Abstract: The present invention is an optical waveform shaper that utilizes a plurality of interferometers. Each interferometer has one of two types of transfer functions. One type is a first transfer function characterized as having a positive second order derivative of the output optical power in respect to the input optical power. Another type is a second transfer function characterized as having a negative second order derivative of the output optical power in respect to the input optical power. The characteristics of both the first transfer function and the second transfer function are actualized when the input optical power is in the neighborhood of zero and the output optical power shows substantially periodic change with respect to the input optical power. At least one of the plurality of interferometers uses the second transfer function.

Abstract: A first optical splitter splits an input optical signal and outputs it to first and second optical paths. A second optical splitter outputs the optical signal from the first optical path to third and fourth optical paths. A third optical splitter outputs the optical signal from the second optical path to fifth and sixth optical paths. In the second optical path, 1-symbol delay element and ?/4 phase shifter element are configured. In the fourth optical path, ?/2 phase shifter element is configured. First and second adjuster circuits adjust the optical path length of the second and the fourth optical paths, respectively, by temperature control. A first optical coupler couples optical signals transmitted via the third and the fifth optical paths. A second optical coupler couples optical signals transmitted via the fourth and the sixth optical paths. Photodetectors convert the optical signals from the optical couplers into electrical signals.

Abstract: A polarization controlling apparatus includes a permanent magnet itself or a permanent magnet to which a part capable of being magnetized is applied, an electromagnet capable of changing the magnitude of a magnetic field to be generated thereby, and a Faraday rotation effect element. The Faraday rotation effect element is disposed at a position at which an interaction magnetic field acts on the Faraday rotation effect element. The interaction magnetic field is produced by an interaction between a magnetic field generated by the permanent magnet and a magnetic field generated by the electromagnet. The Faraday rotation effect element thereby produces a Faraday rotation effect on inputted light. The magnitude of the interaction magnetic field in the Faraday rotation effect element is varied by a magnetic field component generated by the electromagnet to vary the amount of the Faraday rotation effect to be had on the inputted light.

Abstract: An apparatus and method scrambling a polarization state of signal light using at least three Faraday rotators and at least two wave plates. The apparatus also scrambles input signal light and outputs the signal light by a capacitor connected in series or in parallel with a Faraday rotator and being driven in resonance with the Faraday rotator.

Abstract: A polarization controlling apparatus is disclosed, which enhances the degree of freedom in apparatus design. The polarization controlling apparatus includes a permanent magnet itself or a permanent magnet to which a part capable of being magnetized is applied, an electromagnet capable of changing the magnitude of a magnetic field to be generated thereby, and a Faraday rotation effect element, disposed at a position at which an interaction magnetic field produced by an interaction between a magnetic field generated by the permanent magnet and a magnetic field generated by the electromagnet acts, for producing a Faraday rotation effect on inputted light by means of the interaction magnetic field. The magnitude of the interaction magnetic field in the Faraday rotation effect element is varied by a magnetic field component generated by the electromagnet to vary the amount of the Faraday rotation effect to be had on the inputted light.

Abstract: An interferometer comprises a delay element and a phase shift element. The delay element delays an optical DQPSK signal by one-symbol time. The phase shift element shifts the optical DQPSK signal by ?/8. A pair of photodiodes converts each of a pair of optical signals output from the interferometer into an electric signal. A photodetector circuit converts differential current obtained by a pair of the photodiodes into voltage and outputs as a detection signal. A first decision circuit outputs one-bit information based on the voltage of the detection signal. A second decision circuit outputs one-bit information based on a squared value of the voltage of the detection signal.

Abstract: A first interferometer comprises a first delay element and a first phase shift element, and a second interferometer comprises a second delay element and a second phase shift element. The amounts of phase shift in the first and second phase shift element are zero and ?/2, respectively. A first photo detector comprises first and second photodiodes connected in parallel, and a second photo detector comprises third and fourth photodiodes connected in series. The first photodiode is provided with a first optical output of the first interferometer, the second photodiode is provided with a first optical output of the second interferometer, the third photodiode is provided with a second optical output of the first interferometer, and the fourth photodiode is provided with a second optical output of the second interferometer. A signal process circuit recovers transmitted data based on output signals of the first and second photo detectors.

