Dipartimento di Ingegneria Elettrica e dell'Informazione, Politecnico di Bari Via Edoardo Orabona n. 4, 70125 Bari, Italy.
Department of Engineering, The University of Massachusetts, Boston, Massachusetts, 02125 USA.
Sci Rep. 2017 Jan 18;7:40924. doi: 10.1038/srep40924.
In this paper we present a physical discussion of the indirect two-photon absorption (TPA) occuring in silicon carbide with either cubic or wurtzite structure. Phonon-electron interaction is analyzed by finding the phonon features involved in the process as depending upon the crystal symmetry. Consistent physical assumptions about the phonon-electron scattering mechanisms are proposed in order to give a mathematical formulation to predict the wavelength dispersion of TPA and the Kerr nonlinear refractive index n. The TPA spectrum is investigated including the effects of band nonparabolicity and the influence of the continuum exciton. Moreover, a parametric analysis is presented in order to fit the experimental measurements. Finally, we have estimated the n in a large wavelength range spanning the visible to the mid-IR region.
本文对立方相或纤锌矿相碳化硅中的间接双光子吸收（TPA）进行了物理讨论。通过分析与晶体对称性相关的声子特征，研究了声子-电子相互作用。为了对 TPA 的波长色散和克尔非线性折射率 n 进行数学建模，提出了关于声子-电子散射机制的一致物理假设。研究了包括带非抛物性和连续激子影响在内的 TPA 光谱。此外，还进行了参数分析以拟合实验测量结果。最后，我们在从可见光到中红外的大波长范围内估计了 n。
