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Optical Networks. Josef Vojtěch josef . vojtech/zavinac/ cesnet.cz. www.ces.net. czechlight.cesnet.cz. Optical Networks Outline. History Transmission Fibers Attenuation Limited Reach - Amplifiers Doped fiber – EDFA, TDFA Raman SOA OSNR Limited Reach

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slide1

Optical Networks

Josef Vojtěch

josef.vojtech/zavinac/cesnet.cz

www.ces.net

czechlight.cesnet.cz

Optical Networks

optical networks outline
Optical NetworksOutline
  • History
  • Transmission Fibers
  • Attenuation Limited Reach - Amplifiers
    • Doped fiber – EDFA, TDFA
    • Raman
    • SOA
  • OSNR Limited Reach
  • Impairments (CD, PMD, non-linearities)
  • WDM Transmission (WDM, DWDM, CWDM)
  • Present and Future Transmission Systems
  • Capacity Limits, SDM
  • Photonic Services, Precise Time Transfer

OpticalNetworks

optical networks a l ittle b it of history 1
Optical NetworksA Little Bit of History (1)

Back to Antiquity (mirrors, firebeacons, smokesignals) [1]

Till the end 18thcenturywithlamps, flags

1792 – Claude Chappewithmechanical „optical“ telegraph

1830 – the advent oftelegraphy (e.g. Morse)

Submarinecablesstartedbeforethefirsttransatlantic in 1858 but was not working long, shortmessage (one sentence) fromQueen Victoria to President Buchanantook 30 hours!

Initialassumptions: 3 words per minute but in reality lessthan 1 word per minute, only 20 daysthancablefailed, 723 messages! 1866 itssucessor

Terestrial long haul in Russia, USA – telegraphalongrailways, submarinepreferable

Optical Networks

optical networks a l ittle b it of history 2
Optical NetworksA Little Bit of History (2)
  • 1876 – the invention of telephone (A.G.Bell, U.S. Patent No. 174 465)
  • 1895 – radio by Marconi, big competition started
  • 1940 – massive increase of pairs installed - 3 MHz coax-cable system (repeater spacing 1 km), high freq. dependent loss especially above 10MHz
  • 1948 – 4 GHz microwave system
  • 1975 – last most advanced coaxial system with 274Mbit/s

Optical Networks

optical networks a l ittle b it of history 21
Optical NetworksA Little Bit of History (2)
  • Evolution of optical communication systems
  • 1960 – the invention of laser (suitable transmission medium?)
  • 1960s – optical fibre 1000 dB/km, 1970 20dB/km close to 1um
  • 1st generation GaAs lasers 850nm, 10km regeneration
    • 1980 – 45 Mb/s (1st generation) multi-mode fibres
  • 2nd generation 1310 nm
    • 1980s – 1310 nm, 1 dB/km, 100 Mb/s, multi-mode fibres
    • Late 1980s – 2 Gb/s, single mode fibres, repeater spacing 50 km (2nd generation)
  • 3rd generation 1550 nm
    • 1990s – 1550 nm (problem with lasers, dispersion of fibres, typical repeater spacing 60 -70km), 2.5 Gb/s or 10 Gb/s (3rd generation)

Optical Networks

optical networks a l ittle b it of history 3
Optical NetworksA Little Bit of History (3)
  • 4th generation 1550 nm – WDM - DWDM, CWDM
  • Optical amplification, EDFAs developed late 1980s
  • 1990s - DWDM, optical amplification (4th generation)
  • Today comercially available 100G waves each consumes 50GHz~0.4nm, 160 channels in C+L bands ie 1,6 Tb/s, thousands of kilometers, coherent technology

Optical Networks

optical networks optical f ibres mm
Optical NetworksOptical Fibres - MM
  • 1970: 20 dB/km (Kapron, Keck, Maurer), silica fibres
  • Multimode (MM), singlemode (SM) and fewmode (FM) fibres
  • Multimode: step-index (SI) or graded index (GI)
  • MM SI: modal dispersion: different rays disperse in time because of the shortest (L) and longest (L/sinΦC) paths
  • MM SI: 10 Mb/s
  • MM GI: parabolic index, lower modal dispersion, higher bit rates, 100 Mb/s
  • Plastic MM GI, for 1 GE (or even 10 Gb/s)
  • Attenuation: 1 – 4 dB/km, <10 dB/km for plastic

