compensator comprising a VIPA is configured so as to reflect light with each wavelength at an angle varying depending on wavelength when the light is reflected off a mirror. When being coupled at the end of an input fiber, the light with each wavelength is coupled at a specific angle. If the light is coupled with the fiber at a specific angle, coupling efficiency degrades. Therefore, in this case, coupling loss increases. Light having a wavelength with high transmittance in the VIPA is coupled with the fiber at a large angle, while light with a low transmittance is efficiently coupled with the fiber at a small angle or no angle. In this way, the round-top wavelength characteristic of the VIPA can be leveled.

Abstract: The present invention aims at providing a transmission wavelength characteristics variable optical element which can actively equalize changes of the wavelength characteristics due to temperature changes, and providing a wavelength characteristics variable apparatus, an optical amplifier, an optical transmission system, and a control method of the transmission wavelength characteristics, which use such an optical element.

Abstract: Light input from a single-mode fiber is collected into linear light beams by a line focuser, and collected on a VIPA element. A light beam output from the VIPA element is made to pass through a space filter having a predetermined transmission loss characteristic, and focused on a mirror with a focusing lens. The light is reflected by the mirror, again passes through the space filter via the focusing lens, enters the VIPA element, and again enters the single-mode fiber via the line focuser. The insertion loss wavelength characteristic of the wavelength dispersion compensator using the VIPA element is optimized by being superimposed on the transmission loss characteristic of the space filter.

Abstract: A VIPA plate having a configuration where a translucent reflection film and a total reflection film are respectively arranged on one side and the other side of a transparent parallel plate can be used as a wavelength dispersion compensator by using a special mirror and a lens. However, the transparency characteristic of the wavelength dispersion compensator using such a VIPA plate is a periodical characteristic which is asymmetric with a central wavelength in a wavelength regime. Accordingly, not parallel light but converged or diverged light having angular dispersion is input to an etalon plate, so that a filter whose transparency characteristic is an asymmetric periodical characteristic which is reverse to the VIPA plate is configured for the central wavelength in the wavelength regime. With this filter, the transparency characteristic of the wavelength dispersion compensator using the VIPA plate is optimized.