Presentation Information
[10p-N203-9]Measurement of the Complex Anisotropy Ratio of the Nonlinear Optical Susceptibility in the Third Harmonic Generation by Terahertz Free-Electron Laser
〇(P)KHOA PHAN1, You Wei Wang1, Kosaku Kato1, Verdad C. Agulto1, Goro Isoyama2, Makoto Nakajima1 (1.UOsaka, ILE, 2.UOsaka, SANKEN)
Keywords:
harmonic generation,narrow band-gap semiconductor,terahertz free electron laser
The efficient nonlinear optical effect due to free carrier in the infrared region and terahertz (THz) region has been studied in narrow band gap semiconductor. The widely accepted mechanism has been attributed to the momentum-dependent effective mass of the free carrier. This mechanism leads to a real value of the nonlinear susceptibility. Later, several authors extended the calculation and showed that the nonlinear susceptibility is a complex number, in which the momentum-dependent scattering time contributes to the imaginary part.
By utilizing an intense 4-THz beam from a THz free electron laser (FEL), we observed the angular anisotropy of the third harmonic generation (THG) from indium antimonide (InSb). The extracted anisotropy ratios between two components of the third order susceptibility tensor were found to be complex values, indicates a non-negligible contribution of momentum dependence of the scattering time to the imaginary part of the nonlinear susceptibility, in addition to the band nonparabolicity which contributes to the real part. The results provide a deeper understanding of nonlinear optics in the terahertz region.
By utilizing an intense 4-THz beam from a THz free electron laser (FEL), we observed the angular anisotropy of the third harmonic generation (THG) from indium antimonide (InSb). The extracted anisotropy ratios between two components of the third order susceptibility tensor were found to be complex values, indicates a non-negligible contribution of momentum dependence of the scattering time to the imaginary part of the nonlinear susceptibility, in addition to the band nonparabolicity which contributes to the real part. The results provide a deeper understanding of nonlinear optics in the terahertz region.