先端超高周波情報工学 ( 博士後期課程 ) 先端超高速情報工学 ( 留学生特別コース） Advanced High-Speed Communication Engineering Hirohito Yamada Optical devices and integrated optical circuits for photonic network applications Lecture: July 26, 2012

Self-intoroduction Hirohito Yamada 1987Graduated from Dep. of Electronics, Graduate School of Eng.,Tohoku Univ. Doctor Engineering in study of surface emitting laser diodes 1987 – 1997 Research Laboratories, NEC Corp. Research and development of laser diodes for optical communications 1997 – 1998 Physical Sciences, NEC Research Institute, Inc., Princeton, NJ Research of wavelength tunable lasers with photorefractive materials 1998 – 2006 Research Laboratories, NEC Corp. Research of photonic crystal and Si-wire waveguide devices 2006 –Graduate School of Engineering, Tohoku University Education in Department of Electrical and Communication Engineering Research of Si photonic devices for optical communications

Lecture contents Purpose of this lecture: - To understand background of requiring photonic network - To think about future photonic network systems - To study optical devices and integrated optical circuits Lecture contents: - Background of requiring high capacity optical network - Photonic network and photonic node - Optical devices and integrated optical circuits for photonic network Lecture slide can be downloaded from: Any questions:

Background of requiring high-speed network

Total amount of domestic internet download traffic: 1.7Tbps(end of 2011) Increasing trend of domestic network traffic 出典 : H24 年度版情報通信白書 Total domestic internet download traffic Total domestic internet upload traffic Annual growth rate: 40% year

Number of broadband subscriber is over 39 million at the end of 2011 FTTH(fiber to the home): 22.3 million which is10.3% increase over the previous year Number of domestic broadband subscriber FWA: Fixed Wireless Access BWA: Broadband Wireless Access), WiMAX etc. 3.9G: 3.9 generation mobile communication systems, LTE, mobile WiMAX, UMB etc. Cited from: H24 年度版情報通信白書

Spreading application range of optical communication Rack to rack → Board to board → Chip to chip → On chip interconnection Cited from: C. Gunn, “CMOS Photonics™ Technology Enabling Optical Interconnects” Luxtera, Inc. Light Peak Infiniband DDR(20Gbps)AWG24 Up to 20m Active optical cable (AOC) Up to 100m

Spreading application range of optical communication Storage Area Network(SAN) with Active Optical Cable(AOC) Bus interface for the SONY VAIO ZBackplane of a server Universal Bus Interface for PC Light Peak

On chip optical interconnection for LSI Global interconnection Local interconnection Transistor layer - High speed - Low power consumption - Low noise Optical interconnection Cross-section of LSI chip (Intel) 130nm 6-layer cupper wire - Clock frequency - Power consumption - Noise problem Emerging performance limit of LSI Performance limit of electrical interconnection Many core architecture Optical interconnection Electrical interconnection

Developing history of optical-link capacity Developing history of optical-link capacity in Japan 2 nd generation using WDM and Optical Amp. (Optical method) F-32M F-100M F-400M ,000 10,000 FS-400M F-600M F-2.4G F-1.6G F-1.8G FA-10G FA-2.4GFSA-2.4G new F-600M F-6M Year Transmission capacity (Gbit/s) WDM System With optical amplifier SDH System With dispersion shifted optical fiber With DFB-LD With single-mode fiber Commercial system ETDM WDM + ETDM Laboratory ETDM WDM + ETDM OTDM WDM + OTDM 1.6T (40G × 40) 1 st generation with ETDM, EFDM (Electrical method) 3 rd

Multiplexing for high capacity optical link Electrical multiplexing - Electrical time-division multiplexing(ETDM) - Electrical frequency-division multiplexing(EFDM) Up to 100Gbps, limited by response speed of electronics Optical multiplexing - Wavelength division multiplexing(WDM) More than 10Tbps transmission (40Gbps×273 wave ＝ 10.9Tbps, 117km) have been demonstrated in 2001 Using many different wavelength as different channel λ1λ1 λ2λ2 λ3λ3 λ4λ4 λ5λ5 λ6λ6 λ7λ7 λ1λ1 λ2λ2 λ3λ3 λ4λ4 λ5λ5 λ6λ6 λ7λ7 WDM transmission Digital coherent optical transmission Multilevel modulation ‥‥ QAM, DPSK/DQPSK/DP-QPSK etc. Code multiplexing → 1 st generation → 2 nd generation → 3 rd generation

Multiplexing for high capacity optical link 1000 core fiber cable Thin peace of a optical fiber: ϕ = 1 25  m Many fibers can be placed in a cable Spatial multiplexing Multi core fiber 305Tbps(172Gbps×100 wavelength×19 core) transmission with multi core fiber (Press released from NICT, Furukawa Electric Co., Ltd and Optoquest Co.,Ltd on Mar. 2012) - Space division multiplexing Cross section of 19 core fiber (Furukawa Electric Co., Ltd) Each core transmit different signal → 4 th generation

Optical network Photo diode Optical signal Electrical signal Laser diode Laser diode Header analysys Optical devices Electron devices Optical modulator Optical modulator Laser diode Optical modulator Electronic switch Label detection Optical(O) – Electrical(E) – Optical(O) Buffer memory Optical link (optical fiber) node (router) node (router) Construction of router

