V. P. Orekhova

Optical and nonlinear laser properties of the χ(3)-active monoclinic α-KY(WO4)2 crystals

Monoclinic α-KRE(WO4)2 crystals are grown. Their structure is described in two crystallographic settings. The principal refractive indices are determined and the coefficients and characteristic wavelengths are used for calculating refractive indices by the Selmeyer formulas. The data on the anisotropic parametric Raman generation in these crystals under the picosecond pumping are discussed.

Refractive indices of laser nanocrystalline ceramics based on Y3Al5O12

Refractive indices of the nanocrystalline Y3Al5O12 ceramic and a garnet single crystal of the same composition have been measured. In the visible and near IR range (0.4–1.064 μm), the prism method was used; in the medium IR range (2–6.2 μm), the interference method with the use of thin plates was applied. The refractive indices of these crystalline materials are practically the same over the entire spectral range studied and are described by the approximate formula proposed earlier for a single crystal. The parameters of the continuos-wave lasing in the nanocrystalline Y3Al5O12 ceramic doped with Nd3+ and Yb3+ ions measured recently are presented.

The absorption and circular dichroism spectra of langasite family crystals doped with chromium ions

The absorption and circular dichroism spectra of langasite family crystals, La3Ga5SiO14, La3Ga5GeO14, Ca3Ga2Ge4O14, Sr3Ga2Ge4O14 (red), Sr3Ga2Ge4O14 (green), La3Ta0.5Ga5.5O14, and La3Nb0.5Ga5.5O14, which were doped with chromium ions, have been investigated in the range of 240–850 nm. It is shown that chromium ions are incorporated into the structure of the investigated crystals both in the octahedrally (Cr3+ ion in 1a octahedron) and tetrahedrally (Cr4+ ion in 2d tetrahedron) coordinated positions. The ion ratio Cr3+/Cr4+ changes in a wide range in the crystals studied.

Lasing and refractive indices of nanocrystalline ceramics of cubic Yttrium Oxide Y2O3 doped with Nd3+ and Yb3+ ions

A continuous-wave lasing at 1 μm was excited by the radiation of semiconductor laser diodes at room temperature in nanocrystalline ceramics Y2O3 doped with Nd3+ and Yb3+ ions. The refractive indices of the undoped nanocrystalline Y2O3 ceramics were measured in the wavelength range 0.4–9 μm.

Investigation of the optical properties of KGd(WO4)2:Nd3+ crystals with allowance for absorption

The optical properties of a biaxial absorbing KGd(WO4)2:Nd3+ crystal have been investigated. The main refractive indices were measured in the visible spectral range and the absorption and transmission spectra of samples of these crystals were studied. The changes in the refractive indices were in the region of the absorption bands with the use of the Kramers-Kronig relation. Conoscopic pictures of this crystal in the regions of transparency and absorption bands were calculated and are presented.

Dichroism and birefringence of natural violet diamond crystals

Investigation of the optical properties of natural violet diamonds from the Yakutian kimberlites is performed. A red shift of the absorption edge is revealed in the absorption spectra of these crystals. This shift is indicative of the presence of a high concentration of nitrogen in the diamonds studied. Along with the strong band at 0.550 μm, weaker bands at 0.390, 0.456 and 0.496 μm are revealed. It is shown that violet diamond crystals have birefringence and dichroism of about 10−5 and 10−6, respectively. When a light beam propagates perpendicularly to colored lamellas, the dichroism is much larger and the birefringence is smaller than in the case where the beam direction is parallel to lamellas.

Anisotropic optical properties of crystals with the Ca-gallogermanate structure

The optical properties of inactivated and activated crystals with the structure of Ca-gallogermanate have been studied. The components of the gyration pseudotensor for Sr3Ga2Ge4O14 crystals are determined. In the ultraviolet range of the spectra of all the crystals studied, the bands of circular and linear dichroism and the anomalous behavior of the linear birefringence are observed irrespective of the activating dopant. The formation of these bands is not associated with the electron transitions of doping ions and can be caused by structural defects formed in the growth process.

Influence of X-ray irradiation on the optical properties of chromium-doped KliSO4 crystals

The absorption and circular-dichroism spectra of chromium-activated KLiSO4 crystals both nonirradiated and irradiated with an X-ray beam have been studied. It was established that in nonirradiated crystals chromium ions are mainly trivalent (Cr3+) and have octahedral coordination. In irradiated crystals, along with the centers provided by (Cr3+) ions, new centers are formed associated with (Cr4+) and (Cr5+) ions.

Absorption spectra and circular dichroism of Sr3Ga2Ge2O14: Cr and Ca3Ga2Ge2O14: Cr crystals

Absorption spectra and circular dichroism spectra of chromium-doped Sr-gallogermanate crystals of different colors and doped and pure Ca-gallogermanate crystals have been studied. It is shown that chromium ions enter the Sr-gallogermanate crystals in two valence states—Cr3+ and Cr4+. It is assumed that Cr4+ ions replace Ge4+ in the tetrahedra.