Optical Networks

optical networks optical f ibres sm
Optical NetworksOptical Fibres - SM
  • Single mode (SM, Standard SMF, G.652) fibres
  • Supports only one so called „the fundamental mode of the fibre“, all higher modes are cut off @ the operating wavelength
  • An optical mode refers to a specific solution of the wave equation (satisfies boundary conditions, spatial distribution is constant as light travels along a fibre)
  • The cutoff wavelength is specified in ITU G.650, SSMF cutoff approx. 1200 nm
  • 0.2 dB/km@1550 nm, 0.4 dB/km@1310 nm
  • Best conventional fiber ever 0.1484dB/km

Optical Networks

optical networks optical f ibres sm types
Optical NetworksOptical Fibres – SM types
  • ITU G.651 – MMF, new types suitable for 10G
  • G.652 SSMF, non-dispersion-shifted fiber, optimized for 1310nm (but well usable in 1550nm and 100G coherent - big core diameter)
  • G.653, dispersion-shifted optical fiber, zero dispersion at 1550nm, strong nonlinear effects (FWM)
  • G.654, low loss, no longer supported
  • G.655, nonzero dispersion-shifted, small dispersion at 1550nm
  • G.656, for S, C and L bands
  • G.657, G.652-like

Optical Networks

optical networks optical f ibres special
Optical NetworksOptical Fibres - Special
  • Multicore fibres (3-20)
  • Photonic crystal fibres PCF
  • Refractive index experienced (“seen”) by propagating light depends on size and shape of air holes in every point of structure
  • But speed of light similar to 300 000km/s (air), perhaps promising for financial transactions

Optical Networks

optical networks optical reach transmitter
Optical NetworksOptical Reach -Transmitter
  • Conversion of electrical signals into optical streams
  • Light source LED or laser: Fabry-Perot (FP), Distributed Feedback (DFB)
  • Modulation: direct or external (10 Gb/s, DWDM incl. tunable)
  • Output powers typicall: 0 dBm – 4 dBm

OpticalNetworks

optical networks optical reach
Optical NetworksOptical Reach
  • Tx power 1mW ~ 0dBm (P [dBm] = 10 log P[mW])
  • Receiver PIN diode or APD
  • Minimal needed Rx power– sensitivity, examples:
    • -45 dBm (32nW) @ 155Mbps – 180km
    • -36 dBm @ 1GBps – 144km
    • -24 dBm @ 10Gbps – ?
  • Reach extension – regeneration / optical amplification

Optical Networks

optical networks optical amplifiers
Optical NetworksOptical Amplifiers
  • Rare earth doped fibre, Semiconductor (SOA), Raman
  • Erbium Doped Fibre Amplifiers (EDFA)
  • Really began a revolution in the telecommunications industry
  • Late 1980s, Payne and Kaming (University of Southampton)
  • OAs can directly amplify many optical signals
  • Analogous principle: Protocol, bit-rate transparent
  • EDFAs working in the 1550 nm window (C band and later L band)

Optical Networks

optical networks optical amplifiers edfa
Optical NetworksOptical Amplifiers EDFA

High energy level, 1 μs

Metastable energy level, 10ms

1480 nm

Amplified signal

980 nm

Low energy level

  • Light Amplification by Stimulated Emission

Er atoms

Optical Networks

optical networks optical amplifiers edfa1
Optical NetworksOptical Amplifiers EDFA

Er doped fibre, 10 m – 100 m

SIGNAL

SIGNAL

WDM

WDM

PUMP

PUMP

  • Forward, backward pumping
  • Forward: lowest noise
  • Backward: highest output power
  • 980 nm: low noise
  • 1480 nm: stronger pump sources (req. longer Er fibres)
  • 1480 nm & backward; 980 nm & forward
  • Single or dual stage (for DCF)

