Spectroscopic properties and laser performance of Tm3+-doped NaLa(MoO4)2 crystal

Abstract

Detailed polarized spectral properties of Tm3+:NaLa(MoO4)2 crystal have been investigated. The polarized absorption spectra, polarized fluorescence spectra, and fluorescence decay curves were measured at room temperature. The fluorescence decay mechanisms of the G14 and H34 multiplets were discussed. Spectroscopic parameters related to the laser operation at around 1.9 μm via the F34→H36 transition have been evaluated. Room-temperature quasi-cw 1.9 μm laser emission from a Ti:sapphire laser pumped Tm3+:NaLa(MoO4)2 crystal has been demonstrated. The maximum output power of 0.5 W has been achieved with a slope efficiency of 50%.

Spectral properties of Tm3+-doped LiLa(MoO4)2 crystal

“…They are similar to those of other molybate crystals, i.e. Tm 3+ :NaLa(MoO 4 ) 2 (4.84 × 10 −20 cm 2 for polarization and 1.57 × 10 −20 cm 2 for polarization) [19] and Tm 3+ :NaGd(MoO 4 ) 2 (4.05 × 10 −20 cm 2 for polarization and 1.50 × 10 −20 cm 2 for polarization) [20]. For polarization, the absorption cross-sections of the molybate crystals are larger than those of tungstate crystals, such as Tm 3+ :NaGd(WO 4 ) 2 (2.90 × 10 −20 cm 2 for polarization and 1.18 × 10 −20 cm 2 for polarization) [6] and Tm 3+ :NaLa(WO 4 ) 2 (3.94 × 10 −20 cm 2 for polarization and 1.39 × 10 −20 cm 2 for polarization) [25].…”

“…The peak emission cross-sections were calculated to be 1.48 × 10 −20 cm 2 at 1787 nm for polarization and 1.61 × 10 −20 cm 2 at 1837 nm for polarization, which are close to those of other disordered scheelite crystals, such as Tm 3+ :NaGd(WO 4 ) 2 (1.1 × 10 −20 cm 2 ) [6], Tm 3+ :NaLa(MoO 4 ) 2 (1.96 × 10 −20 cm 2 ) [19], and Tm 3+ :NaLa(WO 4 ) 2 (1.28 × 10 −20 cm 2 ) [25] Moreover, the FWHMs are 164 nm for polarization and 143 nm for polarization. These values are also close to those of the structural disordered Tm 3+ -doped tungstate and molybdate crystals reported in the literature [6,19,20,25]. The result indicates that the Tm 3+ :LiLa(MoO 4 ) 2 crystal can be used to realize tunable laser output via the 3 F 4 → 3 H 6 transition.…”

“…The fitted lifetime is 2.13 ms and much longer than the radiative one (0.94 ms) calculated by the J-O theory. It is mainly caused by the effect of re-absorption [19]. To identify the re-absorption, the bulk sample was ground to fine powder and immersed in monochlorobenzene (refractive index n = 1.52), which was used as the refractive index matching fluid to minimize the internal reflection in the particles, and contained in a glass cuvette [39].…”

“…Furthermore, for Tm 3+ ions, the energy gap between the 3 F 4 and 3 H 6 multiplets is only about 5000 cm −1 and the maximum phonon energy of these crystals is about 910 cm −1 [15], therefore, the non-radiative loss from the 3 F 4 multiplet is weak. To our knowledge, efficient ∼2.0 m laser operations have been realized in several Tm 3+ -doped tungstate crystals [6,[16][17][18], but only laser operations in Tm 3+ -doped NaLa(MoO 4 ) 2 and NaGd(MoO 4 ) 2 have been reported for molybdate crystals, in which, the maximum output power of the Tm 3+ :NaLa(MoO 4 ) 2 is 0.5 W with a slope efficiency of 50% [19,20]. Therefore, Tm 3+ -doped molybdate crystals as gain media for ∼2.0 m laser are worth further investigation.…”

Tunable luminescence properties of NaLa(MoO4)2:Ce3+,Tb3+ phosphors for near UV-excited white light-emitting-diodes

“…The distribution of T 3+ induces the inhomogeneous broadening of optical spectra when rare-earth ions are doped in the crystals and occupy the positions of T 3+ ions. The spectroscopic and laser properties of rare-earth ion doped NaT(MoO 4 ) 2 have been investigated in recent years due to their attractive potential for diode pumped tunable solid-state laser and ultrashort pulse laser [19,20]. However, to the best of our knowledge, little attention has been paid to the down-conversion luminescence properties of rare-earth doped NaLa(MoO 4 ) 2 phosphors [21].…”