Influence of ITO layer on laser tolerance of liquid crystal device under continuous-wave laser loading

The laser performance of liquid-crystal devices (LCDs) must be considered because of their applications in laser systems. The phase modulation variation mechanisms, as well as the key absorption factor under continuous-wave (CW) laser loading, remain unclear. In this study, the influence of indium tin oxide (ITO) layers on the laser tolerance of LCDs under CW laser loading was investigated. Comparing the phase modulation variations and thermal effects of passive and active LCDs, the influence of the ITO absorbing layer and the decisive role of temperature on the laser tolerance of the LCDs were confirmed. The results showed that the laser tolerance of the LCD with ITO layers was approximately one-seventh of that of the LCD without ITO layers. ITO layers have proven to be the main absorption factor for active LCDs. However, the variations in phase modulation and morphology under CW laser loading were similar for LCDs with or without ITO layers. The phase modulation variations of the LCDs increased with increasing temperature in the irradiated area. For LCDs with or without ITO, once the CW laser loading induced a similar temperature increase, their phase modulation variations were almost the same. The temperature rise of LCDs is confirmed to be an effective parameter for evaluating the phase modulation degradation of LCDs in high-power CW laser applications. The coincidence between the theoretical and experimental phase modulation variations for LCDs with or without ITO indicates that the temperature-induced refractive index change was the main reason for the LCD phase modulation variation under CW laser loading. These results clarify the basic mechanisms of the phase modulation variation of LCDs under CW laser loading and provide guidance for process optimization and application of LCDs in high-power laser systems. © 2022 Elsevier GmbH