极紫外(Extreme ultra-violet, EUV)光刻机光源主要采用激光产生等离子体技术, 用高功率激光轰击锡液滴靶产生13.5 nm波长的EUV光。其中, 基于逆压电效应的压电式高温锡液滴喷射元件是获取高重频高温锡液滴靶的关键部件。本项工作突破了耐250 ℃高温微细压电陶瓷管的组成设计和精细制备, 以及高温锡液滴喷射元件的结构设计和封装等关键技术, 成功研制了压电式高温液滴喷射元件。并通过自主搭建高温锡液滴靶光学检测平台, 基于此高温液滴喷射元件实现了重复频率20 kHz, 直径~100 μm的高温锡液滴靶的稳定输出。

Laser polarization and its intensity inside a filament core play an important role in filament-based applications. However, polarization dependent clamping intensity inside filaments has been overlooked to interpret the polarization-related filamentation phenomena. Here, we report on experimental and numerical investigations of polarization dependent clamping intensity inside a femtosecond filament in air. By adjusting the initial polarization from linear to circular, the clamping intensity is increased by 1.36 times when using a 30 cm focal length lens for filamentation. The results indicate that clamping intensity inside the filament is sensitive to laser polarization, which has to be considered to fully understand polarization-related phenomena.

We report on a simultaneous generation of double white light lasers through filamentation by focusing a femtosecond laser pulse. The appearance of the two white light lasers can be controlled by tilting the focusing lens. The spectral bandwidth and the pulse energy of the double white light lasers were controlled by tuning laser filamenting pulse energy and polarization. Two white light lasers with pulse energies of 1.54 mJ and 1.84 mJ, respectively, were generated with the pump laser energy of 7.43 mJ. Besides being beneficial in understanding the multiple white light lasers generation process through multiple filamentation and its control, the results are also valuable for white light laser-based applications.

We report on a systematic study of the laser polarization effect on a femtosecond laser filamentation in air. By changing the laser’s ellipticity from linear polarization to circular polarization, the onset position of laser filament formation becomes farther from the focusing optics, the filament length is shorter, and less laser energy is deposited. The laser polarization effect on air filaments is supported by a simulation and analysis of the polarization-dependent critical power and ionization rates in air.

We demonstrate a simple technique to filter out the continuum background in filament-induced remote breakdown spectroscopy. By inserting a polarizer before the detector, the continuum background was reduced by more than 42% in filament-induced breakdown spectroscopy at a distance of 3.8 m, while the fluorescence intensity of aluminum atomic lines remains constant. Supercontinuum through self-phase modulation during filamentation mainly contributes to the continuum background. The polarization-gated technique provides a simple way to remove the continuum background in filament-induced remote breakdown spectroscopy.

Sub-picosecond chirped laser pulse-induced airflow and water condensation were investigated in a cloud chamber. The results indicate that the positively chirped sub-picosecond laser pulses generate a more uniform intensity distribution inside the plasma column, leading to a weaker airflow and an elliptic-shaped snow pile. The negatively chirped sub-picosecond laser pulses generate a spark-like intensity distribution inside the plasma column, which produces a wider range of airflow and a round snow pile. The amount of snow weight and the concentration of NO3 are found to be dependent on the intensity distribution inside the plasma column. The visibly stronger plasma column generates much more snow and a higher concentration of NO3 . These experimental results provide a reference for sub-picosecond laser-induced water condensation in realistic atmospheric conditions.