第 50 卷 第 1 期/2023 年 1 月/中国激光 show a significant increase in the surface transmissivity of lithium niobate with increasing nanostructure height. Upon comparing the experimental data with the simulations, the results for the transmissivity of the lithium niobate primary wafer are found to be consistent (Fig. 11), and the height and RMS roughness of the conical subwavelength structure on the lithium niobate surface increase with an increase in the incident energy, etching time, and ion beam current. When the incident energy is 1000 eV, ion beam cuttent is 40 mA, incident angle is 70°, and etching time is 120 min, the prepared structure appears to have a tapered geometry with a longitudinal height of 143. 5 nm (Fig. 7). The peak transmissivity of this lithium niobate crystal sample is 83. 5% in the visible wavelength range, which is approximately 12. 5 percentage points higher than that of unmodified lithium niobate (Fig. 9).
ConclusionsThe transmissivity of nanostructures generated on the lithium niobate surface at an incident angle of 70°, incident energy of 1000 eV, ion beam current of 40 mA, and different etching time were simulated using COMSOL. The simulated transmissivity curves are consistent with the measured curves, and as the nanostructure height increases, the surface transmissivity of lithium niobate increases significantly. When the ion beam incident angle is 70°, the incident energy of the ion beam is greater than 600 eV, ion beam current is greater than 40 mA, and etching time is greater than 60 min, a large number of conical nanostructures can be formed on the surface of lithium niobate, and the height and RMS roughness of the conical nanostructure increase with the increase in incident energy, etching time, and ion beam current. The transmissivity measurements of lithium niobate crystals etched with different ion beam parameters were performed separately via spectrophotometry. The results show that the higher the nanostructure on the surface of lithium niobate, the more evident the effect of increasing transmittance in the visible band; when the incident energy is 1000 eV, ion beam current is 40 mA, incident angle is 70°, etching time is 120 min, longitudinal height of 143. 5 nm appears on the surface of lithium niobate. At this time, the peak transmissivity of the lithium niobate crystal sample is 83. 5% in the visible wavelength range, which is approximately 12. 5 percentage points higher than that of the original lithium niobate.
