1. 1 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" Generation and processing of UWB Signals over fiber Béatrice Cabon IMEP Institut de Microélectronique Electomagnétisme et Photonique INPG-MINATEC, Grenoble, France Jianping Yao Microwave Photonics Research Laboratory School of Information Technology and Engineering University of Ottawa, Canada

2. 2 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" 1.Introduction to UWB 2.Photonic generation of UWB pulses 1)Based on phase modulation to intensity modulation (PM-IM) conversion 2)Based on a semiconductor optical amplifier (SOA) 3)Based on a nonlinearly biased MZM 3.Summary Outline Part I Photonic generation of UWB Signals

3. 3 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" Introduction: concept Advantages of UWB: 1.High data rate 2.Reduced multipath fading 3.Co-existing with other wireless access techniques Advantages of using direct-sequence impulse UWB: 1.Carrier free, without the need of frequency mixers and local oscillators 2.High multipath resolution 3.Ultra high precision ranging at centimeter level 4.Enhanced capability to penetrate through obstacles

4. 4 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" Introduction : FCC regulation FCC regulation approved in 2002: (1) Bandwidth >500 MHz or fractional bandwidth >20% (2) The unlicensed bandwidth: 3.1-10.6 GHz (3) Maximum power density: -41.3 dBm/MHz FCC spectral mask for indoor commercial UWB system L. Yang, and G. B. Giannakis, IEEE Signal Processing Mag., vol. 21, no. 6, pp. 26-54, Nov. 2004

5. 5 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" Introduction: Ideal UWB pulses Waveform Spectrum t (ps) f (GHz) Gaussian pulse: Gaussian monocycle (first-order derivative): Gaussian doublet (second-order derivative): monocycle doublet Gaussian

6. 6 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" PM-IM conversion based on chromatic dispersion Fig. 1. PM-IM conversion based on chromatic dispersion. Fig. 2. The corresponding RF frequency response. The frequency response is used to shape the spectrum of a Gaussian pulse to a doublet. DC First peak Second notch First notch F. Zeng and J. P. Yao, "Investigation of phase modulator based all-optical bandpass microwave filter," IEEE Journal of Lightwave Technology, vol. 23, no. 4, pp.1721-1728, April 2005.

7. 7 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" Chromatic dispersion based UWB pulse generation and distribution system F. Zeng and J. P. Yao, " An approach to UltraWideBand pulse generation and distribution over optical fiber," IEEE Photonics Technology Letters, vol. 18, no. 7, pp. 823-825, March 2006. 25 km UWB generation and distribution over fiber Fig. 1 BERT output pulse (a) the waveform, and (b) the power spectrum. (a) (b) Fig. 2. UWB doublet (a) the waveform, and (b) the power spectrum. (a) (b)

8. 8 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" TLDNLFPD UFBG PC Circulator t P R  A BC D OA Pump Probe UWB Pulse  TLS PD FBG PC Circulator t P R A BC D OA Pump Probe NLF A DC B t a t a t a t a A DC B t a t a t a t a TLS: Tunable laser source PC: Polarization Controller OA: Optical Amplifier PD: Photodetector FBG: Fiber Bragg grating NLF: Nonlinear Fiber Pulse laser source  UWB generation based on frequency discrimination F. Zeng and J. P. Yao, "Ultrawideband impulse radio signal generation using a high-speed electrooptic phase modulator and a fiber-Bragg-grating-based frequency discriminator," IEEE Photonics Technology Letters, vol. 18, no. 19, pp. 2062- 2064, Oct. 2006. The phase modulation (PM) is realized at the nonlinear fiber (NLF) via cross phase modulation and PM-IM conversion is performed at the edges of the FBG reflection spectrum (frequency discriminator). Cross phase modulation FrequencyDiscrimination

9. 9 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" 1552.80 nm 1549.01 nm Q. Wang, F. Zeng, S. Blais, and J. P. Yao, "Optical Ultrawideband monocycle pulse generation based on cross-gain modulation in a semiconductor optical amplifier," Optics Letters, vol. 31, no. 21, pp. 3083-3085, November 2006. Fig. 1. UWB pulse generation based on cross gain modulation (XGM) in a semiconductor optical amplifier (SOA) and time-delay by FBGs UWB generation based on on a semiconductor optical amplifier Generated monocycle The spectrum of the generated monocycle

10. 10 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" Nonlinearly biased MZM Mach-Zehnder Modulator (MZM): Experimental results: Pulse width 270 ps, bandwidth 8 GHz, centered at 4.5 GHz, Lower frequencies are suppressed Q. Wang and J. P. Yao, "UWB doublet generation using a nonlinearly-biased electro-optic intensity modulator," IEE Electronics Letters, vol. 42, no. 22, pp. 1304-1305, October 2006. By biasing the MZM at the nonlinear regions, UWB doublet pulses can be generated.

11. 11 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions"  Three approaches to generating UWB pulses were proposed and demonstrated: o The first approach was based on PM-IM conversion using either a dispersive device or an optical frequency discriminator. o The second approach was based on XGM in an SOA. o The third approach was based on a nonlinearly biased MZM.  All approaches could be realized using pure fiber- optic components, which have the potential for integration. Summary

12. 12 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" Acknowledgments  The Natural Sciences and Engineering Research Council (NSERC) of Canada  The contributions of Fei Zeng, and Qing Wang.

