Research On The Method Of Increasing The Power Threshold Of Liquid Crystal Optical Phased Array

As the representative of the next generation optical antenna,the optical phased array antenna has become a research hotspot in the international optical field in recent years.The liquid crystal solution is closer to engineering applications than other current solutions,and has many advantages: low driving voltage,low power consumption,high integration,small size and mature supporting industries.It can be widely used in many optical beam control systems such as space optical communication and laser radar.Multi-beam control("one-to-many")and laser beam combining("many-to-one")are the typical requirements for many beam control systems.However,as the number of laser paths increases,the laser power density also increases.So it is imperative to study the tolerance threshold of liquid crystal optical phased array(LC-OPA)device.In this paper,based on the structure of the traditional transmissive LC-OPA device,the threshold of withstand power of the device is improved by means of model reconstruction,material modification,structure optimization,etc.And an optical combination system based on LC-OPA is proposed.The main research contents include:(1)A thermodynamic model of laser-induced transmissive LC-OPA was established.The reason of the temperature effect introduced by laser is analyzed.Under the influence of temperature,the process simulation and theoretical analysis were performed on the device performance degradation,near-field phase distortion,and far-field beam quality degradation.(2)For the main absorption layer of laser in the LC-OPA device,the alternative solution and the improved design of the transparent absorption layer were studied.A hexagonal honeycomb structure was proposed to replace the original scheme.On the basis of reducing the thickness of ITO film,it can further reduce the optical absorption by 50%.And the electric field of the device under the new structure is simulated.The root mean square value of the electric potential distribution is 0.115,which can meet the normal working needs of the device.(3)In view of the heat distribution on the device,we proposed a heat dissipation structure that can be used in the transmission LC-OPA system.The effective heat dissipation structure is micro-channel structure,and the solid heat dissipation material is Boron compounds material,which is transparent to 1064 nm light and has a high thermal conductivity.Then,the heat on the device can be recycled by the heat dissipation liquid.Through the reasonable design of the flow rate and refractive index of the heat dissipation liquid in the cooling structure,the beam turbulence can be avoided and the requirements of the high power threshold LC-OPA system can be met.The transmission LC-OPA with high laser power threshold was developed and its U-phi and deflection characteristics were tested.Through the equivalent experiment,when the incident laser power is 250 W,the temperature rise of the device is only 11.2 ?.(4)Based on the liquid crystal optical phased array,a laser beam combining system was proposed,and one-dimensional beam combining deflection experiment was carried out.In the experiment,the steering angle of the liquid crystal optical phased array was loaded from 0?rad to 15500?rad with the step of 500?rad.And the actual deflection effect diagram was given,the relative steering error was calculated.When the steering angle is small,the relative error is fluctuating,and the root mean square of the relative steering error is 0.025.