Neodymium doping in UV-IR transparent ferroelectric BaMgF4

Abstract

The incorporation of Nd3+ in the ferroelectric fluoride BaMgF4 crystal is investigated for its potential application as self-frequency-converter solid state laser. Low temperature high-resolution optical spectroscopy shows that Nd3+ is located at two well distinguished sites referred as A and B. The whole set of energy levels in the excited F43/2, I411/2, and ground I49/2 states are identified for both Nd3+ sites and their crystallographic location in BaMgF4 lattice is discussed. The radiative lifetime of the F43/2 metastable laser level is obtained to be 1430 and 800 μs for site A and B, respectively, and the luminescence quantum efficiency of the F43/2 metastable state for the dominant A site is 87%. The possibility of annihilating the contribution of the B site in the optical spectrum is demonstrated by means of the incorporation Na+ into the crystal.

Local environment of optically active Nd3+ions in the ultratransparent BaMgF4ferroelectric crystal

“…These ions provide the charge compensation mechanism required when Nd 3+ ions substitute for a divalent cation in the lattice and prevent the presence of undesired defects in the lattice. 11 Additionally, as previously confirmed by site selective spectroscopy, the presence of Na + ions does not affect the spectroscopic characteristics of the major center, which suggest that the charge compensation for the A major center is not local.…”

“…In agreement with the multiplicity of that state, a single and well-resolved line is observed, evidencing the presence of a single Nd 3+ center, as previously reported on Nd 3+ and Na + -codoped BMF. 11 At this point, it is important to mention that previous studies have pointed out that trivalent lanthanide ions substitute for Ba 2+ cations in the BMF crystal lattice. 19 This can be justified on the basis of the well-established set of ionic radii published by Shannon.…”

“…[19][20][21] In particular, the possibility of incorporating Nd 3+ ions has been recently demonstrated, opening the way to the development of potential self-frequency converted all solid-state lasers operating in the UV and vacuum-UV (VUV) and mid-IR spectral regions. 11 Namely, by means of site selective spectroscopy, it has been recently shown that Nd incorporates into the BMF matrix at two well-differentiated centers referred to as A (dominant) and B (minor) centers. As suggested, those two Nd 3+ centers can be associated with Nd 3+ in a Ba 2+ regular lattice site (A center) and with a defectdistorted Ba 2+ site (B center).…”

“…[8][9][10] In this paper, we investigate the properties of Nd 3+ ions in the BaMgF 4 crystal (hereafter BMF), the only ferroelectric fluoride crystal reported up to now. 11 BMF is a nonlinear crystal which exhibits an extraordinary transparency range extending from the deep ultraviolet (UV) (126 nm) to the midinfrared (IR) (13 μm). 12,13 This offers an exceptional advantage for optical devices operating in the UV and mid-IR, where other nonlinear materials cannot be used.…”

VUV–UV 5d–4f interconfigurational transitions of Nd3+ in BaMgF4 ferroelectric crystals

“…The ionic radius of Nd 3 þ is much closer to the one of Ba 2 þ , and therefore the dopant ion was proposed to enter into the Ba 2 þ sites [10]. The charge compensation required by Nd 3 þ doping could be achieved by cation vacancies or by interstitial F À ions [14].…”