对短脉冲激光作用水介质中引起光学击穿的机制进行了分析,通过自由电子密度速率方程的数值解确定激光的击穿阈值.将数值计算结果与波长在可见光和近红外波段,脉宽为ns、ps和fs的激光脉冲在纯净水和含有杂质的水中的实验测量的击穿阈值作了比较.还计算了等离子体中自由电子密度的演化、等离子体吸收系数和能量密度.通过解自由电子密度速率方程得到结果与实验测量的值符合得很好.

The physical mechanism of optical breakdown induced by short-pulse laser in water was analyzed, and the laser breakdown threshold was determined with a numerical calculating method for the rate equation of free electron density. The numerical calculating results were compared to experimentally measured breakdown threshold of pure water and impure water by nanosecond,picosecond and femtosecond laser pulses in the visible and near-infrared.On this basis, the evolution of the electron density and the absorption coefficient and energy density of the plasma during the laser pulse were gotten. A good quantitative agreement was found between calculated and measured values.