Optical nonlinear enhancement through interaction between Ag nanoparticles and CdSe quantum dots

The CdSe/Al 2 O 3 /Ag composite films were prepared on quartz glass substrate by magnetron sputtering and spin coating with the CdSe oily quantum dots. The absorption experiments and analysis results show that all of the CdSe quantum dots, Ag films, and Al 2 O 3 contribute to the absorption peak, and the absorption peak of the CdSe/Al 2 O 3 /Ag composite films shifts to the ultraviolet region (356 nm). The transmission TZ-scan results illustrate that the nonlinear absorption effect of the CdSe/Al 2 O 3 /Ag composite films exhibits reverse-saturated absorption characteristic, and the third-order nonlinear refractive index of the CdSe/Al 2 O 3 /Ag composite films is approximately 10 5 times greater than that of the CdSe quantum dots. With the increase in the CdSe quantum dots concentration, the nonlinear absorption and refraction properties of the CdSe/Al 2 O 3 /Ag composite films are enhanced. However, the nonlinear absorption and refractive index of the CdSe/Al 2 O 3 /Ag composite films decrease with the increase in sputtering power of Ag. The reverse-saturated absorption characteristic is explained by the three-level system. The composite films could be applied to new optical control fields, for example, optical phase recovery.