Optical Amplifiers. Ericsson

Transcription

1 Optical Amplifiers Ericsson

2 Introduction In any link, optical power pumped and the receiver sensitivity is limited and can only support for a limited distance To over come the losses in the network, either electrical or optical amplification is required Optical amplification is more cost effective over electrical one An optical amplifier is a device which amplifies the optical signal directly without ever changing it to electricity

3 Types of Optical Amplifiers Two Types of optical amplifiers available Solid state Optical Amplifiers Semiconductor Optical Amplifiers Fiber Amplifiers Erbium Doped Fiber Amplifiers ( EDFAs ) Raman Amplification ( RA )

4 Amplifiers in Transmission Three type of fiber amplifier used in transmission In-line Amplifier Pre Amplifier: Pre Amp is used for amplifying the incoming signal to a sufficient level for the detectors to sense the signal Post Amplifier Post Amp is used to amplify the output of a Multiplexer to a sufficient level to take care of the link losses

5 Fiber Doped Amplifiers An Erbium Doped Fibre Amplifier consists of a short length of optical fibre doped by small controlled amount of the rare earth element erbium This rare earth element contributes in the amplification process in presence of pump signal Pump laser excites erbium ions which give extra energy to signal Principle of operation is similar to principle of a laser

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7 Raman amplification Raman Scattering affects signal propagation but it may be used for light AMPLIFICATION! TX RX the fibre itself is used as gain medium 1550 nm 1450 nm RAMAN PUMP an effective gain of more t h a n 1 0 d B c a n b e achieved increasing span length (> 40 km) SIGNAL POWER RAMAN POWER RAMAN TRANSFER AMPLIFIED SIGNAL

8 Raman Fiber Amplifier Basic principle of Raman fiber amplifier is Stimulated Raman Scattering (SRS) When stronger optical pump interacts with the medium generates new signal (a Stokes wave) in same direction New generated frequency is lesser then the pump frequency by13.2 THz In normal fiber this effect is very small and it takes a relatively long length to have significant amplification From this phenomenon signal of lower frequency then pump gets amplified and the optimal amplification occurs when the difference in wavelengths is around 13.2 THz Any signal lower then pump can be amplified but the efficiency will not be the same for all Efficiency can be improved by adding an FBG (Fibre Bragg Grating) reflector for the pump wavelength Thus any frequency can be generated from this phenomenon

9 STM-16/64 Budgets Managed Amplifiers STM-16 Budgets ULJE16.2 [nom. 240 km] Dispersion tolerance 5000ps/nm (SK68D, SK25PC & DCF [3] ) Dual Pump Booster & Pre-Amp STM-16 Amplifiable Card Tx -4 dbm (min) -2 dbm (typ) 0 dbm (max) -6 dbm (min) 0 dbm (max) STM-64 Budgets dbm (min) dbm (max) Stability +/- 0.9 dbm db max atten [1] dbm (min) [2] -10 dbm (max) -7.9 dbm (min) [2] -1.4 dbm (max ) [3] DCF [3] Rx -19 dbm (min) -9 dbm (max) STM-16 Amplifiable Card ULJE64.2 (G709 FEC enabled) [nom. 200 km] Dispersion tolerance 3600ps/nm [2] (SK69CB, SK25PC & DCF [2] ) Dual Pump Booster & Pre-Amp STM-64 Tx Amplifiable Card -15 dbm (min) +2.5 dbm (max) DCF [2] db max atten [1] -6 dbm (min) 0 dbm (max) dbm (min) dbm (max) Stability +/- 0.9 dbm dbm (min) -10 dbm (max) -7.9 dbm (min) [4] +0.1 dbm (max) DCF [2] Rx STM-64 Amplifiable Card dbm (min) +2.5 dbm (max)

10 DWDM System architecture Flexible node configurations for all applications Amplifiers Group Mux Unit 2/8/40 chs modularity 40 or 80 channels High amplifiers modularity MH EDFA: up to 34dB gain Modular Raman (co and contra) option 4x2.5G Mux Terminal Line Amplifier OADM Up to 3000 Km Line Amplifier Terminal Plug & Play Intelligent EDFA power control Network dynamic control Full G.709 Frame Technology FEC & EFEC Dynamic optical by pass Fixed OADM : 2, 4, 8 chs Reconfigurable OADM Multidirectional OADM ASON System auto-discovery Automatic channel provisioning and switching

