The Investigation Of Polarization Control Of The Light Fields Through Scattering Media And Its Applications

Structured light field shaping plays an important role in optical trapping,microscopic imaging,3D display and optical communication,etc.However,when interacting with scattering media,the spatial structure and polarization distribution of the structured light will be completely scrambled due to multiple light scattering.As a consequence,wavefront shaping techniques in free-space suffer from great challenges in the presence of scattering,thus hindering the applications in the scattering media,for example,biological tissues.Specifically,a focused laser beam cannot go deep into the biological tissues due to high scattering,limiting trapping depth in tissues for optical tweezers that currently trap cells in the superficial layer of a skin.Besides,the highly focused Gaussian beams inevitably cause photodamage to the trapped cells and tissues,which hinders long-time manipulation of individual cells in the living animals.Actually,optical imaging and optical communications through scattering media also confront the challenge of light scattering.In this dissertation,we propose light field control techniques especially the polarization control through scattering media to shape structured light beyond scattering and apply them for optical trapping,optical communication and holographic display.The detailed contents are listed as follows:1.Tightly focused vector beams and its application in optical trapping of living cells.We theoretically studied tightly focused field distributions of the linearly polarized vortex beams and higher-order Poincare sphere beams based on the Richards-Wolf vectorial diffraction integral.The theoretical study revealed the interplay between spin and orbit angular momenta in the focused fields.Exploiting the superior property of the focused vector beams,we proposed to use the azimuthally polarized beams for optical trapping to solve the problem of photodamage for trapped cells.Compared with the conventional focused Gaussian beams,the azimuthally polarized beams could effectively reduce the photodamage for the trapped cells,which also demonstrated in living zebrafishes.This scheme provides a new way for long-time manipulation and observation of living cells.2.The polarization control of the light fields through the scattering media.We presented a general framework based on the vector transmission matrix to simultaneously tailor the amplitude,phase and polarization of light by shaping both the complex amplitudes of two orthogonal polarization components of the input field impinging onto the scattering media.This approach achieved shaping structured vector beams beyond scattering media and has been applied to hide and encrypt arbitrary image information into a laser beam.Furthermore,we proposed a wavefront shaping technique based on the partial vector transmission matrix and achieved to simultaneously control the intensity and polarization distributions of light in 3D space through scattering media by shaping only the phase of input field.3.Scattered light field imaging and its application in optical OAM communication.We developed scattered light field imaging technique to accurately retrieve the complex amplitude information of the transmitted light fields through a single multimode fiber,which has been applied in OAM-multiplexed data transmission through a commercial multimode fiber.We further demonstrated high-fidelity transmission of color image information via multiplexed OAM channels at an error rate of<0.72%.4.Three-dimensional scattering-enhanced vectorial holography(3D-SVH).Based on the technique of intensity and polarization control in 3D space through scattering media,we proposed a 3D-SVH technique and achieved 3D vectorial projection with ultra-fine depth control.3D-SVH simultaneously brokes the axial resolution and crosstalk limits in conventional 3D Fresnel CGH.3D-SVH could achieve polarization-discernible 3D dynamic projection to reveal the inner structures of a 3D object.The proposed wavefront shaping techniques especially for polarization control through scattering media could be used to solve the problems of light field shaping through complex media.These techniques are expected to pave the way for optical manipulation and imaging of cells in deep tissues.In addition,they can also help to overcome the challenges in information encryption,optical communication and 3D holographic display under scattering environments.