Light deflection induced by ferroelastic layered domains

Abstract

Spccific light deflection phenomena are observed in ferroelastic crystals. Above a critical angle of incidence r , , four deflected beams. which are linearly polarized, are observed with a laser beam incidence. The polarizing directions of the deflected beams are directly related to the directions of axes of the optical indicatrix in the ferroelastic domains. The relation between the angle of incidence I and the angles of deflection l , and the polarizing directions of the deflected beams are explained by the Huygens constructions to the ray-velocity cross sections at the crystal surfaces and the domain walls in the incident plane. This optical phenomenon is confirmed as a specific property of ferroelastic crystals with multidomains. The properties of the deflected beams are described in detail.

Birefringence measurements by means of light deflection at domain walls in ferroelastic crystals

“…In the B deflection process [Eq. ( 4)] the incident slow wave is quasi ordinary (whatever the cutting axis x and the incidence angle i), whereas the low index n f (␤ f ) of the deflected wave follows a quasi-elliptical law, similar to approximation (5). The B deflection process can be considered reciprocal to the A deflection process, by reversal of the light path.…”

“…In what follows, we shall suppose that the crystal sample is a plate cut perpendicularly to the W-walls-as is usually done in any deflection experiment by Tsukamoto et al [1][2][3][4][5] and as we do here. The plate will be designated by the cutting axis perpendicular to the surfaces: x 1 cut, x 2 cut, or any x cut [x axis lying in the plane (x 1 , x 2 ) of the domain walls].…”

“…By combination of Eqs. (1) and approximation (5) we obtain, for x 1 -and x 2 -cut samples, respectively,…”

“…It was described by Tsukamoto et al in for Rochelle salt, rubidium hydrogen selenate, gadolinium molybdate, and bismuth titanium oxide. [1][2][3][4][5] The authors of those papers calculated deflection angles ␣ and ␤ as functions of incidence angle i by computing the Huygens-Fresnel principle at three interfaces (input face of the crystal, domain wall, and output face), assuming knowledge of all optical parameters of the crystal (values of the principal indices, orientation of the principal axes). By the way, the calculation dealing with Poynting vectors is not straightforward but is nevertheless exact in any case, regardless of the crystal symmetry.…”

Combined effects due to phase, intensity, and contrast in electrooptic modulation: application to ferroelectric materials

“…Similar phenomena can be observed with ferroelectric crystals exhibiting a layered domain structure. In such crystals, where the domain walls are all of the same kind and parallel to each other, the deflection phenomenon gives-as a rule-six beams [7], [8], schematically shown in Fig. 3(b).…”