黑体辐射法测量电介质内部被超短激光脉冲加工后的温度  

Measuring the internal temperature of dielectrics machined by the ultrashort laser pulse through the black-body irradiation method

作　　者：王承伟[1,2,3] 赵全忠[2] 钱静[2] 黄媛媛[2] 王关德[2] 李阳博[2] 柏锋 范文中[2] 李虹瑾[2] 

机构地区：[1]同济大学物理科学与工程学院,上海200092 [2]中国科学院上海光学精密机械研究所,强场激光物理国家重点实验室,上海201800 [3]中国科学院大学,北京100049

出　　处：《物理学报》2016年第12期190-198,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11374316)资助的课题~~

摘　　要：黑体辐射法可用于测量电介质内部被超短脉冲激光加工后,电子和晶格的瞬时温度.当一个超短激光脉冲通过物镜聚焦到石英玻璃内部时,在焦点附近诱导出微结构.微结构中热影响区的最大宽度为16μm,热影响区发出的黑体辐射谱通过物镜、带耦合透镜的光纤、光谱仪以及ICCD组装成的系统记录.测试系统收集了电介质内部被单个激光脉冲辐照后,热影响区发射的黑体辐射谱,然后用Planck公式拟合黑体辐射谱,得到电介质温度.电介质被超短激光脉冲辐照后,首先电介质中的价带电子通过强场电离和雪崩电离跃迁到导带,高温高压的等离子体以冲击波的形式向外运动,通过对流方式传递能量,该过程发生在激光辐照石英后21 ns内.21 ns后冲击波转化为声波,中心的气态石英通过热扩散方式影响周围的固态区域,石英温度缓慢下降.在时刻t(单位ns),石英玻璃的温度为5333 exp(-t/1289)K.石英经过3.72μs将冷却到室温,因此重复频率在269 k Hz以上的激光,加工石英玻璃时具有热累积效应.Black-body irradiation method can be utilized for measuring the instantaneous temperatures of electrons and lattice in dielectric machined by the ultrashort laser. One ultrashort laser pulse, of which the pulse energy and pulse duration are 240 μJ and 599 fs respectively, is focused into the fused silica by objective lenses with a magnification of 10 times. The focal point is at the position of 874 μm. The microstructure induced by laser near the focal point is 16 μm wide and 104 μm long. The central region of the microstructure is heavily damaged, and the marginal region is slightly modified. The black-body irradiation spectra are recorded by the system that is composed of objective lenses, a fiber with two lenses, a spectrometer and an intensified charge coupled device （ICCD）. Furthermore, other imaging elements can also be used as alternative to objective lenses, for measuring black-body spectra. The image point, which is conjunctive with the machined region due to the imaging effect of the objective lenses, is coupled into the fiber by one lens. Another lens collimates the diverging light beam from the fiber. The collimated light is incident into the spectrometer and dispersed on the ICCD. Because the minimum gate width of ICCD is much larger than the coupled time of electron and lattice, the temperature of electron equals that of lattice when they are characterized by the black-body irradiation method. The temperatures of the electrons and the lattice are regarded as the temperature of dielectric. When the system acquires the reflection peak of incident ultrashort laser, the delay is set to be 0 ns, and the central wavelength of the peak is 784 nm. Therefore, to eliminate the reflection peak, the second harmonic and supercontinuum spectra, the delay for black-body irradiation acquirement is set to be above 6 ns and the machined region should be confined inside the dielectric. The system collects the black-body spectra emitted by the heat-affected zone in fused silica 9–81 ns after the fused silica

关 键 词：黑体辐射 超短激光 电介质 电子 

分 类 号：O487[理学—固体物理]