Petris Adrian, Gheorghe Petronela, Braniste Tudor, Tiginyanu Ion
National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Street, 077125 Magurele, Romania.
National Center for Materials Study and Testing, Technical University of Moldova, Stefan cel Mare av. 168, 2004 Chisinau, Moldova.
Materials (Basel). 2021 Jun 10;14(12):3194. doi: 10.3390/ma14123194.
The ultrafast third-order optical nonlinearity of c-plane GaN crystal, excited by ultrashort (fs) high-repetition-rate laser pulses at 1550 nm, wavelength important for optical communications, is investigated for the first time by optical third-harmonic generation in non-phase-matching conditions. As the thermo-optic effect that can arise in the sample by cumulative thermal effects induced by high-repetition-rate laser pulses cannot be responsible for the third-harmonic generation, the ultrafast nonlinear optical effect of solely electronic origin is the only one involved in this process. The third-order nonlinear optical susceptibility of GaN crystal responsible for the third-harmonic generation process, an important indicative parameter for the potential use of this material in ultrafast photonic functionalities, is determined.
利用非相位匹配条件下的光学三次谐波产生，首次研究了c面GaN晶体在1550 nm（对光通信很重要的波长）的超短（飞秒）高重复率激光脉冲激发下的超快三阶光学非线性。由于高重复率激光脉冲引起的累积热效应可能在样品中产生的热光效应不能解释三次谐波产生，因此该过程中仅涉及电子起源的超快非线性光学效应。确定了负责三次谐波产生过程的GaN晶体的三阶非线性光学极化率，这是该材料在超快光子功能中潜在应用的一个重要指示参数。
