大功率半导体激光加工光致等离子体折射效应

为了研究大功率半导体激光加工过程中,光致等离子体对激光光束显著的屏蔽作用,以波长为976nm、光斑尺寸为0.5mm1mm、最大功率为4kW的半导体激光加工系统为实验基础,采用了与实际相符的光致等离子体电子密度数学模型和几何光学ABCD矩阵算法,从吸收和折射两方面对光致等离子体的屏蔽作用进行了理论分析和实验研究,得到了在光致等离子体电子密度ne1.01018/cm3的条件下,光致等离子体的折射效应才是引起半导体激光光束屏蔽的主要原因这一结果。结果表明,光致等离子体改变了聚焦光束的形态,使其焦点下移、光斑变大、能量密度变小,其效果类似于一个非线性梯度折射率的负透镜。

Refraction effect of light-induced plasma during high-power diode laser processing

In order to solve the significant shielding effect of light-induced plasma on laser during high-power diode laser processing, with the help of the mathematical model of electron density of light-induced plasma and ABCD matrix algorithm, the shielding effect of light-induced plasma was studied from the view of absorption and refraction based on a diode laser processing system with wavelength of 976nm, spot size of 0.5mm1mm and the maximum power of 4kW. The results showed that laser beam shielding effect is mainly due to refraction effect of light-induced plasma under the condition of electron density ne1.01018/cm3. Laser beam shielding effect changes laser beam shape, i.e., making the laser focus down-shift, enlarging the spot and making the laser energy density smaller. The effect of induced-laser plasma is similar to a negative lens with non-linear gradient refractive index.