Influence of surface roughness on the lasing characteristics of optically pumped thin-film GaN microdisks.
Opt Lett
; 47(6): 1521-1524, 2022 Mar 15.
Article
em En
| MEDLINE
| ID: mdl-35290354
ABSTRACT
Optically pumped whispering-gallery mode (WGM) lasing is observed from a thin-film GaN microdisk processed from GaN-on-Si InGaN/GaN multi-quantum well wafers by selective wet-etch removal of the substrate. Compared with thin-film microdisks processed from GaN-on-sapphire wafers through laser lift-off of the sapphire substrate, the exposed surface is significantly smoother as laser-induced damage is avoided, with a root-mean-square roughness of 1.3 nm compared with 5.8 nm of the latter wafer. The â¼8-µm diameter microdisks, fabricated by pattern transfer from a silica microsphere and dry etching, benefit from the surface smoothness to offer superior optical confinement within the cavity. WGM lasing thresholds of â¼2.9 mJ/cm2 and â¼3.5 mJ/cm2 with quality (Q)-factors of â¼3100 and â¼1700 are observed at the peak lasing wavelengths of â¼453 nm and â¼532 nm, respectively, which are significantly better than thin-film microdisks processed from GaN-on-sapphire wafers despite lower internal quantum efficiency, highlighting the importance of surface smoothness in such optical cavities.
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MEDLINE
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En
Revista:
Opt Lett
Ano de publicação:
2022
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Article