Nippon Telegraph and Telephone Corporation

Ntt Electronics Corporation

Tsutomu Kitoh

Hiroshi Takahashi

Hiroshi Yamazaki

Toshikazu Hashimoto

Manabu Oguma

Yohei Sakamaki

Masahiro Yanagisawa

Takashi Saida

Senichi Suzuki

Takayuki Mizuno

Yasuyuki Inoue

Yasuhiro Hida

Shin Kamei

Motohaya Ishii

Yoshinori Hibino

Munehisa Tamura

Mikitaka Itoh

Tomohiro Shibata

Ikuo Ogawa

Kaname Jinguji

Kenichi Suzuki

Toshio Watanabe

Masaru Kobayashi

Masamichi Fujiwara

Takuya Tanaka

Takashi Goh

Hiromasa Tanobe

Hirotaka Nakamura

Shinya Tamaki

Shunji Kimura

Yoshiteru Abe

Akira Himeno

Akimasa Kaneko

Shuichiro Asakawa

Takeshi Kitagawa

Shunichi Souma

Ryou Nagase

Naoto Yoshimoto

Takaharu Ohyama

Masaki Koutoku

Masaki Kohtoku

Mikitaka Ito

The present invention relates to an optical coupling/splitting device that realizes the splitting of a down-signal and the coupling of up-signals by the same optical device, and reduces coupling losses of the up-signal. An optical coupling/splitting device in the present invention comprises an optical coupling/splitting means for coupling a plurality of up-signals in a multi-mode for output and splitting a down-signal in a single mode for output, and a two-way optical propagation means for propagating the up-signal that is output from the optical coupling/splitting means in a multi-mode for output and propagate the down-signal in a single mode to be output to the optical coupling/splitting means.

Optical coupling/splitting device, two-way optical propagation device, and optical-transmit-receive system

An arrayed waveguide grating provided with a first slab waveguide formed on a substrate; a second slab waveguide formed on the substrate; a first input/output waveguide connected to the first slab waveguide; a second input/output waveguide connected to the second slab waveguide; two or more channel waveguide groups connecting the first and second slab waveguides, each of the channel waveguide groups formed of an aggregate of a plurality of channel waveguides having path lengths sequentially becoming longer by a predetermined path length difference; and an optical filter arranged in at least one of the first and second slab waveguides.

Arrayed waveguide grating, optical module provided with said arrayed waveguide grating, and optical communications system

A interferometer type polarization beam combiner and splitter, which can combine or split polarized light over a wide band, is provided. The interferometer type polarization beam combiner and splitter includes: an optical splitter; an optical coupler; an optical path length difference imparting unit, which includes a plurality of optical waveguides arranged between the optical splitting unit and the optical coupling unit; one or two input/output ports connected to the optical splitter; and two input/output ports connected to the optical coupler. A half-integer of a wavelength of &#x3bb;c is set as a normalized phase difference, for the optical path length difference imparting unit, between two polarization states, and means for generating a difference in refractive index dispersion is provided between the optical waveguides of the optical path length difference imparting unit, so that the change rate of the transmittance with respect to wavelength is suppressed for the two polarization states.

Wideband interferometer type polarization light beam combiner and splitter

An optical wavelength multi/demultiplexer having transmission characteristics with a higher rectangular degree than a conventional one includes an AWG and two-stage lattice circuit. An example of a two-stage lattice circuit according to the present invention includes an input waveguide, a third optical coupler, a third and fourth arm waveguides, a second optical coupler, a first and second arm waveguides, a first optical coupler, and output waveguides. The optical path length differences between the third and fourth arm waveguides and between the first and second arm waveguides are designed to be &#x394;L. The path passing the third and first arm waveguides differs by 2&#xb7;&#x394;L in optical length from that the fourth and second arm waveguides. The paths passing the third and second arm waveguides and passing the fourth and first arm waveguides differ by &#x394;L from that passing the fourth and second arm waveguides.

Optical wavelength multi/demultiplexer

A planar lightwave circuit is provided which can be easily fabricated by an existing planar-lightwave-circuit fabrication process, which can lower the propagation loss of signal light and which can convert inputted signal light so as to derive desired signal light. A planar lightwave circuit having a core and a clad which are formed on a substrate, has input optical waveguide(s) () which inputs signal light, mode coupling part () for coupling a fundamental mode of the inputted signal light to a higher-order mode and/or a radiation mode, or mode re-coupling part () for re-coupling the higher-order mode and/or the radiation mode to the fundamental mode, and output optical waveguide(s) () which outputs signal light. The mode coupling part or the mode re-coupling part is an optical waveguide which has core width and/or height varied continuously.

