Study And Experiment Of Complete-light Modulation Based On Birefringent Material

Light field modulation refers to modulate the amplitude,phase,polarization and frequency information of light according to the requirement,and it brings new changes for scientific research,military and social.With the development of technology,there will be more and more demands on the modulating degree and scale of the system,and the system will eventually be miniaturized and diversified.The current light field modulation is mainly focused on the modulation of amplitude,phase and frequency of the light field,which is proficient and the system is simple and efficient.However,there exist many problems such as instability,discontinuities of polarization state and low efficiency in the polarization modulation of light field.In view of the light field modulating requirements and existing problems of polarization modulating system,we propose a technology of complete-light modulation based on birefringence materials in this paper.Firstly,we used a simple system to achieve continuous modulation of light polarization efficiently and stably.Secondly,we have further simplified the system and improved the modulating degree of light field.Finally,the complete-light modulation of monochromatic light field was achieved.On the basis of the above,the completelight modulation of color field was explored and corresponding theoretical model was completed.The main research work includes:(1)A single optical path polarization modulating technology based on birefringent phase plate was proposed.The polarization modulating model was established by analyzing the polarization control characteristics of the birefringent crystal and using the Jones matrix.The design of the light path was completed.According to the theoretical model,a corresponding birefringent phase plate was designed to produce radial vector light field.(2)The preparation of the birefringent phase plate and the experimental verification of polarization modulation were completed.Through several experiments,the etching process of yttrium vanadate(YVO4)was explored,and a set of processing system for YVO4 was established.The preparation of birefringent phase plate was produced by moving gray scale mask technology.The radial vector field was realized effectively based on the birefringent phase plate,and the utilization rate of light energy was over 90%.(3)A monochromatic complete-light modulating technology based on single birefringent phase plate was proposed.Based on the principle of amplitude modulation of diffraction imaging,the phase iteration algorithm was optimized,and the iterative algorithm with amplitude and phase constraints was introduced.The amplitude and phase modulation of the light field was completed using the diffraction imaging technology combined with the polarization modulation of birefringent phase plate.The birefringence effect was used to realize the synthesis of multiple phases on single phase plate.Based on the above theory,the corresponding birefringent phase plate was designed and fabricated,and the complete-light modulation experimental verification of the monochromatic light field was completed.(4)An amplitude modulation method of color light field based on the principle of phase overlapping was proposed.The synthesis of multiple phases on single phase plate was realized by using different refractive index of phase plates to different wavelengths,and the corresponding simulation experiments were completed.An amplitude modulation method of color light field based on spatial superposition was also proposed.The coding position of each component in the space was designed by using the splitting characteristic of the grating.The design and fabrication of the phase plate were completed.On the basis of above,two theoretical models of complete-light modulation for color field based on vector superposition and spatial superposition were proposed.The corresponding optical paths were designed,and the corresponding imaging simulation experiments were completed.