Research of continuous fiber laser sustained Xe plasma

• Published in: Vacuum 2022-09, Vol.203, p.111229, Article 111229
• Main Authors: Hu, Yanfei, Wang, Xinbing, Zuo, Duluo
• Format: Article
• Language: English
• Subjects: Fiber laser; High-pressure plasma; Laser sustained plasma; Plasma instability; Xe plasma
• ISSN: 0042-207X; 1879-2715
• DOI: 10.1016/j.vacuum.2022.111229

High-speed optical inspection of wafers requires a high-brightness and broadband light source. The brightness of traditional arc discharge lamps is difficult to increase, which is limited by the cathode current density. Laser sustained plasma (LSP) is a promising method to overcome the limitations of existing light source technologies. Then the characteristics of fiber laser sustained plasma in a xenon bulb were investigated, the absorption coefficient was measured, and the spectrum was analyzed. The results show that with the increase of laser power, the volume of plasma gradually increases and moves towards the direction of laser incident. With the increase of Gaussian beam focusing number F, the threshold laser power required to maintain the stable existence of plasma decreases gradually. There are upper and lower limits for laser power at which the LSP could be sustained. When the laser incident at the optimal incident angle, the laser propagation in the plasma is the optimal path for laser energy deposition, and the plasma has higher absorption coefficient, temperature and brightness. When F ≥ 10, the Xe plasma will show spatial instability due to refraction effect. Compared with the traditional short-arc xenon lamp, the LSP spectrum has a higher proportion in short wavelength. •Second moment method is used to accurately determine the plasma size.•Laser sustained plasma exists stably in high pressure xenon gas.•Plasma instability phenomena and stable existence conditions.•Changes in laser power and focusing parameters improve absorption coefficients.