Optical routing Optical protection Optical networks WDM Optical

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광기술의 진보 Optical routing Optical protection Optical networks WDM Optical amplifier PON Singlemode-SDH Singlemode-PDH

광기술의 진보 Optical routing Optical protection Optical networks WDM Optical amplifier PON Singlemode-SDH Singlemode-PDH Fiber links Multimode-PDH '80 '85 '90 '95 2000 2005 Network Transparency

광통신망 발전 추세 Capacity / fiber(Gb/s) 1000 WDM노드 에 의한 광화 10 G x

광통신망 발전 추세 Capacity / fiber(Gb/s) 1000 WDM노드 에 의한 광화 10 G x 4 2. 5 G x 16 2. 5 G x 4 EDFA 10 G 100 10 광 네트워크 10 G x 16 40 G x 4 40 G 2. 4 G GII 1. 6 G 고속인터넷 CATV 1 1990 1995 광액세스 2000 Year 2005

System Capacity (Gb/s) 전송기술 발전 추세 WDM 10 G x 16, 500 Km 100

System Capacity (Gb/s) 전송기술 발전 추세 WDM 10 G x 16, 500 Km 100 10 G x 8, 400 Km TDM 10 G x 4, 400 Km 10 G x 2, 320 Km 40 Gb/s 2. 5 G x 8 20 Gb/s 2. 5 G x 4 10 Gb/s 2. 5 G x 2 10 2. 5 Gb/s 1 SDH 565 Mb/s 155 Mb/s 622 Mb/s 1986 1990 1996 year 2000 Physical Layer • E-TDM(SDH/SONET) --> O-TDM • WDM --> HD-WDM --> OFDM Average Growth Rate(1986 -1996) • TDM: four times per 5 years • WDM: 1. 5 wavelengths per year Enablers • 광증폭기 • 고밀도 WDM 광필터 • 새로운 구조의 광섬유 • 고속 TDM E-TDM: electrical time division multiplexing, HD-WDM: high-density wavelength division multiplexing OFDM: optical frequency division multiplexing

회선분배기술 발전추세 Throughput(b/s) 100 T Transmission Line . Optical XC/ADM. Optical WDM/FDM 10 T

회선분배기술 발전추세 Throughput(b/s) 100 T Transmission Line . Optical XC/ADM. Optical WDM/FDM 10 T 1 T 100 G 1 G Service Node ATM XC. STM. 6 M-150 M Inter face . ATM 52 M XC. 2. 4 -10 G Interface Path Layer • SDH-DCS --> ATM-DCS --> OXC • ADM --> OADM Enablers • 광증폭기 • 파장변환소자 • 광스위치 소자 1. 5 M XC 384 K XC 1980 1990 2000 2010 Year DCS: digital cross-connect system, OXC: optical cross-connect, ADM: add-drop multiplexing

기가비트 전송기술 초고속화 (bit rates) • 전기적 시분할다중 • 광학적 시분할다중 다채널화(channels) • 파장분할다중

기가비트 전송기술 초고속화 (bit rates) • 전기적 시분할다중 • 광학적 시분할다중 다채널화(channels) • 파장분할다중 • 광주파수분할다중 예) 기가급 전송용량 확보 M (bit rates per channel) x N (channels) = total transmission capacity per fiber for N=1, M=10 G, 20 G, 40 G(ETDM, OTDM) <- single channel for M=2. 5 G, N=4(10 G WDM), 8(20 G WDM), 16(40 G WDM) for M=10 G, N=4(40 G WDM), 8(80 G WDM), 16(160 G WDM) 현재 전송실험 결과는 ETDM으로 40 G (NTT, 97년초) OTDM으로 400 G(NTT, 97년) WDM으로 2. 6 T(다중채널수 132채널, 채널당 20 Gb/s, NEC, 96년말)

다중화 방식 시분할 다중화(TDM) ETDM LD LD LD OTDM PD OTDM ETDM PD PD

다중화 방식 시분할 다중화(TDM) ETDM LD LD LD OTDM PD OTDM ETDM PD PD 파장분할 다중화(WDM) 주파수분할 다중화(FDM) LD 1 LD 2 LD 3 LD 4 W D M PD PD

전송 링크(가입자, 국간) DSF 30 km 1 1 1 SMF 3 km 1 1

전송 링크(가입자, 국간) DSF 30 km 1 1 1 SMF 3 km 1 1 External modulator Receiver EDFA N 2 N 1 10 Gb/s pattern generator NSC Low frequency modulation DFB laser N 3 feeder PON Optical booster amplifier External modulator Fiber Optical multiplexing 10 Gb/s pattern generator LEX N 4 Optical In-liner amplifier DSF: dispersion shifted fiber SMF: single mode fiber CPN 10 Gb/s error detector home terminal N 5 Optical Pre amplifier Receiver Optical demultiplexing 10 Gb/s error detector