Optical Networks

optical networks optical amplifiers edfa2
Optical NetworksOptical Amplifiers EDFA
  • Output powers (5 Watts or more)
  • Gain (30 dB), not uniform across C (L) band
  • Input power (-36 dBm)
  • Noise Figure (NF): 3.6, typ 5-7dB, teoretical minimum 3 dB
  • ASE
  • For L band: long Er fibres (> 100 m)
  • Booster, in-line, preamplifiers

Optical Networks

optical networks and equipment oas and practical deployment
Optical networks and equipmentOAs and Practical Deployment

Praha - Pardubice

Since May 17, 2002

Now gone

Masarykova Univerzita, Brno

optical networks real deployments
Optical networksReal deployments
  • OSA (One Side Amplification) – all components are located at one place, for star topologies
  • Praha – Plzeň (OSA), 123 km, 34 dB, 1 GE

Optical Networks

optical networks and equipment oas and practical deployment1
Optical networks and equipmentOAs and Practical Deployment
  • Brno – České Budějovice, 308 km, 70 dB, 2,5 Gb/s, PoS, without optical filters

Masarykova Univerzita, Brno

optical networks and equipment oas and practical deployment2
Optical networks and equipmentOAs and Practical Deployment
  • Brno – Ostrava, 235 km, 51 dB, 1 GE (tested for 2,5 G PoS), without optical filters

Masarykova Univerzita, Brno

optical networks other optical dopped fibre amplifiers o band
Optical NetworksOther Optical Dopped Fibre Amplifiers – O band
  • PraseodymiumDoped Fluoride FibreAmplifier (PDFA)
    • 1310 nm, not as energyefficientcompared to EDFA, higher NF
    • Problemswith fluoride fibres, not very widespread
  • Neodymium DFA
    • 1310 nm, fluoride fibre

OpticalNetworks

s band

OpticalNetworksOtherOpticalDoppedFibreAmplifiers – S band

S band
  • Thulium DFA (TDFA), but poor efficiency in silica, due to high non-radiative decays
  • TDFAs based on fluoride fibres commercially available
    • 1460-1500 nm 19dB gain and 19dBm output
    • Can’t be spliced with silica fibres, hydroscopic
  • Double pumped TDFA in silica with dopants – not commercially available

Er Tm

Optical Networks

19th Nov 2013

s band cont

OpticalNetworksOtherOpticalDoppedFibreAmplifiers – S band

S band cont.
  • Modified EDFA
    • Can handle region about 1510-1530nm, 20dB gain, commercially available, NF higher that TDFA
  • Commercially unavailability of DWDM transceivers forthisregion

Optical Networks

19th Nov 2013

2um 2000nm band

Optical NetworksOther Optical Dopped Fibre Amplifiers

2um (2000nm) band
  • Experimental TDFA operation
  • Bandwidth 1910-2020nm
  • Small signal gain 35dB
  • NF 5-7dB
  • Silica glass
  • Li Y. et al,”Thulium-doped Fiber Amplifier for Optical Communications at 2μm”, OFC2013

Optical Networks

19th Nov 2013

2um 2000nm band cont

Optical NetworksOther Optical Dopped Fibre Amplifiers

2um (2000nm) band cont.
  • Hollow core photonic bandgap fibers
  • Minimal latency, neff close to 1, propagation speed almost c, not 2/3c
  • Nonlinear coefficient 0.07% of SSMF
  • Losses still in order of 4.5dB/km in 2um
  • Theoretically losses can go down to 0.15 dB/km
  • 1966 Charles K. Kaofiber
  • 1000dB/km
  • Source: NKT Photonic

Optical Networks

19th Nov 2013

optical networks semiconductor optical amplifiers
Optical Networks Semiconductor Optical Amplifiers
  • Based on conventional laser principles
  • Active medium (waveguide) between N and P regions
  • + InGaAsP – small and compact components
  • + Cost effective solutions, especially for O and S bands
  • + High gain (up to 25 dB)
  • - Low output powers (15 dBm)
  • +Wide bandwidth
  • - High noise figure (7-8 dB)
  • -- Very short life time - cross gain effects

