1 Simulation of High Speed Photonic Networks Professor Z. Ghassemlooy Optical Communications Research Group School of Computing, Engineering and Information Sciences University of Northumbria at Newcastle, UK

Eng. of S/W Pro., India Presentation Outline 1. Photonic Networks 2. Photonic Packet Switching 3. Photonic Router Modelling 4. OFDM 5. Results 3. Conclusions

3 Optical Communications  1 st generation optical networks: packet routing and switching are mainly carried out using high-speed electronic devices.  However, as the transmission rate continues to increase, electronically processing data potentially becomes a bottleneck at an intermediate node along the network. 1P 100T 10T 1T 100G 10G 1G 100M [bit/s] Voice Data Total Traffic demand forecast (NEC–2001) Capacity increase : 2~4 times a year Bit cost decrease : 1/2 time a year  Solution: All-optical processing & switching

Eng. of S/W Pro., India 2009 Ref: Prof. Leonid G. Kazovsky, et al. “ Broadband Fiber Access ”, available online from

Eng. of S/W Pro., India All-Optical Packet Switching Objectives High Bit Rate High Throughput HeaderProcessing!

Eng. of S/W Pro., India Photonic Network - Packet Routing O/E Processing E/O PatternsOutputs 0000 B (0 D ) OP B (1 D ) OP B (2 D ) OP B (3 D ) OP B (4 D ) OP B (5 D ) OP 1 …… 1110 B (14 D ) OP B (15 D ) OP Matching! H Routing table Electrical domain IC: Large scale, cheap, memory Speed limitation < 40 Gbit/s Optical domain High Speed >> 40 Gbit/s Complexity, costly, no memory Optical vs. Electrical in High-speed Routing All-Optical Processing Integration Light “Frozen”? “Opt. Capacitors”?

Eng. of S/W Pro., India 2009 Photonic Network – All-optical Routing 7 Aim: 1.To optimise the SMZ performance for all-optical functions. 2.To design a bi-directional SMZ and implement it in the router to reduce components, time and cost.

Eng. of S/W Pro., India Photonic Network - Packet Routing Packet header is compared with all entries of a routing table for checking the matching Robust All-Optical Processing Exhaustive Correlation N  2 N N  2 N bit-wise AND operations Reduce routing table entries Minimise number of AND operations Our solution: Pulse-Position-Modulation based Header Processing PPM-HP (PPM-HP)

Eng. of S/W Pro., India Photonic Network - Packet Address Bit duration: T b Slot duration: T s = T b /4 PPM T s No. of slot L = 2 4 TbTb LSB a 3 a 2 a 1 a 0 Add. in Binary One Frame of 4-bit RZ OOK Decimal value = 9 Location 9 Payload Address Clock Optical Packet

Eng. of S/W Pro., India Photonic Network - Routing Table Conventional routing table Address patterns Decimal metric Output ports 00…0000Port 2 00…0011Port 1 00…0102Port 3 00…0113Port 1 00…1004Port 3 00…1015Port 2 00…1106Port 2 00…1117Port 1 ……… 11…102 N -2Port 2 11…112 N -1Port 1 2 N entries Entry Positions (Decimal) Actual PPM frame (length 2 N slots) 11,3,7,…,2 N -1 20,5,6,…,2 N -2 32,4,… PPM … N -1 … … Pulse-position routing table 1M1M (M = 3 ports) Port 1 Port 2 Port 3

Eng. of S/W Pro., India Clk Matched pulse … &1 Entry 1 Entry 2 … Entry M … CP 1 CP 2 CP M Port 1 Port 2 Port M PPM-HP All-optical Switch … &2 &M&M … … Clock Extraction Header Extraction PPM Add. Conversion PPRT … OSWC Synchronisation APLClk APLClk APLClk APLClk PPMA A All-optical Packet-switched Router – PPM Touting Table OSW1 OSW2 OSWM