광섬유의 특성 2. 0 - MULTIPLE INFORMATION CHANNELS - INCREASED NETWORK FUNCTIONALITIES 1. 5

광섬유의 특성 2. 0 - MULTIPLE INFORMATION CHANNELS - INCREASED NETWORK FUNCTIONALITIES 1. 5 LOSS 1. 0 (d. B/km) 14, 000 GHz Fiber Loss around 1550 nm by ITU-T: 0. 28 d. B/km 15, 000 GHz 0. 5 0 900 1100 1300 1500 WAVELENGTH (nm) For 채널 간격 @ STM-64 = 0. 8 nm(100 GHz) 1700 Available channels around 1500 nm = 15000/100 =150 channels Available channels around 1300 nm = 14000/100 = 140 channels

광섬유 전송 제한 요인-2 광섬유 감쇠(attenuation) 특성 • 문제점 - 광섬유 도파에 따른 손실(1310

광섬유 전송 제한 요인-2 광섬유 감쇠(attenuation) 특성 • 문제점 - 광섬유 도파에 따른 손실(1310 nm에서 0. 35 d. B/km, 1550 nm에서 0. 2 d. B /km) • 해결점 - 광증폭기 사용. 1310 nm 근방에서 praseodymium-doped fiber amplifier(PDFA) 또는 neodymium-doped fiber amplifier(NDFA) 사용. 1550 nm 근방에서 erbium-doped fiber amplifier(EDFA) 사용(상용중) - 3 R(reshaping, regenerating, retiming) 재생중계기 사용

D(ps/km. nm) 광섬유 색분산 특성 20 Conventional SMF True Wave TM DSF 10 •

D(ps/km. nm) 광섬유 색분산 특성 20 Conventional SMF True Wave TM DSF 10 • 전세계에 포설된 광섬유는 대부분이 SMF임 • 일본은 DSF가 많이 깔려 있음 2 1. 3 1. 5 1. 6 Slope = 0. 08 ps/km. nm 2 Wavelength (mm) • Non-zero dispersion fiber는 현재 고려중임

광섬유 전송 제한 요인-3 비선형 특성 • 광섬유의 좁은 면적에 고출력의 신호가 전파될 때

광섬유 전송 제한 요인-3 비선형 특성 • 광섬유의 좁은 면적에 고출력의 신호가 전파될 때 발생 refractive index(광섬유 굴절률) : n 2 는 nonlinear-index coefficient • 비선형 현상 - Self phase modulation Stimulated Brillouin scattering(광원의 파장폭이 좁을 수록 영향이 큼) Stmulated Raman scattering Four wave mixing(WDM 전송)

광증폭기(EDFA) 개요 Electrical DC Bias(battery) Amplified electrical signal Weak electrical signal Transistor Analog Electrical

광증폭기(EDFA) 개요 Electrical DC Bias(battery) Amplified electrical signal Weak electrical signal Transistor Analog Electrical amplifier Digital logic circuit Electrical 3 R repeater Optical DC Bias(pumping laser) Weak optical signal Erbium-doped fiber Amplified optical signal Analog Optical amplifier Digital logic circuit (? ) Optical 3 R repeater(? )

EDFA 응용 TX RX G G G In-Line Amplifier Power Amplifier Pre. Amplifier Repeater

EDFA 응용 TX RX G G G In-Line Amplifier Power Amplifier Pre. Amplifier Repeater spacing : 80 km @ 10 Gb/s single channel transmission ~ 60 km @ 10 Gb/s x 10 channels multi-channel transmission Tx #1 #5 Rx #N 광필터 Equivalent (NF)N = (NF)single + 10 log N Cascaded amplifiers accumulate Amplified Spontaneous Emission Noise -> performance degradaion -> limitation in the number of cascaded amplifiers

광신호 검출 • Direct Detection: - APD(수신감도: -25 d. Bm @ 10 Gb/s) -

광신호 검출 • Direct Detection: - APD(수신감도: -25 d. Bm @ 10 Gb/s) - Optical Preamp. + PIN(수신감도: -31 d. Bm @ 10 Gb/s) • Coherent Detection: - FSK mod. + Optical Discriminator + DD - Homodyne or Heterodyne Detection

