Absorption efficiency analysis and optical resonator simulation of Ho:YLF laser pumped with Tm:fiber laser

Abstract In this paper, a Tm:fiber laser pumped Ho:YLF laser is simulated. The absorption efficiency, optimum crystal length, and optical resonator are analytically studied and simulated using LASCAD software, and the atomic-level degeneracies are considered in evaluating the absorption efficiency. In this way, the absorption efficiencies of 65% and 87% are obtained for single-pass 30 mm Ho:YLF crystal with doping concentration 0.5% and 1% respectively. These calculated efficiencies are verified by our experimental measurements and they coincide with acceptable errors. To estimate a proper length for the Ho:YLF crystal with specified doping concentration, the up-conversion, and the reabsorption effects are considered. As a result, we find the 30 mm length crystal is suited for reducing the absorption threshold and prohibiting reabsorption while saturation is controlled. The threshold power and slope efficiency for 65 W pumped powers are calculated by LASCAD software, and the thermal lens focal length of −665 mm is obtained. For a nearly constant beam width inside the cavity and suitable beam overlap efficiency, a concave-concave configuration is chosen for the optical resonator. In the continuous-wave operation, the output power is funded to be 38.4 W and the slope efficiency would be 66%.

Download Full-text

Numerical Simulations of Fractional Fourier Transform of Hypergeometric-Gaussian Beam

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.765-767.780 ◽

2013 ◽

Vol 765-767 ◽

pp. 780-784 ◽

Cited By ~ 2

Author(s):

Zhen Feng Yang ◽

Wen Dan Miao ◽

Zhen Jun Yang ◽

Shu Min Zhang

Keyword(s):

Fourier Transform ◽

Numerical Simulations ◽

Gaussian Beam ◽

Intensity Distribution ◽

Fractional Fourier Transform ◽

Focal Length ◽

Beam Width ◽

Laser Beams ◽

New Type ◽

Lens Focal Length

The fractional Fourier transform (FRFT) of a new type of laser beams called the hypergeometric-Gaussian beam (HyGGB) is investigated in detail. The analytical expression for the FRFT of a HyGGB is derived. The properties of a HyGGB in the FRFT plane with different parameters are illustrated. The results show that the intensity distribution of a HyGGB in the FRFT plane strongly depends on the fractional order, the lens focal length and the initial beam width.

Download Full-text

Erratum: Continuous-wave operation of lateral current injection multiquantum-well laser

Electronics Letters ◽

10.1049/el:19880924 ◽

1988 ◽

Vol 24 (21) ◽

pp. 1351

Author(s):

A. Furuya ◽

M. Makiuchi ◽

O. Wada

Keyword(s):

Continuous Wave ◽

Current Injection ◽

Continuous Wave Operation ◽

Lateral Current ◽

Multiquantum Well

Download Full-text

Optimized Growth and Laser Application of Yb:LuAG Single-Crystal Fibers by Micro-Pulling-Down Technique

Crystals ◽

10.3390/cryst11020078 ◽

2021 ◽

Vol 11 (2) ◽

pp. 78

Author(s):

Anye Wang ◽

Jian Zhang ◽

Shuai Ye ◽

Xiaofei Ma ◽

Baiyi Wu ◽

...

Keyword(s):

Single Crystal ◽

High Power ◽

Slope Efficiency ◽

Continuous Wave ◽

Beam Quality ◽

Axial Direction ◽

Optical Quality ◽

Central Wavelength ◽

High Power Lasers ◽

Crystal Fibers

Single-crystal fibers (SCFs) have a great application potential in high-power lasers due to their excellent performance. In this work, high-quality and crack-free Yb3+:Lu3Al5O12 (Yb:LuAG) SCFs were successfully fabricated by the micro-pulling-down (μ-PD) technology. Based on the laser micrometer and the X-ray Laue diffraction results, these Yb:LuAG SCFs have a less than 5% diameter fluctuation and good crystallinity along the axial direction. More importantly, the distribution of Yb ions is proved to be uniform by electron probe microanalysis (EPMA) and the scanning electron microscope (SEM). In the laser experiment, the continuous-wave (CW) output power using a 1 mm diameter Yb:LuAG single-crystal fiber is determined to be 1.96 W, at the central wavelength of 1047 nm, corresponding to a slope efficiency of 13.55%. Meanwhile, by applying a 3 mm diameter Yb:LuAG SCF, we obtain a 4.7 W CW laser output at 1049 nm with the slope efficiency of 22.17%. The beam quality factor M2 is less than 1.1 in both conditions, indicating a good optical quality of the grown fiber. Our results show that the Yb:LuAG SCF is a potential solid-state laser gain medium for 1 μm high-power lasers.

Download Full-text

Evaluating effects of focal length and viewing angle in a comparison of recent face landmark and alignment methods

EURASIP Journal on Image and Video Processing ◽

10.1186/s13640-021-00549-3 ◽

2021 ◽

Vol 2021 (1) ◽

Author(s):

Xiang Li ◽

Jianzheng Liu ◽

Jessica Baron ◽

Khoa Luu ◽

Eric Patterson

Keyword(s):

Focal Length ◽

Ground Truth ◽

Detection Methods ◽

Viewing Angle ◽

Deep Convolutional Neural Networks ◽

Landmark Detection ◽

High Performing ◽

Detection Techniques ◽

And Performance ◽

Lens Focal Length

AbstractRecent attention to facial alignment and landmark detection methods, particularly with application of deep convolutional neural networks, have yielded notable improvements. Neither these neural-network nor more traditional methods, though, have been tested directly regarding performance differences due to camera-lens focal length nor camera viewing angle of subjects systematically across the viewing hemisphere. This work uses photo-realistic, synthesized facial images with varying parameters and corresponding ground-truth landmarks to enable comparison of alignment and landmark detection techniques relative to general performance, performance across focal length, and performance across viewing angle. Recently published high-performing methods along with traditional techniques are compared in regards to these aspects.

Download Full-text