Compact Optical Waveguides Exhibit Low Light Loss for Use in Biosensors, Wearable Displays :
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Compact Optical Waveguides Exhibit Low Light Loss for Use in Biosensors, Wearable Displays :

Researchers optimized a laser writing process to create extremely narrow waveguides in PDMS.

Compact Optical Waveguides Exhibit Low Light Loss for Use in Biosensors, Wearable Displays :
Tiny, flexible waveguides, made in a clear silicone commonly used for biomedical applications, were created by a research team at École Fédérale de Lausanne (EPFL). To create the waveguides, the team used multiphoton laser direct writing, a microfabrication method in which a light-sensitive chemical is polymerized with a focused laser to create finely detailed 3D structures.

The optical waveguides were fabricated in polydimethylsiloxane (PDMS). Phenylacetylene was used as the photosensitive monomer. Phenylacetylene has a higher refractive index once polymerized, compared to traditional materials. The researchers surmised that the refractive index (RI) of the phenylacetylene would be markedly different from the RI of the surrounding PDMS. This would help ensure that the waveguides, although tiny, would be able to confine light efficiently.

The researchers soaked the PDMS in phenylacetylene, then used an ultrafast laser to induce multiphoton absorption. Multiphoton laser direct writing produces finer structures than one-photon processes because the volume of polymerization at each writing spot is smaller. Multiphoton laser direct writing allowed the researchers to directly initiate phenylacetylene polymerization without a photoinitiator. The researchers caused any nonpolymerized phenylacetylene to evaporate by heating the PDMS.

The data is compiled from : https://www.photonics.com



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