Spectral shifts and spectral switches of partially coherent radially polarized Laguerre-Gaussian pulsed beams propagating through at-mosphere turbulence
The spectral shifts and spectral switches of partially coherent radially polarized Laguerre-Gaussian(PCRPLG)pulsed beams propagating through atmospheric turbulence are investigated.It is found that the on-axis spectrum of the beams will shift rapidly in atmospheric turbulence due to the ap-pearance of two spectral peaks caused by the turbulence.The stronger the turbulence is,the more stable the relative spectral shifts are after the rapid shift,and the off-axis spectrum has a smaller variation range of relative spectral shifts in stronger turbulence.It is also found that the influence of atmospheric turbulence on the spectral shifts of the on-axis and off-axis spectra can be significantly reduced by appro-priately increasing the pulse width.Under different pulse widths,spectral switches appear in both on-axis and off-axis spectra,and the off-axis spectrum will produce a unique phenomenon of two rapid shifts.For a fixed transmission distance,the higher the topological charges are,the smaller the spectral shift of the on-axis spectrum is,and the smaller the variation range of the relative spectral shifts in the paraxial re-gion is.In addition,spectral switches will appear in different topological charges.The larger the coherent length is,the more stable the spectral shifts are,and the farther the spectral switch occurs in the off-axis spectrum.The results of this paper provide a theoretical basis for the application of Doppler lidar.The PCRPLG pulsed beam itself has a strong anti-turbulence ability,and the spectral shifts of the beams can be reduced by adjusting the beam parameters.