Optical Networks

optical networks raman amplification
Optical NetworksRaman Amplification
  • Both discrete but mainly distributed amplifier
  • Stimulated Raman scattering effect
  • Distributed amplification, a communication fibre itself is a gain medium
  • Can add 40 km to increase a maximum transmitter-receiver distance
  • Upgrading of existing links to add more channels
  • A quite weak effect in silica fibre – very high powers have to be used
  • Safety problems (automatic laser shutdown - ALS)

Optical Networks

optical networks raman amplification1
Optical NetworksRaman Amplification
  • Counter-directionally pumping schemes

Optical Networks

optical networks noise limited reach1
Optical NetworksNoise Limited Reach

Receiver needs some minimal OSNR to achieve intended BER (e.g. 1E-12)

Scenario 1: Span 80 km, Gain 18 dB, NF 6 dB, Pin 0 dBm.

Scenario 2: Span 100 km, Gain 22 dB, NF 6.5 dB, Pin 0 dBm.

Optical Networks

optical networks optical f ibres dispersion
Optical NetworksOptical Fibres – dispersion
  • MM: Intermodal dispersion (pulse broadening, the most important limiting factor)
  • SM: Intermodal dispersion is absent, pulse broadening is present still because of Intramodal dispersion (or Group-velocity dispersion CD), even laser pulses have finite spectral width and pulses are modulated
  • CD: different spectral components of the pulse travel at different speeds
  • Increases as the square of the bit rate

Optical Networks

optical networks optical f ibres cd
Optical NetworksOptical Fibres – CD
  • D = DM + DW
  • Material dispersion
  • Waveguide dispersion

Optical Networks

optical networks optical f ibres cd1
Optical NetworksOptical Fibres – CD
  • G.652 (SSMF): Zero dispersion at 1310 nm
  • G.653 (DSF): Zero dispersion at 1550 nm
  • G.655 (NZDSF): Small dispersion at 1550 nm, positive/negative
  • Dispersion Compensating fibres (DCF)

Optical Networks

optical networks c h romatic dispersion compensation
Optical Networks Chromatic Dispersion Compensation
  • Typical values (receivers can have different tolerance to CD!)

Optical Networks

optical networks c h romatic dispersion compensation1
Optical NetworksChromatic Dispersion Compensation
  • Dispersion compensating fibres (DCF)
    • A special kind of fibre, compensates all wavelengths (the only solution for „grey“ transmitters)
    • Adds link loss (and money), especially for long-haul applications
    • Stronger non-linear effects (due to a smaller core diameter)
  • Fibre Bragg gratings (FBG)
    • Typically narrow-band elements – a stabilized DWDM laser is a must
    • „Wide-band“ FBGs available today (for C or L band)
    • Signal filtering, spectrum shaping, tuneable compensators
    • Cost effective solution
  • Electronic post and pre compensation, GTE, VIPA, MZI
  • Tunable

Optical Networks

optical networks optical f ibres pmd
Optical NetworksOptical Fibres – PMD
  • Polarization Mode Dispersion (PMD)
  • The stochastic phenomenon
  • Fibre stress, temperature, imperfections
  • The fundamental mode has two orthogonally polarized modes
  • The two components with different propagating speeds disperse along the fiber
  • The difference between the two propagation times is known as the Differential Group Delay (DGD)
  • PMD is a wavelength averaged value of DGD

Optical Networks

optical networks optical f ibres pmd1
Optical NetworksOptical Fibres – PMD

ITU proposed PMD values

Optical Networks

optical networks optical f ibres pmd2
Optical NetworksOptical Fibres – PMD
  • PMD is measured and quoted in ps for a particular span and discrete components but its coefficient is in ps/(km)1/2
  • PMD accumulates as the square root of distance of a link
  • A single span with high PMD dominates the total PMD for the whole network
  • A big issue for older fibres (late 1980s, 80 000 000 km) and higher bit rates (10 Gb/s and more)
  • Modern fibres have PMD of less than 0,5 ps/(km)1/2
  • Difficult to compensate in optical domain
  • In coherent systems compensated in DSP

