Wejściowe pobudzenie optyczne a parametry transmisyjne światłowodów wielomodowych

• Autorzy: Siuzdak J. , Nowak R. , Stępniak G.

Warianty tytułu

EN

Input optical excitation and transmission parameters of multimode optical fibers

• Języki publikacji: PL

Abstrakty

PL

W pracy zaprezentowano model propagacji światła w światłowodach wielomodowych. Na podstawie tego modelu określono zależności teoretyczne podstawowych parametrów transmisyjnych światłowodu (pasmo i tłumienność) od sposobu jego pobudzenia. Zależności te zostały zweryfikowane doświadczalnie przy pomocy opracowanego w tym celu układu pomiarowego składającego się z przestrajanego generatora, analizatora widma oraz konwerterów E/O i O/E. Badania eksperymentalne zostały przeprowadzone zarówno dla światłowodów kwarcowo-polimerowych, jak również dla światłowodów kwarcowych. W pracy wykazano, że wpływ typu pobudzenia światłowodu na jego parametry transmisyjne jest tym istotniejszy im mniejszy jest współczynnik sprzężenia modów. Wskazano również na możliwość selektywnego pobudzania na wejściu różnych grup modów za pomocą przesunięć offsetowych.

EN

The multimode (MM) optical fibers both silica and plastic are used nowadays in LANs for high bit rate data transmission (up to 10 Gbit/s) and distances of a few hundred meters. In this paper, the influence of the launching conditions on the MM fiber attenuation and bandwidth are investigated both theoretically and experimentally for various launch types. The partial differential equation of mode group power diffusion was solved numerically. Also the initial excitation of mode groups was found. The theory indicated that the influence of initial distribution of modes is the greatest when the MM fiber modes are not coupled. Restricted launches such as offset launches usually lead to the bandwidth increase for regular n(r) profiles as compared to the overfilled launches. The reason is that they excite fewer modes than the overfilled launch. The situation is reversed for the profiles with flaws (such as a central dip). Then some launch types may even lead to the bandwidth reduction below the values guaranteed by the manufacturer. In order to verify the theoretical results a series of measurements was taken. The measurement set up consisted of a tuned generator connected to an optical transmitter (with switched wavelengths 650 nm and 780 nm), and an optical receiver coupled to an electrical spectrum analyzer. An opto-mechanical mechanism made it possible to vary the launch offset by moving a position of the end of a single mode patchcord with regard to the MM fiber center. Two SM patchcords were used with diameters of 4-žm (truly monomode) and 9 žm (bimodal- LP01 and LP11 modes were observed experimentally). Two typical GI MM silica fibers with core diameters 50 žm and 62.5 žm, and numerical apertures of 0.2 and 0.275, respectively, were examined, as well as a silica core plastic cladding SI 200 žm fiber. For the 4 žm exciter the modal bandwidth is the greatest for central launches and decreases for offsets, whereas for the 9 žm exciter the bandwidth only slightly depends on offset. Furthermore, no matter the offset, the bandwidth for the 4 žm exciter is always greater than for the 9 žm one.

Słowa kluczowe

PL

transmisja danych; sieci lokalne; światłowody wielomodowe; pasmo; tłumienność; dyspersja modowa; laser półprzewodnikowy; LED

EN

data transmission; LAN; multimode optical fiber; bandwidth; attenuation; modal dispersion; semiconductor laser; LED

• Wydawca: Wydawnictwo Naukowe PWN SA
• Czasopismo: Kwartalnik Elektroniki i Telekomunikacji
• Rocznik: 2006
• Tom: Vol. 52, z. 2
• Strony: 153--183
• Opis fizyczny: Bibliogr. 31 poz., wykr.

Twórcy

autor

Siuzdak J.

• Instytut Telekomunikacji Politechniki Warszawskiej, ul. Nowowiejska 15/19, 00-665 Warszawa

autor

Nowak R.

• Instytut Telekomunikacji Politechniki Warszawskiej, ul. Nowowiejska 15/19, 00-665 Warszawa

autor

Stępniak G.

• Instytut Telekomunikacji Politechniki Warszawskiej, ul. Nowowiejska 15/19, 00-665 Warszawa

