Enhancing Terahertz Output Through Spatial Light Modulator Control in Laser-Induced Filaments

The method of generating terahertz waves through two-color laser-induced filaments is an effective approach for terahertz wave generation. However, the terahertz output of gas plasma is constrained by optical intensity clamping, and there is an upper limit to the terahertz output as the pump energy increases. Previous research has utilized optical components like phase plates and deformable mirrors for optimizing and regulating the filamentation process; however, these approaches lack flexibility. Here, we propose a method to control the filamentation process using a liquid crystal spatial light modulator (LC-SLM). By employing a segmented lens phase approach, we modulate the incident laser wavefront and then create two focal points along the optical axis and control their positions to enhance terahertz output. Experimental results demonstrate that this method effectively improves terahertz conversion efficiency and overcomes the saturation effect caused by optical intensity clamping. The research findings contribute to the development of gas plasma terahertz sources, and it has potential applications in Terahertz biology and imaging.