Nec Corporation

Photonics Electronics Technology Research Association

Tdk Corporation

Fujitsu Corporation

Nippon Telegraph and Telephone Corporation

National Institute of Advanced Industrial Science and Technology

The University of Tokyo

Junichi Fujikata

Masafumi Nakada

Keishi Ohashi

Tsutomu Ishi

Kazuhiko Hayashi

Kunihiko Ishihara

Shigeru Mori

Nobuyuki Ishiwata

Jun Ushida

Daisuke Okamoto

Kiyokazu Nagahara

Shigeki Takahashi

Kenichi Nishi

Motofumi Saitoh

Toshio Baba

Akio Toda

Hidefumi Yamamoto

Mitsuru Takenaka

Kikuo Makita

Keishi Oohashi

Takahiro Nakamura

Toru Tatsumi

Tsuyoshi Horikawa

Tatsuya Usuki

Liang Ding

Keizo Kinoshita

Akihito Tanabe

Hitoshi Yokota

Hiroaki Honjo

Masahiko Mori

Tohru Mogami

Kazuhiro Shiba

Youichi Sakakibara

Tai Tsuchizawa

Toshihiro Kamei

Eizo Fukami

Shiyang Zhu

Ryohei Takei

Younghyun Kim

Seiichi Itabashi

Kivokazu Nagahara

Shigekazu Okumura

Ming-Bin Yu

Provided is an optical modulator which is small in optical loss, is small in a size, and is low in required voltage and is operable to perform high-speed operation. The optical phase modulatorcomprises a rib-type waveguide structureincluding: a PN junctionwhich is formed of Si and is formed in a lateral direction on a substrate; and an SiGelayerwhich is constituted of at least one layer and is doped with an impurity to a p-type and is superposed on the PN junctionso as to be electrically connected to the PN junction. The rib-type waveguide structurehas a substantially uniform structure along a light propagation direction, and in a direction parallel with the substrate and perpendicular to the light propagation direction, a position of a junction interfaceof the PN junctionis offset from a center of the SiGelayer

Optical modulator and method for manufacturing the same

An electro-absorption optical modulator capable of realizing optical coupling with a Si waveguide with high efficiency, improving modulation efficiency, reducing light absorption by an electrode layer and achieving low optical loss includes a substrate; a first silicon layer doped to exhibit a first type of conductivity and a second silicon layer doped to exhibit a second type of conductivity that are disposed parallel to the substrate; and a GeSi(0&#x3c;x&#x3c;1)/Si stack in which a GeSilayer and a Si layer are stacked on the first and second silicon layers in this order.

Electroab sorption optical modulator

Provided is a SIS-type electro-optic modulator capable of realizing highly efficient optical coupling with a rib-type Si waveguide, improving modulation efficiency, realizing reduction of electric capacity and lead-out resistance in stacked semiconductor layers. The modulator includes a SIS junction constituted by first and second semiconductor layers having different type of conductivity and a dielectric layer interposed therebetween, wherein an electrical signal from electrodes coupled to the first and second semiconductor layers causes free carriers accumulate, deplete or invert on both sides of the dielectric layer, thereby modulating a free carrier concentration felt by an optical signal electric filed, light having a polarization component orthogonal to the width direction of the SIS junction is incident on the dielectric layer, and the width of the SIS junction is &#x3bb;/nor less (&#x3bb; is the wavelength of the incident light and nis an effective refractive index of the modulator to the incident light).

Electro-optic modulator

Provided is an optical device in which an Si cap layer is provided on a Ge layer, and which is capable of effectively reducing dark current, while having a good effect on prevention of production line contamination by Ge. One embodiment of the optical device according to the present invention is provided with: a semiconductor layer which contains Ge and has a (001) surface and a facet surface between the (001) surface and a (110) surface; and a cap layer which is formed from Si, and which is formed on the (001) surface and the facet surface of the semiconductor layer. The ratio of the film thickness of the cap layer on the facet surface to the film thickness of the cap layer on the (001) surface is 0.4 or more; and the film thickness of the cap layer on the (001) surface is from 9 nm to 30 nm (inclusive).

Optical device

An electro-optic device includes a first semiconductor layer including the rib-type waveguide, which includes a rib part and a first slab part, which extends in a first direction from the rib part; a dielectric layer, which is formed on the rib part; a second semiconductor layer, which extends in a second direction, which is opposite to the first direction, from an upper surface of the dielectric layer; a first high-concentration impurity region, which is formed in the first semiconductor layer to be in contact with the first slab part on the first direction side; and a second high-concentration impurity region, which is formed in a region of the second semiconductor layer on the second direction side. The second high-concentration impurity region is formed in a region other than a region overlapping the first semiconductor layer in a lamination direction.

Electro-optic device

An optical phase modulatoraccording to an embodiment of this disclosure comprises a rib-type waveguide structurecomprising: a PN junctioncomprising Si and formed in a lateral direction on a substrate; and a SiGelayerthat is doped with a p-type impurity and comprises at least one layer laminated on the PN junction, so as to be electrically connected to the PN junction

Optical modulator and method of manufacturing same

An output monitoring method for an optical modulator includes: branching light into first and second lights; modulating a phase of the first light within a first waveguide; modulating a phase of the second light within a second waveguide; multiplexing the first and second lights to generate interference light, and outputting the interference light from first and second output ports; detecting a difference or ratio between a portion of the interference light from the first output port and a portion of the interference light from the second output port; and setting an operating point of light based on the detected difference or ratio; and controlling phase modulation of follow-on light that propagates through the first and second waveguides so as to keep the operating point constant.

