1. The efficient generation of anti- Stokes radiation at multiwave forward and backward stimulated Raman scattering Victor G. Bespalov, Russian Research Center "S. I. Vavilov State Optical Institute" Nikolai S. Makarov, Saint-Petersburg State Institute of Fine Mechanics and Optics (Technical University)

2. Outline Principle of quasi-phase matching System of multiwave SRS equations Numerical simulations results Conclusions References The efficient generation of anti-Stokes radiation at multiwave forward and backward stimulated Raman scattering; Saint-Petersburg, 12-17 October 2003 Makarov N.S., mak_nick@newmail.ruBespalov V.G., bespalov@admiral.ru

3. Principle of quasi-phase matching Raman active medium Nonlinearity  (2) Nonlinearity  (3) H2H2 H2H2 H2H2 H2H2  (3)  0  (3) =0 z I 2w LкLк d 31 c-axis LкLк The efficient generation of anti-Stokes radiation at multiwave forward and backward stimulated Raman scattering; Saint-Petersburg, 12-17 October 2003 Makarov N.S., mak_nick@newmail.ruBespalov V.G., bespalov@admiral.ru

4. Principle of quasi-phase matching at SRS Generalized phase on active layers input do not practically change, that in a final result provides a realization of quasi- phase matching conditions The efficient generation of anti-Stokes radiation at multiwave forward and backward stimulated Raman scattering; Saint-Petersburg, 12-17 October 2003 Makarov N.S., mak_nick@newmail.ruBespalov V.G., bespalov@admiral.ru , rad  (3)  0  (3) =0

5. System of forward and backward multiwawe SRS equations  j i – wave mismatching, g j ± – steady-state Raman gain coefficient,  j – frequencies of interacting waves, E j ± – complex wave amplitudes The efficient generation of anti-Stokes radiation at multiwave forward and backward stimulated Raman scattering; Saint-Petersburg, 12-17 October 2003 Makarov N.S., mak_nick@newmail.ruBespalov V.G., bespalov@admiral.ru

6. Model verification: waves profiles at different input pump intensities (left – input pump and right – output pump) t, ns I, GW/cm 2 The efficient generation of anti-Stokes radiation at multiwave forward and backward stimulated Raman scattering; Saint-Petersburg, 12-17 October 2003 Makarov N.S., mak_nick@newmail.ruBespalov V.G., bespalov@admiral.ru

7. Model verification: waves profiles at different input pump intensities (left – output forward Stokes and right – output backward Stokes) t, ns I, GW/cm 2 The efficient generation of anti-Stokes radiation at multiwave forward and backward stimulated Raman scattering; Saint-Petersburg, 12-17 October 2003 Makarov N.S., mak_nick@newmail.ruBespalov V.G., bespalov@admiral.ru

8. Barium nitrate Hydrogen Raman gain dispersion The efficient generation of anti-Stokes radiation at multiwave forward and backward stimulated Raman scattering; Saint-Petersburg, 12-17 October 2003 Makarov N.S., mak_nick@newmail.ruBespalov V.G., bespalov@admiral.ru

9. Influence of high SRS components on calculations precision For best calculation accuracy it is necessary to take into account at least the generation of 3 Stokes and 3 anti-Stokes SRS components The efficient generation of anti-Stokes radiation at multiwave forward and backward stimulated Raman scattering; Saint-Petersburg, 12-17 October 2003 Makarov N.S., mak_nick@newmail.ruBespalov V.G., bespalov@admiral.ru

10. The influence of backward SRS on QPM realization (active layers length) The efficient generation of anti-Stokes radiation at multiwave forward and backward stimulated Raman scattering; Saint-Petersburg, 12-17 October 2003 Makarov N.S., mak_nick@newmail.ruBespalov V.G., bespalov@admiral.ru

