FDTS as Dewetting Coating for an Electrowetting Controlled Silicon Photonic Switch

The self-assembled monolayer FDTS (1H,1H,2H, 2H-Perfluorodecyltrichlorosilane) is presented as suitable dewetting coating material for an electrowetting on dielectrics (EWOD) controlled silicon photonics switch deployed in fiber optic telecommunication systems. The anti-sticking characteristics of Perfluorodecyltrichlorosilane (FDTS) are compared to those of polytetrafluoroethylene (PTFE) as most common dewetting coating for EWOD devices. It is shown that FDTS could outperform other materials such as PTFE when an extremely thin, long-term stable, and uniform layer is required. In the specific case, FDTS is applied in vapor phase as anti-sticking coating to the active optical surface of the integrated silicon photonics switch thus enabling the EWOD driven liquid motion. The suitability of the coating is presented by contact angle measurements and durability tests carried out with the switching liquids. Finally, it is demonstrated by optical measurements that the FDTS coating has a neglectable influence on the optical switching performance.