Shanghai Institute of Optics and Mechanics has made new progress in the research of laser irradiation effects on liquid crystal optical phase control devices

Recently, the Thin Film Optics Laboratory of Shanghai Institute of Optics and Precision Machinery, Chinese Academy of Sciences, in cooperation with Shanghai University of Technology and Suzhou University of Science and Technology, has made new progress in the research of laser irradiation effects on liquid crystal optical phase control devices (LCPDs), proposed effective methods to predict the performance degradation and failure of LCPDs under continuous laser loading, and provided guidance for the practical application of LCPDs in high-power laser systems, Relevant research results were published in Optical Materials and Optik.

Liquid crystal materials have the characteristics of fluidity, anisotropy and electronic controlled molecular orientation. They can be combined with transparent conductive films and orientation films to prepare various liquid crystal phase control devices according to application requirements. They are used to achieve precise adjustment of beam amplitude, wavefront, polarization and direction. They have been widely studied and applied in fusion ignition, laser processing, laser communication, laser radar and other fields. However, the degradation and failure of LCPD caused by laser loading is the primary problem in laser application.

In this study, the researchers obtained the quantitative relationship between LCPD temperature rise and its performance degradation and failure under continuous laser loading by integrating near common optical path interferometric phase measurement technology, online actual temperature rise measurement and other analysis methods, and confirmed that temperature induced liquid crystal refractive index change is the direct cause of LCPD performance degradation and failure under continuous laser loading, and based on the dependence between the refractive index and temperature of liquid crystal materials, LCPD performance degradation and failure model is established. This provides a means to predict the degradation and failure of LCPD under continuous laser loading, effectively predict the actual application of LCPD in high power laser systems, and provide guidance for the design and application of related devices.

Related research has been supported by the National Natural Science Foundation of China, the Open Fund of the State Key Laboratory of Applied Optics, and the Open Fund of the State Key Laboratory of Pulse Power Laser Technology.

Fig. 1 (a) Change of LCPD phase modulation with time under different laser irradiation power. (b) The change of LCPD temperature with time under different laser irradiation power. (c) Comparison between theoretical and experimental values of LCPD phase modulation (solid line is the theoretical value, scatter is the experimental value, red is LCPD with indium tin oxide (ITO) conductive layer, and green is LCPD without ITO conductive layer).

Source: Shanghai Institute of Optics and Precision Machinery, Chinese Academy of Sciences