11. The influence of backward SRS on QPM realization (passive layers length) The efficient generation of anti-Stokes radiation at multiwave forward and backward stimulated Raman scattering; Saint-Petersburg, 12-17 October 2003 Makarov N.S., mak_nick@newmail.ruBespalov V.G., bespalov@admiral.ru

12. The influence of Stokes input intensity on anti-Stokes generation efficiency The efficient generation of anti-Stokes radiation at multiwave forward and backward stimulated Raman scattering; Saint-Petersburg, 12-17 October 2003 Makarov N.S., mak_nick@newmail.ruBespalov V.G., bespalov@admiral.ru

13. The influence of Stokes input pulse duration on anti-Stokes generation efficiency The efficient generation of anti-Stokes radiation at multiwave forward and backward stimulated Raman scattering; Saint-Petersburg, 12-17 October 2003 Makarov N.S., mak_nick@newmail.ruBespalov V.G., bespalov@admiral.ru

14. The influence of pump input intensity on anti-Stokes generation efficiency The efficient generation of anti-Stokes radiation at multiwave forward and backward stimulated Raman scattering; Saint-Petersburg, 12-17 October 2003 Makarov N.S., mak_nick@newmail.ruBespalov V.G., bespalov@admiral.ru

15. The influence of pump input pulse duration on anti-Stokes generation efficiency The efficient generation of anti-Stokes radiation at multiwave forward and backward stimulated Raman scattering; Saint-Petersburg, 12-17 October 2003 Makarov N.S., mak_nick@newmail.ruBespalov V.G., bespalov@admiral.ru

16. The influence of pump wavelength on anti- Stokes generation efficiency The efficient generation of anti-Stokes radiation at multiwave forward and backward stimulated Raman scattering; Saint-Petersburg, 12-17 October 2003 Makarov N.S., mak_nick@newmail.ruBespalov V.G., bespalov@admiral.ru

17. Conclusions Our model of forward and backward multiwave SRS is quality and quantity compared with experimental results For best accuracy of QPM SRS simulations it is necessary to take into account the dispersion of Raman gain coefficient For studying of multiwave SRS influence on QPM structure realization it is necessary to take into account the generation at least of 3 Stokes and 3 anti-Stokes SRS components The influence of backward SRS on QPM structure realization results in the small difference between layers length of optimal QPM structure and small decreasing of resulting anti-Stokes conversion efficiency (~25% at backward and forward SRS, ~30% at forward SRS) The effective anti-Stokes SRS generation occurs in a wide range of input radiation parameters The efficient generation of anti-Stokes radiation at multiwave forward and backward stimulated Raman scattering; Saint-Petersburg, 12-17 October 2003 Makarov N.S., mak_nick@newmail.ruBespalov V.G., bespalov@admiral.ru

18. References Armstrong J.A., Bloembergen N., Ducuing J., Pershan P.S. // Phys. Rev., 1962, 127, pp. 1918-1939. Bespalov V.G., Makarov N.S. Quasi-phase matching generation of blue coherent radiation at stimulated Raman scattering // Optics Communications 2002, 203 (3-6), pp. 413-420. Maier M., Kaiser W., Giordmaine J.A. Backward stimulated Raman scattering // Phys. Rev., 1969, V. 177, №2, pp. 580-599. Raijun Chu, Morton Kanefsky, Joel Falk Numerical study of transient stimulated Brillouin scattering // J. Appl. Phys., 1992, V. 71, №10, pp. 4653-4658. Zaporozhchenko R.G., Kilin S.Ya, Bespalov V.G., Stasel’ko D.I. Formation of the spectra of backward stimulated Raman scattering from the quantum noise of polarization of a scattering medium // Opt.&Spectr., 1999, V. 86, №4, pp. 632-639. 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, 1985, V. 3, pp. 677- 682. The efficient generation of anti-Stokes radiation at multiwave forward and backward stimulated Raman scattering; Saint-Petersburg, 12-17 October 2003 Makarov N.S., mak_nick@newmail.ruBespalov V.G., bespalov@admiral.ru