Research On Phase Characteristics Of Liquid Crystal Light Modulator

Optical modulator plays an important role in modern optical system.It can be widely used in optical communications,optical manipulation,optical computing and optical neural network,and other fields.In a variety of optical modulators,the optical phase modulator has higher optical energy utilization due to only changing the phase of light wave.Due to the birefringence characteristics of liquid crystal,the phase liquid crystal light modulator is easy to use,small in size and low in power consumption.In order to better achieve the phase properties of light modulation,multi electrode structure is introduced into the design of liquid crystal light modulator,but it also brought new problems,because the phase cannot be directly observed,adjusting multi electrode driving voltage is a difficult and tedious process,in order to solve this problem,first we use Jones matrix analysis of phase modulation characteristics of liquid crystal light.And then,an adaptive modulation system was proposed to yield the refractive index profile well matching the ideal one automatically.With this system,the refractive index profile can be real-time evaluated and the modulation process can be efficiently shortened to 10% of that by using conventional modulation method.Liquid Crystal on Silicon(LCoS)is the most competitive liquid crystal light modulator.It is the most competitive solution to realize the wavelength selection switch(WSS).However,there are many limitations in LCoS performance,such as low diffraction efficiency,small deflection angle,low steering accuracy,etc.It is because that when the diffraction Angle is larger,the pixels which were used to simulate the phase curve is less.It deteriorated the simulation results.Therefore,we have done some research on the LcoS.We used the liquid crystal with big birefringence,and the modulation depth of the LCoS which was 2 PI increased to 4 PI.This makes the pixels which were used to simulate the phase curve has doubled,and realized an optical phase modulation device with high diffraction efficiency in large deflection angle.