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Chromatic dispersion tolerance of the optical frequency multiplication technique for radio over single mode fibre. G. -J. Rijckenberg, A.M.J. Koonen and A. Ng’oma* Presenter: Hejie Yang Electro-Optics Communication Systems group, COBRA Institute Eindhoven University of Technology.
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Chromatic dispersion tolerance of the optical frequency multiplication technique for radio over single mode fibre G. -J. Rijckenberg, A.M.J. Koonen and A. Ng’oma* Presenter: Hejie Yang Electro-Optics Communication Systems group, COBRA Institute Eindhoven University of Technology * now with Corning US Hejie Yang – BroadBand Europe, Dec. 5, 2007
Outline: • Optical frequency multiplication (OFM) technique • Theoretical analysis • Simulation and experimental results • Conclusion Hejie Yang – BroadBand Europe, Dec. 5, 2007
Optical frequency multiplication for RoF where n is the order of harmonics generated by frequency sweeping very large dispersion tolerance! Impact of fibre dispersion on delivery of a 30 GHz carrier over SMF, using IM-DSB and OFM (5th harmonic), [Koonen, ECOC’07] Hejie Yang – BroadBand Europe, Dec. 5, 2007
Theoretical analysis – OFM system model (1/3) The power Pn of nth harmonic after propagation through dispersive fibre: Jk :kth order Bessel function of the first kind b: the FM index, wm : the FM sweep frequency, w0 : the optical carrier frequency, t :the differential arm delay of the MZI β0’’: fibre dispersion where Hejie Yang – BroadBand Europe, Dec. 5, 2007
Theoretical analysis – OFM system model (2/3) From Graf’s addition formula of Bessel function the power of nth harmonic: • Two sources of input: • fibre dispersion (β0’’) • interferometric FM-IM conversion in MZI ( t ) Hejie Yang – BroadBand Europe, Dec. 5, 2007
Theoretical analysis – OFM system model (3/3) By tuning the optical carrier frequency wn with respect to the MZI parameter t power of harmonics can be optimized: Three extremes of optical carrier frequency: Without dispersion, correspond to the optical frequency that maximize the generation of even and odd harmonics with l an integer Hejie Yang – BroadBand Europe, Dec. 5, 2007
Theoretical analysis – impact of fibre length • Assuming • for the odd harmonics with n = 2l+1, power of harmonics simplifies to • Assuming • for the even harmonics with n = 2l, power of harmonics simplifies to In both cases: harmonic power determined by dispersion, and have infinite number of zeros the above two values of wm should be avoided Hejie Yang – BroadBand Europe, Dec. 5, 2007
Analytical results β = 3.3, wm=2pfm, D = 16ps/nm/km, t = 10e-10 s, fm=4.44GHz, 5th harmonics Hejie Yang – BroadBand Europe, Dec. 5, 2007
Experimental results • OFM system does not suffer any fading throughout 72 km SMF • between 20-60 km: dispersion dominates • outside this range: other parameters contribute Hejie Yang – BroadBand Europe, Dec. 5, 2007
Conclusion • A model describing the OFM system behavior with chromatic dispersion, experiments confirm the theoretical prediction • The model shows that OFM does not exhibit fading as in the IM-DSB scenario • However, fading can occur in the OFM system for specific sweeping frequency, when chromatic dispersion is the only determining component. • The model can be used to decide optimal operation parameters in OFM systems. Hejie Yang – BroadBand Europe, Dec. 5, 2007
Q & A … Thank you for your attention! Acknowledge for EU-funded FP6 project MUSE – MUltiService access Everywhere Hejie Yang – BroadBand Europe, Dec. 5, 2007