Abstract: An interferometer of the invention includes: a first splitting element which includes a first transparent medium and a first splitting film formed on the first transparent medium, and which splits incident light into a first split beam and a second split beam, the first split beam being the incident light reflected by the first splitting element and the second split beam being the incident light transmitted through the first splitting element; and a second splitting element which includes a second transparent medium and a second splitting film formed on the second transparent medium, and which causes interference between the first split beam and the second split beam passed through different optical paths, the second splitting element being positioned such that a positional relationship between the second transparent medium and the second splitting film with respect to a direction of incidence on the second splitting element of the first split beam is opposite to a positional relationship between the first tr

Abstract: An interferometer for demodulating a differential M-phase shift keying signal includes a PLC type interferometer main body, a heating portion that heats the PLC type interferometer main body, and an intermediate member having a higher stiffness than that of the PLC type interferometer main body, for bonding the PLC type interferometer main body and the heating portion with each other while being sandwiched therebetween. A linear expansion coefficient difference between the PLC type interferometer main body and the intermediate member is equal to or smaller than 4.5×10?6/° C., and a thermal conductivity difference between the PLC type interferometer main body and the intermediate member is equal to or larger than 10 W/mK. A phase of an optical signal flowing through the interferometer is adjusted by using the heating portion and a second heating portion.

Abstract: An interferometer of the present invention includes: a splitting element which splits an incident light beam into a first split beam and a second split beam; and a first phase compensator which is positioned in an optical path of the first split beam, and which compensates a phase difference occurring between the first split beam and the second split beam upon splitting of the incident light beam by said splitting element.

Abstract: A delay interferometer and a demodulator including the delay interferometer and a balanced photodetector are provided. A half mirror splits an optical signal into first and second split beams of light which travel on first and second optical paths, respectively. A first reflector being disposed on the first optical path reflects the first split beam of light toward the half mirror. The second reflector being disposed on the second optical path reflects the second split beam of light toward the half mirror. At least one phase compensator being disposed between the half mirror and at least one of the first and second reflectors includes a medium that exhibits thermooptic effect and has temperature dependency of refractive index. The half mirror couples the first and second split beams of light to generate at least first and second coupled beams of light.

Abstract: An optical packet network system of a ring type, capable of preventing degradation of an optical signal, can be implemented by providing a mechanism relatively simple in structure, capable of erasing light noise if the optical packet signal does not exists. In the optical packet network system made up by interconnecting respective nodes adjacent to each other, and connecting a sending source of an optical packet signal to a ring, a light noise removal function block is provided between the respective nodes adjacent to each other.

Abstract: An optical communication apparatus includes an erbium-doped optical fiber amplifier for amplifying a modulated optical signal, wherein a light which is not modulated is inputted to the erbium-doped optical fiber amplifier together with the optical signal.

Abstract: An address recognition apparatus may include a first normalizing unit, a second normalizing unit and an address determination unit. The first normalizing unit normalizes a first electric signal and generates a first normalized signal, wherein the first electric signal is associated with a first divided set of optical packet signals. The second normalizing unit normalizes a second electric signal and generates a second normalized signal, wherein the second electric signal is associated with a second divided set of optical packet signals. The address determination unit refers to the first and second normalized signals and determines whether a destination address of a set of optical packet signals is identical to or different from an address allocated to a self-station associated with the address recognition apparatus, wherein the set of optical packet signals has been divided into the first and second divided sets of optical packet signals.

Abstract: A semiconductor optical switch may include an optical waveguide, a first electrode, and a first reflector. The optical waveguide may include a branching point, a first incoming path and first and second outgoing paths. The first electrode is provided at the branching point to give carrier injection into the branching point to allow that the branching point reflects an optical signal that is propagating through the first incoming path so that the reflected optical signal propagates through the second outgoing path. The first electrode may give no carrier injection into the branching point to allow that the branching point allows the optical signal to transmit through the branching point and propagate through the first outgoing path. The first reflector is provided on the first outgoing path. The first reflector reflects a leakage of light that has propagated from the branching point.

Abstract: An optical waveform shaping device includes a first waveguide portion, formed on a substrate, for transmitting the optical signal and simultaneously absorbing a portion of the optical signal, which has a signal level equal to or smaller than a predetermined value, so as to shape the optical signal; and a second waveguide portion, formed on the substrate, for transmitting the optical signal, which was transmitted through the first waveguide portion, and simultaneously amplifying the optical signal. The first waveguide portion may be formed using a saturable absorber. A first electrode for supplying electric current to the first waveguide portion so that the first waveguide portion is provided with a function of absorbing the optical signal; and a second electrode for supplying electric current to the second waveguide portion so that the second waveguide portion is provided with a function of amplifying the optical signal may also be provided.

Abstract: Disclosed is a repeater including: a recognizing unit to recognize a destination address of an optical packet from the optical packet which includes the destination address assigned in unit of bit and a bit indicating whether or not a plurality of destination addresses are assigned; an optical splitting unit to split the optical packet into a plurality of optical packets; and selecting units to select transmission channels for the split optical packets on the basis of recognition results by the recognizing units, respectively.

