Fujitsu Corporation

Photonics Electronics Technology Research Association

Tosoh Corporation

Qd Laser, Inc.

Nippon Silica Glass Co., Ltd.

Other

Hewlett-packard Company

Fijitsu Limited

Tomoyuki Akiyama

Shinsuke Tanaka

Koji Tsukuma

Takeshi Hoshida

Mitsuru Sugawara

Yoshikazu Kikuchi

Jun Matsui

Shoichiro Oda

Hitoshi Noguchi

Tsuyoshi Aoki

Nobuaki Hatori

Yasuhiro Nakasha

Yoshiaki Nakata

Hiroji Ebe

Hideo Akama

Masayuki Kudo

Hiroya Nagata

Makoto Usami

Ken-ichi Takahashi

Yohei Sobu

Hideaki Segawa

Nobusuke Yamada

Shinkichi Hashimoto

Masanori Ichida

Kazuyuki Chiba

Hajime Sudo

Koichi Orii

Yukinobu Hara

Hideo Okara

Hisao Yoshino

An optical transceiver includes: an optical transceiver circuit; a light source device to multiplex light rays emitted from light source elements having different wavelengths, and output multiplexed light; a demultiplexer to demultiplex the light output from the light source device into wavelengths to supply the wavelengths to the optical transceiver circuit; monitors to monitor the wavelengths at output ports of the demultiplexer, respectively; and a wavelength controller to control the wavelengths of the light source elements, based on monitoring results of the monitors, wherein the demultiplexer includes unit circuits in each of which three asymmetric Mach-Zehnder interferometers having a predetermined arm length difference are cascaded in a tree shape, and each of the monitors is arranged at an output waveguide of an asymmetric Mach-Zehnder interferometer at an end of the cascaded tree, to be connected to the wavelength controller via a signal line.

Optical transceiver, optical transceiver device using the same, and method of controlling light source wavelengths

Optical transmitter includes: signal processing circuit, optical modulator, optical filter, and delay circuit. The signal processing circuit generates N drive signals for generating a modulated optical signal. Symbol rate of the modulated optical signal is fs and each symbol of the modulated optical signal transmits N bits. The optical modulator includes Mach-Zehnder interferometer and N phase-shift segments each of which shifts a phase of light propagating through an optical path of the Mach-Zehnder interferometer according to the N drive signals. The optical filter removes, from output light of the optical modulator, a frequency component in a range of ±fs/2 with respect to a center frequency of the modulated optical signal, and extracts at least a part of other frequency components. The delay circuit controls timings of the N drive signals so as to reduce optical power of the frequency component extracted by the optical filter.

Optical transmitter that transmits multi-level optical signal

An optical communication element includes a plurality of slabs, an input port group, an output port group, a first waveguide group, and a second waveguide group. The plurality of slabs includes third waveguide. Each of the plurality of slabs include a predetermined number of first ports being arranged at an inlet the third waveguide at equal intervals in a lateral direction perpendicular to a light traveling direction, and input the optical signals, and a predetermined number of second ports being arranged at an outlet of the third waveguide at the equal intervals in the lateral direction so as to face the first ports, and output the optical signals. Each of the third waveguides are configured with a dimension that allows light intensity to be distributed at all traveling positions located in the lateral direction.

Optical communication element and optical neural network

An optical demultiplexer includes a first optical-processing-circuit to include first to third AMZs, each including a pair-of-arms of different lengths, the first AMZ outputting, to the second AMZ, a first signal-light-component and a first local-oscillation-light with center wavelengths adjacent to each other among a plurality of signal-light-components and a plurality of local-oscillation-lights inputted to the pair-of-arms, and outputting, to the third AMZ, a second signal-light-component with a same center wavelength as the first local-oscillation-light and a second local-oscillation-light with the same center wavelength as the first signal-light-component, the second AMZ outputting the first signal-light-component and the first local-oscillation-light, which are inputted to the pair-of-arms from the first AMZ, to a second optical-processing-circuit and a third optical-processing-circuit, respectively, and the third AMZ outputting the second local-oscillation-light and the second signal-light-component, which are inputted to the pair-of-arms from the first AMZ, to the second optical-processing-circuit and the third optical-processing-circuit, respectively.

