Xu Shen, Wang Tianyu, Hurley David, Yue Yanan, Wang Xinwei
Opt Express. 2015 Apr 20;23(8):10040-56. doi: 10.1364/OE.23.010040.
A novel transient thermal characterization technology is developed based on the principles of transient optical heating and Raman probing: time-domain differential Raman. It employs a square-wave modulated laser of varying duty cycle to realize controlled heating and transient thermal probing. Very well defined extension of the heating time in each measurement changes the temperature evolution profile and the probed temperature field at μs resolution. Using this new technique, the transient thermal response of a tipless Si cantilever is investigated along the length direction. A physical model is developed to reconstruct the Raman spectrum considering the temperature evolution, while taking into account the temperature dependence of the Raman emission. By fitting the variation of the normalized Raman peak intensity, wavenumber, and peak area against the heating time, the thermal diffusivity is determined as 9.17 × 10(-5), 8.14 × 10(-5), and 9.51 × 10(-5) m(2)/s. These results agree well with the reference value of 8.66 × 10(-5) m(2)/s considering the 10% fitting uncertainty. The time-domain differential Raman provides a novel way to introduce transient thermal excitation of materials, probe the thermal response, and measure the thermal diffusivity, all with high accuracy.
基于瞬态光加热和拉曼探测原理，即时域差分拉曼，开发了一种新型瞬态热表征技术。它采用占空比可变的方波调制激光来实现可控加热和瞬态热探测。每次测量中加热时间的明确延长会以微秒分辨率改变温度演变曲线和探测到的温度场。利用这项新技术，研究了无尖硅悬臂梁沿长度方向的瞬态热响应。建立了一个物理模型，在考虑拉曼发射的温度依赖性的同时，根据温度演变来重建拉曼光谱。通过拟合归一化拉曼峰强度、波数和峰面积随加热时间的变化，确定热扩散率为9.17×10(-5)、8.14×10(-5)和9.51×10(-5) m(2)/s。考虑到10%的拟合不确定性，这些结果与参考值8.66×10(-5) m(2)/s吻合良好。时域差分拉曼提供了一种新颖的方法，能够高精度地引入材料的瞬态热激发、探测热响应并测量热扩散率。