Processing speed bottleneck in each node Optical link (optical fiber) node (router) node (router) Tollgate Expressway Link capacity: 10Tbps (40Gbps × 256 wave WDM) Processing speed: 100Gbps Traffic jam

Resolving bottleneck by photonic network node (router) ETC system Optical link (optical fiber) node (router) Link capacity: 10Tbps (40Gbps × 256 wave WDM) Processing speed: 100Gbps Expressway

What is photonic network Next generation network routing optical signal without OE/EO conversion (OE/EO: optical → electrical / electrical → optical) OPS router Mesh-type NW OPS router OADM(Optical Add/Drop Multiplexer) WDM ring NW OADM OXC WDM ring NW OADM OBS(Optical Burst Switching) OXC(Optical cross connect) WDM ring-type network WDM mesh-type network OPS(Optical Packet Switching) Photonic MPLS(Multi-Protocol Label Switching)

Switching method Circuit switching Packet switching ex) telephone ex) data communication, Internet Circuit switch One line is exclusively used by end-to-end One line is shared by all user Packet switch LabelData

Packet switching Each packet has a label which inform destination address of data Packet switch labelPort Routing table ① ① ② ③ ④ ⑤ ⑥ ② ③ ④ ⑤ ⑥ labelPort Routing table ① ② ③ ④ ⑤ ⑥ 3 4 Packet switch outputs each packet at any port based on routing table Every data is divided by a unit of packet Routing table is made by the address information

Wavelength Router DEMUXMUX DEMUX Port 1 Port 2 Port 3 Port 4 Port 5 Port 6 Port 7 Port 8 Output port can be switched by changing wavelength MUX

Arrayed waveguide grating(AWG) 50 mm Arrayed Waveguide Grating (AWG) SiO 2 core SiO 2 clad Si substrate 0.5  m Made of silica waveguide N × N wavelength router can be constructed by an N × N AWG AWG made by Si-wire waveguide 50  m Size 1/1000 λ 1, λ 2, λ 3, …, λ N λ 2, λ 3, λ 4, …, λ 1 λ 3, λ 4, λ 5, …, λ 2 λ N, λ 1, λ 2, …, λ N-1 Extremely small AWG can be realized by Si-wire waveguide

Si-wire waveguide Si core 0.3  m Structure of Si-wire waveguide - Strong optical confinement in core Ultra high-∆ channel waveguide with nano-meter size Si-core and silica cladding SEM photograph of the cross section Attractive platform for realizing high-density optical interconnection - Small bending curvature: R< 5 μm Si substrate SiO 2 Si core 0.3  m

Thermo-optic switch with Si-wire waveguide T. Chu et al., Optics Express 13, (2005) Electrode Microheaters Si-wire waveguide Switching characteristics T. Chu et al., Proc. SPIE 6477 (2007) Photograph of the 1×8 switch Footprint size: 4 mm×2 mm Port1 Port2 Port8

Optical Add/Drop Multiplexer(OADM) R-OADM (Reconfigurable OADM) Certain wavelength signal can be dropped out or added in OADM 1 ‥‥ n i i WDM signal Add/Drop wavelength can be settable OADM 1 ‥‥ n i i WDM signal OADM WDM ring NW OADM WDM ring NW OADM

R-OADM made of Si-wire waveguide - Wavelength tuning by T-O effect - Wavelength tuning range: 6.6 nm - Channel switching time: < 100 μsec Wavelength tuning characteristicsDemultiplexing characteristics T. Chu et al., IEEE Photon. Technol. Lett. 18, 1409 (2006)

Tunable wavelength laser Tunable laser with ring resonator

Function and construction of OPS node Routing control ‥‥ Producing routing table Label processing ‥‥ Reading label information and deciding output port based on routing table Switching ‥‥ Switching output port of packet Packet Scheduling ‥ ‥ Controlling output timing to avoid packet collision Buffering ‥‥ Keeping data waiting a while for the timing of output DateLabel Routing (Producing routing table) Label processing (Deciding output port) Switching (Switching output port) Scheduling (Packet collision control) Buffering (waiting data output) Output

Optical label processing t Data Color label Optical fiber grating t Data Matching of label and grating pattern Circulator Missmatching

Optical Buffer 1. Based on Optical Delay Line and Optical Switch 2. Based on Slow Light Electromagnetically Induced Transparency(EIT) 300,000km/s → 28m/s 0.9μK(-273 ℃ ) Natrium (Na) 70 ～ 90K(-203 ～ -183 ℃ ) Rubidium (Rb) 300,000km/s → 1km/s optical switch optical delay line |1> |3> |2> coupling probe probe frequency absorption transmittance

Integrated Optical Circuit Integrating various micro photonic devices Photonic Network Photonic node Integrated optical circuit Optical switchSi waveguideMUX/DEMUX Micro photonic devices for optical network Photonic network Resonator

Reporting Assignment Describe your idea of the future network which can solve problems of explosion of network traffic, and what can we do for enjoying comfortable and ecological network life. Format: Word or PDF File Submission to Deadline: 3 rd August