Fujitsu Corporation

Tadao Nakazawa

Masaharu Doi

Masaki Sugiyama

Hideyuki Miyata

Minoru Seino

Hiroshi Onaka

Hiroshi Miyata

Yutaka Kai

Naoki Hashimoto

Yoshinobu Kubota

Takehito Tanaka

Yoshihiko Kaitoh

Shinji Taniguchi

Yukito Tsunoda

Terumi Chikama

Tetsuo Ishizaka

Kazue Otsuka

Takashi Yamane

Teruo Kurahashi

Yoichi Takasu

Kunio Sugeta

Akira Ishii

Kazumasa Takabayashi

Martin Bouda

Ken Morito

Masaaki Ohyama

Yuji Kotaki

Shinichi Aoki

Naoyuki Mekada

Yumi Nakazawa

Martin c/o Fujitsu Limited Bouda

An acousto-optic device is disclosed which can achieve both of suppression of secular change and prevention of device damage and can maintain a stabilized wavelength selection filtering operation. The acousto-optic device includes a substrate on which a SAW guide for guiding a surface acoustic wave and an optical waveguide for guiding an optical wave are provided. A pyro-electricity coping conductive wiring pattern is provided in a region of the substrate other than the SAW guide and neutralizes polarization charge generated on a surface of the substrate.

Acousto-optic device and fabrication method of acousto-optic device

The present invention aims at providing a control method and a control apparatus for controlling the operation setting of an optical device with high accuracy, so as to reliably obtain characteristics according to a desired relationship to be set corresponding to a signal light, immediately after the control start. To this end, the control apparatus of the present invention comprises an optical coupler that branches a part of a main signal light input to the optical device, a monitoring optical device that operates in accordance with a control parameter same as for the optical device, and processes the monitor light branched by the optical coupler, a light receiver that receives the monitor light processed by the monitoring optical device, a detecting circuit that detects a relationship between the monitor light received by the light receiver, and the wavelength or optical power of the signal light, and a controlling circuit that adjust the control parameter for the optical device to control the operation setting, based on the relationship detected by the detecting circuit, so that characteristics of the optical device become capable of realizing the relationship to be set corresponding to the signal light.

Control method and control apparatus of optical device

An optical waveguide device includes a substrate having an electro-optical effect, an optical waveguide formed on the substrate, an electrode provided for the optical waveguide, a monitoring optical waveguide for guiding part of light outputted from the optical waveguide as monitor light, an attenuation section provided for the monitoring optical waveguide for attenuating the monitor light, and a light detection section for detecting the intensity of the monitor light guided by the monitoring optical waveguide and attenuated by the attenuation section.

Optical waveguide device and optical modulator

The present invention provides an optical waveguide device wherein a driving voltage to be applied is reduced. The optical waveguide device comprises a substrate cut in a Z-axis direction and having an electro-optical effect, an interference type optical waveguide formed on the substrate for causing lights which propagate along a plurality of parallel optical waveguides to interfere with each other, and a lumped-constant type electrode for applying a voltage for the electro-optical effect to the light propagating along the optical waveguides which form the interference type optical waveguide. The lumped-constant type electrode complements potentials to be supplied to adjacent ones of the plurality of parallel optical waveguides to each other such that voltages having an equal absolute value but having the opposite signs are applied to the adjacent optical waveguides. The apparatus of the present invention is applied to, for example, an optical communication system.

Optical waveguide device with reduced driving voltage

An optical waveguide is formed on a substrate and includes a curved ridge structure, a curved optical path, and a buffer layer. The curved ridge structure is formed on the substrate so as to have a curvature in a longitudinal direction of the curved ridge structure. The curved optical path is formed along the curved ridge structure. The buffer layer covers a side of the ridge structure and has a lower refractive index than a refractive index of the substrate.

