Manipulation Of Self-accelerating Beams For High-speed Photonic Interconnection

The self-accelerating beam is a kind of structured light,which has a curved propagation trajectory without the action of an external potential field.Due to its characteristics of self-acceleration,non-diffraction and self-healing,self-accelerating beams are gradually being used in several applicatoins,such as super-resolution imaging,optical tweezers,material processing,and photonic interconnection.The manipulation of the self-accelerating beam depends on the precise control of its amplitude and phase during the beam generation process.In particular,current manipulation schemes of self-accelerating beams are mostly focused on the manipulation of the longitudinal transmission trajectory,while ignoring the degree of freedom of the transversal distribution of the optical field.Thus,the application potential of self-accelerating beams in free-space photonic interconnection has not been comprehensively explored.This thesis is based on the spatial light modulator(SLM,Spatial Light Modulator),which focuses on the generation of complex-amplitude modulated optical field,the manipulation of the optical field distribution for the self-accelerating beam,and free-space high-speed photonic interconnection applications.The main innovations and research outcomes are summarized as follows,(1)A 4f filtering system model under the general condition is established,which can be used to accurately investigate the impact of the size and position deviation of the filter aperture on the quality of complex-amplitude-modulation of the optical field.The ability of the off-axis hologram generation method and the on-axis method to resist variation in the aperture size and the position of the filter aperture is compared.Through the spatial spectrum analysis,I identify that,due to the different spectral distribution characteristics of two schemes,the off-axis method can generate higher-quality beams,while the on-axis method is more robust.Aiming at the problem of low modulation efficiency for digital micromirror devices(DMD,Digital Micromirror Device),a double-light-path multiplexing technique based on DMD is proposed.The simulation results indicate that two spatially separated light paths carry the same optical field information,leading to the doubling of the DMD modulation efficiency.(2)For the two-dimensional Airy beam,the traditional cubic phase hologram is extended to a cubic polynomial hologram,and a beam generation vector containing six variables is proposed to completely describe the hologram loaded on the SLM.The longitudinal progagation trajectory of the two-dimensional Airy beam is a parabola whose launched angle and initial point position can be flexibly chosen.By changing the variables arising in the generated vector,the flexible manipulation of the beam trajectory can be realized without any mechanical operation.When a two-dimensional self-accelerating beam is designed by the use of caustics principle,it is found that the transverse distribution of the optical field is determined by the selection of transversal orthogonal coordinate axis pair.A scheme based on the rotation of the coordinate system is proposed to flexibly rotate the transverse optical field distribution of the beam within a range of 90 degrees,while the longitudinal trajectory of the beam can be kept unchanged.(3)A criterion of normalized power density(NPD)is proposed to characterize the variation of the power density for the main lobe of the beam during the free-space propagation.Then,this criterion is used to compare the length of power density maintainning interval for the Airy beam and the Gaussian beam.In particular,the length of power density maintaining interval for the Airy beam can can be adjusted by the decaying factor.A 100 Gbps real-time high-speed free-space photonic interconnection based on self-accelerating beams is built.When there are no obstacles at the free-space optical path,the receiver can be set along the curved trajectory of the self-accelerating beam to achieve error-free reception.When there is an obstacle at the optical path with a free-space distance of 0.6 m,the sizes of the obstacle that the Gaussian beam,one-dimensional Airy beam and two-dimensional Airy beam can resist,are 0.7 mm,1.65 mm,and 2.1 mm,respectively.The two-dimensional self-accelerating beam has the best ability to resist the obstacle effect.Moreover,the transverse optical field manipulatoin of the self-accelerating beams can further enhance the performance of high-speed free-space photonic interconnection.