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Multiwave quasi-phase matched anti-Stokes stimulated Raman scattering

Multiwave quasi-phase matched anti-Stokes stimulated Raman scattering. Nikolai S. Makarov Saint-Petersburg State Institute of Fine Mechanics and Optics (Technical University). Victor G. Bespalov Russian Research Center "S. I. Vavilov State Optical Institute". Outline.

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Multiwave quasi-phase matched anti-Stokes stimulated Raman scattering

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  1. Multiwave quasi-phase matched anti-Stokes stimulated Raman scattering Nikolai S. Makarov Saint-Petersburg State Institute of Fine Mechanics and Optics (Technical University) Victor G. Bespalov Russian Research Center "S. I. Vavilov State Optical Institute"

  2. Outline • Principle of quasi-phase matching • Systems of multiwave SRS equations • QPM multiwave SRS • Conclusions • References 2

  3. Principle of quasi-phase matching Nonlinearity (2) Nonlinearity (3) Raman active medium 3

  4. Principle of quasi-phase matching at SRS • Generalized phase • =2p-a-s-(ka+ks-2kp)r, • where ki – is the wave vector of interacting wave, that describes the direction of energy conversion “pump – Stokes – anti-Stokes”, on active layers input (1, 3) do not practically change, that in a final result provides a realization of quasi-phase matching conditions. 1 3 2 0 (3)0 (3)=0 4

  5. System of transient multiwave SRS equations j – wave mismatching, g – steady-state Raman gain coefficient, j – frequencies of interacting waves, Ej– complex wave amplitudes. In this system the wave mismatching and Raman gain are the functions of coordinate for nonlinear ((3)0) and linear ((3)=0) layers. Raman gain dispersion Ba(NO3)2 H2 5

  6. System of steady-state multiwave SRS equations j – wave mismatching, g – steady-state Raman gain coefficient, j – frequencies of interacting waves, Ej– complex wave amplitudes. In this system the wave mismatching and Raman gain are the functions of coordinate for nonlinear ((3)0) and linear ((3)=0) layers. Raman gain dispersion Ba(NO3)2 H2 6

  7. Influence of highSRS components on calculations precision • For best calculation accuracy it is necessary to take into account at least the generation of 4 Stokes and 4 anti-Stokes SRS components. 7

  8. Transient multiwave QPM SRS 1 – pump, 2 – first Stokes, 3 – first Anti-Stokes, 4 – second Anti-Stokes. 8

  9. Totallength, layerscount vs pulse duration/dephasing time 9

  10. Anti-Stokes efficiencyvs pulse duration/dephasing time • Both in hydrogen and barium nitrate it is possible to use fixed periodical structure for effective conversion of pulses with duration of 3 ns and more. 10

  11. Our numerical calculations have shown that for best accuracy of QPM SRS simulations it is necessary to take into account the dispersion of Raman gain coefficient and for studying of multiwave SRS influence on QPM structure realization it is necessary to take into account the generation at least of 4 Stokes and 4 anti-Stokes SRS components. • We determined that both in hydrogen and barium nitrate it is possible to use fixed periodical structure for effective conversion of pulses with duration of 3 ns and more. • The maximum efficiency of anti-Stokes SRS conversion reaches 31% for hydrogen and 22% for barium nitrate. Conclusion 11

  12. Acknowledgments • I would like to thank the organizing committee of Conference and Russian Foundation for Basic Research for partial supporting of my participation. • This work was partly supported by Grant RP1-2249 of U.S. Civilian Research and Development Foundation and Program of Ministry of Education “Femtosecond optics and technologies”. 12

  13. V. G. Bespalov, N. S. Makarov, “Quasi-phase matching anti-Stokes SRS generation”, Proc. SPIE, vol. 4268, 2001, pp. 109-116. • V. G. Bespalov, and N. S. Makarov, “Quasi-phase matching generation of blue coherent radiation at stimulated Raman scattering”, Optics Comm., 203 (3-6) (2002) pp. 413-420. • V. G. Bespalov, N. S. Makarov, “SRS generation of anti-Stokes radiation under phase quasi-matching conditions”, Opt. & Spectr., vol. 90, No. 6, 2001, pp. 938-941. • V. G. Bespalov, N. S. Makarov, “Transient quasi-phase matching SRS generation”, Proc. SPIE, (ICONO-2001), 2001 (accepted for publication). • N. S. Makarov, “Analytical solution of quasi-phase matching anti-Stokes SRS amplification in silica fiber”, in book Modern technologies, pp. 166-175, SPb, 2001. • V. G. Bespalov, N. S. Makarov, “Simultaneously Stokes and anti-Stokes Raman amplification in silica fiber”, Proc. SPIE, vol. 4638, 2002, pp. 30-40. • Bischel W. K., Dyer M. J. “Wavelength dependence of the absolute Raman gain coefficient for the Q(1) transmission in H2”, J. Opt. Soc. Am. B, vol. 3, 1985, pp. 677-682. References 13

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