Theoretical And Experimental Research Of Super-oscillating Light Field Based On Vortex Singularities

Traditional optical systems have a diffraction limit,which makes the object with the size smaller than half wavelength can not be distinguishable,and super-resolution technology has always been a focus in optics.In recent years,some studies have indicated that optical superoscillation can be utilized to break the diffraction limit of the optical field to achieve optical superresolution.Super-oscillation refers to the fact that an optical field with a special functional structure will produce more than the upper limit of its Fourier spectral bandwidth in a local region.And we construct a new type of light field theoretically and experimentally,which satisfy both super-oscillation and vortex.Firstly,we introduces the current research situations of super-oscillating light field and the general theoretical construction methods.It is mainly divided into the design of super-oscillating lenses through optimization algorithms and the fabrication of samples by etching with electron beams and plasma beams.Followed by the design of phase holographic masks,the super-oscillating beam is also focused by means of a spatial light modulator(SLM)and a high numerical aperture objective.Secondly,we have theoretically constructed a super-oscillating light field based on the product of a complex polynomial and a Gaussian function.Then,we explore some application prospects and the propagation dynamics of this light field.Based on the previously constructed superoscillating light field,we theoretically calculated its local wavenumber,while other related study have found that the peaks of the local wavenumber of the singularities have the potential to become the new optical ruler,then we started to study the factors that affect the FWHM of the peaks.Thirdly,we propose a generalization of the type of super-oscillating vortex light field,and then we introduce the negative singularities with conjugate complex polynomial,which make the light field can carry two kinds of vortex singularities simultaneously.We have studied the propagation dynamics of this kind of light field based on the paraxial theory,and we discover annihilation and motion of the singularities,what'more,the motional law of the singularities are totally different from the light field which only have one type of the polynomial.Lastly,by introducing the method of phase correction and the encoding method of phase-only SLM,we have designed the phash mask that we desired and we built an experimental system to verify our thories.