Diode-pumped cw and Q-switched Nd:GdVO4 laser operating at 1.34 μm

A diode-pumped 1.34 m Nd:GdVO₄ laser operating in cw and active Q-switching modes has been demonstrated. 4.15 W of cw output power was obtained at the highest attainable pump power of 12.3 W, resulting in an optical conversion efficiency of 33.7%, the slope efficiency was determined to be 37.6%. In Q-switching operation, a maximum average output power of 2.7 W was generated at pulse repetition frequency (PRF) of 50 kHz, with an optical conversion efficiency of 22% and a slope efficiency of 29.2%. The laser pulses with shortest duration, highest energy and peak power were achieved at PRF of 10 kHz, the parameters being 15 ns, 160 J, and 10.7 kW, respectively. By intracavity frequency-doubling with a type II phased-matched KTP crystal, 0.62 W average power at 0.67 m was produced at a PRF of 15 kHz, the resulting pulse energy, peak power, and pulse width being 41.3 J, 2.2 kW, and 19 ns, respectively. A group of analytical formulae, based on rate equations, are presented to evaluate the operational parameters of an actively Q-switched laser. Calculated results were found to be in close consistency with the experimental data.     

Diode-pumped CW Tm:GdVO_4 laser at 1.9 μm

A high power cryogenic cooling Tm-doped (2%) GdVO4 laser double-end-pumped by fiber-coupled-diode with the center wavelength of 804.5 nm at 21 ℃ is reported. The highest continuous-wave (CW) power of 2.35 W at 1903 nm is attained at pump power of 24 W. The slope efficiency is 12.5% and the threshold is 3.2 W. Single- and double-end-pumped types are investigated.     

Room-temperature continuous-wave interband cascade laser emitting at 3.45 μm

We report a type-Ⅱ GaSb-based interband cascade laser operating a continuous wave at room temperature. The cascade region of interband cascade laser was designed using the ‘W' configuration of the active quantum wells and the ‘Carrier Rebalancing' method in the electron injector. The devices were processed into narrow ridges and mounted epitaxial side down on a copper heat sink. The 25-μm-wide, 3-mm-long ridge without coated facets generated 41.4 mW of continuous wave output power at T = 15℃. And a low threshold current density of 267 A/cm~2 is achieved. The emission wavelength of the ICL is 3452.3 nm at 0.5 A.     

High-efficiency continuous-wave diode-pumped Tm:Ho:LuAG laser at 2.1 μm

Continuous Wave (CW) laser action has been observed from a Ho:Tm:LuAG rod at 2.1 m pumped by a diode laser at 785 nm in the temperature range of 77–200 K. The maximum power observed was 1.38 W at an incident power of 4 W at a crystal temperature of 77 K. The optical-to-optical conversion efficiency was observed to be 35.6% at a threshold power of 0.2 W with a 95% output coupling mirror.     

Diode-pumped vertical external cavity surface emitting laser at 1 μm

We demonstrated a diode-pumped vertical external cavity surface emitting laser with simple plane-concave cavity. When the pump power at a wavelength of 811.6 nm is 1.5 W, the maximum output power is 40.4 mW at the wavelength of 1005.8 nm. The optical-optical conversion efficiency is 2.7%. .     

Pulsed laser performance at 1.06 μm from Nd:SGGM

A single Xe gas filled flash lamp has been used to pump a Nd-doped SGGM rod 5 mm in diameter and 80 mm in length. Laser emission has been observed at 1.06 m in the free running mode of operation in the input energy range of 1–25 J. The laser performance has been evaluated using two different diffuse/filter combinations to block the ultraviolet radiation from the Xe lamp and the results have been compared. The intrinsic slope efficiency was determined to be approximately 1.5% with an 80% output coupler and a spectralon diffuser.     

