Redistribution of Cr3+ ions from Li+ to Nb5+ sites in ZnO codoped LiNbO3:Cr crystals

Growth of Mn2+, Co2+ and Ni2+-doped near-stoichiometric LiNbO3 by Bridgman method using K2O flux

“…The Ni 2+ ion in octahedral co-ordination has the electronic configuration (A) 3d 8 where (A) represents the closed organic shell. The energy levels of Ni 2+ ion in octahedral symmetry with a ground state of 3 A 2g (F) are 3 T 2g (F), 1 E(D), 3 T 1g (F), 1 T 2g (D), 3 T 1g (P), etc. Three spin-allowed transitions 3 A 2g (F) → 3 T 1g (P), 3 A 2g (F) → 3 T 1g (F) and 3 A 2g (F) → 3 T 2g (F) ordered by increasing energy are expected.…”

“…The energy levels of Ni 2+ ion in octahedral symmetry with a ground state of 3 A 2g (F) are 3 T 2g (F), 1 E(D), 3 T 1g (F), 1 T 2g (D), 3 T 1g (P), etc. Three spin-allowed transitions 3 A 2g (F) → 3 T 1g (P), 3 A 2g (F) → 3 T 1g (F) and 3 A 2g (F) → 3 T 2g (F) ordered by increasing energy are expected. In addition to these three spin-allowed transitions, two spin-forbidden transitions 3 A 2g (F) → 1 T 2g (D) and 3 A 2g (F) → 1 E(D), two weak absorption bands also exist [7,8].…”

“…Un-doped LN single crystals have been extensively applied for planar waveguide substrates, Q-switches, phase modulators and surface acoustic wave wafers because of its large acoustic-optic and electro-optic coefficient [1][2][3]. LN crystals doped with transition-metal (TM) ions, e.g., Ti 3+ , Cr 3+ and Fe 2+ [4,5], or rare-metal (RE) ions, e.g., Eu 3+ and Er 3+ [6,7] have also attracted much attention because of their potential applications in electro-optic, waveguide and laser technologies.…”

“…TM and RE are incorporated into LN single crystals in order to characterize their optical behaviors. Among the transition metal ions, Mn 2+ is a typical luminescent ion [3][4][5]. It has been studied in various inorganic hosts covering a wide range of emissions from blue to red.…”

“…It was reported [9] that host materials doped with Ni 2+ ions in octahedral sites showed green light, red light and a broad emission band in the near infrared which is used for tunable solid state lasers in this important spectral region. However, LiNbO 3 is a typical non-stoichiometric material, and is usually grown by Czochralski method from a congruent melt with a Li content, χ = [Li]/([Li] + [Nb]) = 48.6 mol% [2,3]. The Li deficiency induces many intrinsic defects.…”