第三代半导体因其高热导率、宽禁带等优异性能，将被广泛应用于新型电子器件和光电器件，而电子与光学声子的耦合会在很大程度上影响其发热率、导热率、光电转化效率等使用性能，因此，研究电子与光学声子的耦合可以为这类材料的开发、利用与改性提供科学指导。然而，电子与光学声子的耦合的模式分辨一直是实验研究的难点，许多实验方法只能检测到所有载能粒子相互作用的平均效果，无法揭示各个模式之间的深层次耦合关系。此外，以往的工作多数围绕传统半导体进行，针对第三代半导体的实验研究还存在较大空白。本项目将采用基于飞秒激光的“双泵浦-探测”方法进行研究，两束泵浦激光分别对电子与光学声子的模式进行独立调控，电子的状态对光学声子弛豫过程的影响由探测激光检测，从而得到典型第三代半导体碳化硅（SiC）、氮化镓（GaN）中电子与光学声子的耦合的模式分辨信息，为深入研究第三代半导体的热物性以及相关的热物理过程提供实验依据。

Due to high thermal conductivity, wide band gap and the other merits, the third-generation semiconductors will be widely applied in novel electronics and optoelectronics. The coupling between electrons and optical phonons will significantly affect the performance of these semiconductors including heat generation rate, thermal conductivity and light-to-electricity conversion efficiency. Therefore, studying the electron-optical phonon coupling could provide scientific guide for exploring, utilizing and improving this kind of materials. However, mode-wise study of the electron-optical phonon coupling is not trivial in experiments. Many experimental methods are only able to detect the averaging effect of the interactions among all the energy carriers with little illumination of the deeper-level coupling relation between different modes. In addition, most of the previous works focused on the conventional semiconductors while there is a lack of experimental investigation on the third-generation semiconductors. In this work, "dual pump-probe" technique based on femtosecond laser will be utilized. The two pump laser beams are used for independently tuning the electron mode and the optical phonon mode. The effect of the electron state on the relaxation of the optical phonons is detected by the probe laser, from which the mode-wise information about the electron-optical phonon coupling could be obtained for the representative third-generation semiconductors including silicon carbide and gallium nitride. This work will provide experimental reference for further investigating the thermal properties of the third-generation semiconductors and the related thermophysical processes.