Optical Networks

optical networks nonlinear optical effects
Optical NetworksNonlinear Optical Effects
  • When an intesity of electromagnetic fields becomes too high, the response of materials becomes nonlinear
  • For optical systems, nonlinear effects can be both advantageous (Raman and Brillouin amplification) and degrading (Four Wave Mixing, Self Phase Modulation and Cross Phase modulation)

Optical Networks

optical networks nonlinear optical effects srs
Optical NetworksNonlinear Optical Effects - SRS
  • Stimulated Raman Scattering (SRS)
  • A signal is scattered by molecular vibrations of fibre – optical phonons
  • Can occur both in forward and backward directions
  • Shifted to longer wavelengths (lower energy) by 10 to 15 THz in the 1550 nm window
  • Wide bandwidth of about 7 THz (55 nm)
  • Maybe used for amplification (Raman fibre amplifiers), so called counter directionally pumping schemes
  • In DWDM systems: transfer of power from shorter wavelengths to longer ones

Optical Networks

optical networks nonlinear optical effects sbs
Optical NetworksNonlinear Optical Effects - SBS
  • Stimulated Brillouin Scattering (SBS)
  • A signal is scattered by sound waves – acoustic phonons
  • Shifted to longer wavelengths (lower energy) by 11 GHz in the 1550 nm window
  • Narrow bandwidth of about 30 MHz
  • A problem for monochromatic unmodulated signals

Optical Networks

optical networks nonlinear optical effects1
Optical Networks Nonlinear Optical Effects
  • Self-Phase Modulation (SPM)
  • When the intensity of the signal becomes too high, the signal can modulate its own phase
  • The refractive index is no longer a constant
  • Significant for fibres with small effective areas (G.655, DCF)
  • Higher bit rates (10 Gb/s and higher)

Optical Networks

optical networks nonlinear optical effects2
Optical NetworksNonlinear Optical Effects
  • Cross-Phase Modulation (CPM)
  • A signal modulates the phases of adjacent channels
  • Difficult for amplitude and phase modulations ie coherent technologies
  • Slow 1/10G OOK signals harm 100G DP-QPSK signals
  • Vendors recommend to use coherent-only solutions without compensation DCFs or even CD compensation – so called DCM-free designs
  • Problem with 10G wavelengths

Optical Networks

optical networks nonlinear optical effects3
Optical NetworksNonlinear Optical Effects
  • Four Wave Mixing (FWM)
  • New „ghost“ signals appear in the transmission spectral range
  • Depends on several factors like launched powers, the CD, the refractive index, the fibre length
  • Severe limitations for G.653 fibres and DWDM transmissions in the 1550 nm window (C band)
  • Solution to this problem is to deploy L band DWDM systems (1565 nm – 1625 nm), where CD is high enough

Optical Networks

optical networks nonlinear optical effects fwm1
Optical NetworksNonlinear Optical Effects (FWM1)

Pin = 20 dBm

83 km, G.652

Optical Networks

optical networks nonlinear optical effects fwm2
Optical NetworksNonlinear Optical Effects (FWM2)

Pin = 25 dBm

83 km, G.652

Optical Networks

optical networks nonlinear optical effects fwm3
Optical Networks Nonlinear Optical Effects (FWM3)

Pin = 27 dBm

83 km, G.652

Optical Networks

optical networks nonlinear optical effects fwm4
Optical NetworksNonlinear Optical Effects (FWM4)

Pin = 30 dBm

83 km, G.652

Optical Networks

optical networks wavelength division multiplex system
Optical NetworksWavelength Division Multiplex System

[11]

  • Basic passive WDM principle for 2 channels over MM fibre
  • Still used, typically 1310+1550 nm over SMF
  • CWDM

