Efficient 805 nm diode-pumped continuous-wave 1.9 µm Tm³⁺ : NaLa(MoO₄)₂laser

Abstract

In a 1.8 mm-thick a-cut Tm3+ : NaLa(MoO4)2 crystal, end-pumped by a single-stripe 805 nm diode laser in a hemispherical cavity, a maximum continuous-wave output power of 320 mW with a slope efficiency of 45% around 1.9 µm was achieved when the absorbed pump power was 890 mW. The result shows that the Tm3+ : NaLa(MoO4)2 crystal is a promising gain medium for a ∼807 nm diode-pumped solid-state 1.9 µm laser operating at medium and low power levels.

Hydrothermal synthesis and luminescent properties of NaLa(MoO4)2:Dy3+ phosphor

“…Of all the hosts, molybdates have attracted many scholars' great interest and attention due to their excellent spectroscopic properties, chemical stabilities, and potential applications in catalysis, lasers, phosphors, optical fibers, scintillators and magnets. The NaLa(MoO 4 ) 2 crystal has tetragonal symmetry with the space group I4 1 /a, and belongs to the family of double molybdate (DM) compounds [16]. NaLa(-MoO 4 ) 2 is also assigned to be isostructural to the scheelite SrMoO 4 and its central Mo 6 þ metal ion is coordinated by four O 2À ions, which make MoO 4 2 À relatively stable [12].…”

Efficient infrared (≈1.9–2.0 μm) laser operation in color-defect-free Tm:NaGd(MoO4)2crystal

“…The laser efficiencies of several Cz-grown Tm-doped DMos have been tested previously using a Ti-sapphire laser for optical pumping at λ ≈ 795-800 nm and a hemispherical optical cavity. For 7.5 at.% Tm:NaLa(MoO 4 ) 2 , approximately 500 mW of output laser power was obtained at λ ≈ 1900-2000 nm in the quasi-continuous wave (q-cw) regime with a slope efficiency of η = 50% (for T OC = 6.6%), but a pumping duty cycle as small as 5% was used [12], and up to approximately 400 mW in the continuous wave (cw) [13] regime with η = 53% (for T OC = 7.2%). A similar efficiency, but with lower output power (<140 mW) has been demonstrated through diode laser pumping of a microchip laser of this crystal [14].…”

Efficient 1.9µm monolithic Tm3+:NaLa(MoO4)2 micro-laser

“…Because it melts congruently at about 1140 • C, Tm 3+ -doped crystals with large size and high optical quality can be easily grown by the Czochralski method with short growth period in air [12]. Compared with those of the widely investigated Tm 3+ -doped fluoride, YAG, YAP, vanadate, and KLu(WO 4 ) 2 crystals, the difficulty in growth and cost can be greatly reduced for the Tm 3+ :NLM crystal [13]. Detailed spectroscopic properties of Tm 3+ :NLM crystal have been investigated [12].…”

“…Detailed spectroscopic properties of Tm 3+ :NLM crystal have been investigated [12]. Due to the disordered structure of the NLM host, the inhomogeneous broadening of spectral lines of Tm 3+ :NLM crystal leads to the broad and relative smooth absorption and fluorescence bands [12,13], which can reduce the requirement of strict temperature control of LD pump source and provide a wide tunable range of output laser. Using a Tm 3+ :NLM crystal as gain medium, 1.9 µm quasicontinuous-wave (quasi-CW) and CW lasers with slope efficiencies of about 50% have also been demonstrated in 795 nm Ti:Sapphire laser and 805 nm single-stripe diode end-pumped linear hemispherical resonators, respectively [12,13].…”

“…Due to the disordered structure of the NLM host, the inhomogeneous broadening of spectral lines of Tm 3+ :NLM crystal leads to the broad and relative smooth absorption and fluorescence bands [12,13], which can reduce the requirement of strict temperature control of LD pump source and provide a wide tunable range of output laser. Using a Tm 3+ :NLM crystal as gain medium, 1.9 µm quasicontinuous-wave (quasi-CW) and CW lasers with slope efficiencies of about 50% have also been demonstrated in 795 nm Ti:Sapphire laser and 805 nm single-stripe diode end-pumped linear hemispherical resonators, respectively [12,13]. However, a monolithic micro-laser, which is consisted of only a thin slice of gain medium and the cavity mirrors deposited onto the medium faces directly, has an advantage of simplicity and compactness [14][15][16], and is more useful in some industrial and military applications.…”