Применение метода отклонения лазерного пучка для определения термооптических коэффициентов в кристалле гадолиний-иттриевого ортосиликата, легированного ионами эрбия

Results of use of the laser beam deflection technique for determination of thermo-optic coefficients (TOCs) of the Er3+-doped gadolinium-yttrium oxyorthosilicate crystal (Er3+:(GdY) SiO– Er:GYSO) are presented. A 0.1 at.% Er-doped gadolinium-yttrium oxyorthosilicate crystal was grown by the Czochralski method under nitrogen atmosphere. Raw materials such as Er2O3, Gd2O3, Y2O3, and SiO2 were weighed according to the formula (Er0.001Gd0.8995Y0.0995)2SiO5. Optical properties of the biaxial Er:GYSO crystal are described within the frame of the optical indicatrix with orthogonal principal axes Np , Nm , and Ng . To characterize the anisotropy of the TOCs a sample from the grown Er:GYSO crystal was prepared in a shape of a rectangular parallelepiped with dimensions of 7.0 (Np ) × 8.0 (Nm ) × 8.5 (Ng ) mm3. Each face of the sample is perpendicular to one of the optical indicatrix axes Np , Nm and Ng . For determination of the TOCs the laser beam deflection technique for a material with a linear temperature gradient is used. Measurements are performed at the wavelength of 632.8 nm. The thermal coefficient of the optical path (TCOP) for the Er:GYSO crystal measured at the wavelength of 632.8 nm at different light polarization E and propagation direction k were obtained. The TCOP values are positive for all directions of the light propagation k // Np , Nm , Ng . This means that the sign of the thermal lens which is directly related to the TCOP value will also be positive, and the positive thermal lens is then expected for Np Nm-, and Ng -cut Er:GYSO. Applying an analysis of the thermal lensing the dn /dT value for Yb:GYSO is estimated to be 6.5×10–6 K–1.  В статье представлены результаты использования метода отклонения лазерного пучка для определения величин термооптических коэффициентов (ТОК) в кристалле гадолиний-иттриевого ортосиликата, легированного ионами эрбия Er3+ (Er3+:(GdY)2SiO5– Er:GYSO). Кристалл Er:GYSO, легированный ионами эрбия в количестве 0,1 ат.%, выращен методом Чохральского в атмосфере азота. Шихта состояла из оксидов Er2O3, Gd2O3, Y2O3 и SiO2 в пропорции, соответствующей формуле (Er0.001Gd0.8995Y0.0995)2SiO5. Оптические свойства кристалла Er:GYSO описываются на основе оптической индикатрисы с тремя ортогональными главными осями Np , Nm  и Ng . Для характеризации TOК использовался образец кристалла Er:GYSO в форме прямоугольного параллелепипеда размером 7,0 (Np) × 8,0 (Nm ) × 8,5 (Ng ) мм3. Грани образца перпендикулярны осям оптической индикатрисы Np , Nm  и Ng . Метод отклонения лазерного пучка в результате распространения через исследуемый материал, в котором создан линейный градиент температуры, использован для определения TOК. Измерения проведены на длине волны 632,8 нм. Установлены также термические коэффициенты оптического пути (TКOП) для кристалла Er:GYSO на длине волны 632,8 нм для различных поляризаций света E и волнового вектора k. Величины TКOП являются положительными для всех направлений распространения света k // Np , Nm , Ng . Это означает, что знак термической линзы, которая непосредственно связана с величиной TКOП, будет также положительным и, следовательно, положительная термическая линза будет наблюдаться в кристалле Er:GYSO, вырезанном вдоль направлений Np , Nm  и Ng . Из анализа значений термической линзы величина dn/dT в кристалле Yb:GYSO оценена как 6,5×10–6 K–1

Thermo-optic coefficients of monoclinic Er3+:(GdY)2SiO5 crystal

Thermo-optic coefficients of the Er3+-doped gadolinium-yttrium oxyorthosilicate crystal Er3+:GdYSO are determined at a wavelength of 632.8 nm for light polarizations E // Np, Nm and Ng. Linear thermal expansion coefficients are estimated for this crystal in the directions of the optical indicatrix axes Nm and Ng

Optical properties of spinel based glass-ceramics of the Zno-Al2O3-Ga2O3-SiO2 system doped with Co2+ ions

