Laser dressing of the electronic bands in semiconductors

We discuss the validity of the renormalized effective mass approximation to treat the interaction of a laser held with a semiconductor, in a one-body approximation. The electronic band structure of the semiconductor is modele d by two-parabolic, isotropic bands in the (k) over right arrow.(p) over ri ght arrow approximation. To incorporate the laser field into an effective m ass formalism (renormalized effective mass approximation) we apply the dres sed-atom approach to the two-band model (dressed-band approximation), the e igenvalue problem for the dressed bands is solved analytically and a k expa nsion is performed. The validity of the renormalized mass approximation is studied, comparing the results for the quasi-energy spectrum and for the ef fective mass obtained from the renormalized mass approximation, the dressed -band approximation and the "exact" results derived from the diagonalizatio n of the Floquet matrix. We show that for the laser intensities which will not damage the semiconductor samples in experiments, the agreement is excel lent. (C) 1999 Elsevier Science Ltd. All rights reserved.