Abstract: An optical device includes a transparent material layer having a desired curved surface configuration, a layer including a variable refractive index material having a dielectric constant anisotropy and having a property in which a sign of a difference &Dgr;&egr; in dielectric constant due to the anisotropy is reversed at driving frequencies f1 and f2, at least two transparent electrodes arranged to sandwich the transparent material layer and the layer including the variable refractive index material, and a driving device supplying a voltage including the driving frequencies f1 and f2 between the transparent electrodes.

Abstract: An optical waveguide and an optical waveguide circuit having polarization insensitivity or a required low-level polarization dependence without degradation of the optical characteristics and reliability are disclosed, and a fabricating method of an optical waveguide and an optical waveguide circuit having polarization insensitivity or a required low-level polarization dependence without increasing the fabricating burden and the cost are disclosed. The optical waveguide comprises a planar substrate; a lower cladding which is provided on the planar substrate, where the lower cladding has a ridge; a core, provided on the ridge of the lower cladding, for transmitting light; and an upper cladding provided in a manner such that the core is covered with the upper cladding. The ridge has a shape predetermined so as to decrease polarization dependence of the optical waveguide to a required low level.

Abstract: In a semiconductor photo-detector of the present invention, a first semiconductor layer, a second semiconductor layer having, and a photo-absorption part composed of a photo-absorption layer sandwiched between these layers are disposed on a substrate, at least the photo-absorption layer is formed at a position apart inwardly by a finite length from an end surface of the substrate, an end surface of the second semiconductor layer and the substrate or the end surface of the substrate is provided with a light incident facet angled inwardly as it separates from the surface of the second semiconductor or the surface of the substrate.

Abstract: Two keys which are updated in the same updating cycle at different times are prepared as signature keys (main key and auxiliary key) for electronic signature, and the updating cycle of each key is divided into, for example, three periods. The first and last periods after the updating are used for the auxiliary key while the intermediate period is used for the main key, and an electronic signature is carried out with the main key. The electronic signature is confirmed with either of two confirmation keys which are updated synchronously with updating the two keys used as the signature keys. This eliminates the need of stopping issuance of the electronic signature or limiting a service offer upon updating the signature keys.

Abstract: The present invention relates to an electro-optic sampling oscilloscope. The delay circuit in the electro-optic sampling oscilloscope comprises a delay time detecting circuit, a regulation time determining circuit, a counter circuit and a delay regulating circuit. The delay time detecting circuit detects in the trigger signal a value corresponding to the delay time of a reference clock from a reference clock generating circuit. The regulation time determining circuit determines a regulation time based on the value detected by the delay time detecting circuit so that the regulation time is an integer multiple of the reference clock. The counter circuit is triggered by the trigger signal to count the reference clock through a specific value. The delay regulating circuit employs a signal related to the regulation time from the regulation time determining circuit, to delay the signal output from the counter circuit by the regulation time.

Abstract: The micro-mirror apparatus of the invention has; a mirror 33, a plurality of torsion springs 35, 36 for supporting the mirror 33 so as to be tiltable relative to an upper substrate 27, a lower substrate 21 arranged facing a lower face of the mirror 33, a convex portion 34 provided on an upper face of the lower substrate 21 and a plurality of lower electrodes 22, 23 formed on an outer face of the convex portion 34. For the torsion spring 36, an aspect ratio of height/width in a cross-section perpendicular to a longitudinal direction thereof is at least 1.8.

Abstract: Optical wavelength control method and apparatus which are capable of controlling an optical wavelength of a light source with a central wavelength which is uncertain and unstable at nanometer order is disclosed. In the optical wavelength control apparatus, the control target light entered from the variable wavelength light source is scanned at a prescribed period and optical pulses having a phase corresponding to the optical wavelength of the control target light are obtained. Then, a phase difference between a phase of the optical pulses and a phase corresponding to a reference optical wavelength is detected, and the variable wavelength light source is controlled by feeding back the phase difference to the variable wavelength light source such that the optical wavelength of the control target light is controlled by an optical frequency pulling with respect to the reference optical wavelength according to the phase difference.