Requirements for ~40 Gb/s ETDM • Device Technology - high speed & high frequency

Requirements for ~40 Gb/s ETDM • Device Technology - high speed & high frequency device (f. T/fmax: 120~250 GHz for 40 Gb/s) • Circuit Technology - multiple-feedback technique for baseband amp. - narrow-band timing circuit - multi-stage D-F/F for MUX & DMUX - layout to avoid 3 -dimensional distributed interconnection effect • Package Technology (chip-size cavity package) • Manufacturability (proces& material maturity), Reliabily (long MTTF, high temperature endurability), Cost-Effectiveness, etc. • Dispersion Tolerance (~2 km at 40 Gb/s on non-dispersion shifted fiber) • Polarization Mode Dispersion Tolerance (< 100 km at 40 Gb/s NDSF) • New Optical Fiber (larger bit rate distance product, large effective core area)

WDM망 운용 관리 • Transparent WDM networking layer • Two-way design impact - Network

WDM망 운용 관리 • Transparent WDM networking layer • Two-way design impact - Network Element hardware design - Network Management software design • Managing a transparent WDM Network - Performance monitoring - Network configuration - Fault recovery • WDM management communication network

40 Gb/s ETDM 전송시험 현황 다중화 방식 송 신 기 NTT ETDM 40 Gb/s

40 Gb/s ETDM 전송시험 현황 다중화 방식 송 신 기 NTT ETDM 40 Gb/s RZ (LN Mod. / Mode-locked LD) 40 Gb/s 직접 검출 300 km DSF 3 -광중계기 OFC’ 97 Fujitsu OTDM 20 Gb/s RZ (LN Mod. ) 2: 1 광시분할다중 2 x 40 Gb/s WDM 20 Gb/s 광시분할역다중 667 km DSF 9 -광중계기 IEICE Spring Conf. ‘ 97 Fujitsu OTDM 20 Gb/s RZ(LN Mod. ) 2: 1 광시분할다중 2 x 40 Gb/s WDM 20 Gb/s 광시분할역다중 100 km SMF 1 -광중계기 OECC’ 97 Fujitsu OTDM 20 Gb/s RZ(LN Mod. ) 2: 1 광시분할다중 5 x 40 Gb/s WDM 20 Gb/s 광시분할역다중 105 km SMF 1 -광중계기 ECOC’ 97 Nortel OTDM 20 Gb/s RZ(EA / LN Mod. ) 2: 1 광시분할다중 20 Gb/s 광시분할역다중 160 km SMF 1 -광중계기 OFC’ 97 HHI OTDM 10 Gb/s RZ(Mode-locked LD) 4: 1 광시분할다중 10 Gb/s 광시분할역다중 150 km SMF OFC’ 97 주) RZ: Return-to-Zero LD: Laser Diode SMF: Single Mode Fiber DSF: Dispersion Shifted Fiber 수 신 기 전송 링크 발표처 기관 LN Mod. : Li. Nb. O 3 Modulator EA: Electro-Absorption

점대점 전송방식에 따른 가격 비교 OC-12 LTM 622 Mb/s OC-12 LTM 622 Mb/s WDM

점대점 전송방식에 따른 가격 비교 OC-12 LTM 622 Mb/s OC-12 LTM 622 Mb/s WDM 4 x OC-12 = 2. 5 Gb/s OC-48 LTM OC-48 2. 5 Gb/s OC-12 LTM 622 Mb/s C 1 = Cost of OC-12 LTM Total Cost = 4 C 1 + optics Total Cost = 2 C 1 • Optics 가격은 수요의 정도와 시간에 따라 큰 폭으로 감소 WJT - NFOEC’ 93

전달망 구성에 따른 가격 비교 OC-12 OC-48 2. 5 Gb/s OC-48 ADM OC-48 2.

전달망 구성에 따른 가격 비교 OC-12 OC-48 2. 5 Gb/s OC-48 ADM OC-48 2. 5 Gb/s OC-12 EDFA 4 x OC-12 = 2. 5 Gb/s WDM OC-12 Drop + Add 622 Mb/s aggregate C 2 = Cost of OC-48 ADM Total Cost = C 2 OC-12 ADM Total Cost = C 2/2 + optics WJT - NFOEC’ 93 4 x OC-12 = 2. 5 Gb/s

WDM VS. TDM METRO Application 1. 00 OC-192 OC-48 Cost 0. 80 Short span

WDM VS. TDM METRO Application 1. 00 OC-192 OC-48 Cost 0. 80 Short span distance < 90 km 3 R repeaters are not necessary 0. 60 --> TDM solution more cost effective 0. 40 Long-haul Application 0. 20 1. 00 0. 00 3 5 7 9 Years Limitation factors : Amplifier tech. & 3 R repeaters 11 13 0. 80 Cost 1 0. 60 0. 40 0. 20 OC-48 is more cost effective due to: - elimination of chromatic dispersion - low dependency of polarization mode dispersion 0. 00 - operation at a much lower OSNR 1 Cost of WDM is almost 18% less than TDM OC-192 OC-48 3 5 7 9 Years 11 13