Abstract: A variable light signal delay apparatus includes a first delay optical fiber, a second delay optical fiber having a length different from the first delay optical fiber, and an optical switch having two input ports, two output ports, and paths, through which a light signal propagates, provided between the first delay optical fiber and the second delay optical fiber, in which a light signal input from at least one of the input ports propagated through either the first delay optical fiber or the second delay optical fiber or through neither the first delay optical fiber nor the second delay optical fiber to be output from a desired first output port.

Abstract: An object of this invention is to realize a pulse pattern generating apparatus that outputs a test signal of high waveform quality even when the shape of an eye pattern is changed. This invention is an improvement of a pulse pattern generating apparatus that generates a test signal of a predetermined pattern by using plural digital-analog converters and outputs the test signal to a test subject.

Abstract: A semiconductor optical switch may include an optical waveguide, a first electrode, and a first reflector. The optical waveguide may include a branching point, a first incoming path and first and second outgoing paths. The first electrode is provided at the branching point to give carrier injection into the branching point to allow that the branching point reflects an optical signal that is propagating through the first incoming path so that the reflected optical signal propagates through the second outgoing path. The first electrode may give no carrier injection into the branching point to allow that the branching point allows the optical signal to transmit through the branching point and propagate through the first outgoing path. The first reflector is provided on the first outgoing path. The first reflector reflects a leakage of light that has propagated from the branching point.

Abstract: An optical amplification apparatus includes an optical amplification medium which has an input end and an output end, and amplifies an optical signal by a predetermined amplification rate; a first light source for launching excited light which excites the optical amplification medium; an isolator connected to the output end of the optical amplification medium; and a second light source for launching idle light which has a predetermined wavelength and is launched into the optical amplification medium from a point between the optical amplification medium and the isolator. The optical amplification medium, the first light source, the isolator, and the second light source are contained in the package of the optical amplification apparatus. The apparatus may further include a set of an optical absorption member for absorbing the idle light and an circulator connected to the input end of the optical amplification medium, or an input-side isolator connected to the input end of the optical amplification medium.

Abstract: There is provided a light signal processing device. The light signal processing device includes a label recognition circuit and an electro-absorption optical switch. The label recognition circuit includes: a plurality of photodiodes coupled to each other in parallel; a resonant tunneling diode coupled in series with the photodiodes; and a data buffer coupled to a connection point between the photodiodes and the resonant tunneling diode. The label recognition circuit is adapted to latch an optical bit signal inputted into the photodiodes. The electro-absorption optical switch is driven directly by an output signal outputted from the label recognition circuit.

Abstract: An interferometer of the invention includes: a first splitting element which includes a first transparent medium and a first splitting film formed on the first transparent medium, and which splits incident light into a first split beam and a second split beam, the first split beam being the incident light reflected by the first splitting element and the second split beam being the incident light transmitted through the first splitting element; and a second splitting element which includes a second transparent medium and a second splitting film formed on the second transparent medium, and which causes interference between the first split beam and the second split beam passed through different optical paths, the second splitting element being positioned such that a positional relationship between the second transparent medium and the second splitting film with respect to a direction of incidence on the second splitting element of the first split beam is opposite to a positional relationship between the first tr

Abstract: An optical logic device performs a logic operation on a plurality of input light signals. The optical logic device has a photoelectric conversion portion, in which photoreceivers for receiving input light signals are provided in parallel, that outputs an electric signal obtained by adding up outputs of the photoreceivers, and a comparator that compares a voltage level of the electric signal outputted from the photoelectric conversion portion with a predetermined voltage level.

Abstract: There is provided a PD-TIA module that can be used for recognition of an address of an optical packet signal in a system having variation in mark rate all the time, such as an optical packet communication system. An optical communication module comprises a photoelectric converter for converting an optical signal into a current signal, a current/voltage conversion means connected to the photoelectric converter, for converting the current signal into a voltage signal, and a limiting amplifier for receiving and amplifying an electric signal subjected to voltage conversion by the current/voltage conversion means while comparing the electric signal as amplified with a predetermined threshold value, thereby outputting a signal for “0” or “1”.

Abstract: A light modulating apparatus which is to be used in a transmission system using wavelength division multiplexing has: a signal generating section for producing a transmission signal and the like; a first light modulating section for modulating light emitted from a light source, on the basis of the transmission signal; a variable phase shifter which changes a phase of a light quantity control signal; a second light modulating section for modulating a light signal emitted from the first light modulating section, on the basis of an output of the variable phase shifter; a branching section for branching a light signal emitted from the second light modulating section, into an output light signal and an electric signal; and an analysis controlling section for sampling the electric signal, controlling the variable phase shifter on the basis of sampled data, and adjusting a timing of the modulation in the second light modulating section.

Abstract: An interferometer of the present invention includes: a splitting element which splits an incident light beam into a first split beam and a second split beam; and a first phase compensator which is positioned in an optical path of the first split beam, and which compensates a phase difference occurring between the first split beam and the second split beam upon splitting of the incident light beam by said splitting element.