Two-photon and three-photon absorption in ZnO nanocrystals embedded in Al2O3 matrix influenced by defect states.
Opt Lett
; 44(1): 179-182, 2019 Jan 01.
Article
em En
| MEDLINE
| ID: mdl-30645579
ABSTRACT
The broadband nonlinear absorption in ZnO nanocrystals embedded in Al2O3 matrix was investigated by Z-scan and pump-probe techniques from 400 nm to 800 nm. The effective two-photon absorption and three-photon absorption coefficients were determined to be â¼1.1×103 cm/GW at 400 nm and â¼1.1×10-1 cm3/GW2 at 800 nm, respectively, which are at least two orders of magnitude greater than that in ZnO bulk crystal. It may be attributed to the defect-states-mediated multiphoton absorption process, which was proofed by comparison experiments with different densities of interfacial defect states. The corresponding lifetimes for the intraband relaxation, defect-states trapping, and interband recombination processes were measured by femtosecond transient absorption measurements as τ1 â¼ 1 ps, τ2 â¼ 13 ps, and τ3 â¼ 350 ps, respectively.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Ano de publicação:
2019
Tipo de documento:
Article