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Progress Toward Fast Reconfigurable Optical Cross ... - SURFnet

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					Progress Toward Fast Reconfigurable
       Optical Cross-connect

     Prasanna A. Gamage, Huug De Waardt

            COBRA Research Institute,
         Technical University of Eindhoven.

           In Co-operation with SurfNet.
Outline

   Overview
       Existing Reconfigurable Cross-connect - DAS3


   Motivation
       DAS3 → DAS4

   Fast Reconfigurable Optical Cross-connect Design
       Optical Cross-connect design
       EDFA Gain Dynamics in reconfigurable Transmission Systems


   Summary
 Existing System – DAS3
TR

TR

TR   M
     U
                          D
                          M
                                                                                 D
                                                                                 M
                                                                                                       M
                                                                                                       U
                                                                                                                TR   – Transponder
                          U                                                      U
TR   X                                                                                                 X

TR
                          X                                                      X
                                                                                                                MUX – Multiplexer
                                                                                                                DMUX – De-multiplexer
VU – Free University of                                            ASTRON – The Netherlands Institute                – Erbium Doped
     Amsterdam                                                              for Radio Astronomy
                                       MUX
                                                                                                                       Fiber Amplifier
                                                        DAS3
TR                                                                                                         TR

TR                                                                                                         TR
                          D                                                      D
     M                             M                                    M                          M
                          M                                                      M
TR   U                        TR   U                                    U                          U       TR
                          U                                                      U
     X                             X                                    X                          X
                          X                                                      X
TR                                                                          TR                             TR

                                                                            TR                             TR


Dt – Technical University                                                        LU – University of Leiden
     of Delft                                       MUX


                                         TR   TR   TR    TR   TR   TR


                               UvA – University of Amsterdam

        Issue
             Logical topology switching time is around 15 minutes
                   Can become a major hindrance for applications sensitive to latency
Motivation
                                                    DAS4-FPX
                  VU                                                                                   ASTRON

             TR               TR                                                          TR                    TR

             TR               TR                                                          TR                    TR
                          D                                                                    D
             TR   M           TR    M                                               M     TR           M        TR
                          M                                                                    M
                  U                 U                                               U                  U
                          U                                                                    U
             TR   X                 X                                               X                  X        TR
                          X                                                                    X
             TR

             TR

                                              MUX                        MUX
                                   MML                                              UvA
                                         TR   TR    TR              TR   TR    TR



                  Dt                                          DAS3                                 LU
             TR                                                                                            TR

             TR                                                                                            TR
                          D                                                                    D
                  M                 M                                               M              M
                          M                                                                    M
                  U                 U                                               U              U
                          U                                                                    U
                  X                 X                                               X              X
                          X                                                                    X




                                                          MUX


                                                         TR    TR              UvA



   Objective of the project
        Fast Reconfigurable Optical Cross-connect switch with logical topology
         switching time on the order of milliseconds.
Motivation
                                                                 DAS4-FPX
                        VU                                                                                                 ASTRON

                   TR                       TR                                                TR                             TR

                   TR                       TR                                                TR                             TR

                   TR                       TR                                                TR                             TR

                   TR                                                                                                        TR

                   TR

                   TR


                                                 MML                                    UvA
                                                       TR   TR   TR      TR   TR   TR


   Focus
         Understand the impact of switching on EDFA performance.
            Power excursion due to EDFA gain dynamics.

   Logical Topologies
    VU         Astron        VU         Astron              VU                 Astron              VU             Astron          VU        Astron




          Case 1                   Case 2                             Case 3                             Case 4                        Case 5



    MML            UvA       MML            UvA             MML                    UvA             MML             UvA       MML                UvA
Fast Reconfigurable Optical Cross-Connect Design

   Basic Building Blocks
   Wavelength Selective Switch (WSS) technologies
   Fast Reconfigurable Optical Cross-connect Design
   Analysis of EDFA Gain Dynamic in Reconfigurable
    Transmission Systems
       Simulation results
Basic Building Blocks
   Arrayed waveguide gratings (AWG)
       Wavelength channel Mux/Demux
   Optical power splitters
       Can be used for broadcasting
   Tunable optical filters
   Wavelength Selective Switch (WSS)
       Individual wavelengths on a common input fiber
        can be selectively switched to any of multiple                               Wavelength         1   λ1 λ7
        output fibers.                                                                Selective         2   Ø