12 Simulation Software to Model Routers OptiWave (systems, devices, components) OptiWave (systems, devices, components) R-Soft (systems & devices) R-Soft (systems & devices) Photoss (WDM systems & devices) Photoss (WDM systems & devices) Virtual Photonic Inc. (VPI) (systems & devices) Virtual Photonic Inc. (VPI) (systems & devices)

Simulation Software - Matlab No optical communications tool box Complex to model optical networks – Need strong theory Can be used with other software packages such as VPI to save modelling and debugging time Ideal for the end users with a strong mathematical and programming background 13

14 Simulation Software - VPI Very powerful for optical networks and optical devices modelling Support C and Matlab Support C and Matlab Has visual interface (drag and drop) – e.g. oscilloscopes etc Provide extensive simulation examples and manuals Provide extensive simulation examples and manuals Online discussion forum Online discussion forum

15 VPI Simulation Software Laser Source Optical Scope BER Tester SMZ Eng. of S/W Pro., India 2009 A typical optical switch

Eng. of S/W Pro., India 2009 Simulation of Devices - SOA Semiconductor Optical Amplifier Best to use Matlab: Segmentisation of SOA improves accuracy Not possible with the current VPI 16 L Injection current (I) Input facet of active region Input signals Output signals Output facet H w segment 1 segment 2 ………….. ………… …. segment 5 t=0 g t=l/v g t=L/v g Input signal output signal NiNi N(1) N(5)

17 Total gain with no input Signal output gain corresponding to the input power at different wavelengths Simulation of Devices – SOA Results

18 Optical Switches MEMS * (Lucent Tech.) Bubbles * (Agilent) TOAD * (Princeton) SMZ * (Japan) Cat.1 Large scale (> 16  16) Slow response (  s-ms) Non-optically controlled Cat.2 Small scale (2  2) Fast response (fs-ps) Full-optically controlled Crosstalk Contrast

Eng. of S/W Pro., India 2009 VPI – SMZ Switch 19 CP1=CP2 Recovery region

Eng. of S/W Pro., India 2009 VPI – SMZ Switch 20 Optical receiver Data pulse train

AA bar VPI Simulation Software – Inverter Gate Input packets Control pulse Output1 Output2 SOA Input (CLK) CP 1 (CLK) CP 2 (A) Output (A bar)

Eng. of S/W Pro., India 2009 Packet Address Correlator To carry packet routing decision one needs to check (correlated) packet address with entries of routing table … … AND gate A B A*B PP packet address One PPRT entry Matched SOA1 SOA2  in  SW A B ABAB

Eng. of S/W Pro., India 2009 PPM-HP Router - Clock Extraction Clock extraction requirements: Asynchronous and ultrafast response High on/off contrast ratio of extracted clock Clock, header and payload: same intensity, polarization and wavelength 4 Clock Extraction Clk Optical packet

Eng. of S/W Pro., India 2009 PPM-HP Router - Clock Extraction 5 2222 2222 SOA1 SOA2 1212 2222 SMZ-1 2222  in  SW 1212 G CP Optical delay Attenuator Polarization Beam Splitter (PBS) Polarization Controller (PC) Amplifier Optical fiber span SMZ-2 1212 2222 2222 2222 2222  SW  in 1212 SOA1 SOA2  Clk Self-extraction: packet as the control signal High on/off contrast ratio: two switching-stage

Simulation – Clock Extraction 13 2 nd stage Packet in Extracted clock 1 st stage Crosstalk

Eng. of S/W Pro., India (a) (b) VPI – Packet Address Conversion

1  2 SMZ Switch with a High Contrast Ratio CEM: clock extraction module low inter-output CR (< 10 dB) Improved CR (> 32 dB)

Eng. of S/W Pro., India 2009 Fibre Delay Line – Passive using Matlab A B C In Out Fibre loop Switch Eye diagram after 200 iterations without regeneration

Eng. of S/W Pro., India 2009 Fibre Delay Line - Active with Regeneration A B C In Out DSF fibre loop Switch Optical amplifier Optical regenerator Clock Eye diagram after 200 iterations with regeneration