11 Line Amplifier Optical Amplification only LINE IN SSA LINE OUT West East OSC RX OSC TX Dual OSU OSC TX OSC RX East West DSA LINE OUT LINE IN DCM

12 Line Terminal long span 80-channel filters, Raman East or West Compatible Coloured Clients ODU1 / STM16/ OC48/ Gbe/.../multi rate Tribs STM64/OC192 ODU2 Tribs STM64/OC192 ODU2 Tribs 8 x Optical Levelling Unit 2.5G/GBe NRZ Transponder 10G NRZ Transponder 10G RZ Transponder GMT 40 40Ch 100GHz Mux 40Ch 100GHz Mux GMT 40 GIU SSA Monitor PMU OSC TX OSC RX D-OSU LINE OUT STM256/OC768 ODU3 Tribs ODU1 / STM16/OC48 Gbe/FC/270 video Tribs 40G Transponder 10G Mux 40Ch 100GHz Demux SSA LINE IN ODU1 / STM16/ OC48/Gbe/ Tribs 2.5G Modular Trans/Muxponder 40Ch 100GHz Demux RPU-C Tribs can be mixed in any combination

13 Amplification Single and Dual stage EDFA (Erbium Doped Fibre Amplifiers) Used in all NE types Two gain ranges Variable gain Span loss variation Span loss changes Flat gain Spectrum Optimised transmission Low Noise Factor Buried VOA Transient control 9 db changes without errors Raman as required

14 Multi-Haul (MH) amplifiers features High-power and low-power MH amplifiers can be mixed Low power (cheaper) is good for shorter distances and 40 channels Low power also supports constant gain mode High power amplifiers are good for longer distances and/or 80 channels The MH amplifiers can not be mixed with any of the older types of amplifiers (LH, ELH) or with the Metro amplifier Amplifiers work in constant power mode (in core networks) Note: You can also mix transponder types to provide the optimum solution, for example RZ between end to end Terminals and NRZ between Terminal and mid span OADM.

15 Amplifiers choices Core Metro & Core Amplifiers set MH High Power MH Low Power Output Power 20.5 dbm 18 dbm Gain ranges SSA22/20, DSA22/20 : db SSA22/18, DSA22/18 : db Max. distance (any topology) SSA29/20, DSA29/20 : db (Extended range 24-41dB) 3000 km 1000 km Configurations SSA (PA/BA), DSA horizontal (DCM), DSA vertical (PA/BA) SSA (PA/BA), DSA horizontal (DCM), DSA vertical (PA/BA) Different options allow to adapt to specific network requirements Limited number of variants can be used to optimise spare handling

16 Raman amplification Raman amplifiers pump extra light into the fibre such that this power is transferred to the signal Normally contra-directional, can be fitted co-directional in addition for very long single spans using the same card (new card with 3 pumps LU21KB). Older card (LU21KA) available for places where less power needed Multi-span Raman system also possible ALS mechanism driven by OSC unit TO BZ NO MI BG BS VR PD VE PV GE PR PI BO FI CV RM TS AN PE SS Ol 249 km / 53 db NA Nola SA OR NU BA Sardinia Signal Sicily CA 377 km / 68 dbpa MZ CT CZ 15 db Without Raman 20 db Total raman gain 35 db RPU Co - Gain Contra - Gain 72 SPAN db span LOSS loss DSA - TX Coup Coup DSA -RX ler Raman Noise N ler RPU Single Span with Raman - Examples 49dB G 60dB G 70dB G 72dB G

17 East Caribbean submarine fibre systems ECFS (C&W + FT) Point-to-point links Uses submarine cables 16x10Gb EOL due to high span losses Contra-propagating Raman required on 195km (46dB), 215km (46dB) and 240km (49dB) links Co-propagating and contrapropagating Raman on 290km (66dB) link In-service Q km 130km 105km 155km 215km 160km 240km 90km 290km 195km

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