Abstract: A chromatic dispersion distribution measurement apparatus, comprises: a power calculation unit for calculating a power value of an input light to be input into an optical device to be measured, in order to calculate a chromatic dispersion distribution in the optical device to be measured, in accordance with an output light power of an output light from the optical device to be measured as a function of a transmission distance along the optical device to be measured; and a control unit for controlling an input light power of the input light to the optical device to be measured in accordance with the power value of the input light which is calculated by the power calculation unit.

Abstract: A chromatic dispersion distribution measuring apparatus which can determine a sign of a dispersion value, and a measuring method thereof. The chromatic dispersion distribution measuring apparatus comprises: a plurality of light sources for emitting lights having different wavelengths; an intensity measuring section for measuring a light intensity of a four-wave mixed light caused by any two lights, as a function of a transmission distance; a chromatic dispersion calculating section for calculating a chromatic dispersion value of the optical device, in accordance with the light intensity; a time measuring section for measuring a propagation time of a reflected light caused by each light; and a sign determining section for determining a sign of the chromatic dispersion value of the optical device, on the basis of two different chromatic dispersion values and two propagation times of reflected lights of two lights related to the two chromatic dispersion values.

Abstract: A chromatic dispersion distribution measurement apparatus for calculating a chromatic dispersion distribution in an optical communication path under test, comprises: an intensity ratio calculation unit for calculating an intensity ratio of a first light and a second light that are reflected from an optional position of the optical communication path under test and propagated to an incident end of the optical communication path under test by taking the same propagation time; and a chromatic dispersion value calculation unit for calculating a chromatic dispersion value in the optical communication path under test in accordance with the intensity ratio calculated by the intensity ratio calculation unit.

Abstract: A chromatic dispersion distribution measurement apparatus, comprises: a portion information obtaining unit for obtaining a portion information which specifies a portion of an optical device to be measured; a sign information obtaining unit for obtaining a sign information which indicates a correct sign to be marked on a chromatic dispersion value in the specified portion; and a sign converting unit for converting an initial sign marked on the chromatic dispersion value in the specified portion, into the correct sign in accordance with the sign information obtained by the sign information obtaining unit.

Abstract: A chromatic dispersion distribution measurement apparatus, comprises: a chromatic dispersion value calculation unit for calculating a plurality of actual chromatic dispersion values in an optical device at a plurality of wavelengths; and a chromatic dispersion interpolation unit for interpolating an expected chromatic dispersion value between the actual chromatic dispersion values calculated by the chromatic dispersion value calculation unit, in order to obtain a chromatic dispersion distribution as a function of wavelength.

Abstract: A chromatic dispersion distribution measurement apparatus, comprises: an output light intensity measurement unit for measuring an intensity of an output light outputted from an optical device to be measured; and an input light intensity control unit for automatically controlling an intensity of an input light to be inputted into the optical device to be measured, in accordance with the intensity of the output light, which is measured by the light intensity measurement unit.

Abstract: The object of the present invention is to provide an optical pulse generator which very stably generates for a long period of time a high cycling frequency optical pulse chain. In order to obtain this object, in a ring type resonator R, the present invention provides an optical path length regulator 14 which performs high precision optical path length adjustment and an optical path length regulator 60 which performs wide range optical path length adjustment, and extracts a clock signal by converting an optical pulse emitted from the ring type resonator R to an electrical signal by a clock extractor 42, detects the frequency difference between a base frequency signal output form a synthesizer 52 by a frequency difference detector 50, and controls said optical path length regulator 14 and said optical path length regulator 60.

Abstract: According to the present invention, damage to a photo-detector disposed in clock signal extractor by means of an optical pulse having an optical power exceeding a rated value is prevented. A ring resonator generates a repetitive, high-frequency optical pulse. Optical branching circuit branches a portion of the optical pulse circulating through ring resonator, while optical branching circuit further branches a portion thereof to protective device. Pumping source generates an excitation light for exciting a rare-earth doped optical fiber. Optical multiplexer couples the optical pulse branched by optical branching circuit, and the excitation light. Upon excitation by means of the excitation light, rare-earth doped optical fiber amplifies and emits the incoming optical pulse. The optical power of the excitation light is adjusted such that the output of rare-earth doped optical fiber reaches a saturation power.

Abstract: An optical phase locked loop circuit, which controls so that the optical frequency of the light 19A generated by the slave laser 19 has the offsetting factor to the optical frequency of the coherent light 11A generated by the master laser 11, corresponding to the frequency of the signal 16A generated by the signal generator 16, is provided with a LPF 1, an optical power controller 2 and a variable optical attenuator 3. Upon detecting the phase difference caused by the difference frequency between the light 19A and the coherent light 11A, the output control light 3A is obtained by transmitting the output control light 20B through the variable optical attenuator 3. The signal 13B proportional to the optical power of the output control light 3A is extracted by the LPF 1. The optical power of the light 3A is stabilized by using the optical power controller 2 and the variable optical attenuator 3 in order to vary the optical power attenuation in the light 20B corresponding to the extracted signal 13B.

Abstract: A polarization is controlled by introducing a phase difference in an incident light at first, then introducing a phase difference by 45 degrees, and then the polarized light is rotated. The light is passed through an analyzer so arranged that the direction of the transmission axis of the analyzer does not coincide with the principal axes of the means for introducing the phase differences, thereby to convert the polarized condition into a light volume which is used to control the phase differences and the rotation.

Abstract: An optical fiber testing apparatus for testing an optical fiber as to presence and location of a fault such as breakage by inputting a pulsed coherent light beam to the optical fiber and synthesizing a return light beam reflected back from the optical fiber with a reference light beam having a frequency deviated from the pulsed light beam by a predetermined amount, wherein the synthesized waveform is detected through optical heterodyning. The electric signal obtained from the heterodyning detection is detected by an envelope detector, of which dynamic range is effectively virtually broadened by using correcting data prepared previously. The optical fiber test can be accomplished through a single measurement without involving expensiveness of hardware.

Abstract: A resin useful for electrocoating is obtained by reacting a reaction product of an epoxy group-containing compound with a carboxyl group-containing butadiene/acrylonitrile copolymer with simultaneously or separately an amino group-containing compound and a fully or a partially blocked isocyanato group-containing compound, and a composition comprising said resin or a composition comprising a reaction product obtained by reacting a reaction product of an epoxy group-containing compound and a carboxyl group-containing butadiene/acrylonitrile copolymer with an amino group-containing compound and a fully or partially blocked isocyanato group-containing compound is used for a cathodical electrodeposition.