Kerr nonlinearity and multi-photon absorption in germanium at mid-infrared wavelengths

TitleKerr nonlinearity and multi-photon absorption in germanium at mid-infrared wavelengths
Publication TypeJournal Article
Year of Publication2017
AuthorsSohn, B-U, Monmeyran, C, Kimerling, LC, Agarwal, AM, Tan, DTH
JournalApplied Physics Letters
Volume111
Issue9
Pagination091902
Date Published2017/08/28/
ISBN Number0003-6951
Keywords2-photon absorption, all-optical modulation, silicon
Abstract

Multiphoton absorption coefficients and nonlinear refractive indices of germanium in the near and mid-infrared (2-5 mu m) are reported. The nonlinear coefficients are measured by open and closed aperture Z-scan with 150 fs pulses at a repetition rate of 1 kHz. The nonlinear refractive index of Ge has a peak value of 9.1 x 10(-5) cm(2)/GW at a wavelength of 3 mu m. The effect of free electrons generated by multiphoton absorption is discussed by investigating the variation of multiphoton absorption coefficients at different input powers. Kramers-Kronig relations are also discussed with regard to the relationship between nonlinear refractive index and two photon absorption coefficient. Published by AIP Publishing.

Short TitleAppl. Phys. Lett.