Efficient 1856 nm emission from Tm,Mg:LiNbO_3 laser

Abstract

Efficient continuous-wave laser emission at 1856 nm from a Tm,Mg:LiNbO 3 crystal slab with high Tm 3+ doping concentration is reported. A maximum output power of 2.62 W is realized with a slope efficiency of 19.6% and the beam quality factor M 2 of 1.7 at room temperature. We believe that this is the first demonstration of watt-level laser operation in Tm,Mg:LiNbO 3 crystal and the output power is four orders of magnitude higher than that reported previously in Tm-doped LiNbO 3 crystal. Performance degradation due to the photorefractive effect under high intensity 1856 nm laser is not observed thanks to the co-doping of magnesium ions. Quantitative analysis about the long-term photorefractive effect is also provided. Multi-wavelength laser operation is realized by using different narrow-band output couplers. This demonstration opens up a viable pathway towards 2-μm integrated optic devices for achieving laser oscillation, electro-optic and nonlinear optical effects within just one sample simultaneously. Opt. 12(3), 555-563 (1973). 25. A. Ashkin, G. D. Boyd, J. M. Dziedzic, R. G. Smith, A. A. Ballman, J. J. Levinstein, and K. Nassau, "Opticallyinduced refractive index inhomogeneities in LiNbO 3 and LiTaO 3 ," Appl. Phys. Lett. 9(1), 72-74 (1966).

Crystal growth, spectroscopic characterization, and laser operation of Tm/Mg: LiTaO_3 crystal

“…Compared with the Tm/Mg: LN laser presented by R. Zhang et al (2.62 W output power at 1856 nm with a slope efficiency of 19.5% was obtained with a threshold value of 3.42W) [12], the Tm/Mg: LT laser has a higher threshold value (10 W), which can be ascribed to the fact that the Tm 3+ ion concentration of Tm/Mg: LT crystal is lower than that of Tm/Mg: LN crystal. However, the Tm/Mg: LT laser has higher slop efficiency (38.5%).…”

“…The maximum emission cross section is 1.07 × 10 −20 cm 2 at 1762 nm, the second largest emission cross section is 0.81 × 10 −20 cm 2 at 1834 nm. Compared with the other crystals (Tm:YAG, Tm:YAP, Tm:YLF, and Tm:LLF) as shown in Table 1 [7][8][9][10][11][12], Tm/Mg: LT crystal exhibit larger emission cross section, indicating a potential for a wide tuning range and short pulse generation for this crystal.…”

“…During the past few years, different Tm doped crystalline host materials have been already investigated for their favourable properties to obtain an efficient laser emission [7][8][9][10][11][12], and Table 1 presents an example of demonstrated laser action in common Tm-doped crystals. However, only the Tm: YLF, Tm:YVO 4 , and Tm/Mg: LN crystals [9,11,12] obtained an efficient laser action with a center wavelength below 1.91 μm.…”

“…However, only the Tm: YLF, Tm:YVO 4 , and Tm/Mg: LN crystals [9,11,12] obtained an efficient laser action with a center wavelength below 1.91 μm. As a quasi-three level system, the laser emission near 1.9 μm is difficult to achieve due to the reabsorption effect in the Tm-ion laser.…”

“…As a quasi-three level system, the laser emission near 1.9 μm is difficult to achieve due to the reabsorption effect in the Tm-ion laser. Recently, we have demonstrated an efficient continuous wave (CW) laser output at 1856 nm wavelength from a Tm, Mg codoped lithium niobate (LiNbO 3 , LN) crystal, which provides a great opportunity for efficient short 2-μm (1.8-2.0 μm) wavelength lasers [12]. Lithium tantalate (LiTaO 3 , LT) crystal, which is structurally isomorphous to LN, is one of the most excellent and useful ferroelectric materials for piezoelectric, linear electric-optic, and nonlinear optic device applications [13,14].…”