Far-zone Manipulating Characteristics Of Schell-model Array Beams

In statistical optics,the Schell-model source is one kind of common sources whose spectral degree of coherence between arbitrary two points only depends on the difference of two position-vector.In general,the structure of correlation function would affect the distribution of spectral intensity in the beam field.Therefore,many researchers have proposed various partially coherent beams,such as the flat-top distribution,the rectangular distribution,the array distribution and so on,by designing different structures of correlation function.Related research does matter in the beam propagation and light field manipulation since it may have some potential applications in photon lithography,particle capture and communications,etc.In addition,twist phase can make the partially coherent beam rotate gradually along the propagation axis,which provides more freedom for light field manipulation.Due to the unique advantage in beam shaping,optical imaging,and other fields,the twist phase has attracted the attention of numerous researchers.In this dissertation,three Schell-model array light sources have been discussed,and their corresponding propagation optical characteristic have been researched.Otherwise,the influence of structural parameters of light source on the light field spectral intensity distribution has also been analyzed.The main contents could be summarized as follows:(i).A partially coherent source which can generate light field with ring-shaped twisted array profile is discussed.And its distribution of spectral density and degree of coherence of the light field are also discussed.It is shown that both the spectral density and degree of coherence would rotate along the propagating direction but with opposite rotating direction.Furthermore,the distribution of the ring-shaped array of the spectral density has been found,including the number of the rings,the number of the lobes of each ring,and the distance of all adjacent lobes,which can be properly controlled by adjusting structural parameters of the source.(ii).A partially coherent beam source which can produce the far field with ring-shaped hollow array profile is discussed.And the distribution of the far-zone spectral density generated by such beam source are investigated in detail.It is shown that characteristics of the far-zone spectral density,including the size of the hollow of the each lobe,the distance of the adjacent lobes,the orientation of the each lobe,and the number of the lobes,can be effectively manipulated by adjusting the corresponding parameters of the beam source.(iii).A light field with a rotating anisotropic Gaussian array profile is generated by introducing a kind of partially coherent source.The expression of the cross-spectral density function of light source on propagation is derived.And the behavior of the spectral density of this beam is discussed step by step.The result shows that the spectral density profile of each lobe of the array and the profile of the spectral degree of coherence can undergoes a rotation of more than 90 degrees along its propagation direction.In addition,it is also shown that one can manipulate the spectral density profile of the Gaussian array,including number of columns,number of rows,and distance between the lobes of array,by modifying the structural parameters of the proposed source.This result may provide a method for generating an array profile with flexible-adjusted beam twist.