Vol. 29, issue 05, article # 2

Abstract:

Based on the numerical solution of the parabolic wave equation for the complex spectral amplitude of the wave field by using the splitting into physical factors method the fluctuations of energy density of the broadband pulsed optical radiation for various modes of Laguerre–Gaussian beam under different turbulent conditions on the propagation path were studied. It has been shown that with the increase of optical turbulence the relative variance of energy density fluctuations of pulsed radiation of femtosecond duration becomes much lower than that of continuous-wave radiation and, in contrast, may become smaller than unity. Provided the pulse duration is short the energy density fluctuations tend to decrease as the order of Laguerre–Gaussian beam mode rises. The level of residual spatial correlation of strong energy density fluctuations of pulsed radiation exceeds the level of continuous-wave intensity correlation in all examined Laguerre–Gaussian beam modes and the typical two-scale structure of spatial correlation for strong fluctuations of continuous-wave radiation in the case of pulsed radiation is less expressed.

Keywords:

Laguerre–Gaussian beam, short pulse, turbulent atmosphere, parabolic wave equation, method of splitting into physical factors, complex spectral amplitude

References:

1. Gibson G., Courtial J., Padgett M.J., Vasnetsov M., Pas’ko V., Barnett S.M., Franke-Arnold S. Free-space information transfer using light beams carrying orbital angular momentum // Opt. Express. 2004. V. 12, N 22. P. 5448–5456.
2. Wang J., Yang J.-Y., Fazal I.M., Ahmed N., Yan Y., Huang H., Ren Y., Yue Y., Dolinar S., Tur M., Willner A.E. Terabit free-space data transmission employing orbital angular momentum multiplexing // Nature Photon. 2012. V. 6. P. 488–496.
3. Yan Y., Xie G., Lavery M.P.J., Huang H., Ahmed N., Bao C., Ren Y., Cao Y., Li L., Zhao Z., Molisch A.F., Tur M., Padgett M.J., Willner A.E. High-capacity millimetre-wave communications with orbital angular momentum multiplexing // Nature Commun. 2014. V. 5. Article number: 4876. 9 р.
4. Ren Y., Xie G., Huang H., Ahmed N., Yan Y., Li L., Bao C., Lavery M.P.J., Tur M., Neifeld M.A., Boyd R.W., Shapiro J.H., Willner A.E. Adaptive-optics-based simultaneous pre- and post-turbulence compensation of multiple orbital-angular-momentum beams in a bidirectional free-space optical link // Optica. 2014. V. 1, N 6. P. 376–382.
5. Ren Y., Xie G., Huang H., Bao C., Yan Y., Ahmed N., Lavery M.P.J., Erkmen B.I., Dolinar S., Tur M., Neifeld M.A., Padgett M.J., Boyd R.W., Shapiro J.H., Willner A.E. Adaptive optics compensation of multiple orbital angular momentum beams propagating through emulated atmospheric turbulence // Opt. Lett. 2014. V. 39, N 10. P. 2845–2848.
6. Willner A.E., Huang H., Yan Y., Ren Y., Ahmed N., Xie G., Bao C., Li L., Cao Y., Zhao Z., Wang J., Lavery M.P.J., Tur M., Ramachandran S., Molisch A.F., Ashrafi N., Ashrafi S. Optical communications using orbital angular momentum beams // Adv. Opt. Photon. 2015. V. 7. P. 66–106.
7. Allen L., Beijersbergen M.W., Spreeuw R.J.C., Woerdman J.P. Orbital angular momentum of light and the transformation of Laguerre–Gaussian laser modes // Phys. Rev. A. 1992. V. 45, N 11. P. 8185–8189.
8. Yao A.M., Padgett M.J. Orbital angular momentum: Origins, behavior and applications // Adv. Opt. Photon. 2011. V. 3. P. 161–204.
9. Anguita J.A., Neifeld M.A., Vasic B.V. Turbulence-induced channel crosstalk in an orbital angular momentum-multiplexed free-space optical link // Appl. Opt. 2008. V. 47. P. 2414–2429.
10. Banakh V.A., Smalikho I.N. Fluctuations of energy density of short-pulse optical radiation in the turbulent atmosphere // Opt. Express. 2014. V. 22, N 19. P. 1–13.
11. Banah V.A., Gerasimova L.O., Smaliho I.N. Chislennoe issledovanie rasprostranenija korotkoimpul'snogo lazernogo izluchenija v turbulentnoj atmosfere // Kvant. jelektron. 2015. V. 45, N 3. P. 258–264.
12. Falic A.V. Bluzhdanie i fluktuacii intensivnosti fokusirovannogo lagerra-gaussova puchka v turbulentnoj atmosfere // Optika atmosf. i okeana. 2015. V. 28, N 9. P. 763–771.
13. Anan'ev Ju.A. Opticheskie rezonatory i lazernye puchki. M.: Nauka, 1990. 264 p.
14. Banah V.A., Falic A.V. Ushirenie lagerrova puchka v turbulentnoj atmosfere // Optika i spektroskopija. 2014. V. 117, N 6. P. 969–975.
15. Ahmanov S.A., Vyslouh V.A., Chirkin A.S. Optika femtosekundnyh lazernyh impul'sov. M.: Nauka, 1988. 312 p.
16. Vinogradova M.B., Rudenko O.V., Suhorukov A.P. Teorija voln. M.: Nauka, 1979. 383 p.
17. Banakh V.A., Smalikho I.N., Falits A.V. Effectiveness of the subharmonic method in problems of computer simulation of laser beam propagation in a turbulent atmosphere // Atmos. Ocean. Opt. 2012. V. 25, N 2. P. 106–109.
18. Zuev V.E., Banah V.A., Pokasov V.V. Sovremennye problemy atmosfernoj optiki. V. 5. Optika turbulentnoj atmosfery. L.: Gidrometeoizdat, 1988. 270 p.
19. Aksenov V.P., Pogutsa C.E. Increase in laser beam resistance to random inhomogeneities of atmospheric permittivity with an optical vortex included in the beam structure // Appl. Opt. 2012. V. 51, N 30. P. 7262–7267.
20. Siegman A.E. How to (maybe) measure laser beam quality // Optical Society of America TOPS. California, October, 1997. P. 1–18. DOI: 10.1364/DLAI.1998.MQ1.
21. Banah V.A., Buldakov V.M., Mironov V.L. Fluktuacii intensivnosti chastichno-kogerentnogo svetovogo puchka v turbulentnoj atmosfere // Optika i spektroskopija. 1983. V. 54, issue 6. P. 1054–1059.