Journal of Russian Laser Research最新文献

In this paper, we investigate the continuous-wave lasing characteristics of Ho :GdVO₄ crystal under diode-pumping conditions. Using a 1.0 at.%-doped crystal, we obtain the maximum output power equal to 9.0 W at 2047.9 nm, with an absorbed pump power of 28.2 W. The slope efficiency and optical efficiency measured with respect to the absorbed pump power are 50.7% and 31.9%, respectively. In addition, we estimate the beam quality factor at the maximum output level to be about 1.8.

We present the expression of a partially coherent sine beam and derive the propagation equations of such a beam in non-Kolmogorov turbulence. The intensity profiles of the beam in non-Kolmogorov turbulence are simulated and analyzed. The obtained results show that the sinusoidal array profile is destroyed by non-Kolmogorov turbulence and beam parameters during the propagation, and the intensity profile of such a beam becomes a sheet, when a and b are set. The array profile properties of partially coherent sine beams introduced here display new properties, and these beams help free space optical communications.

In this paper, we study quantum correlations in a Heisenberg XYZ model with the Dzyaloshinskii–Moriya interaction based on the Sharma–Mittal quantum discord and its limiting cases. The results obtained show that the Sharma–Mittal quantum discord is a faithful quantifier and that the Dzyaloshinskii–Moriya interaction significantly enhances quantum correlations within the bipartite system. In contrast, temperature has the opposite effect, leading to a reduction in the quantity of quantum correlations in the system.

We formally generate picosecond laser pulses in an Erbium-doped fiber laser (EDFL) by incorporating a new type of a saturable absorber (SA) with Chromium–Titanium–Aluminum carbide (Cr₂TiAlC₂). The SA film is prepared by a casting method, using polyvinyl alcohol (PVA) as a host. The novel ultrafast laser operates at 1559.96 nm; the laser pump power range is 164 – 305 mW. Using a 90 : 10 output coupler, the designed laser produces a pulse duration of 2.04 ps and a repetition rate of 1.855 MHz. We obtain a maximum output power of 3.2 mW and a pulse energy of 1.72 nJ at a maximum laser pump power of 305 mW. To the best of our knowledge, this is the first time that a Cr₂TiAlC₂-based SA is used to produce ultrashort laser pulses.

We present a coiled and tapered graded-index few-mode-fiber (FMF) polarization controller (PC) as a saturable absorber (SA) in an all-fiber laser. We obtain the 845 fs ultrashort pulse with a signal-to-noise ratio (SNR) of 65 dB, using a tapered graded-index FMF of 40 cm in the cavity. The spectrum is centered at 1588.2 nm with a 3 dB spectral bandwidth of 4.04 nm. Furthermore, a Q-switched mode-locked state is observed between 140 and 360 mW of the pump power in the cavity. The results further demonstrate the application of a coiled and tapered graded-index FMF PC as a SA for stable high-energy ultrashort pulse formation and provide a technical method for generating ultrashort pulses.

In this paper, we present a finite element model that utilizes simulation software to simulate the process of moving nanosecond pulsed laser cleaning on the surface paint layer of 2A12 Aluminum alloy. The objective is to analyze the impact of different laser parameters on the distribution of temperature field within both the paint layer and the substrate surface. Furthermore, we perform experimental validation to verify the findings. The results assume that both laser power and scanning speed influence the outcomes of the cleaning process. At a constant scanning speed, the maximum temperature of both the paint surface and the substrate surface linearly increases with rising laser power. In contrast, at a fixed laser power, the scanning speed influences cleaning outcomes through spot overlap, and the surface temperature of the paint layer rises as the scanning speed decreases. The optimum cleaning effect, with a surface roughness (Ra) of 1.0139 μm, is achieved at a scanning speed of 2500 mm/s and a laser power of 30 W. The surface roughness exhibits first a decrease and then increase pattern with rising laser power. These findings offer valuable insights into process parameters for nanosecond pulsed laser cleaning of surface paint layers on Aluminum alloy.

We successfully demonstrate the generation of nanosecond pulses in a passively Erbium-doped fiber laser (EDFL) by an Ag₂S-based saturable absorbeer (SA). A simple and low-cost liquid phase exfoliation (LPE) method is used to fabricate the SA. Through LPE, the SA element is coated onto a thin film of polyvinyl alcohol (PVA), which serves as the host material. The Ag₂S SA film exhibits good nonlinear absorption characteristics to give it strong potential as an ideal SA. It has a modulation depth of 25.3% and a saturation intensity of 1.11 MW/cm². The laser is able to generate a self-started mode-locked pulse at a threshold pump power of 145.83 mW with a fundamental repetition rate of 0.98 MHz and a pulse duration of 256 ns, respectively. At the maximum pump power, the laser delivers a pulse energy of 2.08 nJ and an output power of 2.11 mW. This demonstration suggests that Ag₂S SA has good capacity for generating nanosecond mode-locked lasers in the C-band region.

Optical domain–wall (DW) solitons have attracted considerable attention for their special applications in wavelength-division multiplexing and signal processing in optical communications. In this study, we construct a dispersion-managed fiber laser with a composite filtering effect composed of nonlinear polarization rotation (NPR) filtering and Lyot filtering for achieving dual-wavelength domain–wall dark–bright pulses. Our optical-domain dark–bright pulse is characterized by even, though it has two optical wavelength components, still has the same repetition frequency. The phenomenon of dual-wavelength dark and bright pulses occurs by adjusting the composite filtering, and the dark and bright pulses can be separated by continuing the filtering. Our work presents a novel approach to achieve dual-wavelength domain–wall dark–bright pulses.

In order to meet the visual characteristics of human eyes, in this paper, we propose a ghost imaging method based on binocular vision matching fusion. The imaging process of the left-eye camera and the right-eye camera in binocular vision system is realized, using ghost imaging algorithm, and its weak signal imaging characteristics can effectively compensate the parallax between the left-eye camera and the right-eye camera. The Speeded Up Robust Features algorithm is used to match the feature points of the two sub-images. Combined with the fusion algorithm of New Sum of Modified Laplacian, the two sub-images after registration are fused to obtain a clearer image. Whether from the visual perception (human vision) or objective analysis (CC, SSIM, IE, RMSE, PSNR, and BER), it can be proved that the proposed scheme has better image quality, better fidelity and robustness, and is closer to the ideal image, which provides a new method for binocular vision imaging technology.

We study the graphene (Gr)-strengthened CoCrFeNiMo_0.2 high-entropy alloys (HEAs) prepared by laser cladding. The corrosion properties of the alloys under simulated acid rain conditions are studied through rainfall experiments, electrochemical experiments, and immersion experiments. The experimental results show that the microstructure of the Gr-strengthened CoCrFeNiMo_0.2 HEAs mainly including three morphologies. Mo element occurs segregation. Gr concentrates on the alloy surface during melting. The alloy has a face centered cubic (FCC) single-phase structure. With increase in the rainfall and immersion period, the corrosion resistance of the Gr-strengthened HEAs decreases. With increase in the pH, the corrosion resistance of the alloys increase. The corrosion current densities of Gr-strengthened CoCrFeNiMo_0.2 HEAs are small, indicating that the alloys have excellent corrosion resistance. Electrochemical impedance spectroscopy (EIS) shows that as the pH increases, the capacitance arc radius, impedance modulus, and phase angle show increasing trend. The reason for excellent corrosion resistance are as follows: the Gr enriched on the surface plays a shielding role during alloy melting, Gr reacts with alloy elements to form a passive film on the alloy surface, the lattice distortion and grain refinement are caused by Gr, providing the single-phase structure of the alloy.