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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 1:31 |
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Conference: Bucharest University Faculty of Physics 2021 Meeting
Section: Solid State Physics and Materials Science
Title:
Growth, optical and NIR laser properties of 3.5 at.% Nd:LGSB bifunctional crystal
Authors:
Alin Broasca (1,2,*), Madalin Greculeasa (1,2), Flavius Voicu (1), George Stanciu (1), Stefania Hau (1), Cristina Gheorghe (1), Catalina-Alice Brandus (1), Nicolaie Pavel (1), Lucian Gheorghe (1)
*
Affiliation:
1) National Institute for Laser, Plasma and Radiation Physics, Solid-State Quantum Electronics Laboratory, Magurele 077125, Romania
2)Doctoral School of Physics, University of Bucharest, Faculty of Physics, Magurele 077125, Romania
E-mail
alin.broasca@inflpr.ro
Keywords:
Crystal growth; Spectroscopy; Nonlinear optical crystal; Laser crystal; Bifunctional crystal
Abstract:
Bifunctional laser and nonlinear optical (NLO) crystal of 3.5 at.% Nd:LGSB with incongruent melting was grown by the Czochralski technique. The growth conditions were optimized and a high-quality crystal with relatively large dimensions of about 12 mm in diameter and 35 mm in length was grown along the c-axis. The pulling speed and the rotation rate were 2 mm/h and 8 rpm, respectively, and the composition of the starting melt was La0.64Nd0.038Gd0.572Sc2.75(BO3)4. The X-ray powder diffraction spectrum revealed the trigonal phase (space group R32) as the single crystalline phase of the grown crystal. The good crystalline quality of the obtained crystal was also confirmed by X-ray rocking curve measurements. The refractive indices of the crystal were measured by the minimum deviation method, and the dispersion curves of the refractive indices were determined by fitting the experimental data with Sellmeier equations. The phase-matching curves for the second harmonic generation (SHG) of type I and type II were also determined. The spectroscopic properties of the 3.5 at.% Nd:LGSB crystal were evaluated, and efficient laser emission at 1062 nm was obtained under the pump at 807 nm with a fiber-coupled laser diode. An uncoated crystal sample oriented along the phase-matching direction for type I SHG of 1062 nm radiation (θ= 35.3 and φ= 60 degrees) with a thickness of 6 mm was used in the laser emission experiments. A short (less than 10 mm length) plane-concave resonator consisting of a plane rear mirror and several concave out-coupling mirrors (OCM) with a radius of 100 mm and various transmissions T at laser wavelength were used. The laser operated with a high slope efficiency of ηsa= 0.56, delivering the highest output power of 2.1 W for 4.04 W of absorbed pump power for an OCM with T= 0.05.
Acknowledgement:
This work was supported by the Romanian Ministry of Research, Innovation and Digitization, CNCS/CCCDI - UEFISCDI, projects PCE 49/2021 PN-III-P4-ID-PCE-2020-2203 and NUCLEU-LAPLAS VI 16N/2019.
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