高橋 浩

JGN II光テストベッドの敷設光ファイバを用いて6.25GHz間隔, 126km, 1046チャネル×2.67Gb/s伝送に成功した. スーパーコンティニウム光源を用いることで1000以上の光キャリアを一括して発生させた. また伝送光ファイバにおける四光波混合の影響を評価し1000チャネルWDM伝送における伝送光ファイバへの入射パワー条件を明らかにした. さらに累積クロストークを考慮したときのMUX/DEMUXへの要求性能を明確にした.

Over 1000-channel DWDM transmission experiment has been achieved. A 1046 x 2.67 Gbit/s, 6.25 GHz-spaced DWDM signal is successfully transmitted over 126 kin field-installed fibres in the test-bed of JGN II by employing a single supercontinuum lightwave source, which generates more than 1000 carriers and uniform precise channel spacing of 6.25 GHz.

Over 1000-channel DWDM transmission experiment has been achieved. A 1046 x 2.67 Gbit/s, 6.25 GHz-spaced DWDM signal is successfully transmitted over 126 kin field-installed fibres in the test-bed of JGN II by employing a single supercontinuum lightwave source, which generates more than 1000 carriers and uniform precise channel spacing of 6.25 GHz.

We have realized a novel Mach-Zehnder interferometer (MZI) thermo-optic switch that can operate over a much wider wavelength range than a conventional MZI switch. We constructed the novel MZI switch by incorporating a phase-generating coupler (PGC) as an optical coupler. The PGC generates a nonlinear wavelength-dependent phase, which functions as a virtual wavelength-dependent delay part that cancels out the wavelength dependence of a MZI. We fabricated the novel MZI switch on a silica-based planar fight-wave circuit and achieved a low insertion loss of less than 1.6 dB and a high extinction ratio of 30 dB over a wide wavelength range of 160 nm. (C) 2005 Optical Society of America.

We propose a new way for designing optical waveguides with the optimum shape. This approach is called the wavefront matching method and we describe its fundamental aspects and report some experimental results. © 2005 IEEE.

We review recent progress on optical switches that employ silica-based planar lightwave circuits (PLC) including a 16 x 16 matrix switch, a 1 x 128 switch, an 8-channel 1 x 8 switch array, and a 32-channel 2 x 2 switch array. These switches are composed of silica-based waveguides and have a solid-state structure with no moving parts, thus they exhibit low insertion loss, high repeatability, and excellent long-term reliability. We also describe IC-on-PLC technology, where IC chips are integrated on the PLC surface for higher functionality and greater compactness. We report the results of reliability tests on the PLC switches, and show that they can put to practical use.

We propose and fabricate planar waveguide type optical tweezers that use arrayed waveguide gratings as waveguide lenses. We confirm in experiments that the proposed tweezers can manipulate several particles simultaneously without mechanical movable parts. (c) 2004 Optical Society of America.

We use our recently proposed wavefront matching method to design waveguide lenses with modulated widths. We fabricated a waveguide lens pair in a silica waveguide, and confirmed its operational principle experimentally. (c) 2005 Optical Society of America.

We report experimental results for small-angle waveguide crossings designed with our recently proposed wavefront matching method. We successfully obtained lower loss and crosstalk values than conventional straight waveguide crossings.

We propose a novel compact optical circuit arrangement for a matrix switch. The fabricated 8 x 8 silica-based PLC switch is half the size of a previously reported switch and exhibits an insertion loss as low as 2.5 dB.

We propose a new way for designing optical waveguides with the optimum shape. This approach is called the wavefront matching method and we describe its fundamental aspects and report some experimental results.

This paper presents a 10-Gb/s wireless link system that uses a 120-GHz-band sub-terahertz electro-magnetic waves. In the transmitter photonic techniques are used for generation, modulation, and emission of the sub-THz signals, while the receiver is composed of all-electronic devices using InP-HEMTs.

We review the athermalization techniques that have been proposed for AWGs and discuss the advantages and disadvantages provided by each approach. We then describe our recent progress on the design and fabrication of a silica-based athermal AWG with a 1.5%-Δ waveguide and report its compactness and excellent optical characteristics including its extremely low insertion loss.

A differential-phase-shift quantum key distribution experiment was carried out with a planar light-wave circuit (PLC) Mach-Zehnder interferometer. This scheme has two advantages: it requires no polarization control and has a high repetition frequency, provided that a stable interferometer is available. Stable polarization-insensitive operation was achieved with an interferometer fabricated by PLC technology. Raw key creation at a rate of 3076 bits/s with a 5.0% quantum bit-error rate was achieved over 20 km of fiber. The stability of the PLC interferometer was examined. (C) 2004 Optical Society of America.

We applied a super-multi-fiber PLC connector for connecting up to 64 ch to the board packaging of an 8 × 8 delivery and coupling switch (DC-SW) module with a fiber sheet. The DC-SW module is composed of plural PLCs and needs a large amount of fiber crossing. The PLC connector can attach fibers to and remove them from a PLC endface and realizes a PLC receptacle module instead of a PLC pigtail module. The fiber sheet resolves the problem of fiber congestion. We demonstrate the smart optical fiber wiring and board packaging of a DC-SW whose optical performance matches that of a conventional switch in which the pigtail fibers of the PLC modules are fusion spliced and squeezed into a package.

