Second-order optical response in semiconductors
Abstract
We present a new general formalism for investigating the second-order optical response of solids, and illustrate it by deriving expressions for the second-order susceptibility tensor χ2(-ωΣωβ,ωγ), where ωΣ=ωβ+ωγ, for clean, cold semiconductors in the independent particle approximation. Based on the identification of a polarization operator P that would be valid even in a more complicated many-body treatment, the approach avoids apparent, unphysical divergences of the nonlinear optical response at zero frequency that sometimes plague such calculations. As a result, it allows for a careful examination of actual divergences associated with physical phenomena that have been studied before, but not in the context of nonlinear optics. These are (i) a coherent current control effect called ``injection current,'' or ``circular photocurrent,'' and (ii) photocurrent due to the shift of the center of electron charge in noncentrosymmetric materials in the process of optical excitation, called ``shift current.'' The expressions we present are amenable for numerical calculations, and we demonstrate this by performing a full band-structure calculation of the shift current coefficient for GaAs.
- Publication:
-
Physical Review B
- Pub Date:
- February 2000
- DOI:
- 10.1103/PhysRevB.61.5337
- Bibcode:
- 2000PhRvB..61.5337S
- Keywords:
-
- 78.20.Bh;
- 42.65.An;
- 42.65.Hw;
- 42.65.Ky;
- Theory models and numerical simulation;
- Optical susceptibility hyperpolarizability;
- Phase conjugation;
- photorefractive and Kerr effects;
- Frequency conversion;
- harmonic generation including higher-order harmonic generation