Optical demultiplexer and communication device

An optical analog-to-digital (AD) converter includes, wherein the optical AD converter converts an analog signal of information included in inputted signal light into a digital signal, and is formed of N stages corresponding to a number N of bits of the digital signal, optical waveguides configured to respectively guide the signal light, base light obtained by branching local light, and reference light obtained by branching the local light, a light receiver configured to detect and compare light levels of the signal light and the reference light, and output a binary comparison result, and an optical modulator configured to variably control a light level of the base light, based on the binary comparison result, in each stage of the N stages, wherein an output variably controlled of the optical modulator is multiplexed with the reference light of a next stage.

Optical AD converter and optical receiver

An optical demultiplexing device includes a light source, a demultiplexer, a plurality of converters, a detector, a switch, and a controller, wherein the demultiplexer includes a plurality of asymmetric Mach-Zehnder interferometers (AMZ) each of which lengths of a pair of arms are different from each other, the plurality of AMZs are coupled to each other so that a plurality of wavelength lights input from the light source is demultiplexed and respectively output to the converters different from each other, and the controller controls the light source so that the plurality of wavelength lights is sequentially input to the demultiplexer one by one, and controls the switch so that an electrical signal detected by the detector is output to an output destination according to a wavelength light of a conversion source of the electrical signal.

Optical demultiplexing device and transmission device

An optical transmitter transmits a modulated optical signal in which each symbol carries M bits. M is an integer larger than one. The optical transmitter includes: a signal generation circuit configured to generate M&#xd7;N binary electric signals based on transmission data, bit rates of the M&#xd7;N binary electric signals being equal to each other, N being an integer larger than one, when the optical transmitter multiplexes N optical signals in time-division multiplexing; a Mach-Zehnder interferometer; and M&#xd7;N phase-shift elements provided along an optical path of the Mach-Zehnder interferometer and respectively configured to shift phases of light propagated in the optical path corresponding to the M&#xd7;N binary electric signals. The M&#xd7;N phase-shift segments are comprised of N electrode groups. Each of the N electrode groups includes M or more electrodes to which corresponding M binary electric signals among the M&#xd7;N binary electric signals are given.

Optical transmitter for transmitting multilevel optical signals

An optical element including a plurality of first circuits, the optical element includes a first cascade circuit in which one or more of first circuits are connected in cascade, a second cascade circuit in which one or more of first circuits are connected in cascade, and a combiner circuit configured to connect the first cascade circuit and the second cascade circuit. A first circuit included in the plurality of first circuits includes a first cascade structure in which N (N is an integer of 1 or larger) of 2-input and 2-output phase shifters and (N+1) of 2-input and 2-output couplers are alternately connected in cascade, and a first controller configured to control the N phase shifters in a direction in which optical input power decreases, the first controller being connected to one of two outputs of the first cascade structure.

Optical element and optical transmitter

An optical modulator includes: an encoder that encodes an input data signal; a branch circuit that branches an optical signal into first and second optical signals; a first arm through which the first optical signal branched at the branch circuit passes; a first phase shifter group on the first upper arm that adjusts a phase shift amount of the first optical signal that passes through the first arm; a second arm through which the second optical signal branched at the branch circuit passes; a second phase shifter group on the second arm that adjusts a phase shift amount of the second optical signal that passes through the second arm such that a sign of the phase shift amount of the second optical signal becomes opposite to a sign of the phase shift amount of the first optical signal; and a multiplexing circuit that multiplexes the first optical signal.

