Recently, Xuan Li research team of Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, has made new progress in improving the conversion efficiency of liquid crystal/polymer grating lasers. For the first time, low-functional monomers have been used to prepare liquid crystal/polymer gratings and are coated with PI. The rubbing orientation on the glass substrate makes the liquid crystal molecules phase-separated in the grating align along the liquid crystal grooves, increasing the amount of refractive index modulation, thereby enhancing the optical feedback, and ultimately increasing the conversion efficiency of the laser. By using two beams of coherent light to irradiate the prepolymer mixed with the monomer and the liquid crystal, the monomer is polymerized in the bright region of the interference fringe to form a polymer. As the concentration gradient liquid crystal moves to the dark region, the monomer moves to the bright region, finally forming the liquid crystal layer and The periodic structure of alternating polymer layers is a liquid crystal/polymer grating. The grating prepared with low exposure intensity has no liquid crystal droplets and low scattering. Because the residual monomer in the dark region reacts to form a polymer draw, the phase-separated liquid crystal molecules are arranged along the direction of the grating vector, resulting in a small amount of refractive index modulation and a weak optical feedback capability. Directly rubbing the existing prepolymer system, the effect is not ideal. Through investigation, it was found that the strength of the anchoring energy of the polymer on the liquid crystal molecules depends on the monomers involved in the reaction. We use low-functional monomers to reduce the anchoring energy while simultaneously rubbing orienting on the glass substrate and eventually allowing the liquid crystal molecules to follow the grating grooves. Directional arrangement increases the amount of refractive index modulation. The laser's conversion efficiency increased from 2.3% to 4.6%, and the threshold decreased from 0.71 to 0.25. (Li Rong reporter Zhang Zhaojun) Angle Valve,Brass Angle Valve,Plastic Brass Angle Valve,Chrome Plated Brass Angle Valve Zhejiang minmetals huitong import and export Co., Ltd , https://www.zjminmetals.com
Changchun Institute of Optics, "Liquid Crystal/Polymer Organic Lasers" has been advanced