Output monitoring method for optical modulator and output monitoring device

An optical end coupling type silicon optical integrated circuit is provided using an SOI substrate. This optical integrated circuit is constituted so as to connect with an external optical circuit at an end coupling part and have signal light incident to an optical circuit that includes a curved part. In the plane of the optical integrated circuit, the position of one end coupling part selected from among any thereof and the position of any multimode optical waveguide element to which a respective optical waveguide is connected via a respective curved part satisfy a positional relationship defined on the basis of a beam divergence angle [theta] of stray light.

Optical end coupling type silicon optical integrated circuit

An electro-optical modulator includes a substrate; an optical waveguide formed of a silicon-containing i-type amorphous semiconductoron the substrate; and a silicon-containing p-type semiconductor layerand a silicon-containing n-type semiconductor layerarranged apart from each other with the silicon-containing optical waveguide formed of an i-type amorphous semiconductorinterposed therebetween and constituting optical waveguides together with the silicon-containing optical waveguide formed of an i-type amorphous semiconductor. The silicon-containing p-type semiconductor layerand/or silicon-containing n-type semiconductor layerarea crystalline semiconductor layer.

Electro-optical modulator

Provided is a silicon-based electro-optic modulator which is small in size and capable of high speed operation. A first silicon semiconductor layer () doped to exhibit a first type of conductivity and a second semiconductor layer () doped to exhibit a second type of conductivity are at least partly stacked together, and a relatively thin dielectric () is formed at the interface between the stacked first and second silicon semiconductor layers (). The first silicon semiconductor layer () has a rib waveguide shape () comprising a rib portion () and slab portions (). A first heavily doped region () formed by a high concentration doping process is arranged at a location, in the first silicon semiconductor layer (), neighboring to each of the slab portions (). The first heavily doped region () has almost the same height as that of the rib portion () of the rib waveguide ().

Silicon-based electro-optic modulator

An optical receiver circuit has a function of converting a differential optical signal into a differential current signal. The optical receiver circuit has a pair of light-receiving elements including first and second light-receiving elements operable to convert an optical signal into a current signal and a pair of signal lines. An anode of the first light-receiving element and a cathode of the second light-receiving element are connected to a first signal line of the pair of signal lines via first and second AC coupling capacitors, respectively. A cathode of the first light-receiving element and an anode of the second light-receiving element are connected to a second signal line of the pair of signal lines via third and fourth AC coupling capacitors, respectively. Differential signal currents are generated in the first and second signal lines in response to reception of differential optical signals inputted into the first and second light-receiving elements.

Optical receiver circuit

An optical modulator includes an optical phase modulator which applies an operating voltage to at least one arm so as to modulate an optical phase of an optical signal transmitted via at least one arm and an optical phase adjuster which applies a voltage below the operating voltage to at least one arm so as to adjust an operating point. In the optical phase adjuster, an optical phase coarse adjuster applies a voltage below the operating voltage to at least one arm so as to change an optical phase of an optical signal by 180&#xb0; or more, while an optical phase fine adjuster applies a voltage below the operating voltage to at least one arm so as to changer an optical phase of an optical signal by 90&#xb0; or less. Thus, it is possible to automatically calibrate an operating point of an optical modulator with low power consumption.

Optical modulator and operating point control method

A waveguide-coupled MSM-type photodiode of the present invention comprises a structure in which a semiconductor light-absorbing layer and an optical waveguide core layer are adjacent and optically coupled to each other, has formed metal-semiconductor-metal (MSM) junctions which are arranged at an interval on the semiconductor light-absorbing layer, and is characterized in that of the MSM electrodes arranged at the interval, a voltage is set so that a reverse bias is applied to those MSM electrodes that are arranged on a light incidence side.

Waveguide-coupled MSM-type photodiode

In a region in which silicon semiconductor layers having first and second conductive types are stacked, a concavoconvex structure including a SiGe(x=0.01 to 0.9) layer is formed on a surface of the first silicon semiconductor layer, a relatively thin dielectric is formed on the concavoconvex structure, and a silicon semiconductor layer having the second conductive type is further stacked.

Silicon-based electro-optical device

An optical modulator includes a plurality of electrode pads arranged in a zigzag alignment; two arms which are partially bent to circumvent the electrode pads so as to carry out optical phase modulation at various parts based on voltages input via the electrode pads; an optical branch structure branching the arms; and an optical coupling structure aggregating the arms together. Each arm is made of a silicon-base electro-optic element including a substrate; a first conductive semiconductor layer having a rib waveguide structure; a dielectric layer deposited on the rib waveguide structure; and a second conductive semiconductor layer deposited on the dielectric layer. The first conductive semiconductor layer is connected to first electrode wires via first contacts, while the second conductive semiconductor layer is connected to second electrode wires via second contacts. Thus, it is possible to miniaturize the optical modulator which can operate at a low voltage.

Optical modulator and optical modulation device with zigzag electrode and waveguide arm alignment

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Tokyo, Japan

Junichi Fujikata