Reply to ‘‘Comment on ‘Observation of time-nonreversible optical interaction with zinc-blende semiconductors’ ’’

Abstract

The preceding Comment by L. C. Lew Yan Voon et al. does not provide any grounds to doubt the results and interpretations developed in the commented paper.The paper' commented on by Lew Yan Voon, Fainstein, Etchegoin, Santos, and Cardona reports the experimental results on the observation of time-nonreversible polarization-sensitive interaction of light with zincblende crystals, namely, GaAs and InSb. It is mainly devoted to observation of the change of the natural timenonreversible effect resulting from stimulation of the crystal with intense optical excitation. Also, a microscopic picture of time-nonreversible light-matter interaction is discussed.The comment does not dispute the interpretation of the high-excitation experiments.However, it criticizes the attribution of the observed low intensity dichroism to symmetric terms linear in the light wave vector. If this comment were based on correct arguments, it could be a valuable contribution to the problem of reversality of light-matter interaction. However, we found that all the arguments produced in the comment are either mistaken or based on misunderstanding of paper 1.Specific points are made as follows. (i) The comment claims that Fig. 5(b) of Ref. 1 is incorrect. However, the corresponding part of the cornment clearly indicates that the commentators have not understood this figure and the explanations given in the figure caption and the text (p. 11512, lines 17 -33, first column). Of course ". .. helicity is defined with respect to the propagation direction" and therefore does not change in the time-reversed scenario. This is indeed a very well known fact. We relied on this fact in our interpretation and it is clearly stated in the text as follows: ". .. time reversal does not affect the handedness of light polarization. " However (according to the selection rules), the time-reversed scenario presented on the left side of Fig. 5(b) requires light of opposite polarization (right instead of left) to promote the corresponding time-reversed transition. Thus, diagram 5(b) indicates a clash with the assumption of time reversality. This is depicted as a cross (sign of forbiddance) on the arrow connecting left and right sides of the diagram. Consequently, we believe that Fig. 5 is correct and the commentators have not spotted any mistake in the figure.(ii) The comment states that the time-reversal operator commutes with the Hamiltonian inclusive of the spinorbit interaction and on this basis claims that gyrotropic linear dichroism could not be caused by the spin-orbit interaction. In response to this comment, we need to declare very clearly that there is an essential physical difference between the question of reversality of the crysta/ Hamiltonian itself and reversality of the Hamiltonian of the whole system, which includes the crystal and the light interacting with it. We, of course, do not doubt reversality of the crystal Hamiltonian, i.e. , its commutivity with the time-reversal operator. This is in fact clearly stated in the text of the paper as follows: ". .....

Relationship of time-reversal symmetry breaking to optical Kerr rotation

“…In proving Equation 5, we have dispelled some incorrect ideas, recently promulgated, 2,4,5,[13][14][15][16][17][18][19][20][21][22] as well as affirm and clarify the work of a number of studies. To summarize: (1) Kerr rotation may only arise from microscopic time reversal symmetry breaking; as will circular dichroism in normal incidence reflection.…”

Onsager relations and time-reversal symmetry in nonlinear optics

“…This point is made by Etchegoin et al (1994) and supported by them using a microscopic analysis of the Onsager relations for the dielectric tensor appropriate to the electronic band structure of GaAs. These criticisms were amplified in Lew Yan Voon et al (1995) but were totally rejected in Zheludev et al (1995). Zheludev et al (1995) noted that in their experiment Etchegoin et al (1994) consider induced ellipticity of linearly polarized incident light in transmission rather than the rotation of the plane of polarization in normal specular reflection, but failed to adequately address the microscopic proof of Etchegoin et al (1994).…”

“…These criticisms were amplified in Lew Yan Voon et al (1995) but were totally rejected in Zheludev et al (1995). Zheludev et al (1995) noted that in their experiment Etchegoin et al (1994) consider induced ellipticity of linearly polarized incident light in transmission rather than the rotation of the plane of polarization in normal specular reflection, but failed to adequately address the microscopic proof of Etchegoin et al (1994). Both agree that the Onsager relations may be violated in the high excitation case (pump-induced case) which renders statistical averaging inappropriate.…”

Partial Reciprocity of Faraday Rotation in Gyrotropic Crystals

“…In relation to this problem, it is worth noticing that the MG as a spatial dispersion effect induced by magnetic field should not, in principle, manifest itself as an optical rotation, while due to the time reversal symmetry it should lead to changes in the real part of the dielectric permittivity (or the refractive indices), as a result of the so-called 'kH -effect' [7]. The MG effect has been widely discussed [8][9][10][11], though the common point of view was not reached. In our recent papers it has been shown that partial non-reciprocity of the Faraday rotation exists even in quartz crystals, in spite of the fact that the MG effect is forbidden by the point symmetry of those crystals [12] for the experimental geometry used in the works [12,13] (k H Z).…”