Planar lightwave circuit, design method for wave propagation circuit, and computer program

When a conventional synchronized AWG is employed to extend a transmission passband, an increase in loss near the optical center frequency can not be avoided. Because of passband width limit, a problem has existed in that the synchronized AWG could not be applied for a large, complicated communication system wherein a signal light passes a number of points. Therefore, an optical wavelength multiplexing/demultiplexing circuit of the present invention is a synchronized AWG, which includes an optical splitter arranged in an interference circuit that is connected on the side of one slab waveguide. The splitting ratio of the optical splitter varies, depending on the optical frequency, and the value becomes minimum near the optical center frequency of the synchronized AWG. The optical splitter is operated so that the splitting ratio is comparatively great at optical frequencies distant from the optical center frequency.

Optical wavelength multiplexing/demultiplexing circuit, optical module using optical wavelength multiplexing/demultiplexing circuit, and communication system

An optical wavelength multiplexing/de-multiplexing circuit having a low loss and a flat transmission spectrum is provided. The optical wavelength multiplexing/de-multiplexing circuit compensates a temperature dependence of a center transmission wavelength which remains in an athermal AWG, and has an excellent accuracy of the center transmission wavelength in a whole operating temperature range or has a comparatively wide operable temperature range. The temperature dependence of the transmission wavelength in the athermal MZI is modulated and set so as to cancel the temperature dependence of the center wavelength which remains in the athermal AWG. The present invention focuses particularly on an optical coupler in the MZI and modulates the temperature dependence of the transmission wavelength in the MZI by providing the optical coupler itself with a mechanism which changes a phase difference between two outputs by temperature.

Optical wavelength multiplexing/ de-multiplexing circuit

The present invention discloses an interferometer optical switch that can carry out switching over a broad band and has a high extinction ratio and large fabrication tolerance. The interferometer optical switch employs a phase generating coupler, the phase difference of the output of which has wavelength dependence, as at least one of the optical multi/demultiplexing device included in the interferometer optical switch. A wavelength insensitive interferometer optical switch is implemented by making the sum 2&#x3c0;{&#x3c6;(&#x3bb;)+&#x3c6;&#x394;(&#x3bb;)+&#x3c6;(&#x3bb;)} constant regardless of the wavelength, where &#x3c6;(&#x3bb;) is the phase produced by the first optical multi/demultiplexing device, 2&#x3c0;&#x3c6;&#x394;(&#x3bb;) is the phase difference of the optical delay line with an optical path length difference of &#x394;L, and 2&#x3c0;&#x3c6;(&#x3bb;) is the phase produced by the second optical multi/demultiplexing device.

Interferometer optical switch and variable optical attenuator

The present invention provides an optical functional circuit where a holographic wave propagation medium is applied and a circuit property is excellent such as small transmission loss and crosstalk. The optical functional circuit where a plurality of circuit elements are formed on a substrate includes the wave propagation medium for converting an optical path of a leakage light so that the leakage light that is not emitted from a predetermined output port of the circuit element is not coupled to a different circuit element. This wave propagation medium is constituted by an optical waveguide that is provided with a clad layer formed on the substrate and a core embedded in the clad layer, and a part of the optical waveguide is formed in accordance with a refractive index distribution which is multiple scattered.

Optical functional circuit

An arrayed waveguide grating type optical multiplexer/demultiplexer circuit in which wavelength dispersion is reduced. An input wave guide (), a first slab waveguide (), an arrayed waveguide (), a second slab waveguide () and an output waveguide () are connected sequentially. Furthermore, a parabola waveguide () is provided between the input waveguide () and the first slab waveguide (), and a taper waveguide () is provided between the second slab waveguide () and the output waveguide (). A parabola waveguide length Zexists in a range Z=Z=Zdetermined by a parabola waveguide length Zwhere the ratio of absolute amplitude between the main peak and the first side peak in the field distribution of far-field of the parabola waveguide () has an upper limit of 0.217, and a parabola waveguide length Zwhere the relative phase of the main peak and the first side peak in the field distribution of far-field has a lower limit of 3.14 radian.

Arrayed waveguide grating type optical multiplexer/demultiplexer circuit

A wave transmission medium includes an input port-and an output port-. A field distributionand a field distributionare obtained by numerical calculations. The field distributionis a field distribution of the propagation light (forward propagation light) launched into the input port-. The field distributionis a field distribution of the phase conjugate light (reverse propagation light) resulting from reversely transmitting from the output port side an output field that is expected to be output from the output port-when an optical signal is launched into the input port-. According to the field distributionsand, a spatial refractive index distribution is calculated such that the phase difference between the propagation light and reverse propagation light is eliminated at individual points (x, z) in the medium.

Wave transmission medium and waveguide circuit

An optical multi/demultiplexing circuit includes at least one phase generating optical coupler and an optical delay line coupled to the phase generating optical coupler. The phase generating optical coupler consists of at least one input and at least two outputs. At least one of the phase generating optical coupler has a wavelength dependent or frequency dependent output phase difference in the passband of the circuit so that it can change the transmittance characteristics of the optical multi/demultiplexing circuit.

Optical multi/demultiplexing circuit equipped with phase generating device

Growing community of inventors

Atsugi, Japan

Tsutomu Kitoh