Abstract: An optical signal processing method is disclosed that enables improvements of a signal to noise ratio of an optical signal and reduction of size and power of an optical signal processing device. The optical signal processing method includes steps of dividing an input optical signal into a first polarization optical component and a second polarization optical component orthogonal to the first polarization optical component; supplying the first polarization optical component to a first gain device whose gain saturates at a first value; supplying the second polarization optical component to a second gain device whose gain saturates at a second value less than the first value; combining output light from the first gain device and output light from the second gain device; and outputting the combined optical signal through a polarization element.

Abstract: A first optical splitter splits an input optical signal and outputs it to first and second optical paths. A second optical splitter outputs the optical signal from the first optical path to third and fourth optical paths. A third optical splitter outputs the optical signal from the second optical path to fifth and sixth optical paths. In the second optical path, 1-symbol delay element and ?/4 phase shifter element are configured. In the fourth optical path, ?/2 phase shifter element is configured. First and second adjuster circuits adjust the optical path length of the second and the fourth optical paths, respectively, by temperature control. A first optical coupler couples optical signals transmitted via the third and the fifth optical paths. A second optical coupler couples optical signals transmitted via the fourth and the sixth optical paths. Photodetectors convert the optical signals from the optical couplers into electrical signals.

Abstract: An optical signal processing method is disclosed that enables improvements of a signal to noise ratio of an optical signal and reduction of size and power of an optical signal processing device. The optical signal processing method includes steps of dividing an input optical signal into a first polarization optical component and a second polarization optical component orthogonal to the first polarization optical component; supplying the first polarization optical component to a first gain device whose gain saturates at a first value; supplying the second polarization optical component to a second gain device whose gain saturates at a second value less than the first value; combining output light from the first gain device and output light from the second gain device; and outputting the combined optical signal through a polarization element.

Abstract: An optical signal processing method is disclosed that enables improvements of a signal to noise ratio of an optical signal and reduction of size and power of an optical signal processing device. The optical signal processing method includes steps of dividing an input optical signal into a first polarization optical component and a second polarization optical component orthogonal to the first polarization optical component; supplying the first polarization optical component to a first gain device whose gain saturates at a first value; supplying the second polarization optical component to a second gain device whose gain saturates at a second value less than the first value; combining output light from the first gain device and output light from the second gain device; and outputting the combined optical signal through a polarization element.

Abstract: The optical waveform shaper comprises a plurality of interferometers connected in series. The transfer function of each interferometer is either one of a first transfer function, in which the second order derivative of the output optical power in respect to the input optical power is positive when the input optical power is in the neighborhood of zero, or a second transfer function, and the output optical power shows substantially periodical changes to the input optical power, or a second transfer function, in which the second order derivative of the output optical power in respect to the input optical power is negative when the input optical power is in the neighborhood of zero, or a second transfer function, and the output optical power shows substantially periodical changes to the input optical power. At least one of the interferometers uses the second transfer function.

Abstract: An optical signal processing method is disclosed that enables improvements of a signal to noise ratio of an optical signal and reduction of size and power of an optical signal processing device. The optical signal processing method includes steps of dividing an input optical signal into a first polarization optical component and a second polarization optical component orthogonal to the first polarization optical component; supplying the first polarization optical component to a first gain device whose gain saturates at a first value; supplying the second polarization optical component to a second gain device whose gain saturates at a second value less than the first value; combining output light from the first gain device and output light from the second gain device; and outputting the combined optical signal through a polarization element.

