|Title||Kerr nonlinearity and multi-photon absorption in germanium at mid-infrared wavelengths|
|Publication Type||Journal Article|
|Year of Publication||2017|
|Authors||Sohn, B-U, Monmeyran, C, Kimerling, LC, Agarwal, AM, Tan, DTH|
|Journal||Applied Physics Letters|
|Keywords||2-photon absorption, all-optical modulation, silicon|
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 Title||Appl. Phys. Lett.|