YLF Slab Laser Research Articles

Hundred-watts-level Ho:YLF slab laser with good beam quality

We demonstrated a hundred-watts-level and good beam quality Ho:YLF slab laser with a hybrid cavity. When the incident pump power was 263 W, we obtained a maximum output power of 105 W. The slope efficiency with the incident pump power was 52.5%, and the optical-to-optical conversion efficiency was 39.9%. The instability of the maximum output power was measured to be 0.35% in 30 min. With the increase of the output power, the central wavelength of laser shifted from 2051 nm to 2063 nm. The beam quality factors M 2 were measured to be 1.13 in the stable direction and 2.45 in the unstable direction. Hundred-watts-level Ho:YLF slab laser with good beam quality has not been reported yet to the best of our knowledge.

Research on output spot evolution of multi-pass gain Tm:YLF slab laser based on multi-transverse mode competition

In this paper, the multi-transverse mode competition rate equation model of the Tm:YLF slab laser is established based on the cavity structure of multi-pass gain. As the pump power increased, the changing trend of the number of particles in each mode is analyzed. The direction of beam quality change is also mastered, verified by the three-pass gain laser with the evolution of pump power. Due to the limited compression capacity of the x-axial output spot of the three-pass gain laser, the output spot changes significantly under different cavity lengths and output mirror curvatures. By discussing the output spot evolution, it is known that the large curvature output mirror and the appropriate cavity length can optimize the output spot. Finally, under the pump power of 72 W, the four-pass gain laser obtains a laser output of 1.8 W. It’s beam quality is MX2 = 1.77;MY2 = 1.99, the optical–optical conversion efficiency is 2.5 %, and the slope efficiency is 15 %. The beam quality of a three-pass gain laser is MX2 = 2.67; MY2 = 1.70, the optical–optical conversion efficiency is 3.2 %, and the slope efficiency is 11 %. It is verified that the compression of the four-pass gain laser is stronger than that of the three-pass gain laser on the x-axis, laying the foundation for developing a compact multi-pass gain laser.

100 W Ho : YLF Slab Laser with Two Crystals End-Pumped by a Tm:YAP Laser

100 W Ho : YLF Slab Laser with Two Crystals End-Pumped by a Tm:YAP Laser

12.7 W intra-cavity pumped Ho:YAG laser with near-diffraction-limited beam quality.

We demonstrated a compact and efficient Ho:YAG slab laser intra-cavity pumped by a Tm:YLF slab laser for the first time. In the Tm:YLF laser operation, the maximum power of 32.1 W with optical-to-optical efficiency of 52.8% was obtained. In the intra-cavity pumped Ho:YAG laser operation, the output power of 12.7 W at 2122 nm was obtained. The beam quality factors M2 in the vertical and horizontal directions were 1.22 and 1.11, respectively. The RMS instability was measured to be lower than 0.1%. To the best of our knowledge, this was the maximum power for the Tm-doped laser intra-cavity pumped Ho-doped laser with near-diffraction-limited beam quality.

High-efficiency Ho:YLF slab laser with 125 W continuous-wave output power.

We demonstrate a compact and efficient Ho:YLF slab laser that is pumped by a self-made Tm:YAP slab laser. The maximum output power of 125 W at 2064 nm was obtained with the incident pump power of 245 W. To the best of our knowledge, this is the first report for an Ho:YLF laser oscillator to reach hundred-watts-level output power. The slope efficiency with respect to the incident pump power was 62.5%, and the optical-to-optical conversion efficiency was 51%. The RMS instability of the maximum output power was measured to be 0.24% in 30 min. The beam quality factors M2 were 475 and 1.59 in the x and y directions, respectively.

202 W dual-end-pumped Tm:YLF laser with a VBG as an output coupler

Abstract We demonstrated a 202 W Tm:YLF slab laser using a reflecting volume Bragg grating (VBG) as an output coupler at room temperature. Two kinds of active heat dissipation methods were used for the VBG to suppress the shift of wavelength caused by its increasing temperature. The maximum continuous wave (CW) output power of 202 W using the microchannel cooling was obtained under the total incident pump power of 553 W, the corresponding slope efficiency and optical-to-optical conversion efficiency were 39.7% and 36.5%, respectively. The central wavelength was 1908.5 nm with the linewidth (full width at half maximum) of 0.57 nm. Meanwhile, with the laser output increasing from 30 to 202 W, the total shift was about 1.0 nm, and the wavelength was limited to two water absorption lines near 1908 nm. The beam quality factors M2 were measured to be 2.3 and 4.0 in x and y directions at 202 W.

Study of high power Tm:YLF Innoslab wavelength-selected laser

In this study, a laser diode dual-end-pumped Tm:YLF slab laser has been developed. Without using a Fabry–Pérot etalon or a volume Bragg grating, the emission wavelength was selected by different transmissions of the output coupler. The single emission wavelength of 1908.6 nm (1886.4 nm) is selected by the T = 20% (T = 40%) transmission of the output coupler with an FWHM of approximately 1.36 nm (1.10 nm). The corresponding maximum continuous-wave output power of 213 W (173 W) was acquired. The output power stability is about 0.16% (0.23%) in 30 minutes. The optical-to-optical efficiency and slope efficiency are 35.8% (29%) and 43.7% (37.9%), respectively.