Abstract: Disclosed herein is an optical signal processing device which can give stable temporal order to the modulation-phases of a plurality of optical signals. The optical signal processing device includes an optical demultiplexer and an optical multiplexer for adaptation to WDM (wavelength division multiplexing). The optical demultiplexer has an input port and a plurality of output ports. The input port is adapted to accept WDM signal light obtained by wavelength division multiplexing a plurality of optical signals having different wavelengths. The optical multiplexer has an output port and a plurality of input ports. The plural output ports of the optical demultiplexer and the plural input ports of the optical multiplexer are connected by a plurality of optical paths, respectively. Each optical path is provided with a delay adjuster.

Abstract: The present invention relates to a method for waveform shaping of signal light. This method includes the steps of supplying signal light to a first waveform shaper to obtain intermediate signal light, dividing the intermediate signal light into first and second signal lights, supplying the first signal light to a clock recovery circuit to obtain a clock pulse, and supplying the second signal light and the clock pulse to a second waveform shaper to obtain regenerated signal light synchronous with the clock pulse.

Abstract: Disclosed herein is an optical signal processing device which can give stable temporal order to the modulation-phases of a plurality of optical signals. The optical signal processing device includes an optical demultiplexer and an optical multiplexer for adaptation to WDM (wavelength division multiplexing). The optical demultiplexer has an input port and a plurality of output ports. The input port is adapted to accept WDM signal light obtained by wavelength division multiplexing a plurality of optical signals having different wavelengths. The optical multiplexer has an output port and a plurality of input ports. The plural output ports of the optical demultiplexer and the plural input ports of the optical multiplexer are connected by a plurality of optical paths, respectively. Each optical path is provided with a delay adjuster.

Abstract: The present invention relates to a method for waveform shaping of signal light. This method includes the steps of supplying signal light to a first waveform shaper to obtain intermediate signal light, dividing the intermediate signal light into first and second signal lights, supplying the first signal light to a clock recovery circuit to obtain a clock pulse, and supplying the second signal light and the clock pulse to a second waveform shaper to obtain regenerated signal light synchronous with the clock pulse.

Abstract: A first polarizer separates an input light of the wavelength &lgr;2 into an X polarized wave and a Y polarized wave normal to each other. The input light of wavelength &lgr;2 is a linearly polarized wave. The X polarized wave is input to the second polarizer after passing through a semiconductor optical amplifier. The Y polarized wave is led by a reflecting device to the second polarizer. The refractive index of a waveguide of the semiconductor amplifier changes depending on the intensity of an input light. A signal light which is intensity-modulated according to a transmission signal and has the wavelength &lgr;1 is input to the semiconductor optical amplifier. The second polarizer couples the X and Y polarized waves. The third polarizer receives and outputs an output light from the second polarizer.

Abstract: An optical transmission system includes an optical path cross-connect device and an electrical cross-connect device connected by a plurality of working and standby input/output interface links. Optical signals in the working and standby systems are entered from the optical path cross-connect device into the electrical cross-connect device via the working and standby interface links, respectively, and switching of working and standby transmission lines is performed electrically by the electrical cross-connect device without momentary disconnect.

Abstract: An optical cross-connect device for optical networks is connected to reserve optical transmission lines and working optical transmission lines, and is used to switch optical signals. The optical cross-connect device includes a bypass component, a routing component and connection links. The bypass component includes an optical-space switch that is connected to the reserve optical transmission lines. The routing component also includes an optical-space switch that is connected to the working optical transmission lines. The connection links are connected between both input and output parts of the optical-space switch of both the bypass component and the routing component.

Abstract: A biological implantable pressure sensor element comprises a fixed volume pouch formed by a sealed, flexible, impermeable membrane comprising therewithin a gel mass contained in a gel volume, said gel being hydrated with an aqueous solution comprising an agent having at least a first and a second NMR-detectable form, the proportion of the first to the second form of the agent in the gel volume being determined by their electrolytic interaction with the gel, whereby when an external pressure is applied to the sensor element a d (chemical shift)/d(.sigma./K) greater than 0.0001 ppm is attained, wherein .sigma. is the external pressure and K is the modulus of the gel. A kit contains sterile, individually wrapped sensor elements.