Abstract: A quadrature signal generation system which has a pair of input terminals for receiving a first A.C. signal and a second A.C. signal. The first A.C. signal and the second A.C. signal have a predetermined frequency and a phase relation of approximate 90° with each other. The system also has a multiplier circuit for providing a product of the first A.C. signal and the second A.C. signal, resulting in a third A.C. signal. Furthermore, the system has a square-difference circuit for providing a difference of a square of the first A.C. signal and a square of the second A.C. signal, the difference being a fourth A.C. signal. The frequency of the third A.C. signal, and the fourth A.C. signal are equal to twice the frequency of the first A.C. signal and the second A.C. signal, and the third A.C. signal and the fourth A.C. signal have a fine phase relation of 90° with each other.

Abstract: An electro-optical probe used for an oscilloscope (e.g., electro-optic sampling oscilloscope) is mainly constructed by a probe head and a probe unit. The probe head contains a metal pin and an electro-optical element having a reflector at its terminal surface. The probe unit contains a reduced number of optical parts, which are arranged such that an optical axis of incoming beams of the electro-optical element differs from a optical axis of outgoing beams of the electro-optical element. That is, laser beams output form a laser diode are subjected to convergence by a converging lens to produce converged beams, which are incident on the electro-optical element as its incoming beams. The incoming beams are subjected to reflection by the reflector to produce reflected beams, which are output from the electro-optical element as its outgoing beams. Then, the reflected beams are converted to parallel beams by a collimator lens, or they are converged by a converging lens.

Abstract: A scheme for detecting telop character displaying frames in video image which is capable of suppressing erroneous detection of frames without telop characters due to instability of image features is disclosed. In this scheme, each input frame constituting the video data is entered, and whether each input frame is a telop character displaying frame in which telop characters are displayed or not is judged, according to edge pairs detected from each input frame by detecting each two adjacent edge pixels for which intensity gradient directions are opposite on some scanning line used in judging an intensity gradient direction at each edge pixel and for which an intensity difference between said two adjacent edge pixels is within a prescribed range as one edge pair, edge pixels being pixels at which an intensity value locally changes by at least a prescribed amount with respect to a neighboring pixel among a plurality of pixels constituting each input frame.

Abstract: The present invention provides an optical fiber distortion measuring apparatus and optical fiber distortion measuring method which make it possible to measure the amount of distortion of an optical fiber efficiently and in a short period of time. The time change waveform when a light pulse having a frequency of &ngr;1 is applied is compared with initial data (the time change waveform obtained in a case in which there is no distortion). Then, the light intensity L1 at a position Dx at which the light intensities do not agree is obtained. Next, the time change waveform is measured when a light pulse having a frequency of &ngr;2 is applied, and the light intensity L2 at position Dx is obtained. After this, the loss (resulting from distortion) in light intensities L1 and L2 is corrected, and light intensities LC1 and LC2 are obtained.

Abstract: In this invention, a mixture of a diazotizing reagent which reacts with nitrous ions to produce a diazo compound, a coupling reagent which couples with a diazo compound to produce an azo dye, and an acid is placed in pores of a transparent porous body to prepare a sensor element. Nitrogen dioxide gas is sensed in accordance with a color change before and after the sensor element is exposed to air to be measured for a predetermined time.

Abstract: In this invention, resist patterns formed by development are dried using a supercritical fluid such that no moisture enters the patterns.

Abstract: The present invention provides a light generation method and a light source that are preferable in obtaining a single-mode light having high outputs, a small wavelength spectral bandwidth, and a low intensity noise. A white output from a white-light source and having wavelength components over a wide-band in a wavelength spectrum passes through an isolator and is then filtered by a disc-shaped optical filter. A transmitted light is input to a semiconductor optical amplifier having its polarization plane regulated by a polarization controller. An output from the amplifier passes through an isolator and is then filtered by a disc-shaped optical filter again to generate a single-mode light having a small spectral bandwidth and high outputs. Polarization control by the polarization controller corresponds to control of the polarization plane of a semiconductor laser in the semiconductor optical amplifier so as to obtain a maximum gain from the amplifier.

