A Short Review on Fluoride Laser Crystals Grown by Czochralski Method at IPEN

Abstract

In this article there are presented the developments on the crystal growth by the Czochralski method of uoride laser materials at the Center for Lasers and Applications from Institute of Nuclear and Energy Research, IPEN, Brazil. A brief report of the Czochralski furnace preparation for uorides growth regarding to its construction materials, inuence of the heating assemblies in the thermal proles and the benets of using a suitable atmosphere is provided. Moreover, to demonstrate the importance of this technique to the advances on laser systems over the last years there are described the specic growth conditions established to obtain uoride crystals with suitable properties for practical application as laser hosts. LiREF4 (RE = rare earth) scheelite crystals have been studied to compare LiYF4 (YLF) with its isomorphs, including solid solutions of the type-LiY1−xLnxF4 (Ln = Gd or Lu) and LiGd1−xLuxF4, relating to their optical quality, spectroscopic and laser properties. Some results regarding the development of new laser hosts of these materials doped with Nd, Er, Pr and co-doped Yb, Nd and Tm are also presented. The growth particularities of transition metals doped uoride crystals such as BaLiF3:TM (TM = Ni and Co) and LiSrAlF6:Cr are also reported.

Oxyfluoride Glass-Ceramics for Transition Metal Ion Based Photonics: Broadband Near-IR Luminescence of Nickel Ion Dopant and Nanocrystallization Mechanism

“…Red and yellow emissions can be obtained in the K 2 SiF 6 nanocrystals doped with tetra- or divalent manganese, respectively. , ZnF 2 has a rutile-type crystal structure (Figure c) that is formed by the stacking of ZnF 6 octahedra . TMIs, such as Co 2+ and Ni 2+ , , can substitute for Zn 2+ in the slightly distorted octahedral sites, and hence, ZnF 2 is a potential fluoride crystal host for tunable lasers . The precipitation of these three fluoride crystal phases from oxyfluoride GCs could provide octahedral sites for the incorporation of most optically active TMIs, making them highly interesting for TMI-based photonics.…”

“…Fluoride crystals have been considered as preferable hosts in order to achieve favorable spectroscopic properties of TMIs . The low phonon energy of fluoride crystals should lead to a decrease of nonradiative transitions and to an increase in the luminescence efficiency of TMIs, akin to that of REIs.…”

“…As shown in Figure a, KZnF 3 is a typical member of the fluorine perovskites [ Pm ̅3 m space group (No. 221)] that could provide a perfectly octahedral fluorine site for the divalent 3d ions, such as Ni 2+ , Co 2+ , and Mn 2+ , through the substitution of the Zn 2+ position . Thus, interesting and unique spectroscopic properties have been obtained and intensively studied in such TMIs-doped KZnF 3 crystals. − K 2 SiF 6 is one of the hexagonal complex alkaline fluorides (Figure b), which is also extremely suitable for doping TMIs, especially for manganese ions.…”

“…Fluoride crystals have been considered as preferable hosts in order to achieve favorable spectroscopic properties of TMIs. 22 The low phonon energy of fluoride crystals should lead to a decrease of nonradiative transitions and to an increase in the luminescence efficiency of TMIs, akin to that of REIs. Furthermore, from the well-known spectrochemical series of Dq(F − ) < Dq(O 2− ), a smaller crystal field splitting can be expected in fluoride host lattices in comparison to oxide materials.…”

Growth Peculiarities and Properties of KR3F10 (R = Y, Tb) Single Crystals

“…At present, large-size fluoride single crystals are grown from the melt using the Czochralski and Bridgman (Stockbarger) methods [31][32][33][34], and less often using the Kyropoulos and vertical gradient freeze (VGF) methods. The micro-pulling-down (µ-PD) method for obtaining single-crystal fibers has also been presented [35,36].…”