Study On Characteristics Of LCoS Phase Modulator Applied In Near Infrared Wavelength

LCoS spatial light modulator(LCoS SLM)is an emerging liquid crystal optical device that can flexibly adjust the amplitude,phase,and polarization state of light waves.In recent years,with the development of photoelectric technology and modern communication technology,LCoS spatial light modulators have been widely used in the field of communication,and the most important of which is in the wavelength selective switch(WSS)with the 1550 nm wavelength,as a diffraction grating to be modulated by the light wave.With high-resolution characteristics of LCoS SLM,combined with the exact electrical signal driving system,the interaction of light wave signals between different wavelength channels is realized.Therefore,the study of LCoS spatial light modulators in the near infrared wavelength is of great significance.The LCoS spatial light modulator is researched in this thesis.The research content includes as the followings:Firstly,according to the working principle of the LCoS spatial light modulator,the advantages and disadvantages of the phase modulation performance of the LCoS device in different modes at 1550 nm are analyzed and compared,then the characteristics of the phase modulation at different cell gap are simulated and the ECB mode is selected for the LCoS SLM.Secondly,the fabrication of the LCoS panel is finished and the key factors in the process flow that may affect the performance is discussed.Thirdly,the driving circuit of the LCoS system and the working process in FPGA is analyzed,and the relationship of image grayscale and the working voltage of the liquid crystal device is discussed.The color video display is realized by the field sequencial drving.Finally,a test platform with the amplitude method is build in for evaluating the phase modulation of the LCoS device.In this system,the modulated phase is measured which is more than 2?at 1550 nm.The deviation of phase modulation characteristics of different regions on the device is discussed.According to the result,we analyze the causes of the deviation of the LCoS phase modulation.It is proposed to optimize the LCoS phase modulation quality by adjusting the voltage working range,adjusting the gray level,and changing the put in image sources.The optimization results are simulated and verified by Matlab and the great optimization effect is obtained.