Three photon absorption in silicon for 2300 - 3300 nm

• Published in: Applied physics letters 2008-09, Vol.93 (13), p.131102-131102-3
• Main Authors: Pearl, Shaul, Rotenberg, Nir, van Driel, Henry M.
• Format: Article
• Language: English
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.2991446

We measure the spectral dependence of the degenerate three photon absorption coefficient, γ , for a Si [100] wafer using 200 fs pulses in the range 2300 - 3300 nm , i.e., photon energy between half and one-third the indirect band gap. For pulses linearly polarized along the [001] crystal axis γ increases from a value of near 0 cm 3 ∕ GW 2 at 3300 nm to a peak value of 0.035 cm 3 ∕ GW 2 at 2700 nm before decreasing with shorter wavelength; this is consistent with the dispersion expected from allowed-allowed-allowed transitions. At 2600 nm the γ value is ∼ 30 % larger for light polarized along [011] than along [001].