A low loss wavelength-selective switch is proposed and demonstrated. The switch has a 1 x 4 transversal filter configuration that includes arrayed waveguide gratings and thermooptic phase shifters, and can route arbitrary wavelength input light to arbitrary outputs with no loss variation. We confirmed its operating principle and obtained an average loss of 2.7 dB and a worst extinction ratio of more than 20 dB.

トランスバーサルフィルタ回路構成による1xN空間光スイッチにAWGを組み込んだ空間・波長選択光スイッチについて報告する.石英系PLC上の熱光学効果を適用する場合は,本構成によるスイッチは,消費電力が出力選択によらず一定になる特徴を有し,AWGやLDなどの温度依存性のデバイスとの集積性に適するという利点を有する.今回,我々は4出力の光スイッチおよび5波長-4出力の波長選択スイッチを試作し,動作原理を確認するとともに,消光比20dB程度の良好な特性を得た.出力数もしくは波長数を増やすことは可能であり,今後波長ルータヘの応用が期待される.

光遅延線と光カプラより構成される干渉回路は光信号処理回路の基本要素として広く用いられている.しかし,その透過スペクトルは原理的に光周波数軸上で等間隔の周斯性を持つため,波長軸上で等間隔のチャネル配置を有するCWDM等のシステムに適用できなかった.今回,光カプラの出力の位相差に波長依存性を持たせることにより,波長軸上で等間隔なスペクトル特性を有する干渉回路を実現できることを示す.最も簡単な干渉回路の例としてマッハツェンダ干渉計(MZI)に本手法を適用し,良好な実験結果を得たので報告する.

Pulse waveform shaping with a silica-waveguide-based circuit employing an arrayed-waveguide grating pair and an array of amplitude and phase controllers is demonstrated. The frequency components of a modelocked laser have been flexibly synthesised to produce 40 GHz square pulses with various widths.

We have realized a first optical filter composed of optical delay lines and couplers that has a periodic response with respect to wavelength, whereas a conventional optical filter is known to have a periodic response to relative optical frequency. This new filter can be constructed by using a phase-generating coupler (PGC) that supplies the optical delay lines with a wavelength-dependent nonlinear phase. The PGC, which is also composed of optical delay lines and couplers, can simultaneously provide a desired phase and an arbitrary amplitude coupling ratio. We applied our transformation method to a conventional Mach-Zehnder interferometer (MZI) as an-example of an-optical frequency filter and converted it to an optical wavelength filter. We fabricated the designed MZI on a silica-based planar lightwave circuit and successfully realized what is believed to be the first MZI with a uniform wavelength period. (C) 2004 Optical Society of America.

We demonstrate the generation of 90-125 GHz inillimeter-wave signal with a phase noise of less than -75 dBc/Hz at 100 Hz; by using optical heterodyning that employs an arrayed-waveguide grating (AWG) integrated with 3-dB combiners.

石英系平面光波回路(PLC)技術を用いた光スイッチは、低損失で集積性と信頼性に優れ、光スイッチングシステムを構築する上で最も有望なデバイスの一つである。今回、光アドドロップ(OADM)システムヘの適用を目指した集積型32連2x2スイッチを実現した。本スイッチには、OADMシステムに適した新しい回路構成や集積度を高めるための低消費電力技術が投入されており、小型なチップ上に32アレイの集積を可能とした一方、極めて良好な光学特性を得たので報告する。

石英系平面光波回路(PLC)技術を用いた光スイッチは、低損失で集積性と信頼性に優れ、光スイッチングシステムを構築する上で最も有望なデバイスの一つである。今回、光アドドロップ(OADM)システムヘの適用を目指した集積型32連2x2スイッチを実現した。本スイッチには、OADMシステムに適した新しい回路構成や集積度を高めるための低消費電力技術が投入されており、小型なチップ上に32アレイの集積を可能とした一方、極めて良好な光学特性を得たので報告する。

A novel optical bandpass filter is proposed that consists of an arrayed-waveguide grating pair and an optical slit. A 200 GHz cyclic and 40 GHz passband optical filter using the proposed configuration, which is useful for WDM single sideband filtering, is successfully demonstrated.

AWG (arrayed-waveguide erating)型の波長合分波器は,大容量WDMシステムのキーデバイスとして注目されている.また,石英系ガラス導波路を用いて作製すると,低損失,高信頼性などの優れた特性を有し,既に商用のWDMシステムに導入されている.本論文では,AWGの原理,基本特性,技術改良点,応用回路について論ずる.具体的には,回折の基本式,スペクトル形状,石英系導波路作製方法,チャネル数拡大,低損失化,偏波無依存化,分散特性及び分散補償器,集積化デバイスについて,最近の実験結果を具体的に示してその進展について述べる.

