Structural, optical and thermal properties of Zr–Fe co-doped congruent LiNbO₃single crystals

Abstract

Zr–Fe‐doped congruent lithium niobate single crystals were grown by the Czochralski technique. The crystal structure and lattice parameter of the grown crystals were assessed by powder X‐ray diffraction and the strain developed as a result of doping has been calculated (−1.19 × 10−3) by using the Williamson–Hall relation. The incorporated dopant concentration along with the dopant distribution in the specimen crystal was estimated by X‐ray florescence spectrometry. A multi‐crystal X‐ray diffraction analysis was carried out to identify the crystalline perfection of the sample and revealed that the investigated crystal does not contain any structural grain boundaries but does contain point defects and micrometre size mosaic blocks. Birefringence measurements were carried out using a prism coupler spectrometer and found that the optical birefringence is 0.0822 for 532 nm and 0.705 for 1064 nm. A thermal conductivity (κ) study reveals that the doped sample has a lower κ value than the undoped equivalent.

Control of Intrinsic Defects in Lithium Niobate Single Crystal for Optoelectronic Applications

“…The DCs of CLN (Figure 5a) and nSLN_L (Figure 6a) consist of a single diffraction peak that signifies that these crystals are free from any internal sub-grain boundary [76][77][78], which is otherwise usually observed because of the strain generated during the post-growth cooling due to The DCs of the Mg-doped LN (Figure 5b-d) crystals contain a single diffraction peak. The full-width at half-maximum (FWHM) of the DCs estimated using curve fitting are 76, 112, and 65 arc-sec for 2.0, 4.0, and 6.0 mol % Mg doped samples respectively.…”

“…In fact the cracking of the 6 mol % Mg doped crystal (6Mg:CLN) when grown with the pulling rate the same as that used for other compositions (2Mg:CLN and 4Mg:CLN) implies the presence of a relatively higher strain in that particular sample. The DCs of CLN ( Figure 5a) and nSLN_L ( Figure 6a) consist of a single diffraction peak that signifies that these crystals are free from any internal sub-grain boundary [76][77][78], which is otherwise usually observed because of the strain generated during the post-growth cooling due to structural phase transformation at~1140 • C (paraelectric to ferroelectric), growth imperfections, and instabilities. The FWHM of the DCs was evaluated by Lorentz fitting as tabulated in Table 2.…”

Investigations on Crystalline Perfection, Raman Spectra and Optical Characteristics of Transition Metal (Ru) Co-Doped Mg:LiNbO3 Single Crystals

“…Different types of dopants have been used for various applications of the LN crystals such as Mg, Zn, In, and Zr for suppressing the optical damage and metal ions like Fe, Mn, Cu, Ce, and Ru to improve photorefractive properties. 12 − 14 …”

Enhanced Ultraviolet Damage Resistance in Magnesium Doped Lithium Niobate Crystals through Zirconium Co-Doping

“…Generally, this property is thought to be related to the replacement of Zr 4+ ions against Nb 5+ on Li sites because the element Zr is adjacent to Nb in the periodic table. It has been reported that Zr 4+ ions co-dope with some transition metal elements in LN crystals [ 15 , 16 ], such as Fe, Mn, Cu, and Ce, which can considerably reduce the light-induced scattering as well as improve the response speed. Besides, Zr doping also improves the near infrared emission efficiency in LN:Er, LN:Yb,Er crystals [ 17 ]; meanwhile, it can also stabilize the signal output of the Ti-diffused LN waveguides under the high-power pumping without optical damage observed [ 18 ].…”