Etching behavior of ground fused silica and light enhancement modulated by surface/subsurface cracks

Abstract

The mechanical defects (scratches/cracks) originated from grinding processing need to be dislodged so that improving the optical performance of fused silica. In this paper, HF‐based (HF represents hydrofluoride acid) etchant was used as a subsequent fabrication for loose‐abrasive ground fused silica, and the surface morphology and characteristics of samples were evaluated, meanwhile, the electric/light field distribution around treated cracks was simulated using the finite difference time domain (FDTD) method. The results show that sufficient material removal amount blunts the cracks to be a series of parabolic‐shaped and smooth craters fused with each other, whose diameter and depth grow as a power function with etched depth. Triple subsurface defect depth should be removed so as to mitigate surface roughness to be ∼2.46 µm and promote transmission from initial 22.55%–54.02%. FDTD simulation results reveal that deep etching alleviates the light intensification factor (LIF) of craters within 1.8 as the diameter‐to‐depth ratio of craters is increased over 10. Moreover, a thickness removal model of ground fused silica involving the cracks distribution characteristics, cracks etching behavior as well as the LIF variation of craters is established, in which the supposed etched depth is determined to promote the manufacturing efficiency and laser damage resistance of the material.

The role of silanol groups on the reaction of SiO2 and anhydrous hydrogen fluoride gas

“…The density ρ was assumed as 2.2 g/cm 3 in the present study for both the Si thermal oxide layer and the silica glass 25,26 …”

“…The density 𝜌 was assumed as 2.2 g/cm 3 in the present study for both the Si thermal oxide layer and the silica glass. 25,26 XPS was used also for evaluating surface silanol density. Quantification of the surface silanol density is generally difficult, and several methods with a secondary-ion mass spectrometer, 27,28 a high-resolution elastic recoil detection analysis, 29 and an XPS 24,28,30 have been proposed so far.…”

Effect of metal grids configuration on photothermal properties of infrared optical windows

“…A numerical simulation of the electric/light field distribution near the substrates was carried out using an analysis software based on the FDTD algorithm [6] . The FDTD method is based on an iterative solution to Maxwell's equations, and the distribution of both the electric field and the magnetic field within the space can be solved gradually and alternately [7,8] . The components of Maxwell's equation are unfolded in the right-angle coordinate system along x, y and z direction by the following formula [9] :…”

Research on Subsurface Damage Measurement of Fused Silica in Ultra-Precision Grinding Based on Laser Damage Performance

“…Fracture defects such as subsurface cracks caused by grinding are the manufacturing defects that are most likely to cause laser irradiation damage and must be completely removed in the subsequent polishing process so that the fused silica optics can withstand the irradiation of high-power lasers [1][2][3][4][5][6]. The polishing process is expensive, however, and requires a long process cycle.…”