Optical modulator, optical transmitter, and optical communication apparatus

An optical communication component includes three or more couplers, a pair of waveguides, a phase shifter, a detector, and a controller. Each of the couplers multiplexes two input optical signals and two-branch outputs the multiplexed optical signals. Each of the pair of waveguides connects between the couplers and outputs each of the optical signals two-branch output from one of the couplers to another one of the couplers. The phase shifter, included in each of the waveguides, adjusts a phase amount of each of the optical signals passing through the waveguides. The detector detects an amount of power of the optical signal that has been subjected to phase adjustment and that is two-branch output from a most downstream coupler, from among the couplers, located in the traveling direction of the optical signal. The controller controls, based on the detected amount of power, each of the phase shifters.

Optical communication component, optical transmitter, and control method

A modulated light source includes an FP laser that emits light in a plurality of Fabry-Perot (FP) modes, a band-pass filter whose center wavelength can be modulated, a light reflector that selectively feeds only light having passed through the modulation filter back to the FP laser, and a wavelength adjustment mechanism that adjusts the center wavelength so as to coincide with one of the predetermined FP mode when the light fed back to the FP laser is used as seed light for stimulated emission of radiation to cause selective light emission at an oscillation wavelength.

Modulated light source

An optical add-drop device includes optical circuits. Each of the optical circuits includes first to third sub optical circuits. Each sub optical circuit includes an input coupler, output coupler, and a phase shifter. In each of the optical circuit, two ports of the output coupler in the first sub optical circuit are respectively coupled to the input coupler in the second sub optical circuit and the input coupler in the third sub optical circuit. The output coupler in the second sub optical circuit in each of the optical circuits is coupled to a drop port or the input coupler in the first sub optical circuit in the adjacent optical circuit. The input coupler in the third sub optical circuit in each of the optical circuits is coupled to an add port or the output coupler in the third sub optical circuit in the adjacent optical circuit.

Optical add-drop device

An optical demultiplexer is disclosed that separates light including a plurality of wavelengths into light of respective wavelengths. Unit circuits are cascaded in a tree structure. In optical demultiplexer components having the same structure, a combination of arm length differences in waveguide pairs is the same with respect to the N&#x2212;1 Asymmetric Mach-Zehnder interferometers in which the phase shifters are arranged, where N equals number of 2&#xd7;2 couplers. In three of the optical demultiplexer components in at least one of the unit circuits, N is three or more. Each of control circuits controls the phase shifters arranged in a corresponding optical demultiplexer component of a corresponding unit circuit in order to increase or decrease a value of a function having, as an argument, a power value acquired by a monitor from among monitors arranged at four optical waveguides at an output side of the corresponding unit circuit.

Optical demultiplexer, optical transport apparatus, and method of controlling optical demultiplexing

An optical transmission apparatus includes first and second optical waveguides to transmit light of multiple wavelengths; optical couplers on the waveguides, to couple the lights transmitted through the waveguides, so as to output the coupled light to the waveguides; phase shifters provided at preceding stages of part of the optical couplers, to change a phase shift amount of the light transmitted through the first and/or second optical waveguides, wherein the number of optical couplers in the part is greater than or equal to the number of the types of wavelengths; a monitor to monitor the intensity of the light output to the second optical waveguide via the optical coupler at the last stage; and a controller to control the phase shifters by changing the phase shift amount for each of the phase shifters in a direction in which the output of the monitor decreases.

Optical transmission apparatus and optical element

An optical element includes a gain chip, a ring modulator, which is a band-pass filter, a first optical waveguide and a second optical waveguide that are optically connected to the ring modulator, and a heater, wherein the first optical waveguide and the second optical waveguide are formed to be equal in optical path length (have no difference in optical path length) between a first light coupling point and a second light coupling point and equal in shape and length between the first light coupling point and the second light coupling point (to be symmetrical with the ring modulator interposed therebetween (with respect to the ring modulator)).

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Yokohama, Japan

Tomoyuki Akiyama