Recent advances in monoclinic crystal optics

Abstract

This article is mainly devoted to the modeling and measurement of the absorption and fluorescence angular distributions in polarized light of monoclinic crystals. Up to now theoretical crystal optics were mostly devoted to crystals having a high crystallographic symmetry. In these crystals belonging to the cubic, hexagonal, tetragonal, trigonal or orthorhombic lattice classes, the tensor properties related to the real part of the dielectric permittivity and to its imaginary part can be described in the same frame which orientation does not vary as a function of wavelength. The situation is much more complicated in the case of monoclinic crystals because it is necessary to define a specific frame for each property and each wavelength that are considered. The main features of monoclinic crystal optics are described in detail, followed by a review of monoclinic materials and the consequence of these features on their related optical properties.

All-space existence and dispersion of athermal directions in monoclinic KY(WO4)2

“…It should be noted that optical axes causes a peculiarity in the solutions (see inset in Fig. 3), very similar to the one observed recently for anisotropic absorption of another monoclinic crystal [30]. The remaining m-p plane contains no athermal direction.…”

“…5 shows the position of athermal directions for "laser cavity" definition in the principal planes of optical indicatrix as a function of light wavelength. The calculations are performed for visible and near-IR, up to 1.1 μm, the region of applicability of dispersion formulas for n and dn/dT [30]. The consideration of 1 μm range is interesting for Yb-lasers.…”

“…Such waves for biaxial crystals are sometimes called "o-wave" and "e-wave" [27,28], accordingly, as their propagation is similar to the case of uniaxial crystal. Similar notations were introduced also recently in the review paper [30] devoted particularly to the description of anisotropy of optical properties of biaxial monoclinic crystals. It should be noted that the terms "fast" and "slow" wave, from the one hand, and "o-wave" and "e-wave", from another, are not identical.…”

Thermo-optic dispersion formulas for YCOB and GdCOB laser host crystals

“…1. The orientation of the optical indicatrix (a^Z ~26° and c^X ~15°) of GdCOB is nearly wavelength independent between 0.4 and 2.2 μm [18]. From the as-grown bulk crystals, two rectangular samples were cut in the frame of the optical indicatrix having the dimensions of 6.01(X) × 7.41(Y) × 6.88(Z) mm 3 for YCOB and 6.97(X) × 5.17(Y) × 5.67(Z) mm 3 for GdCOB.…”

Raman and fluorescence correlative microscopy in polarized light to probe local femtosecond laser-induced amorphization of the doped monoclinic crystal LYB:Eu

“…Since the LYB:Eu is a potential laser crystal [10], these observations are of strong interest when considering possibilities to tune both structural and optical properties of this material by direct laser writing, especially for weaker crystal modifications related to waveguide writing for laser amplification applications [11][12][13][14][15]. Moreover, since such crystal is a low symmetry crystal, intensity thresholds for laser-induced modifications should significantly depend on the considered crystal orientation [16]. Finally, such correlative approach provides a versatile tool for micro-spectroscopy that can also apply for advanced imaging microscopy to probe wanted DLW but also undesired laser-induced damages, in the case of laser material ageing.…”