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Comment on "Dispersive Terahertz Gain of a Nonclassical Oscillator: Bloch Oscillation in Semiconductor Superlattices"

A. Lisauskas·N. V. Demarina·E. Mohler·H. G. Roskos
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Abstract

In two recent Letters [Phys. Rev. Lett. 90, 046806; Phys. Rev. Lett. 94, 057408], Hirakawa et al. investigate the emission of coherent terahertz (THz) radiation from optically excited superlattices. The authors interpret the spectra of the THz transients in terms of a semiclassical transport model and conclude that the data provide evidence for the existence of the so-called Bloch gain. We show that the interpretation of the data in terms of a conductivity is, however, not performed correctly, thus making the conclusions of cited authors void.

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A. Lisauskas, N. V. Demarina, E. Mohler, H. G. Roskos. 2006-05-26. Comment on "Dispersive Terahertz Gain of a Nonclassical Oscillator: Bloch Oscillation in Semiconductor Superlattices". https://arxiv.org/abs/cond-mat/0605651

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