LuLiF4 Laser Research Articles

Orthogonally Polarized Dual-Wavelength Gain-Switched Ho:LuLiF4 Pulse Laser

A compact, orthogonally polarized, gain-switched a-cut Ho:LuLiF4 laser with intra-cavity pumping by a self-Q-switched Tm:YAP laser is demonstrated here for the first time. The π-polarization laser at 2052 nm and σ-polarization laser at 2066 nm were experimentally observed with the maximum output power values of 299 mW and 126 mW, respectively, and the two polarization directions were always kept mutually orthogonal as the pump power increased. The ratio of the output power between the two orthogonal polarization lasers was nearly 1:1 at a pump power of 18.4 W. The minimum pulse width of the Ho:LLF laser was 326 ns, the maximum repetition rate was 24 kHz, and the maximum average energy was 28 μJ.

Experimental and theoretical investigation on Q-switched Nd:LuLiF4 laser

A diode-pumped continuous-wave (CW) and passively Q-switched Nd:LuLiF4 laser was investigated. Under an incident pump power of 11.2 W, an output power of up to 1.92 W was generated, corresponding to a slope efficiency of 17.4%. By using a Cr4+:YAG wafer as saturable absorber, stable Q-switched pulse trains with an average output power of 1.13 W and a pulse duration of 13.8 ns were captured at a repetition rate of 32.5 kHz, delivering a pulse energy of 36.4 μJ. A rate equation model was further introduced to theoretically analyze the dynamical mechanism, in which the Gaussian spatial distribution theory was taken into account.

1.31 and 1.32 μm dual-wavelength Nd:LuLiF4 laser

We demonstrate the operation of Nd:LuLiF4 laser with efficient 1.31 and 1.32μm dual-wavelength. Maximum continuous-wave output power of 1.63W is obtained at an incident pump power of 9.97W and 8% transmission of output coupler (OC), giving a slope efficiency of 17.9%. When monolayer graphene is employed as saturable absorber, stable passively Q-switched 1.31 and 1.32μm dual-wavelength laser operation still remains. The maximum average output power of 1.33W, the largest pulse energy of 17.3μJ and the highest peak power of 111.6W are achieved with the 8% OC. Meanwhile, the shortest pulse duration of 133ns and the highest repetition rate of 91kHz are rendered by the 3.8% OC cavity.

808-nm diode-pumped dual-wavelength passively Q-switched Nd:LuLiF4 laser with Bi-doped GaAs

Diode-pumped CW and passively Q-switched Nd:LuLiF4 lasers with stable, synchronous dual-wavelength operations near 1047 and 1053nm were demonstrated for the first time. The maximal CW output power of 821 mW was obtained at an incident pump power of 6.52W. Employing high quality Bi-doped GaAs as saturable absorber, stable dual-wavelength Q-switched operation was realized. Under 6.52W incident pump power, the minimal pulse duration of 1.5ns, the largest single pulse energy of 11.32μJ, and the highest peak power of 7.25kW were achieved.

51-ps passively mode-locked Nd:LuLiF_4 laser

We report on the first investigation of a passive mode-locking Nd:LuLiF4 laser at 1047 nm with semiconductor saturable absorber mirror. The maximal average output power of 1.21 W was obtained with a slope efficiency of 10.8%, under an incident pump power of 12.6 W. The pulse duration of 5.1 ps and a spectral width of 0.45 nm were obtained with a repetition rate of 40 MHz. This corresponds to the single pulse energy of 30.3 nJ and the peak power of 5.93 kW.

Tunable continuous wave and passively Q-switched Nd:LuLiF4 laser with monolayer graphene as saturable absorber

Tunable continuous wave and passively Q-switched Nd:LuLiF4 laser performances were demonstrated. Employing a 2 mm thick quartz plate as the birefringence filter, three continuous tuning ranges from 1045.2 to 1049.9 nm, 1051 to 1055.1 nm and 1072.1 to 1074.3 nm could be obtained. Q-switched laser operation was realized by using a monolayer graphene as a saturable absorber. At an incident pump power of 5.94 W, the maximum average output power was 669 mW with the pulse duration of 210 ns and the pulse repetition rate of 145 kHz at T = 10%.