Abstract: A tellurite glass as a glass material of optical fiber and optical waveguide has a composition of 0<Bi2O3≦20 (mole %), 0≦Na2O≦35 (mole %), 0≦ZnO≦35 (mole %), and 55≦TeO2≦90 (mole %). The tellurite glass allows an optical amplifier and a laser device that have broadband and low-noise characteristics. In a splicing structure of non silica-based optical fiber (as a first fiber) and a silica-based optical fiber (as a second fiber), optical axes of the first and second optical fibers are held at different angles &thgr;1 and &thgr;2 (&thgr;1≠&thgr;2) respectively from a vertical axis of a boundary surface between their spliced ends, and a relationship between the angles &thgr;1 and &thgr;2 satisfies Snell's law represented by an equation of sin &thgr;1/sin &thgr;2=n2/n1 (where n1 is a refractive index of the first optical fiber and n2 is a refractive index of the second optical fiber) at the time of splicing the first and second optical fibers.

Abstract: A channel-to-channel skew compensation apparatus is provided with N number of frame synchronization circuits 11 for generating frame signals to indicate data position of parallel data on a common time axis for each data transmission channel; a reference timing determination circuit 16 for determining a reference timing based on N frame signals output from the frame synchronization circuit 11; a skewing amount detection section 15 for generating N skewing amount signals according to the reference timing determined by the reference timing determination circuit 16; and a timing compensation section 13 for adjusting output timing of parallel data for each transmission channel according to the skewing amount signal generated by the skewing amount detection section 15.

Abstract: A phase-lock loop (PLL) is formed by a voltage-controlled oscillator (51), a local optical pulse source (2), an optical branching device (12) for branching the locally generated optical pulse stream from the local optical pulse source (52), a harmonic component local generation part (30) for locally generating harmonic component electrical signal from the one of two branched locally generated optical pulse streams, and a phase comparison part (40) for comparing the phases of the locally generated harmonic component electrical signal and an incoming signal component electrical signal generated from an incoming optical signal pulse stream and for supplying the voltage-controlled oscillator (51) with a control voltage corresponding to the phase difference between the two input electrical signal. The other branched output from the optical branching device (12) is output as a locally generated optical pulse stream bit-phase synchronized with the incoming optical signal pulse stream.

Abstract: In a semiconductor photo-detector of the present invention, a first semiconductor layer, a second semiconductor layer having, and a photo-absorption part composed of a photo-absorption layer sandwiched between these layers are disposed on a substrate, at least the photo-absorption layer is formed at a position apart inwardly by a finite length from an end surface of the substrate, an end surface of the second semiconductor layer and the substrate or the end surface of the substrate is provided with a light incident facet angled inwardly as it separates from the surface of the second semiconductor or the surface of the substrate.

Abstract: A micro-fluidic cell for optical detection of gases provided according to the present invention includes a concentration cell and a detection cell, and increases the sensitivity of optical detection of gases, selectivity of components, and accuracy of quantitative determination, and also achieves a low electric power consumption and a small-sized, light-weight configuration of the entire apparatus.

Abstract: A packet classification search device and method are implemented which are capable of searching rules of packet classification having very long search bit width at high speed while using a CAM which has a limited bit width. The fields of rules of packet classification are grouped into groups, and the grouped fields of each rule are stored along with search related information (except for the initial group) and number of searches information in a CAM. The next number of searches information (if further groups exist which must be searched), comparison related information, and actions related to packets (if further groups exist which must be searched, directing searching again, while if no further groups exist which must be searched, actions for packet classification) are stored in a search result storage device. By doing this it is made possible to search with the bit width of the group unit.