                                                                                       Switch           3   λ3
       Broadcasting is not possible                                                                    4   λ2   λ5
                                                                                  Common
       Reciprocal device               λ λ λ λ λ λ λ λ λ
                                        1   2   3   4   5   6   7   8   9   λ10                         5   Ø
                                                                                  input
                                                                                                        6   Ø


                                                                                                        7   λ4 λ9
                                                                                                        8   λ8

                                                                                                        9   λ6   λ 10



                                                                                  Electrical controls
Schematic Design – Fast Reconfigurable Optical
Cross-Connect
                                    MML                       MML




                                    UvA                       UvA




                                    ASTRON                    ASTRON




   Broadcast-Select Architecture
       Scaling
                                    VU                        VU
          Large port count
       Enough amplification
          Counter the losses
                                             Splitter   WSS
Simulation – Reconfigurable Transmission System
for EDFA Gain Dynamic Analysis
   Optical power transient behavior due to switching
       Optical power excursion in remaining channels due to channel drop
       Optical power excursion in channels due to channel add

        Sudden optical power surge could impair the receiver performance.
TX                                     DAS4-FPX                                        D
                                                                                            RX
      M
                                                                                       M
TX    U                                                                                     RX
                                                                                       U
      X
                                                                                       X
TX                                                                                          RX

     MML                                                                              MML


TX                                                                                          RX
                                                                                       D
      M
                                                                                       M
TX    U                                                                                     RX
                                                                                       U
      X
                                                                                       X
TX                                                                                          RX
                                                      EDFA transient response
     UvA                                                does not propagate            UvA



TX                                                    R T                                   RX

TX                             D                  D   R T                              D    RX
      M                            M                        M
                               M                  M                                    M
      U                            U                        U
                               U                  U                                    U
TX    X    84 km       97 km   X
                                   X
                                                  X   R T   X    97 km       84 km     X    RX

TX                                                                                          RX

 ASTRON                                               EDFA transient response        ASTRON
                                                        does not propagate

TX                                                    R T                                   RX

TX                                                    R T                                   RX

TX                             D                  D   R T                              D    RX
      M                            M                        M
                               M                  M                                    M
      U                            U                        U
                               U                  U                                    U
TX    X            45 km       X
                                   X
                                                  X
                                                            X        45 km             X    RX

TX                                                                                          RX

TX                                                                                          RX

     VU                                                                                VU
TX1
                                        DAS4-FPX     D
                                                          RX1
       M
                                                     M
TX2    U                                                  RX2
                                                     U
       X
                                                     X
TX3                                                       RX3

      MML                                           MML


TX1                                                       RX1
                                                     D
       M
                                                     M
TX2    U                                                  RX2
                                                     U
       X
                                                     X
TX3                                                       RX3

      UvA                                           UvA



TX1                                                       RX1

TX2                             D                    D    RX2
       M                            M
                                M                    M
       U                            U
                                U                    U
TX3    X    84 km       97 km   X
                                    X
                                                     X    RX3

TX4                                                       RX4

  ASTRON                                           ASTRON



TX1

TX2                                                       RX1

TX3                             D                    D
       M                            M                     RX2
                                M                    M
       U                            U
                                U                    U
TX4    X            45 km       X
                                    X
                                                     X    RX3

TX                                                        RX4

TX                                                  VU
      VU
TX1
            DAS4-FPX       D
                                RX1
                                           VU         Astron
       M
                           M
TX2    U                        RX2
                           U
       X
                           X
TX3                             RX3


      MML                 MML                   Case 1


TX1                             RX1
       M
                           D              MML            UvA
                           M
TX2    U                        RX2
                           U
       X
                           X
TX3                             RX3
                                           VU         Astron
      UvA                 UvA


TX1                             RX1             Case 2
TX2                        D    RX2
       M
                           M
       U
                           U
TX3    X                        RX3
                           X
                                          MML            UvA
TX4                             RX4

  ASTRON                 ASTRON
                                         Switching
                                               Channels compete
TX1
                                                for gain
TX2                             RX1            Momentary increase
                           D
                                                in channel optical
TX3    M                        RX2
       U
                           M                    power due to
                           U
TX4    X
                           X    RX3             channel drop and
                                                add
TX                              RX4


