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Overview

Parallel Optical All Pass Filter Equalisers and Implementation by Wisit Loedhammacakra Supervision team Dr Wai Pang Ng Prof R. Cryan Prof. Z. Ghassemlooy Northumbria Communication Research Laboratories (NCRL) Northumbria University 13 th June 2007. Overview. Long-haul communication systems

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Overview

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  1. Parallel Optical All Pass Filter Equalisers and ImplementationbyWisit LoedhammacakraSupervision teamDr Wai Pang NgProf R. CryanProf. Z. GhassemlooyNorthumbria Communication Research Laboratories (NCRL)Northumbria University13th June 2007

  2. Overview Long-haul communication systems Problem Statement Chromatic Dispersion Parallel Optical All Pass Filter Equaliser Conclusion

  3. Tx Rx Ideal communication system: • Unlimited transmission bit rate (B) • Unlimited transmission distance (L) Attenuation and dispersion limit BL product (as a benchmark for system’s performance) Long-haul Communication System 1Ideal Communication Systems Audio Video Data • Quality of digital communication systems can be monitored from bit error rate (BER) of system. • Error-free detection, BER less than 10e-9 (Single error in one billion transmittedbits)

  4. Long-haul Communication System 2Evolution of Long-haul communication systems x x x x x x Source: Agrawal

  5. Long-haul Communication System 3 Optical Communication systems

  6. Problem StatementSingle Mode Fibre (SMF) ?  Attenuation Dispersion 1.31 μm chromatic dispersion (CD) is zero, but high attenuation is 0.5 dB/km. 1.55 μm has high CD of 17 ps/nm-km while attenuation is the lowest (0.2 dB/km).

  7. Chromatic Dispersion 1 Fibre Transmitted pulse Dispersed pulse restored pulse 3 bits pattern of dispersed pulse 3 bits pattern of restored pulse

  8. Chromatic Dispersion 2 Core of fibre

  9. Chromatic Dispersion 3Output Pulses of Different Lengths of SMF

  10. Chromatic Dispersion 4Chromatic Dispersion Effect Summed signal Transmitted pulse Summed signal Dispersed pulse at 111 km

  11. Chromatic Dispersion 5The Bit Rate-length Product Doubling the bit rate (B) would reduce the repeater-less length (L) of optical communication systems by a factor of 4. CD is the main limiting factor for repeater-less length.

  12. Chromatic Dispersion 6Dispersion Compensation Techniques

  13. Parallel optical all pass filter equaliser (p-OAPF)

  14. (a) (b) (c) (a) (b) (c) p-OAPF Equaliser 1Compensated System by Using OAPF

  15. p-OAPF Equaliser 2OAPF is Implemented With IIR Structure

  16. p-OAPF Equaliser 3Compensated System by Using p-OAPF

  17. p-OAPF Conclusion Adjust the phase of the optical pulse back to the phase of transmitted optical pulse CD limits 10 Gb/s system at 30 km Be implemented in optical domain by using IIR structure and optical components Capable of extending the length to 90 km in 10 Gb/s systems

  18. Publications Papers 1. W. Loedhammacakra, W. P. Ng, and R. A. Cryan, "Investigation of an Optical All Pass Filter for a 10 Gb/s Optical Communication System," presented at PG-NET 2005 Proceeding, Liverpool John Moores University, UK, pp. 170-175, 27-28 June 2005. 2. W. Loedhammacakra, W. P. Ng, and R. A. Cryan, "An Improved Chromatic Dispersion Compensation Technique Employing an Optical All Pass Filter Equaliser in a 10Gb/s Optical System," presented at The Tenth High Frequency Postgraduate Student Colloquium, University of Leeds, UK, pp. 105-108, 5-6 September 2005. 3. W. Loedhammacakra, W. P. Ng, and R. A. Cryan, "Chromatic Dispersion Compensation Using an Optical All Pass Filter for a 10 Gb/s Optical Communication System at 160 km," presented at London Communication Symposium 2005, University College London, UK, pp. 255-258, 8-9 September 2005. 4. W. Loedhammacakra, W. P. Ng, and R. A. Cryan, “Chromatic Dispersion Compensation Employing Optical All Pass Filter by Using IIR Structure for 10 Gb/s Optical Communication System,” presented at the IEE Photonics Professional Network Seminar on Optical Fibre Communications and Electronic Signal Processing, The IEE Savoy place, London, UK, pp 17/1-17/6, 15 December 2005. 5. W. Loedhammacakra, W. P. Ng, R. A. Cryan, and Z. Ghassemlooy, “Investigation of Optical All Pass Filter to Compensate Chromatic Dispersion in a 10 Gb/s Optical Communication System at 160 km,” CSNDSP 2006, Patras, Greece, pp. 454 – 458, 19 – 21 July 2006. 6. W. P. Ng, W. Loedhammacakra, R. A. Cryan, and Z. Ghassemlooy, “Performance Analysis of the Parallel Optical All-pass Filter Equalizer for Chromatic Dispersion Compensation at 10 Gb/s,” under-review by Globecom 2007. 7. W. P. Ng, W. Loedhammacakra, R. A. Cryan, and Z. Ghassemlooy, “Characterisation of a Parallel Optical All Pass Filter for Chromatic Dispersion Equalisation in 10 Gb/s System ,” under-review by IET processing on signal processing. Posters 1. Chromatic Dispersion Compensation Technique Employing OAPF in Optical Communication Systems, presented at UK Grad Poster Competitive 2006, Northumbria University, Newcastle, Aril 2006. 2. High Speed Optical Network Need Low Dispersion, presented at Britain’s Early-State Engineers on UK Engineering research and R&D, House of Commons, London, December 2006.

  19. Acknowledgements I would like to thank: • My supervision team (Dr. Wai Pang Ng, Prof. R. Cryan and Prof. Z. Ghassemlooy) • OCR Group leader (Prof. Z. Ghassemlooy) for all of his support • Dr Krishna Busawon and Dr Mark Leach for all of the useful discussions we had • My colleague in Room E405 and E409 Especially, Hoa, Popoola, Sujan and Ming Feng for discussion and helpful.

  20. Question & Discussion Thank you

  21. Optical All Pass Filter Equaliser 1Phases of SMF, Rectangular and Dispersed Pulse The interested bandwidth is between 193.49 – 193.51 THz, which phase response of dispersed pulse is same as phase response of SMF.

  22. Optical All Pass Filter Equaliser 2Phase Response of Ideal Equaliser and OAPF The phase response of the ideal equaliser is used as the optimisation criterion. The phase response of OAPF at upper frequency does not equalise properly.

  23. Optical All Pass Filter Equaliser 3Optical Communication System

  24. Optical All Pass Filter Equaliser 6Output Pulses A dispersed pulse was equalised back to 100 ps at FWHM. The larger pulse width on the right hand side of compensated pulse is not properly compensated and resulted in higher ISI and BER.

  25. Optical All Pass Filter Equaliser 5Phase response The compensated phase is close to zero at lower frequency. At the higher frequency, the phase response is not properly compensated.

  26. Results 1Compensated Phase Response by p-OAPF

  27. Results 2Compensated Pulse by p-OAPF

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