Transparent glass-ceramics containing Co2+:Zn(Al,Ga)2O4 spinel nanocrystals with sizes of 6–11 nm were studied. Absorption band of the Co2+ ions in the material is shifted to longer wavelengths as compared with glass-ceramics with no Ga2O3 addition. Absorption saturation at 1.54 μm was observed and its characteristics (absorption recovery time, ground-state and excited-state absorption cross-sections) were measured. The developed glass-ceramics are promising as saturable absorbers for 1.6 μm erbium lasers

Thermal expansion of KYbXY1-X(WO4)2 crystals

Average and differential linear thermal expansion coefficients of KYbxY1-x(WO4)2 crystals are determined in the directions of the optical indicatrix axes Np, Nm and Ng using dilatometric technique. Dependence of the average and differential linear thermal expansion coefficients on the temperature in the range of 75–290 C and ytterbium contains x from 0 to 1.0 are discussed

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

The analytical expressions for thermo-optic coefficients, dn/dT, for “fast” and “slow” light waves propagating along the arbitrary direction in a biaxial crystal are derived. On the basis of these expressions, the all-space analysis of existence of athermal directions is performed for monoclinic and biaxial KY(WO4)2 at 1.03 μm. The calculations are performed for an arbitrary light propagation direction and polarization (not restricted to the principal planes). The appearance of directions that can be athermal for both “fast” and “slow” waves is predicted. The dispersion of athermal directions is analyzed for visible and near-IR. The existence of upper and lower dispersion limits for athermal behavior of KY(WO4)2 is shown. It is shown that the optical indicatrix axes can be athermal itself at some light wavelengths. Wavelength- and temperature-dependent position of the optical axes of KY(WO4)2 is also determined

Use of the Laser Beam Deflection Technique for Thermo-Optic Coefficients Study in Gadolinium-Yttrium Oxyorthosilicate Doped with Erbium Ions

Results of use of the laser beam deflection technique for determination of thermo-optic coefficients (TOCs) of the Er3+-doped gadolinium-yttrium oxyorthosilicate crystal (Er3+:(GdY)2SiO5 – Er:GYSO) are presented. A 0.1 at.% Er-doped gadolinium-yttrium oxyorthosilicate crystal was grown by the Czochralski method under nitrogen atmosphere. Raw materials such as Er2O3, Gd2O3, Y2O3, and SiO2 were weighed according to the formula (Er0.001Gd0.8995Y0.0995)2SiO5. Optical properties of the biaxial Er:GYSO crystal are described within the frame of the optical indicatrix with orthogonal principal axes Np , Nm , and Ng . To characterize the anisotropy of the TOCs a sample from the grown Er:GYSO crystal was prepared in a shape of a rectangular parallelepiped with dimensions of 7.0 (Np ) × 8.0 (Nm ) × 8.5 (Ng ) mm3. Each face of the sample is perpendicular to one of the optical indicatrix axes Np , Nm and Ng . For determination of the TOCs the laser beam deflection technique for a material with a linear temperature gradient is used. Measurements are performed at the wavelength of 632.8 nm. The thermal coefficient of the optical path (TCOP) for the Er:GYSO crystal measured at the wavelength of 632.8 nm at different light polarization E and propagation direction k were obtained. The TCOP values are positive for all directions of the light propagation k // Np , Nm , Ng . This means that the sign of the thermal lens which is directly related to the TCOP value will also be positive, and the positive thermal lens is then expected for Np - Nm-, and Ng -cut Er:GYSO. Applying an analysis of the thermal lensing the dn /dT value for Yb:GYSO is estimated to be 6.5×10–6 K–1

Luminescence of oxyfluoride glasses containing YB3+–RE3+ ions

The optical absorption and up-conversion luminescence of oxyfluoride glasses in the system SiO2–PbO–PbF2–CdF2 coactivated by Yb3+–RE3+ ions (where RE = Er, Tm, Ho, Dy, Pr, or Tb) are investigated. Excitation with a laser diode in the IR range (960 nm) gives intense green, blue, and red luminescence. The color characteristics of the up-conversion luminescence in the CIE 1931 system are determined. The efficiency of energy transfer from the Yb3+ to the RE3+ ions is found to be 70% for RE = Er, Tm, and Ho. The efficiency of cooperative energy transfer reaches 10% for glass with Yb–Tb ions