强激光作用下单晶硅的热畸变特性研究

Study of Thermal Deformations of Silicon Substrate Subjected to Irradiation of High Power Laser

高功率激光已经广泛应用于核聚变、激光加工、激光化学以及材料处理等领域.在强激光的辐照下,由于大量光子进入材料体内被吸收,局部蓄热,因而形成较大的温度场梯度.考虑到有限厚介质的表面热对流,利用格林函数方法理论计算了硅基板的三维温度分布和热变形,给出了硅基板温度分布和热变形跟基片半径和厚度的关系表示式以及关系曲线图.计算结果表明:温升不仅与介质的吸收系数密切相关,而且与对流换热系数有关.在激光照射的初始阶段,基片热变形量迅速增加;其后,随着激光照射时间的增加,热变形增加量逐步变缓.

High-power lasers are required for nuclear fusion applications whereas more-modest power levels are required for laser machining, laser chemistry, and material processing applications. Heat, which is produced in a medium as a result of absorption of optical energy from an incident high-power laser beam, diffuses through the medium in accordance with a heat conduction equation. For finite-thickness media with convective surface losses, the thermal deformation distributions of silicon substrate are calculated by use of the well-known Green＇s function methods. The results show that the thermal deformations are closely related to the absorption coefficient of the medium. The initial thermal deformations of the medium surfaces increase quickly at the beginning of laser heating. After that, the thermal deformations are insensitive to laser heating times.