Optical waveguide, optical device, and method of manufacturing optical waveguide

A configuration of acousto-optical tunable filters (AOTF) having stable output characteristics so that the output does not significantly vary with time. The configuration includes a plurality of AOTFs cascaded together. Each AOTF generates a surface acoustic wave in an optical waveguide in accordance with RF signals applied to the AOTF. A phase of a beat generated by the RF signals applied to one of the plurality of AOTFs is different from a phase of a beat generated by the RF signals applied to a different AOTF of the plurality of AOTFs.

Acousto-optical tunable filters cascaded together

The present invention relates to an optical modulator allowing appropriate interaction between signal electrodes and an optical waveguide, only by matching phases at input ends of the signal electrodes. The optical modulator includes an optical waveguide with its center part branched into two at two Y-branch waveguides, forming first and second waveguide arms, a first signal electrode transmitting a first electric signal interacting with first light propagating through the first waveguide arm in a predetermined manner, a second signal electrode transmitting a second electric signal interacting with second light propagating through the second waveguide arm in a predetermined manner, and earthed electrodes, and can match the interacting timing between the first electric signal and the first light to the interacting timing between the second electric signal and the second light, at a first input end supplying the first electric signal and a second input end supplying the second electric signal.

Optical modulator

The present invention has an object to provide a Mach-Zehnder optical modulator with the excellent productivity and reliability, which can obtain a favorable optical response characteristic even if a high frequency electric signal is applied to a signal electrode. To this end, the present optical modulator is configured such that, in a Mach-Zehnder optical modulator in which an optical waveguide and a coplanar electrode are formed on a surface of a substrate having an electro-optic effect, floating electrodes formed using a conducting material, are provided on side faces along parallel waveguides, among side faces substantially perpendicular to the surface of the substrate. Thus, even when a high frequency electric signal is applied to the signal electrode, a phenomenon is suppressed in which a particular frequency resonates within the substrate, and an occurrence of dip in a particular frequency is avoided.

The present invention aims at providing a connecting method capable of suppressing an influence of stray light for a plurality of optical function devices formed on the same substrate, and an optical apparatus applied with the control method. To this end, in the connecting method of optical function devices according to the present invention, the plurality of optical function devices formed on the same substrate are cascade connected so that both ends of an optical path passing through the plurality of optical function devices are positioned on the same end face of the substrate. According to such a connecting method, it becomes possible to effectively suppress a leakage of stray light from an optical input side to an optical output side.

Connecting method of optical function devices, and optical apparatus

The invention provides an optical modulator module by which a dip appearing in a frequency characteristic of a microwave from a DC component to a high-frequency component can be reduced while maintaining the mechanical strength and facilitating handling of a substrate and besides securing the long-term reliability without processing the substrate itself. The optical modulator module includes a substrate, an optical modulator including an optical waveguide, a signal electrode, and a ground electrode, and a housing in and to which the optical modulator is accommodated and secured. The shape of a longitudinal section of the other portion of the optical modulator module than the substrate is asymmetrical with respect to a perpendicular line with which the portion of the signal electrode which extends in parallel to the optical waveguide is bisected in the longitudinal direction.

Optical modulator module and optical modulator

The present invention aims at providing a connecting method of optical devices capable of suppressing a periodic wavelength dependence loss and the like, due to the inter-polarization-mode interference caused when connecting a plurality of optical devices by using an optical path having a polarization-preserving characteristic, and an optical apparatus applied with the connecting method. To this end, the connecting method according to the present invention, is to connect a plurality of optical devices to one another by using an optical path of polarization-preserving type having optical characteristics in which a light is propagated along two different polarization axes for substantially equal distances. Thus, even if the polarization direction of the light input/output to/from the respective optical devices is not completely coincident with the direction of the polarization axis of the optical path, it is possible to offset the periodic wavelength dependence loss and the like caused by the inter-polarization-mode interference in the optical path, to be suppressed.

Growing community of inventors

Kawasaki, Japan

Tadao Nakazawa