Optical Networks

optical networks dense wdm dwdm
Optical NetworksDense WDM - DWDM

[11]

  • Typicallyamplified, long distances
  • Thermallystabilizedlasers and filters
  • Grids:
    • 200 GHz
    • 100 GHz
    • 50 GHz standard ~ 0,4 nm (C band ~ 80 channels)
    • 33 GHzsubmarine

Optical Networks

optical networks transmission systems c coarse wdm
Optical NetworksTransmission SystemsC(coarse)WDM
  • + passive, non thermally stabilized lower power consumption, less space, cheaper lasers and filters
  • - Limited number of channels, limited reach
  • Typically in MAN

Optical Networks

slide62

Optical NetworksPresent Transmission Systems

  • Common 50/100 GHz systems, C band, approx. 80/40 channels, C+L band approx. 160 channels
  • Commercially available 25 GHz systems and e.g. undersea 33 GHz systems
  • Bandwidth demand satisfied by serial speed of single channel growth 2,5->10->40->100G
  • 10->40G transition
    • 40G NRZ tolerance very weak CD 50ps/nm (equals to 3km of G.652 fibre), PMD 2,5 ps
    • ODB, DPSK proposed, but more strict design rules compared to 10G
    • DQPSK (20Gbaud)

NRZ ODB DPSK DQPSK

Optical Networks

slide63

Optical NetworksPresent Transmission Systems

  • 100G coherent DP-DQPSK (25GBaud) solves some issues
    • + Works over 50 GHz grid
    • + Design rules almost 10G; CD, PMD electronic compensation
    • - Sensitive to non-linearities, FWM->DCFs removal->coexistence with present 10G channels?
    • - Cost of complicated modulation format (TX+RX) + necessity of powerful DSPs and ADCs
  • Proposed alternative modulation formats: 16 QAM, OFDM, 3ASK-PSK,…

TE TM

Optical Networks

slide65

Optical NetworksPresent Transmission Systems

  • Profits from integration

Source: www.oiforum.com

Optical Networks

slide66

Optical NetworksPresent Transmission Systems

  • „Digital“ DWDM system
    • Profits from photonic integration – photonic integrated circuits (PIC)
    • Do not use optical processing (ROADM) but massive OEO regeneration in nodes

DWDM system on chip, source: Infinera

Optical Networks

slide67

Optical NetworksFuture Transmission

  • Works on 400 Gb/s and 1Tb/s per one serial lambda
  • DP-DQPSK
    • High channel bandwidth
      • ROADM + WSS have to support „flexi grid“
  • OFDM, 16 or 32 or 64-QAM with or without DP
    • High OSNR, low nonlinearities
      • Raman or hybrid amplification
      • Decrease spacing of inline amplifier huts

Optical Networks

slide69

Optical NetworksChannel Capacity Limit

  • Shannon’s law C = B . log2 (1+SNR)
  • C/B (capacity per unit bandwidth) is limited by noise
  • And non-linearities too

Optical Networks

slide70

Optical NetworksFurther Capacity Increase

  • Fibre attenuation decrease, decrease of nonlinearities
  • Amplifier NF decrease, bandwidth increase
  • Spatial Division Multiplexing

Optical Networks

slide71

Optical NetworksFuture Transmission

New Fibers

  • Multicore fibers

[Jun Sakaguchi, Proc. OFCNFOEC2011, OWJ2]

  • Issues:
    • Amplification – experimental EDFA, Raman
    • Cross-talk - MIMO
    • Splices ?
    • Connectors ?
    • New fibers instalation

ECOC12, NTT: Over 1Pbit/s transmission

Optical Networks

slide72

Optical NetworksFuture Transmission

New Fibers

  • Few mode fibers - FMF

[OFCNFOEC2011,PDPB9]

OpticalNetworks

slide73

Optical NetworksFurther Bandwidth

  • Practical experiences with L band, in lab at first
  • Single span 150 and 200km G.652 fibre on spools
  • High launched power about +8.5 and +14.5 dBm/ch
  • Power transfer (Raman effect) from lower to higher wavelengths
    • 0.58/0.38 dB