Eng. of S/W Pro., India 2009 SMZ - Simulation Parameters

Eng. of S/W Pro., India 2009 VPI – PPM Routing Table 31

32 VPI Simulation Software – Router

Simulation Results-Time Waveforms (a) input packet at node A (b) extracted clock at nodes A (c) extracted clock at nodes B FWHM = 2ps

Routing Table Single PPM RT Multiple PPM RTs Conventional RT

E 1A E 2A E 3A E 1B E 2B E 3B E 1C E 2C E 3C E 1D E 2D E 3D E A (24 – 31)E B (16 – 23)E C (8 – 15)E D (0 – 7) E1E1 E2E2 E3E3 Check MSBs a4 a4 a3 a3 (X=2) a2 a1 a0a2 a1 a0 a 4 a 3 =11 a 4 a 3 a 2 a 1 a 0 (N=5) a 4 a 3 =10 a 4 a 3 =01 a 4 a 3 =00 VPI – PPM Multiple Routing Table

Simulation Results-Multi-hop An optical core network with 32 edge nodes (4 hops)

37 Simulation - Multiple-hop Routing Node/Router 1 Node/Router 2 Node/Router 3 Signal intensity is varied Noise level is increased B B M B M B: broadcast M: multicast Node/Router 1 Node/Router 2 Node/Router 3

Eng. of S/W Pro., India 2009 SMZ - Simulation Results Inter-channel crosstalk Eye diagram

Eng. of S/W Pro., India 2009 Simulation Results – Network Performance Multiple-hop OSNR Predicted & simulated OSNRs

1xM All-optical Packet-switched WDM Router WDM MUX WDM MUX Input Output 1 Output 2 DEMUXDEMUX … … WDM MUX e 1 e 2 e M … … … E 1 E 2 E 3 E M PPM-HP 1 PPM-HP 2 … … … PPM-HP L … OutputM... PK 1 PK 2 PK L... PK 3 E 1 E 2 E 3 E M E 1 E 2 E 3 E M L L L PK 1 PK 2 PK L PK 1 PK 2 PK L … … L: The numbers of input wavelengths M: The numbers of the output ports (In this simulation L = 2 and M =3)

Simulation Results- Time Waveforms Packets at the inputs of the WDM router Packets observed at the output 2 of the WDM router

Optical OFDM 42 Orthogonal Frequency Division Multiplexing (OFDM) Harmonically related narrowband sub-carriers The sub-carriers spaced by 1/Ts The peak of each sub-carrier coincides with trough of other sub-carriers Splitting a high-speed data stream into a number of low-speed streams Different sub-carrier transmitted simultaneously

Applications of OOFDM Modems Access and local area networks - Access and local area networks - IMDD modems Future high-capacity long-haul networks Coherent modems: Combating optical fibers dispersion and polarization mode dispersion 43

OOFDM Modems - Modelling Matlab: easy to model the OFDM modem 32-QAM modulation 32-QAM detectionm with additive noise 44

OOFDM Modems – Modelling 45 VPI Screen shots (OTDM to WDM Transmultiplexers)

Software Modelling VPI is not very flexible when it come to modelling algorithm, consequently Matlab code can be used as a part of VPI VPI has visual interface (drag and drop), with the ability to use test and measurement tools Solid mathematical background is essential to fully utilise VPI, otherwise it could lead to mis- understanding and consequently obtaining wrong results 46

47 It All Starts From An Initial Idea Simulation softwares enables us to develop new ideas & gain some insight before designing systems System block diagram Simulation layout Experimental setup

Eng. of S/W Pro., India Conclusions What one should look for in simulation software packages in photonic switching network: 1. Easy to learn and use 2. Lower PC hardware specifications 3. Fast and as realistic as possible 4. Quality technical support, training and online discussion forums 5. Updateability 6. Compatibility with other simulation softwares

Special Thanks for Dr. Wai Pang Ng Dr. Hoa Le Minh Dr M F Chaing A. Shalaby M. A. Jarajreh

Eng. of S/W Pro., India Thank you for your attention ! Any questions?

Eng. of S/W Pro., India 2009 Future Contact Web: Web: Tel: Tel: