Three-Dimensional Residue-Free Volume Removal inside Sapphire by High-Temperature Etching after Irradiation of Femtosecond Laser Pulses

Figure 2

(a) SEM micrographs inside sapphire with a laser irradiation condition of 𝑝_𝑥=0.2𝜇m and 𝑝_𝑧=1.0𝜇m after etching at 100^∘C for 24 hours. The inset presents a close-up oblique view tilted at 20^∘. (b) Optical micrographs of the same sample as (a), (b1) before etching, and (b2) after.

(a)

(b)