1 Hejie Yang – BroadBand Europe, Dec. 5, 2007 Chromatic dispersion tolerance of the optical frequency multiplication technique for radio over single mode fibre G. -J. Rijckenberg, A.M.J. Koonen and A. Ngoma* Presenter: Hejie Yang Electro-Optics Communication Systems group, COBRA Institute Eindhoven University of Technology * now with Corning US

2 Hejie Yang – BroadBand Europe, Dec. 5, 2007 Outline: Optical frequency multiplication (OFM) technique Theoretical analysis Simulation and experimental results Conclusion

3 Hejie Yang – BroadBand Europe, Dec. 5, 2007 where n is the order of harmonics generated by frequency sweeping very large dispersion tolerance! Optical frequency multiplication for RoF Impact of fibre dispersion on delivery of a 30 GHz carrier over SMF, using IM-DSB and OFM (5 th harmonic), [Koonen, ECOC07]

4 Hejie Yang – BroadBand Europe, Dec. 5, 2007 Theoretical analysis – OFM system model (1/3) The power P n of n th harmonic after propagation through dispersive fibre: J k : k th order Bessel function of the first kind :the FM index, m :the FM sweep frequency, 0 :the optical carrier frequency, :the differential arm delay of the MZI β 0 : fibre dispersion where

5 Hejie Yang – BroadBand Europe, Dec. 5, 2007 Theoretical analysis – OFM system model (2/3) From Grafs addition formula of Bessel function the power of n th harmonic: Two sources of input: - fibre dispersion (β 0) - interferometric FM-IM conversion in MZI ( )

6 Hejie Yang – BroadBand Europe, Dec. 5, 2007 Theoretical analysis – OFM system model (3/3) By tuning the optical carrier frequency n with respect to the MZI parameter power of harmonics can be optimized: Three extremes of optical carrier frequency: with l an integer Without dispersion, correspond to the optical frequency that maximize the generation of even and odd harmonics

7 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 m should be avoided

8 Hejie Yang – BroadBand Europe, Dec. 5, 2007 Analytical results β = 3.3, m =2 f m, D = 16ps/nm/km, = 10e-10 s, f m =4.44GHz, 5 th harmonics

9 Hejie Yang – BroadBand Europe, Dec. 5, 2007 Experimental results OFM system does not suffer any fading throughout 72 km SMF between km: dispersion dominates outside this range: other parameters contribute

10 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.

11 Hejie Yang – BroadBand Europe, Dec. 5, 2007 Thank you for your attention! Acknowledge for EU-funded FP6 project MUSE – MUltiService access Everywhere Q & A …