石英系アレイ導波路回折格子(AWG)はWDMシステム用波長合分波器として基幹系光通信システムに広く使われており,高性能化や大規模化の研究開発が盛んに行われている.最近は, WDM方式のメトロ,アクセス 系への適用も検討され,低コスト化の要求が更に高まっている,そこで我々は,低コスト化に適した偏波無依存化技術として,導波路構造を調整してコア内応力の非対称性を制御し偏波依存性を解消する方法について検討した.今回,応力解析により偏波依存性の導波路構造依存性を明らかにするとともに,本構造を石英系AWGに適用して偏波無依存化の効果を実験的に検証したので報告する.

石英系ガラス導波路を用いた平面光波回路型の光スイッチは集積性・信頼性に優れており、大規模の光スイッチングシステムを構築する上で有用なデバイスである。本報では、スイッチ素子の構造、デバイスの設計について述べるとともに、スイッチ素子の性能向上を図る最近の技術について説明する。また、応用例として、16×16マトリクススイッチ、1×128分岐スイッチ、8連1×8スイッチ、8×8DCスイッチ等の実際の動作特性についても述べる。

我々がこれまで開発を進めてきたフォトニックMPLSルータの波長ラベルスイッチ部(光クロスコネクト部)には、機能集積性・信頼性に優れる平面光波回路型スイッチ(PLC- SW)を用いている。今回、高集積化が進んだPLC- SWデバイスを用いて光スイッチ実装部の機能高集積実装を行った。本報告では、まず、実用レベルに達している光クロスコネクト部について簡単に述べた後、今回開発した光スイッチ実装部の構成及びその特性について述べる。また、PLC光スイッチ実装部のパッケージレベルでの信頼性試験(テルコデイア規格GR-63相当)について、良好な結果を確認したので報告する。

An optical switch based on a transversal filter configuration is demonstrated. The switch consists of cascaded 3 dB optical power splitters and a phase shifter array. By using a silica-based planar lightwave circuit, a 1 x 4 optical switch was realised. A characteristic of the switch is that its power consumption is constant regardless of the output selection.

WDMネットり一クシステムの大容量化・高度化のためには、光クロスコネクトや光アドドロップ多重技術が不可欠であり、光スイッチはその中核部品の一つとして注目を集めている。我々が開発を進めてきた石英系PLC光スイッチは、優れた光学特性を有し、実用化に近いスイッチである。ここでは、8連2x2および8連1x8のスイッチモジュールについてTelcordia規格に準じる試験を行い、十分な機械的強度と長期信頼性を有することを確認したので報告する。

石英系平面光波回路(PLC)を用いた光スイッチ(PLC-SW)は,低損失かつ長期安定性に優れ,光クロスコネクトシステムなどWDM光波ネットワークにおいて使用する光スイッチデバイスとして有望な素子の一つである.PLC-SWはアーム部に薄膜ヒータを装荷したマッハ・ツェンダー干渉計を基本素子として熱光学効果によって光路切り替えを行う導波路型デバイスである.近年,ネットワーク多チャネル化の要求に対応すべく,デバイスの小型化・大規模化の必要性が高まっており,それに伴って消費電力低減も重要な課題となっている.本稿では,PLC-SWにおいて超高Δ導波路および断熱溝構造を採用した光スイッチを提案し,スイッチ素子単体の大きさを従来の1/3,消費電力も従来の1/10まで低減できることを明らかにするとともに,本構造をIxN光スイッチに適用し,その実用性についても確認したので報告する.

Silica-based planar lightwave circuits (PLC) are key components of functional devices designed for use in optical fiber communication systems because, compared with bulk optics devices, they offer compactness, excellent stability and reliability in addition to high functionality. This talk reviews the current status of PLC development. The fabrication process, basic characteristics, packaging and reliability are. presented, many device applications are described, and experimental results related to optical switches, interleave filters, chromatic/polarization dispersion compensators, gain spectrum equalizers and wavelength multiplexers are reported. Finally, the history of PLC development is summarized, and future target devices are described along with the kind of development needed for such devices designed for use in the next generation of optical communication systems.

本稿では石英系ガラス導波路からなるマッハツェンダー干渉計の構造および回路構成の最適化を行うことで、導波路の光路長と方向性結合器の結合率に作製ばらつきが生じても、消光比の高い光スイッチが得られることを示す。具体的にこの設計法を8連1×8スイッチに適用して作製・評価を行い、作製後の光路長調整なしで十分な消光比(平均値56dB)が得られ、また環境温度依存性の考察も行い、広い温度範囲においても特性を維持できることを示す。

A novel method of flattening the passband of an arrayed waveguide grating with a small excess loss, which employs a new concept that uses the assist of the weak first-order mode, is described. A 16-channel 100 GHz-spacing demultiplexer with a fibre-to-fibre loss of less than 3.6 dB and a flattened excess loss of 1.85 dB is demonstrated. The I dB down passband is widened 2.2 times.

A novel method of flattening the passband of an arrayed waveguide grating with a small excess loss, which employs a new concept that uses the assist of the weak first-order mode, is described. A 16-channel 100 GHz-spacing demultiplexer with a fibre-to-fibre loss of less than 3.6 dB and a flattened excess loss of 1.85 dB is demonstrated. The I dB down passband is widened 2.2 times.