Diode-pumped Q-switched Nd:YLF laser at 1313 nm

In this letter, we describe the operation of an end-pumped acousto-optic Q-switched Nd:YLF laser. According to the theoretical analysis and calculation for Nd:YLF crystal, the thermal focal length of σ-polarized laser is positive in plane-parallel resonator, while that of π-polarized laser is negative. Hence laser operation at σ-polarized 1313 nm should be stable in plane-parallel cavity. When absorbed pump power is 12.45 W and the pulse repetition frequency is 10 kHz, 3.1 W output laser at 1313 nm is achieved. As a result, the optical–optical conversion efficiency is 25.4 % and slope efficiency is 31.2 %, respectively.     

Diode-pumped continuous-wave and passively Q-switched 1.06 μm YVO4/Nd:GdVO4 laser

In this letter, a diode-pumped continuous-wave and passively Q-switched 1.06 μm laser with a novel composite YVO₄/Nd:GdVO₄ crystal was demonstrated for the first time. Theoretical calculations showed that the temperature distribution in YVO₄/Nd:GdVO₄ crystal was lower than that in GdVO₄/Nd:GdVO₄ and Nd:GdVO₄ crystals under the same conditions. After optimizing the mode matching degree, a CW output power of 5.6 W of YVO₄/Nd:GdVO₄ laser was obtained at the incident pump power of 12 W when the output coupler with transmission of 30% was employed. Using Cr^4 +:YAG crystals with initial transmission (T₀) of 80% and 90% as saturable absorbers, the pulsed YVO₄/Nd:GdVO₄ laser characteristics were investigated. At the incident pump power of 12 W, the maximum average output power of 2.76 W and the maximum repetition rate of 189 kHz was achieved when T₀ = 90% Cr^4 +:YAG was used. The shortest pulse width was 28.1 ns when the initial transmission of the used Cr^4 +:YAG was 80%.     

Diode-pumped passively Q-switched Nd : YAG laser at 1123 nm

A diode-pumped Nd:YAG laser at 1123 nm is passively Q-switched by using a low doping concentration Cr⁴⁺:YAG crystal as a saturable absorber. When pumped by a 1.5-W laser diode, the laser produces pulses of 50-ns duration with a pulse energy of as much as 15 J and a peak power of 300 W at a pulse-repetition rate of 10 kHz. PACS 42.60.Gd; 42.55.Rz; 42.55.Xi     

Diode-pumped 1123-nm Nd:YAG laser

We demonstrated a diode-pumped Nd:YAG laser with a plano-concave resonator. When the pump power is 1.57 W, the output power of 1123-nm laser is 132 mW at the temperature of 20 ℃, and the power change is less than 2% in an hour. A periodically poled LiNbO3 (PPLN) was used as outer cavity frequency-doubling crystal and 561-nm laser was observed.     

A 1.54 μm Er glass laser pumped by a 1.064 μm Nd:YAG laser

Laser oscillation in Er-glass, co-doped with Yb sensitiser, has been achieved by pumping with the 1.064 μm output of a Nd:YAG laser.     

A high-power continuous-wave diffraction-limited Nd:GdVO4 laser operating at 1.34 μm

High-power and high beam quality continuous-wave (CW) Nd:GdVO₄ lasers operating at 1.34 μm were experimentally demonstrated. The lasers consisted of either one or two crystals, which were both end-pumped by high-power fiber-coupled diode lasers. With one crystal, the maximum CW output power generated was 8.4 W. When two crystals were used, a maximum output power of 15.7 W was achieved with the incident pump power of 76.2 W, showing a slope efficiency of 26.2% and an optical-to-optical efficiency of 20.6%. The beam divergence at an output power of 15 W was measured to be about two times that of the diffraction limit.     