Experimental study of a VBG-based Tm : YLF slab laser at different output coupler parameters

The performance of a Tm : YLF slab laser is studied at different output coupler parameters. Use is made of a -cut slab crystal doped with 2.5 at. % thulium ions. With a volume Bragg grating and a Fabry – Perot etalon, the selected output wavelength of this Tm : YLF slab laser is . For the optimised output coupler with a transmission of 20 % and a radius of curvature of , the output power exceeds and the slope efficiency with respect to the absorbed pump power reaches 48.4 %. In addition, the beam quality of the Tm : YLF slab laser is improved.

High power narrow-linewidth Tm:YLF slab laser with volume Bragg grating and Fabry-Perot etalon

The laser performance of a dual-end pumped Tm:YLF laser is investigated and optimized. With a volume Bragg grating and a Fabry-Perot etalon, at maximum output level, the wavelength peak is 1908.0 nm and the narrow linewidth of 0.1 nm is obtained. For an optimized output coupler with a transmission of 30% and a curve radius of 600 mm, the output power exceeded 115.0 W, obtaining a slope efficiency of 38.4% with respect to the absorbed pump power.

330 mJ single-frequency Ho:YLF slab amplifier

We report on a double-pass Ho:YLF slab amplifier which delivered 350 ns long single-frequency pulses of up to 330 mJ at 2064 nm, with a maximum M2 of 1.5 at 50 Hz. It was end pumped with a diode-pumped Tm:YLF slab laser and seeded with up to 50 mJ of single-frequency pulses.

Tm:YLF slab wavelength-selected laser

A Tm:YLF slab laser was wavelength selected to operate at 1890 nm. The oscillator consisted of a single 2.5% doped Tm:YLF slab, a volume Bragg Grating (VBG) mirror and a 90% output-coupler. The slab crystal was pumped with a 300 W diode stack using a pump reproducing configuration. The output power exceeded 80 W and the beam quality factors in the horizontal and vertical directions were 182 and 2.5 respectively.

Ho:YLF & Ho:LuLF slab amplifier system delivering 200 mJ, 2 µm single-frequency pulses

A single-frequency single-pass amplifier based on Ho:YLF and Ho:LuLF in a scalable slab architecture delivering up to 210 mJ at 2064 nm is demonstrated. The amplifier was end-pumped by a 1890 nm Tm:YLF slab laser and was seeded with a 69 mJ single-frequency Ho:YLF ring laser operating at 50 Hz.

High-power diode-pumped Tm:YLF slab laser

A 2% Tm3+-doped LiYF4(Tm:YLF) slab is double-end-pumped by two laser diode stacks. The pumped volume has a rectangular cross section. The Tm:YLF laser produced 148 W of continuos-wave output at 1912 nm in a beam with M x 2 ≈199 and M y 2 ≈1.7 for 554 W of incident pump power. The slope efficiency with respect to the incident pump power was 32.6%, and the optical-to-optical efficiency was 26.7%.

Diode-end-pumped double Nd:YLF slab laser with high energy, short pulse width, and diffraction-limited quality

We have developed a novel electro-optic Q-switched diode-end-pumped solid slab laser that combines high energy, short pulse width, high repetition rates, and diffraction-limited beam quality. With two partially end-pumped Nd:YLF slabs and a 100 mm long off-axis positive branch stable-unstable oscillator, 24.2 mJ, 7.1 ns electro-optic Q-switched pulse at 1 kHz repetition rate with a beam quality of M(x)(2)=1.4 and M(y)(2)=1.3 was generated. The peak power reached 3.5 MW. Efficient external second-harmonic generation was achieved by use of lithium triborate with low peak-power intensity.

Thermal stress effects of the diode-end-pumped Nd:YLF slab

The thermal stress effects of the diode-end-pumped Nd:YLF slab laser crystals are numerically investigated. The theoretical model is established by considering the divergence of the pump beam in the slab and the additional heat generated in the upconversion. Using the three dimensional finite element analyses, accurate numerical solutions based on the theoretical model are achieved. Our analyses focuses on the thermal fracture damage of the Nd:YLF slab under both the lasing and non-lasing conditions, and the predicted values are compared with the experimental results.

Intra-cavity side-pumped Ho:YAG laser

We present a novel, compact and power scalable Ho:YAG laser based on intracavity side-pumping by a high-power Tm:YLF slab laser. 14 W of continuous wave output power is obtained at 2.09 microm in the current experiments, with the clear prospect of reaching the 100 W regime in a power scaled version.

Efficient, high power, Q-switched Nd:YLF slab laser end-pumped by diode stack

A high power diode stack end-pumped electro-optically Q-switched Nd:YLF slab laser with a stable and off-axis negative-branch confocal unstable hybrid resonator was demonstrated. By using a cylindrical lens in the stable direction the thermal lens effect was compensated. Pulse energy of 25mJ was obtained with a pulse width of 22.4ns at repetition rates of 500Hz and a conversion efficiency of 22%. The stability was better than 0.8% and the beam propagation M2 factor was about 1.2.

Diode-end-pumped electro-optically Q-switched Nd:YLF slab laser.

We report a very compact Nd:YLF slab laser that is end pumped by a quasi-continuous-wave diode stack. A hybrid resonator is used to generate high output power in a near-diffraction-limited beam (i.e., a beam propogation M2 factor of less than 1.2). A pulse energy of 14.3 mJ was obtained with a pulse width of 8.5 ns at a repetition rate of 500 Hz, which corresponds to a Q-switched peak power of 1.68 MW.