Optical Networks

19th Nov 2013

slide74

Optical NetworksFurther Bandwidth

Field deployment – C + L

  • EF line Praha-Brno 300km, mixture of G.655 fibre with G.652 local loops

Optical Networks

19th Nov 2013

slide75

Optical NetworksBandwidth Virtualization

  • Photonic Service
  • End-to-end connection between two or more places in network
  • Described by Photonic-path and allocated bandwidth
    • Photonic-path is a physical route that light travels from the one end point to the other or to multiple other end points respectively
    • Allocated bandwidth is a part of system spectrum that is reserved for user of Photonic Service all along the Photonic-path.
    • Minimal impact of network (no processing) on transmitted data
    • Path is all-optical , no OEO except special cases.

OpticalNetworks

slide76

Optical NetworksPhotonic Services

  • Advantages
    • Transparency to modulation formats
    • Low transmission latency as the shortest photonic path is formed
    • Constant latency (i.e. negligible jitter), because non or only specially tailored electrical processing is present
    • Stable service availability (due allocated bandwidth) with some exception for protection switching
    • Future-proof design thanks to grid-less bandwidth allocation

OpticalNetworks

optical networks photonic services real time
Optical NetworksPhotonic Services – Real Time
  • Real time has nothing to do with speed, but with timeliness constraints
  • For the interaction with external processes (processes running outside network) real time network services are needed if timing of interaction limits quality or even the acceptability of network application.
  • Real-time network service should respond to an event within a predetermined time (i.e. there are "real time constraints" - operational deadlines from event to system response). The timeliness constraints or deadlines are generally a reflection of the physical process being monitored or controlled.

OpticalNetworks

optical networks photonic services precise time transmission
Optical NetworksPhotonic Services – Precise Time Transmission
  • Comparison of atomic clock scales on live network : CESNET (CZ) +ACONET (AT)
  • Tests in 2010
  • Comparison of time scales between Czech and Austrian national time and frequency laboratories in Praha and Wien (IPE-BEV) over operational DWDM since Aug 2011 – RUNNING

OpticalNetworks

optical n etworks precise time transmission
Optical NetworksPrecise Time Transmission
  • Photonic path – dedicated lambda over operational DWDM network:
    • Mixture of fibre types (G.652/655)
    • Mixture of transmission systems Cisco/Open DWDM Czechlight
    • Mixture of CD compensation types (DCF, FBG)
    • One way distance 550km, total attenuation 137 dB

OpticalNetworks

optical networks precise time transmission
Optical NetworksPrecise Time Transmission
  • Next line in service since summer 2013
    • CESNET-VUGKT (Praha-Pecný), single fiber bidirectional line 76km
    • Passive transmission of time, parallel data are amplified
    • Significantly smaller noise

OpticalNetworks

optical networks precise time transmission1

Tx

Tx

Rx

Rx

Optical NetworksPrecise Time Transmission
  • Amplified bidirectional transmission necessary for longer distances
  • Tested in lab on fiber spools
  • Must be very careful with amplifiers gains
  • Reflections creates feedback and line is lasing

Optical Networks

optical networks acknowledgements
Optical NetworksAcknowledgements
  • Lada Altmanová, Michal Altmann, Miloslav Hůla, Miroslav Karásek, Jan Nejman, Václav Novák, Martin Míchal, Stanislav Šíma, Karel Slavíček, Pavel Škoda, Jan Radil and Jan Gruntorád

Optical Networks

optical networks references 1
Optical NetworksReferences 1
  • [1] Agrawal G.P., „Fiber-Optic Comminications Systems“, 2002.
  • [2] Kartalopoulos S.V., „DWDM Networks, Devices and Technology“, 2003.
  • [3] Ramaswami R., Sivarijan K.N., „Optical Networks“, 2nd edition, 2002.
  • [4]Radil, J. - Karásek, M., „Experiments with 10 GE long-haul transmissions in academic and research networks.“, In: I2 member meeting, Arlington, VA, 2004.
  • [5] Vojtěch J., „CzechLight and CzechLight amplifiers“. In: 17th TF-NGN meeting, Zurych, Switzerland, April 2005.
  • [6] Vojtěch J., Karásek M., Radil J., „Extending the Reach of 10GE at 1310 nm “. In: ICTON 2005 meeting, Barcelona, Spain, 2005.