            Case 1 → 2    VU
TX

       VU
Simulation model – WSS
Fast Reconfigurable Optical Cross-Connect Switch
Simulation setup - Reconfigurable Transmission
System
Simulation Results

    Subset of logical topology transitions representing all the possible
     power level changes
    VU        Astron    VU             Astron   VU             Astron   VU             Astron




         Case 1               Case 2                  Case 1                  Case 3



MML               UvA   MML             UvA     MML             UvA     MML             UvA




    VU        Astron    VU             Astron   VU         Astron       VU             Astron



         Case 1               Case 4                  Case 1                  Case 5



MML               UvA   MML             UvA     MML            UvA      MML             UvA
Simulation Results
                               Optical Power Evolution – Channel at MML Node                                 Optical Power Evolution - Channel at MML Node (Close Up)
                          5                                                                                   2
                                                       Transient
                          0
                                                                                                             1.5




                                                                                       Optical Power (dBm)
    Optical Power (dBm)




                          -5
                                                                                                              1
                     -10                                                                                                                    1.6 dB
                                                                                                             0.5
                     -15
                                                                                                              0
                     -20                                                                                                         140 µs


                     -25                                                                                -0.5

                                                                   Case 1 to 2                                                                         Case 1 to 2
                     -30                                                                                     -1
                        0                  0.5               1                   1.5                           1        1.1       1.2       1.3       1.4            1.5
                                                 Time (ms)                                                                           Time (ms)



   Power excursion – MML Node
                              Power excursion of added channel is 1.6 dB
Simulation Results
    Optical Power Evolution – Channel at ASTRON Node (Close Up)                                            Optical Power Evolution – Channel at ASTRON Node
        1                                                                                            5


                                                                                                     4




                                                                               Optical Power (dBm)
    Optical Power (dBm)




                          0.5                                                                        3
                                                  0.8 dB                                                                                         4.73 dB
                                                                                                     2


                           0                                                                         1
                                       135 µs

                                                                                                     0

                                                           Case 1 to 2                                                                          Case 1 to 2
                     -0.5                                                                            -1
                         1      1.1   1.2       1.3        1.4           1.5                           0                 0.5               1               1.5
                                         Time (ms)                                                                             Time (ms)



   Power excursion – ASTRON Node
                           Power excursion of added channel is 0.8 dB
                           Power excursion of the remaining (express) channel 4.73 dB

   Power excursion for all the transitions
                           In the remaining channel < 4.8 dB
                           In the added channels    < 1.8 dB
Summary
   Briefly discussed the DAS4 reconfigurable cross-connect optical
    switch.
   Simulated the reconfigurable transmission system to analyze the
    impact of EDFA gain dynamics on system performance.
       Momentary power increase in the remaining channel due to channel drop
        < 4.8 dB for all the cases
       Momentary power increase in channels due to channel add < 1.8 dB for all
        the cases
   Next phase will be the implementation of our design.




                            Acknowledgement: SurfNet
Insertion Losses
Switch = 17 dB ( 1x8 coupler ≈ 9 dB, WSS insertion loss = 6.5 dB, Connector loss = 0.5 dB + PDL = 1 dB)
8x8 AWG = 7.5 dB (Polarization dependent loss + Loss Uniformity + Insertion loss = 0.5 + 1 + 6)
Connector loss = 0.25 dB

10 Gbps Transponder (OIF Specification)
Transmitter                                  PIN Receiver
Spectral Range = 1530 nm to 1565 nm          Sensitivity = - 16.5 dBm @ BER = 10-15 (Post FEC)
Extinction ratio = 10 dB                     Rx overload = + 7 dBm
Output Power = -2.5 dBm




                                                                                              AWG
                                                                                           CH# λ (nm)
                                                                                            1 1558.17
                                                                                            2 1558.58
                                                                                            3 1558.98
                                                                                            4 1559.39
@ 1550nm                  Loss        Dispersion                                            5 1559.79
SMF – G.652               0.26 dB/km 17 ps/nm-km                                            6 1560.20
                                                                                            7 1560.61
True Wave RS – TW-RS 0.23 dB/km 4 ps/nm-km                                                  8 1561.01

				
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