Nippon Telegraph and Telephone Corporation

Ntt Electronics Corporation

Masayuki Okuno

Takashi Goh

Akira Himeno

Shinji Mino

Motohaya Ishii

Takashi Yamada

Takeshi Kitagawa

Shunichi Souma

Yasuyuki Inoue

Masao Kawachi

Kuniharu Kato

Mitsuru Nagano

Masahiro Yanagisawa

Makoto Abe

Takashi Saida

Yasufumi Yamada

Shunichi Soma

Yoshinori Hibino

Takao Kimura

Yasuaki Hashizume

Fumiaki Hanawa

Atsushi Murasawa

Takanori Ishikawa

Daisuke Ogawa

Katsumi Katoh

Masahiko Naito

Akihito Doi

Akira Nagai

Tetsuo Yoshizawa

Toru Maruno

Excess optical power in a waveguide device is appropriately terminated. According to one embodiment of the present invention, the waveguide device comprises a termination structure filled with a light blocking material for terminating light from the end section of a waveguide. This termination structure can be formed by forming a groove on an optical waveguide by removing the clad and core, and filling the inside of that groove with a material attenuating the intensity of the light (light blocking material). In this manner, light that enters into the termination structure is attenuated by the light blocking material, and influence on other optical devices as a crosstalk component can be suppressed. With such termination structure, not only the influence on optical devices integrated on the same substrate, but also the influence on other optical devices directly connected to that substrate can be suppressed.

Waveguide device and module

A planar optical waveguide including a clad layer, an optical waveguide having a core embedded in the clad layer; and a groove formed in the clad layer and having a reflection interface for totally reflecting a leaked light leaked from the optical waveguide to the clad layer. Since the reflection interface for totally reflecting the leaked light is formed in the clad layer, the leaked light is prevented from entering into the tap coupler, and the variation of the branching ratio can be reduced.

Planar optical waveguide

An optical module controls its output characteristics electrically and an optical switch constitutes the optical module. An optical waveguide circuit (PLC) and an electronic circuit (IC) for driving the PLC are mounted on the same substrate. The IC is composed of a bare chip to be molded afterward. Wiring of the IC is grouped and integrated on the PLC substrate to achieve higher density and miniaturization of the optical module.

Optical module and optical switch

Optical module and optical switch constituting the same

An optical module controls its output characteristics electrically and an optical switch constitutes an optical module. An optical waveguide circuit (PLC) and an electronic circuit (IC) for driving the PLC are mounted on the same substrate. The IC is composed of a bare chip to be molded afterward. Wiring of the IC is grouped and integrated on the PLC substrate to achieve higher density and miniaturization of the optical module.

An interferometer includes a waveguide core, and thin film heaters with widths W and W . The thin film heaters are mounted directly above the waveguide core, and operate as two types of different annealing regions. The annealing, which is carried out by supplying current to the thin film heaters, can alter the quality of the cladding, and change the stress applied on the waveguide core, thereby making it possible to control the polarization dependency. Thus changing the width of the thin film heaters and/or the amount of the supply current thereto enables the permanent control of the effective refractive index (birefringence index) independently in the transverse electric polarization mode and the transverse magnetic polarization mode. This enables the transverse electric polarization mode to be adjusted to a phase difference of &lgr;/2, and the transverse magnetic polarization mode to a phase difference of zero.

Interferometer and its fabrication method

A no polarization dependent waveguide type optical circuit can resolve polarization dependency completely and can reduce reflected return light. An intermediate portion of the two connecting waveguides are formed with S-shaped waveguides of the same shape consisted of respectively two curved waveguides or two curved waveguides and straight waveguides connecting the curved waveguides. One polarization mode converter is provided in a groove formed across the S-shaped waveguide, and a perpendicular line to an incident surface of light of the polarization mode converter and the S-shaped waveguide forms an angle greater than 0&deg;.

No polarization dependent waveguide type optical circuit

A guided-wave circuit module includes a guided-wave circuit chip having an input waveguide part and an output waveguide part at the ends thereof, a guided-wave circuit part having a predetermined function and positioned between the input waveguide part and the output waveguide part; and a holder for supporting the guided-wave circuit chip, wherein the guided-wave circuit part of the guided-wave circuit chip does not come in contact with the chip holder; at least part of the input and output waveguide parts of the guided-wave circuit chip is fixed to the holder with a fixing agent; and the packaged chip does not have a warp which leads to deterioration of characteristics. A fixing agent having a high hardness is applied to the periphery of the endfaces of the input and output waveguide parts of the guided-wave circuit module and to the periphery of the fiber endfaces of the optical fiber array connected to the module. Therefore, these endfaces can accurately be polished and the waveguide can be connected to the optical fibers at a sufficiently low fiber connection loss and a high return loss.

Guided-wave circuit module and wave-guiding optical component equipped

A waveguide-type optical matrix switch including as its switching element a Mach-Zehnder interferometer which includes two directional couplers and an optical phase shifter. The two directional couplers are arranged by placing two optical waveguides in close proximity at two positions on a substrate, and have an identical coupling ratio. The optical phase shifter is disposed over at least one of the two optical waveguides between the directional couplers. The two optical waveguides have an effective optical path length difference of half a wavelength of a light signal between the two directional couplers, and are intersected in the optical switch element. The waveguide-type optical matrix switch is little affected by fabrication errors in the coupling ratio of the directional couplers, and superior in the extinction ratio.

Waveguide-type optical matrix switch

A method for adjusting a characteristic of a guided-wave optical circuit which includes one or more waveguides formed by a substrate, a cladding layer formed on the substrate, and a core portion having one or more cores embedded in the cladding layer. The method is carried out by producing a reversible thermal hysteresis phenomenon, after the clading layer and core portion have been formed. The thermal hysteresis phenomenon is produced in a thermal hysteresis produced region preselected so as to include at least a portion of the cladding layer and/or the core portion, thereby adjusting a refractive index difference between the cladding layer and the core portion. To produce a reversible thermal hysteresis phenomenon, the following steps are carried out: raising the temperature of the thermal hysteresis produced region to a predetermined temperature; maintaining the predetermined temperature of the thermal hysteresis produced region for a predetermined time period; and cooling the thermal hysteresis produced region at a predetermined cooling rate. At least one of the values of the predetermined temperature, predetermined time period, and predetermined cooling rate is controlled so that the refractive index difference between the cladding layer and the core portion is adjusted to a desired value, thereby adjusting the characteristic of the guided-wave optical circuit.

Guided-wave optical circuit and method for adjusting a characteristic

Growing community of inventors

Hitachinaka, Japan

Masayuki Okuno