Wyniki wyszukiwania - BazTech

1

Propagation properties of partially coherent array beams with a non-uniform polarization

Yang Xianyang, Fu Wenyu

Optica Applicata

|

2023

|

Vol. 53, nr 2

307--319

EN

We study a new class of partially coherent array beams with a non-uniform polarization, named radially polarized Gaussian Schell-model array (RPGSMA) beams and analyze the reliability conditions for the array beams based on the unified theory of coherence and polarization, Moreover, the statistical properties of such beam propagating in free space are investigated in detail. It is found that, the propagation properties of the RPGSMA beams are closely related to initial beam parameters. With an appropriate choice of the beam parameters, the average intensity will evolve into optical lattice patterns, and the degree of coherence (DOC) from the lattice distribution on the original plane evolves into a Gaussian profile in the far field, and the degree of polarization (DOP) appears a periodical grid-like distribution on propagation. These results may be beneficial to particle trapping and free-space optical communications.

2

Properties of an electromagnetic twisted Gaussian Schell-model array beam propagating in anisotropic atmosphere turbulence

Yang Xianyang, Fu Wenyu, Hu Xuehua, Li Xue

Optica Applicata

|

2022

|

Vol. 52, nr 4

639--654

EN

The effect of anisotropic atmosphere turbulence on propagation characteristics of an electromagnetic twisted Gaussian Schell-model array (EM TGSMA) beam is investigated. An analytical expression for the cross-spectral density function of such beam propagating through anisotropic turbulent atmosphere is derived and used to explore the evolutionary behavior of the spectral intensity, degree of polarization (DOP) and degree of coherence (DOC). An example illustrates the fact that twisted strength and anisotropic turbulent factors have an important impact on the behavior of spectral density, DOC and DOP, in particular. The rotation angle of the array beams can also be controlled by adjusting twisted strength. Furthermore, strong anisotropic turbulence was also found to cause significant mergence of the array beams. Our results might be beneficial for free-space communications of the partially coherent beams endowed with twist.

3

Research on the propagation of partially coherent cosh-Gaussian beams through an ABCD optical system in non-Kolmogorov turbulence by effective tensor approach

Ma Hongjie, Li Jinsong, Chen Yueyang

Optica Applicata

|

2021

|

Vol. 51, nr 1

147--158

EN

An efficient tensor approach is used to study the propagation of partially coherent cosh-Gaussian beams through an ABCD optical system in non-Kolmogorov turbulence. Analytical expressions for the average intensity of the beam propagation are derived. The properties of the average intensity are investigated with a numerical example. One finds that the propagation of the beam with larger spatial coherence length is less affected by distance when the propagation distance is long enough, and as the Ch-parameter increases, the beam propagation is less effected by turbulent atmosphere. It is also found that the average intensity distribution of the cosh-Gaussian beams with larger spatial correlation length is more affected by the structure constant of turbulence (i.e., turbulence level). By choosing a suitable Ch-parameter and spatial coherence length, the partially coherent cosh-Gaussian beams can be better transmitted in non-Kolmogorov turbulence. Our results will be useful in free-space communication.

4

Q-switched partially coherent lasers with controllable spatial coherence

Wang Yushuang, Ji Xuanxuan, Chen Ziyang, Pu Jixiong

Optica Applicata

|

2021

|

Vol. 51, nr 2

245--256

EN

We develop a Q-switched degenerate laser, delivering a partially coherent light pulse of duration about 16 ns. The spatial coherence of the output laser pulse can be varied by tuning the spatial filter inside the laser resonator, and the oscillating transverse mode structure can be determined by measuring the degree of coherence of the output laser pulse. It is shown that the larger is the diameter of the spatial filter, the more are the oscillating transverse modes, and the lower is the degree of coherence. Based on coherent-mode representation for the partially coherent source, we can estimate the transverse mode contribution to the output partially coherent laser. The experimental results on suppressing speckle demonstrate that the generated partially coherent light possesses the characteristics of rapid reduction of spatial coherence, making it an ideal source for high-speed imaging and ranging applications.

5

Evolution properties of multi-Gaussian Schell model beams propagating in uniaxial crystal orthogonal to the optical axis

Lu X., Shen Y., Zhu X., Zhao C., Cai Y.

Optica Applicata

|

2016

|

Vol. 46, nr 1

19--34

EN

An analytical formula for the multi-Gaussian Schell model is derived for the beam propagating in a uniaxial crystal orthogonal to the optical axis. The propagation properties of multi-Gaussian Schell model beams in a uniaxial crystal orthogonal to the optical axis is investigated by using the analytical formula. Some results are illustrated by numerical examples related to the propagation properties of multi-Gaussian Schell model beams. It is found that the propagation properties of the multi-Gaussian Schell model beams are very different from the propagation properties in the free space. They are closely related to the initial coherence and the ratio of the extraordinary and ordinary refractive indices. The results provide a way for studying the propagation properties of the multi-Gaussian Schell model beams in the uniaxial crystal orthogonal to the optical axis.

6

Focusing properties of partially coherent dark hollow Gaussian beams through a thin lens system

Dong Y., Zhao C., Wang K., Zhao C., Cai Y.

Optica Applicata

|

2015

|

Vol. 45, nr 2

151--161

EN

This paper investigated the focal shift of partially coherent dark hollow Gaussian beams through a thin lens system. An analytic expression of the irradiance distribution of the focusing partially coherent dark hollow Gaussian beams in the back focal plane has been given by using the Collins formula. The focus shift of focused partially coherent dark hollow Gaussian beams in different parameters is studied in detail by numerical calculations. It is found that the absolute value of the focal shift of partially coherent dark hollow Gaussian beams decreases as the transverse coherence width or the order of the dark hollow Gaussian beams or a parameter of the dark hollow Gaussian beams increases.