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To enhance the surface quality of metal 3D-printed components, magnetic abrasive finishing (MAF) technology was employed for post-processing polishing. Experimental investigation employing response surface methodology was conducted to explore the impact of processing gap, rotational speed of the magnetic field, auxiliary vibration, and magnetic abrasive particle (MAP) size on the quality enhancement of internal surfaces. A regression model correlating roughness with crucial process parameters was established, followed by parameter optimization. Ultimately, the internal surface finishing of waveguides with blind cavities was achieved, and the finishing quality was comprehensively evaluated. Results indicate that under optimal process conditions, the roughness of the specimens decreased from Ra 2.5 μm to Ra 0.65 μm, reflecting a reduction rate of 74%. Following sequential rough and fine processing, the roughnesses of the cavity bottom, side wall, and convex surface inside the waveguide reduced to 0.59 μm, 0.61 μm, and 1.9 μm, respectively, from the original Ra above 12 μm. The findings of this study provide valuable technical insights into the surface finishing of metal 3D-printed components.

We study the nonlinear optical limiting effect of graphene dispersions in ethanol and acetone at a wavelength of 1064 nm. The nonlinear optical limiting effect of graphene dispersion under three different linear transmittances (about 70%, 80%, and 90%), two different thicknesses (1 and 3 cm), and two different solvents (ethanol and acetone) are measured. The influences of concentration, thickness, and solvent on the nonlinear optical limiting effect of the graphene dispersion are analyzed. The experimental results show that the concentration and solution thicknesses have great influence on the optical limiting ability of graphene dispersions. The graphene dispersions with ethanol and acetone as solvents can be used to achieve excellent nonlinear optical limiting effects. The optical limiting ability of the graphene dispersion in acetone is better than that of the graphene dispersion in ethanol.

In this paper, we investigate the optical limiting effect of C 70 solution at a wavelength of 1064 nm. We experimentally measured the transmittance of C 70 solution under three different concentrations (0.25, 0.5, and 1 mmol/L), three different solution thicknesses (5, 10, and 20 mm), and two different solvents (toluene and xylene) and obtained the values of absorption cross sections and relaxation times in the five-level absorption model of C 70 solution. The influences of concentration, thickness, and solvent on the optical limiting effect of the C 70 solution are analyzed. We also measured transmittance of C 60 solution under the same conditions and compared the results with those of C 70 solution. The experimental results show that concentration and solution thicknesses have great influence on the optical limiting ability of C 70 solution. The optical limiting effect of C 70 solution is better than that of C 60 solution at low concentration and worse than that of C 60 solution at high concentration.

We propose a novel topological photonic crystal nonlinear laser power limiter based on topological edge states and optical Kerr effect. In the proposed laser power limiter, a one-dimensional photonic crystal in topological edge state allows the relatively weak signal light with a certain wavelength to pass through with high transmission, but blocks most of the intense hostile or accidental laser with the same wavelength due to the change of topological edge state generated from optical Kerr effect. Taking a 1064 nm wavelength as an example, we have designed such a nonlinear laser power limiter corresponding to the wavelength. When the optical power density is low (less than 0.12 MW/cm 2 ), the light transmission can reach 82.54%, and the transmission can be reduced to 1.04% when the optical power density is increased to 11.66 MW/cm 2 . Therefore, this method provides a new promising approach to realize laser protection at the desired wavelength.

In this paper, we investigate third-order nonlinearities in aluminum-doped zinc oxide (AZO) thin film by the Z-scan method at a wavelength of 1064 nm. We carried out experiments under different pulse widths (26 ns, 62 ns, and 101 ns) and energy densities (5.3  J/cm 2 , 10.6  J/cm 2 , and 15.9  J/cm 2 ) and obtained the nonlinear absorption coefficient, nonlinear refractive index, and third-order nonlinear susceptibility of AZO thin film. The Z-scan results show that AZO thin film exhibits a larger nonlinear refractive index (-5.48×10 -13   m 2 /W) and third-order nonlinear susceptibility (1.97×10 -6   esu) than those of some other semiconductor materials at the wavelength of 1064 nm. This suggests that AZO thin film may be a very promising nonlinear medium for nonlinear photonics applications in the tens of nanoseconds regime.