Bibliografia

• 1. H.G. Unger: Planar optical waveguides and fibres, Oxford University Press, Oxford, 1977.
• 2. G. Yabre: Comprehensive theory of dispersion in graded index optical fibres, Journal of Lightwave Technology, vol. 18, no. 2, February 2000, pp. 166-177.
• 3. D. Marcuse: Principles of optical fiber measurements, Academic Press, New York, 1981.
• 4. L. Raddatz, I.H. White, D.G. Cunningham, M.C. Nowell: An experimental and theoretical study of the offset launch technique for the enhancement of the bandwidth of multimode fiber links, Journal of Lightwave Technology, vol. 16, no. 3, March 1998, pp. 324-331.
• 5. T. Ishigure, M. Kano, Y. Koike: Which is a more serious factor to the bandwidth of GI POF: differential mode attenuation or mode coupling?, Journal of Lightwave Technology, vol. 18, no. 7, July 2000, pp. 959-965.
• 6. R. 0lshansky, D.B. Keck: Pulse broadening in graded-index optical fibers, Applied Optics, Vol. 15, no. 2, February 1976, pp. 483-491.
• 7. R. Olshansky: Mode coupling effects in graded index optical fibers, Applied Optics, vol. 14, no. 4, April 1975, pp. 935-945.
• 8. D. Gloge: Impulse response of clad optical multimode fibers, Bell System Technical Journal, vol.52, no. 6, 1973, pp. 801-816.
• 9. J.M. Senior: Optical fiber Communications. Principles and Practice. Prentice Hall, New York, 1992.
• 10. M. Rousseau, L. Jeunhomme: Numerical solutions of the coupled power equation in step-index optical fibers, IEEE Transactions on Microwave Theory and Techniques, vol. 25, no. 7, July 1977, pp. 577-585.
• 11. Tele-fonika Kable SA: Fibre optic cables, www.tele-fonika.com.pl
• 12. K. Holejko, R. Nowak, R. Holejko: Laser beam diagnostics with CCD cameras, Instytut Telekomunikacji PW.
• 13. P. Pepljugorski, M.J. Hackert, J.S. Abott, S.E. Swanson, S.E. olowich, A.J. Ritger, P. Kolesar, Y.C. Chen, P. Pleunis: Development of system specification for laser-optimized 50-µm multimode fiber for multigigabit short-wavelength LANs, Journal of Lightwave Technology, vol. 21, no. 5, May 2003, pp. 1256-1274.
• 14. T.P. Tanaka, S. Yamada: Numerical solution of power flow in multimode W-type optical fibers, Applied Optics, vol. 19, no. 10, 15 May 1980, pp. 1647-1652.
• 15. J.N. Kutz, J.A. Cox, D. Smith: Mode mixing and power diffusion in multimode optical fibers, Journal of Lightwave Technology, vol. 16, no. 7, July 1998, pp. 1195-1202.
• 16. ITU G.651: Characteristics of a 50/125 µm multimode graded index optical fibre cable, 1998.
• 17. T.A. Lenahan: Calculation of modes in an optical fiber using the finite element method and EISPACK, Bell System Technical Journal, vol. 62, no. 9, November 1983, pp. 2663-2694.
• 18. M. Webster, L. Raddatz, I.H. White, D.G. Cunningham: A statistical analysis of conditioned launchfor Gigabit Ethernet links using multimode fiber, Journal of Lightwave Technology, vol. 17, no. 9, September 1999, pp. 1532-1541.
• 19. TIA-526-14-A: OFSTP-14 - Optical Power Loss Measurement of Installed Multimode Fiber Cable Plant (1998) (r2003).
• 20. P. Pepeljugoski, S.E. Golowich, A.J. Ritger, P. Kolesar, A. Risteski: Modeling and simulation of next generation multimode fiber links, Journal of Lightwave Technology, vol. 21, no. 5, May 2003, pp. 1242-1255.
• 21. A.K. Agarwal, G. Evers, U. Unrau: New and simple method for selective mode group excitation in graded-index optical fibres, Electronics Letters, vol. 19, no. 17, 18 August 1983, pp. 694-695.
• 22. N. Guan, K. Takenaga, S. Matsuo, K. Himeno: Multimode fibers for compensating intermodal dispersion of graded-index multimode fibers, Journal of Lightwave Technology, vol. 22, no. 7, July 2004, pp. 1714-1719.
• 23. K. Yamashita, Y. Koyamada, Y. Hatano: Launching condition dependence of bandwidth in graded-index multimode fibers fabricated by MCVD or VAD method, Journal of Lightwave Technology, vol. 3, no. 3, June 1985, pp. 601-607.
• 24. G.D. Smith: Numerical solution of partial differential equations. Finite difference methods, Oxford University Press, Oxford 1989.
• 25. M.J. Hackert: Explanation of launch condition choice for GRIN multimode fiber attenuation and bandwidth measurements, Journal of Lightwave Technology, vol. 10, no. 2, February 1992, pp. 125-129.
• 26. J.B. Schlager, M.J. Hacket, P. Pepljugorski, J. Gwinn: Measurement for enhanced bandwidth performance over 62.5 µm multimode fiber in short- wavelength local area networks, Journal of Lightwave Technology, vol. 21, no. 5, May 2003, pp. 1276-1284.
• 27. D. Harshbarger, P. Pondillo: Multimode fiber for use with laser sources, Corning Inc., WP4119, December 1999.
• 28. M.J. Hackert: Characterizing multimode fiber bandwidth for Gigabit Ethernet applications, Corning Inc., WP4062, August 2001.
• 29. Y. Koyamada, K. Yamashita;Launching condition dependence of graded-index multimode fiber loss and bandwidth, Journal of Lightwave Technology, vol. 6, no. 12, December 1988.
• 30. S.E. Golowich, W.A. Reed, A.J. Ritger: A new modal power distribution measurement for high-speed short reach optical systems, Journal of Lightwave Technology, vol. 22, no. 2, February 2004, pp. 457-468.
• 31. L. Raddatz, I.H. White, D.G. Cunningham, M.C. Nowell: Influence of restricted mode excitation on bandwidth of multimode fiber links, IEEE Photonics Technology Letters, vol. 10, no. 4, April 1998, pp. 534-536.