Diode-pumped passively Q-switched dual-wavelength c-cut Tm,Ho:LLF laser at 2 μm

A compact diode-end-pumped passively Q-switched dual-wavelength c-cut Tm,Ho:LuLiF4 laser with a Cr:ZnS crystal as the saturable absorber is demonstrated for the first time, to the best of our knowledge. The maximum dual-wavelength average output power of 60 mW is obtained at 2065 and 2067 nm for the output coupler transmission of 5%, when the absorbed pump power is 2 W. The pulse width and pulse energy are about 54 ns and 6.5 μJ respectively, and are nearly independent of the absorbed pump power. The pulse repetition frequency can be tuned between 3 and 8.8 kHz by changing the absorbed pump power between 0.67 and 1.8 W. Furthermore, the influence of output coupler transmission on the laser performance is also investigated.

Efficient dual-wavelength Nd:LuLiF_4 laser

We report an efficient continuous-wave (CW) and passively Q-switched dual-wavelength Nd:LuLiF4 laser at 1314 and 1321 nm for the first time. Maximum CW output power of 6.08 W is obtained, giving an optical-to-optical conversion efficiency of 30.2% and a slope efficiency of 32.1%. Even using high doping V3+:YAG as the saturable absorber to passively Q-switch the laser, stable dual-wavelength operation remains. Maximum pulse energy extracted from the resonator is 108.7 μJ at 17.2 kHz pulse-repetition rate, and maximum peak power is 885 W.

Orthogonally polarized dual-wavelength single-longitudinal-mode Tm,Ho:LLF laser

We first report a diode-pumped continuous wave orthogonally polarized dual-wavelength single-longitudinal-mode laser with a single c-cut Tm,Ho:LuLiF₄ laser crystal. The simultaneous dual-wavelength single-longitudinal-mode laser near 2 μm is realized by using two uncoated intracavity Fabry-Perot etalons. The output wavelengths are 2064 nm in π-polarization and 2066 nm in σ-polarization respectively, which are orthogonal to each other. At the absorbed pump power of 1 W, the maximum single-longitudinal-mode output powers at 2064 and 2066 nm are 76 and 32 mW respectively. The orthogonally polarized dual-wavelength single-longitudinal-mode laser is possible to be applied to the 2 μm differential absorption lidar and the generation of THz radiation.

Passively Q-switched Tm,Ho:LuLiF4 laser with near constant pulse energy and duration

A compact diode-pumped passively Q-switched Tm,Ho:LuLiF4 laser with a Cr:ZnS saturable absorber is demonstrated for the first time. The maximum average output power of 74 mW is achieved at the absorbed pump power of 1.5 W, and the threshold power is only 0.68 W. The laser operates at the wavelength of 2,055 nm and produces pulses with near constant duration of 1.2 μs and pulse energy of 13 μJ at the pulse repetition frequency from 1 to 5.2 kHz. The stable long-pulse laser can be used in laser lidar systems for accurate wind velocity measurements.

Efficient in-band pumped Ho:LuLiF_4 2 μm laser

An efficient Ho:LuLiF(4) laser in-band pumped by a cladding-pumped Tm-doped silica fiber laser operating at 1937 nm is reported. At low-cavity output coupling, the Ho:LuLiF(4) laser yielded 5.1 W of output at a wavelength of 2066 nm for 8.0 W of absorbed pump power with a slope efficiency of 70%. At high-cavity output coupling, the lasing wavelength shifted to 2053 nm and the laser produced an output power of 5.4 W with a slope efficiency of 76%. The beam propagation factor (M(2)) was measured to be approximately 1.1 at the maximum output power confirming fundamental transverse mode (TEM(oo)) operation. The influence of resonator design on laser performance is discussed, along with prospects for further power scaling and improvement of the laser efficiency.