Nonlinear optical properties of ZnS nanocrystals incorporated within the polyvinyl alcohole photopolymer matrices
✍ Scribed by F. Ramtolli; G. Saccinni
- Publisher
- John Wiley and Sons
- Year
- 2002
- Tongue
- English
- Weight
- 92 KB
- Volume
- 37
- Category
- Article
- ISSN
- 0232-1300
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✦ Synopsis
Abstract
Photoinduced nonlinear optical effects in ZnS nanocrystallites incorporated within the photopolymer polyvinyl alcohol matrices were studied. As a basic method we have used photoinduced optical second harmonic generation (SHG). The Q‐switched HF‐laser (λ = 2.64.μm; pulse duration 30‐40 ps) was used as a source of probing (fundamental) light beam and the pulsed nitrogen (λ = 337.7 nm) was applied as a source of the photoinducing pump light. With increasing photoinducing beam power, the output SHG signal (at λ = 1.32 μm) increases. The maximal second‐order non‐linear optical susceptibility corresponds to tensor component d~123~ = d~14~ = 3.8 ± 0.2 pm/V at a photoinducing power density equal to about 1.25 GW/cm^2^. With decreasing temperature, the SHG signal increases within the temperature range 25‐30 K. Time‐dependent pump‐probe measurements of the SHG indicate an existence of the SHG maximum for a pump‐probe delaying time 20 ps. The ZnS hexagonal structural components play a crucial role in the observed photoinduced second‐order non‐linear optical effects. Large values of the non‐linear optical constants as well the good technological parameters open a possibility to enhance the non‐linear optical susceptibilities of the investigated ZnS nanocrystallites.