A 13.3-W laser-diode-array end-pumped Nd:GdVO4 continuous-wave laser at 1.34 μm

We report a high-power laser-diode-array end-pumped 0.3 at.% Nd:GdVO₄ continuous-wave laser operating at 1.34 m. The maximum output power of 13.3 W was obtained at the incident pump power of 49.2 W, giving the corresponding optical conversion efficiency of 27% and the average slope efficiency of 28.5%. The thermal focal length of the Nd:GdVO₄ crystal under the pump power from 15.3 to 50 W was measured experimentally. PACS 42.55.Xi; 42.70.Hj     

Diode-pumped efficient continuous-wave Yb:Y3Ga5O12 laser at 1035 nm

An efficient diode-pumped Yb:Y3Ga5O12 (Yb:YGG) laser was demonstrated by using a high-quality Yb:YGG crystal grown by the optical floating zone method. Continuous-wave laser power up to 2.65?W had been obtained under an incident pump power of 6.71?W at 970?nm, corresponding to an optical-to-optical efficiency of 39.5% and maximum slope efficiency of 84.5%. A modeling calculation of the Yb:YGG laser was also performed, and the theoretical results were consistent with the experimental results.     

6.5-ns actively Q-switched Nd:YVO_4 laser operating at 1.34 μm

With a plano-concave cavity,diode-pumped continuous-wave(CW) and actively Q-switched Nd:YVO4 laser operating at 1.34 μm is demonstrated.Maximum CW output power of 4.76 W and Q-switched average output power of 2.64 W are obtained with output coupler(transmission T = 3.9%).For the Q-switching operation,the theoretically calculated pulse energy and pulse width,with a pulse repetition frequency(PRF) range of 5-40 kHz,coincide with the experimental results.With a T = 11.9% output coupler,the maximum peak power of 24.3 kW and minimum pulse width of 6.5 ns are obtained when the PRF is 10 kHz.To the best of our knowledge,this is the shortest actively Q-switched pulse duration ever obtained in a 1.3-μm Nd-doped vanadate laser.     

A single-longitudinal-mode continuous-wave Ho~(3+):YVO_4 laser at 2.05 μm pumped by a Tm-fibre laser

We present a single-longitudinal-mode continuous-wave Ho~(3+):YVO_4 laser at 2.05 μm pumped by a Tm-doped fibre laser. Use of a cavity etalon enables spectral selectivity for single-mode operation. The highest power achieved in the single longitudinal mode at 2052.5 nm is 282 mW at a slope efficiency of 6.9%, corresponding to an optical conversion efficiency of 3.0%. These features demonstrate that this single-longitudinal-mode Ho:YVO_4 laser is suitable for use as a seed laser in some Lidar systems(e.g., coherent Lidar or differential absorption Lidar). To the best of our knowledge, this is the first report on such a single-longitudinal-mode Ho:YVO_4 laser at 2.05 μm.     

Efficient Cr3+ sensitized Nd3+: GdScGa-garnet laser at 1.06 μm

Room-temperature cw lasing at 1.061 m has been obtained in Cr,Nd: GdScGa-garnet. Threshold powers as low as 7 mW and slope efficiencies up to 41% have been measured. Cross pumping of Nd³⁺ via Cr³⁺ is nearly as efficient as direct pumping. Time-resolved measurements of the transfer rate yield a transfer efficiency of 0.86 and an average transfer time of 17 s. An improvement in pulsed broad band pumping can also be expected.     

Diode-pumped Tm:LuAG laser at room temperature

The lasing characteristics of Tm:LuAG at room temperature are reported.The maximum output power at 2.023-μm wavelength is 4.91 W and the slope efficiency is 25.39%.The mode matching between pump mode and laser mode is optimized by changing the pump beam waist radius and its location.Different output couplers are used to realize the optimal laser output.The relationship between operation temperature and output power is also discussed.     

Efficient Tm:LuVO₄ laser at 1.9 μm

We report an efficient laser-diode-pumped Tm-doped LuVO? crystal laser at about 1.9 μm. For the first time to our knowledge, the π-polarized Tm:LuVO? laser was achieved. The maximum output power and slope efficiency were 1.32 W and 28.7%, respectively. By comparison, it has been found that the a-cut Tm:LuVO? crystal should be more suitable for applications in high-power lasers. The central laser wavelength was observed to be located at about 1.9 μm and shifted to shorter with the increase of intracavity light intensity, which could be explained based on the reabsorption of light in the Tm:LuVO? crystal.