Scratches in fused silica are notorious laser damage precursors to UV laser damage initiation. Ductile and brittle scratches were intentionally generated using various polishing slurries. The distribution, profile and the dimension of scratches were characterized. The damage resistance of polished surfaces was evaluated using raster scanning damage testing protocol. The results show that both ductile and brittle scratches greatly increase area proportion of laser damage about one to two orders of magnitude relative to unscratched surface and brittle scratches are more deleterious. Moreover, finite difference time domain (FDTD) simulation was used to numerically calculate the light field distribution around scratches on rear surface (i.e. exit surface for light) which indicates that modulated light intensity is susceptible to the profile and size of scratches. FDTD simulation results also indicate that the light field intensification is elevated with the dimension of scratches and light modulation effects in triangular scratches are usually not as notable as serrated and parabolic scratches.

Optical modulators are required to have high modulation bandwidths and a compact footprint. In this paper we experimentally demonstrate a novel Si/In$_2$O$_3$ hybrid plasmonic waveguide modulator, which is realized by an asymmetric directional coupler (ADC) consisting of a silicon photonic waveguide and a Si/In$_2$O$_3$ hybrid plasmonic waveguide. The optical signal is modulated by radio-frequency (RF) signal applied on the Au electrodes at the top of MOS capacitor and contacting the In$_2$O$_3$ thin film. The record-high modulation bandwidth of >40 GHz is realized by a silicon-doping-free metal-oxide-In$_2$O$_3$ capacitor integrated in a 3.5-$\mu$m-long asymmetric directional coupler (ADC) for the first time.

Under the background of the national digital transformation of education and teaching in China, and regarding the demands of cross-grades integrated talent cultivation, the National Virtual Simulation Experimental Teaching Center for Equipment Manufacturing in the University of Shanghai for Science and Technology (USST), relying on virtual simulation experiments, has been continuously carrying out virtual simulation experimental teaching reforms for cross-grades cultivation. These reforms include the "integration of primary, secondary, and higher education" and the "integration of undergraduate and postgraduate education" empowered by wisdom education, breaking through disciplinary boundaries and educational - stage barriers. By creating intelligent and boundaryless virtual simulation experimental teaching scenarios, expanding digital virtual simulation experimental teaching resources, and innovating the cross-grades virtual simulation experimental teaching system, the center provides students with more flexible practical spaces and richer learning resources. This can meet students' individualized demands and academic interests better, and offers significant support for cultivating high - quality talents with innovative spirits and practical abilities.

Deposited substances generated from hydrofluoric acid based (HF-based) etching are found to be the precursors that deteriorate the resistance of fused silica optics to laser damage. In this paper, the surface of polished fused silica was treated with a buffer oxide etchant (BOE, 5–10%wt. HF + 10%wt. N H 4 F + 80 − 85 % w t . H 2 O ). The optic surface area affected by the etching-induced deposits ( N H 4 ) S i F 6 was found to increase significantly with the amount of material removal and sensitivity to the post-cleaning procedure. Three shapes of deposited particles are simultaneously identified on the treated samples. The 3D finite-difference time-domain (FDTD) was used to simulate the light field distribution near the deposited particles, which demonstrates that fused silica is subject to more light modulation when a particle is exposed on the front surface laser than on the rear surface laser. In addition, dense particles barely increase the light intensification factor (LIF) while markedly increase the light focused probability inside fused silica. Moreover, a multiple linear regression (MLR) analysis for the LIF builds a fitting plane model of the LIF and the particle height as well as the horizontal size, revealing that the LIF increases with the size of the deposited particle, especially its height. The laser damage testing results indicate that a deposited layer of ∼ 76 n m in height had little influence on the laser-induced damage threshold (LIDT) of the optics and larger deposited particles with up to 9 µm thickness may deteriorate the LIDT to 41.62% that of the reference sample. Both the simulation and experimental results demonstrate that deposited particles with a height of more than 0.1 µm should be inhibited to achieve fused silica with superior laser damage performance.