Double Absorption of Light in Crystals

Yanqiu Li

This paper presents dark oscillations of light-indhced absorption in heavy reduced Co: KNSBN crystal, points out there are double carriers and multiple traps in the crystal and explains the experimental results with the newly established model of double carriers and multiple traps.

М. P. Kulish

Evgueni F. Martynovich, V. P. Dresvyanskiy, С. А. Зилов +3 more

A spatially periodic distribution of the luminescence intensity of F2 and F 3 + color centers is observed in LiF crystals with induced anisotropy. The period of spatially periodic modulation of the luminescence intensity generally coincides with the period of the change in the polarization state of excitation light. For F2 centers, the experimental axial spatially periodic dependence of the luminescence intensity is close to the calculated dependence obtained in the description of the absorption and radiative transitions in the centers by linear oscillators oriented along six C 2 axes of the cubic crystal. However, for F 3 + centers, the same experiment shows a spatially periodic distribution of luminescence intensity with a modulation period shorter by a factor of 2. It is shown that this effect of modulation frequency doubling in the spatially periodic pattern of the luminescence of color centers arises due to the nonlinear dependence of the luminescence intensity on the excitation light intensity. For F 3 + centers, upon luminescence excitation in the absorption band with λmax = 452 nm, the modulation frequency doubling is due to the saturation of the metastable triplet state of such a center.

Joseph A. Giordmaine

A. A. Martynov, O. K. Pogosov

J. Steinlechner, S. Ast, Christoph Krüger +4 more

The efficient generation of second-harmonic light and squeezed light requires non-linear crystals that have low absorption at the fundamental and harmonic wavelengths. In this work the photo-thermal self-phase modulation technique is exploited to measure the absorption coefficient of periodically poled potassium titanyl phosphate (PPKTP) at 1,550 nm and 775 nm. The measurement results are (84±40) ppm/cm and (127±24) ppm/cm, respectively. We conclude that the performance of state-of-the-art frequency doubling and squeezed light generation in PPKTP is not limited by absorption.