13. 13 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" 1.MWP processing and modulation schemes 2.Low cost RoF links for UWB 3.Example of UWB: MB-OFDM 4.Up conversions of UWB signals 1)UWB/O 2)O/UWB 5.Summary Outline Part II Processing of UWB Signals

14. 14 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" 1- MWP Processing and modulation schemes External modulation : larger bandwidth (50 GHz for EOM), larger electrical gain of the link, but expensive Optical domain Ouput: Microwave signal Input: Microwave signal Optical source Photodetector Optical device Advantages: Range and bandwidth extensions (MMW, UWB over fiber…) Input: Microwave signal Direct modulation : low cost, easy implementation, but limited bandwidth (30 GHz), non-linearity, RIN, chirp

15. 15 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" 2- Low cost RoF links for UWB Direct modulation: SMF and MMF Critical considerations: Fiber Laser Diode UWB in UWB out Access Node - Non-linear L-I curve - RIN - Chirp - Non-linearity - Shot noise - Thermal noise - Dark current - SMF Chromatic dispersion - MMF Intermodal dispersion Photodiode + TIA Central Station VCSEL or DFB Ref : Y. Le Guennec et al,, LEOS’ 2006 Ref : Y. Le Guennec et al, Technologies for UWB-Over-Fiber, LEOS’ 2006

16. 16 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" 3- Example of UWB : MB-OFDM Band #1 Band #2 Band #3 Band #4 Band #5 Band #6 Band #7 Band #8 Band #9 Band #10 Band #11 Band #12 Band #13 Band #14 34323960 4488501655446072 6600712876568184 87129240976810296 F (MHz) PSD (dB/MHz) Band Group #1 Band Group #2 Band Group #3 Band Group #4 Band Group #5  122 sub-carriers, 22 pilots  Frequency hopping (with TFC) MB-OFDM (Multi Band-Orthogonal Frequency Division Multiplexing):  OFDM + TFC (Time Frequency Code) → Multi users possibility.  Spectrum is divided into 14 sub-bands of 528 MHz wide, data rate up to 480 Mb/s

17. 17 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" 4- MWP up-conversions of UWB UWB/O up-conversion O/UWB up-conversion Laser Diode Modulator or UWB –on optical carrier UWB « frequency converted» Photodiode + TIA Fiber UWB « frequency converted» UWB – »baseband»

18. 18 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" UWB/O up-conversion Principles : 1) f sci Freq (GHz) 0 0 -50 PSD (dBc/Hz) 0.4 -0.4 Non linear MWP mixing f sc 1 f sc2 ….. Frequencyhopping Freq (GHz) 2) 3.1 10.6 0 60 Freq (GHz) PSD (dBc/Hz) optical optical PD Non linear MWP mixing PD UWB - OFDM UWB

19. 19 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" F H + F IF Example: Optical up-conversion for frequency hopping over fiber MB-OFDM frequency hopping using optical MW mixing IF = OFDM UWB signal freq F IF freqPP Ref : Y. Le Guennec et al,, LEOS’ 2006 Ref : Y. Le Guennec et al, Technologies for UWB-Over-Fiber, LEOS’ 2006 Up - conversion

20. 20 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" MWP mixing : nonlinear modulations a) Laser diode (LD) PD out IF P DC Bias Tee + in LO P in UWB P b) Electro-optic external modulator (EOM) EOM PD out IF P DC Bias Tee + in LO P in UBW P I P op t V

21. 21 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" MWP mixing : cascaded modulations c) LD + EOM, linear in UWB P in LO P EOM DC Bias Tee PD out IF P Allow remote inputs V P opt I d) EOM + EOM, linear in UWB P EOM1 DC Bias Tee PD out IF P EOM2 in LO P Bias Tee

22. 22 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" Up conversion O/UWB e) Photodiode (PD) in UWB P in LO P out IF P Non linear MWP mixing photodiode V I

23. 23 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" Optical microwave up-conversion of OFDM (802.11a)  Direct modulation: low cost mixing solution, no additional component  Bias current close to the threshold current I bias (mA) EVM (% rms) P-I curve -Compromise between optimal mixing in non linear zone and clipping -Higher photodetected RIN to consider in 528 MHz BW Frequency hopping with direct modulation Experimental OFDM up-conversion from 1.5 GHz to 5.8 GHz

24. 24 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" Perspectives for UWB/O at 60 GHzLinearRegime Min T Optical carrier suppression PD - sub-carrier at 2 f LO = 40 GHz The 60 GHz optical heterodyne signal is generated by the double side band suppressed carrier “DS-SC” method UWB - PRBS 2 Gb/s signal on sub-carrier of 2 GHz UWB signal around 40 GHz SA PMF EOM 1 2 PMF SMF X UWB f sc =2 GHz f LO =20 GHz PDs 60GHz DFB 1550nm EDFA

25. 25 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" Input PRBS 2 Gb/s Output Up converted PRBS around 60 GHz 2 Gb/s

26. 26 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" O-UWB up-conversion : experimental results @ IMEP UWB signal up-converted at 8 GHz P LO =10 dBm UWB signal, BW 3.4 GHz IR-UWB signal 8 GHz BW 6-10 GHz

27. 27 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" Monocycle input signal, time domain Monocycle – FFT Frequency domain BW=3.416 GHz

28. 28 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" Up-conversion of UWB at 8 GHz Perspectives : 60 GHz up-conversion

29. 29 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" 5- Summary  Two approaches to up-converting UWB signals o The first approach, UWB/O uses EOM and LD o The second approach, O/UWB, uses a PD all based on a non-linearity  Approaches allow transmission at 60 GHz for future picocellular WLAN’s applications

30. 30 ISIS-IPHOBAC SUMMER SCHOOL, May 17-18, 2007, Budapest, Hungary "Broadband Architectures and Functions" Acknowledgments  UROOF IST project,  The contributions of Giang NGUYEN, René GARY and Yannis LE GUENNEC