Optical Networks

optical networks references 2
Optical NetworksReferences 2
  • [7] www.seefire.org, Deliverables
  • [8] czechligh.cesnet.cz, Publications
  • [9] ECOC 2004 , 2005 proceedings
  • [10] OFC 2004 , 2005 proceedings
  • [11]http://www.cisco.com/univercd/cc/td/doc/product/mels/cm1500/dwdm/dwdm_ovr.htm

Optical Networks

optical networks laboratory experiments
Optical networksLaboratory experiments
  • 1GE NIL
    • 300 km G.652 (EDFAonly)
    • 325 km G.652 (EDFA + Raman)
  • 10GE NIL
    • 2x10G+2x1G WDM 202km G.652 (EDFA + DCF)
    • 2x10G WDM 250km G.652 (EDFA + Raman + DCF)
    • 10G DWDM 302 km G.655+652 (EDFA + Raman)
    • 8x10G DWDM 250km G.652 (EDFA + FBG)
  • 10GE NIL bidirectional (single fibre) transmission
    • 2x4x10G 210km G.652 (EDFA + FBGs)

Optical Networks

optical networks laboratory experiments1

Tx1

Tx8

Rx1

Rx8

250 km G.652

.

.

.

.

EDFA 1

EDFA 2

MUX

FBG

DEMUX

Optical networksLaboratory experiments

Optical Networks

optical networks laboratory experiments2

Rx4

Rx5

Tx1

Rx8

Tx4

Tx5

Tx8

Rx1

210 km G.652

EDFA 1

EDFA 2

λ1+λ2+λ3+λ4

λ5+λ6+λ7+λ8

λ5+λ6+λ7+λ8

λ1+λ2+λ3+λ4

MUX 1

EDFA 3

EDFA 4

MUX 2

FBG 1

FBG 2

λ5+λ6+λ7+λ8

λ1+λ2+λ3+λ4

DEMUX 1

DEMUX 2

Optical networksLaboratory experiments
  • Bidirectional transmission over single fibre

Optical Networks

optical networks pdfas soas 1310 nm
Optical networksPDFAs/SOAs 1310 nm

Eye diagram after preamp, l = 100 km

Optical Networks

optical networks pdfas soas for 1310 nm
Optical networksPDFAs/SOAs for 1310 nm

Eye diagram after preamp, l = 120 km

Optical Networks

optical networks pdfas soas for 1310 nm1
Optical networksPDFAs/SOAs for 1310 nm

Eye diagram after preamp and optical filter, l = 120 km

Optical Networks

optical networks and equipment first 100gb s tests in czech republic
Optical networks and equipmentFirst 100Gb/stests in Czech Republic

Alcatel-Lucent and CESNET, 2011

  • Laboratory and field tests over CESNET2 network
  • 100G coherent transceivers can work in compensated networks – possible to deploy 10G OOK NRZ and 100G
  • Over 1063km!
  • ALU system verified to work with Cisco

and CzechLight – multivendor environment

possible in production networks!

  • 100G possible on single fibre lines! 655km!
  • Alien wavelengths possible – 100G

even together with Photonic Services

(e.g. atomic clocks comparison), 300km!

OpticalNetworks

optical networks and equipment 100 10 1 gb s tests
Optical networks and equipment100/10/1 Gb/stests

Oclaro (former Opnext), 2012

  • More laboratory verification
  • 100G together with 10G and 1G NRZ
  • Even slower signals, 100Mb/s as Photonic Service
  • Nothinh In Line with 100G coherent:
  • 240 km with EDFAs only
  • 277.5 km with EDFAs and Ramans
  • NIL with 10G was about 250 km

OpticalNetworks