Stabilization of silver nanoparticles with dyes for optical limiting

Lasers are getting more and more common, so also the risk for injury of the eyes or sensor due to laser radiation increases. Optical limiting is a method, which one can use to protect them. To use the method one can make... [ view full abstract ]

Lasers are getting more and more common, so also the risk for injury of the eyes or sensor due to laser radiation increases. Optical limiting is a method, which one can use to protect them. To use the method one can make filters with materials, which are nonlinear optical active. Optical limiting leads to an attenuation of their transmission above a certain laser intensity. 

There are several materials like nanoparticles and dyes, which are nonlinear active. In case of metal nanoparticles, especially silver nanoparticles lead to good optical limiting.[1]

In our study we used dyes as stabilization agents for silver nanoparticles to produce hybrids out of dyes and nanoparticles. Different reduction technique were used like reduction with Sodium borohydride (NaBH₄), and a variation of a polyol synthesis. In case of the polyol synthesis, dimethylacetamid (DMA) was used as solvent and pentaerythritol propoxylate was used as reduction agent. As stabilization agents in case of the NaBH₄-reduction Alcian Blue and acid fuchsin was used. Chromazurol and azophloxine were used for the polyol synthesis. 

In case of the reduction with NaBH_{4 ,} one can see that the dyes normally lead to a better attenuation compared to the silver nanoparticles stabilized with polyvinylpyrrolidone (PVP). This is also the case with the silver nanoparticles stabilized with azophoxin, but there the threshold is higher. 

Our results indicate that hybrids of silver nanoparticles and dyes are promising candidates for optical limiting. 

[1] Muller, Olivier; Dengler, Stefanie; Ritt, Gunnar; Eberle, Bernd (2013): Size and shape effects on the nonlinear optical behavior of silver nanoparticles for power limiters. In: Applied Optics 52 (2), S. 139–149.