| Autor: |
Furey, Brandon J., Barba-Barba, Rodrigo M., Carriles, Ramon, Bernal, Alan, Mendoza, Bernardo S., Downer, Michael C. |
| Předmět: |
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| Zdroj: |
Journal of Applied Physics; 5/14/2021, Vol. 129 Issue 18, p1-13, 13p |
| Abstrakt: |
Spectra of the degenerate two-photon absorption coefficient β (ω) , anisotropy parameter σ (ω) , and dichroism parameter δ (ω) = [ σ (ω) + 2 η (ω) ] / 2 of crystalline 110-cut GaAs, GaP, and Si, at 300 K were measured using femtosecond pump–probe modulation spectroscopy over an excitation range in the vicinity of each material's half-bandgap E g / 2 (overall 0.62 < ℏ ω < 1.91 eV or 2000 > λ > 650 nm). Together, these three parameters completely characterize the three independent components of the imaginary part of the degenerate third-order nonlinear optical susceptibility tensor Im { χ a b c d (3) (ω) }. In direct-gap GaAs, these components peak at ℏ ω ≈ 0.78 E g , which is close to the peak at ℏ ω = 0.71 E g predicted by the Jones–Reiss phenomenological model. The dispersion is comparable with ab initio calculations. In indirect-gap GaP and Si, these components tend to increase with ℏ ω over our tuning range. In Si, the dispersion differs significantly from predictions of semi-empirical models, and ab initio calculations do not account for transitions below the two-photon direct bandgap, motivating further investigation. Kleinman symmetry was observed to be broken in all three materials. We also note anomalies observed and their possible origins, emphasizing the advantages of a 2-beam experiment in identifying the contribution of various nonlinear effects. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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