Theoretical Analysis on High Power Threshold of LCOPA with Micro-channel Heat Sinks

The liquid crystal optical phased array (LCOPA), with low SWaP (size, weight and power consumption), has been widely researched in laser communication, laser radar, laser guidance, laser weapons and many other application scenarios. As the number of laser paths increases, the laser power density also increases, such as multi-beam control (“one-to-many”) and laser beam combining ("many-to-one"), it is imperative to study the high power threshold of LCOPA. To solve the heat problem induced by high power laser of LCOPA, in this paper, we proposed a transparent high power threshold of LCOPA with micro-channel heat sinks. A high thermal conductivity and transparent (to $1064 \mathrm{~nm}$ light) Boron compounds material was used to compose the micro-channel heat sinks. Heat on LCOPA was carried away through the circulation of the index matching fluid in micro-channel. Several typical factors (micro-channel structure parameter, cooling index matching fluid rate and substrate material parameter) are analyzed to evaluate the influence of phase distortion when a relative high power laser is pumped into the LCOPA. Typically, the optical turbulence caused by micro-channel heat sinks with cooling fluid was considered in simulation. When the incident laser power is 500 W, and the total absorption is 5 %, the flow rate is $1.5 \mathrm{~m} / \mathrm{s}$, the laser induced beam quality deterioration on the LC layer is less than 15 % under the condition of the width and depth of micro channels are $250 \mu \mathrm{m}$.