Temperature-Dependent and Threshold Behavior of Sm3+ Ions on Fluorescence Properties of Lithium Niobate Single Crystals.

Mingming Yang,Yunzhong Zhu,Xin Yang,Biao Wang,Siwei Long,Decai Ma,Shaopeng Lin

doi:10.3390/ma11102058

Abstract

Temperature-dependent and threshold behavior of Sm3+ ions on fluorescence properties of lithium niobate (LiNbO3, LN) single crystals were systematically investigated. The test materials, congruent LiNbO3 single crystals (Sm:LN), with various concentrations of doped Sm3+ ions from 0.2 to 2.0 mol.%, were grown using the Czochralski technique. Absorption spectra were obtained at room temperature, and photoluminescence spectra were measured at various temperatures in the range from 73 K to 423 K. Judd–Ofelt theory was applied to calculate the intensity parameters Ωt (t = 2, 4, 6) for 1.0 mol.% Sm3+-doped LiNbO3, as well as the radiative transition rate, Ar, branching ratio, β, and radiative lifetime, τr, of the fluorescent 4G5/2 level. Under 409 nm laser excitation, the photoluminescence spectra of the visible fluorescence of Sm3+ mainly contains 568, 610, and 651 nm emission spectra, corresponding to the energy level transitions of 4G5/2→6H5/2, 4G5/2→6H7/2, and 4G5/2→6H9/2, respectively. The concentration of Sm3+ ions has great impact on the fluorescence intensity. The luminescence intensity of Sm (1.0 mol.%):LN is about ten times as against Sm (0.2 mol.%):LN at 610 nm. The intensity of the fluorescence spectra were found to be highly depend on temperature, as well as the concentration of Sm3+ ions in LiNbO3 single crystals, as predicted; however, the lifetime changed little with the temperature, indicating that the temperature has little effect on it, in Sm:LN single crystals. Sm:LN single crystals, with orange-red emission spectra, can be used as the active material in new light sources, fluorescent display devices, UV-sensors, and visible lasers.

Highlights

Lithium niobate (LiNbO3, LN), as a full-feature crystal, possesses many excellent properties, such as electro-optical, nonlinear optical, and acousto-optical properties, that enable it to be widely used in electro-optic (EO) signal modulation, lasers, biological imaging, temperature sensors, and many other examples
Absorption spectra, the locations of the Sm3+ ions and the shifts in the absorption edges after examining the emission spectra, we found that the optimal concentration of Sm3+ ions is 1.0 mol.%
− examining the emission spectra, we found that the optimal concentration of

Summary

Introduction

Lithium niobate (LiNbO3 , LN), as a full-feature crystal, possesses many excellent properties, such as electro-optical, nonlinear optical, and acousto-optical properties, that enable it to be widely used in electro-optic (EO) signal modulation, lasers, biological imaging, temperature sensors, and many other examples. Sm3+ -containing hosts have been offered as infrared counters, as an activated solid, and as a means to increase the photovoltaic solar cell conversion efficiency via down-conversion of the solar spectrum [12,13] Most of those reports have mainly focused on fluorosilicate glasses [14], alkyl-bariumbismuth-tellurite (LKBBT) glass [15], and other glasses at room temperature [16]. Our work is mainly focused on the impact of temperature and Sm3+ -doped concentration on the spectral emission properties of Sm:LN single crystals. The effect of temperature and Sm3+ -doped concentration variation, on the emission properties of Sm3+ -doped LN single crystals, was investigated systematically. We calculated the stimulated emission cross-section σem , which is an important parameter signifying the energy extraction rate from a lasing material

Materials and Methods

Results

Only the LiNbO

With the increasing comparable radii of and

Fluorescence Analysis

Conclusions