Eu₂O₃-PVA Saturable Absorber Thin-Film-Based All-Optical C-band Switch

In this study, the all-optical C-band switching capability of the nonlinear characteristics of Europium Oxide-Polyvinyl Alcohol (Eu₂O₃-PVA)-based saturable absorber (SA) thin film is experimentally shown. Eu2O3-PVA-based thin film saturable absorber was fabricated using a simple method and its all-optical switching performance was obtained by installing an all-fibre-based experimental testbed. In the experiments, a continuous wave (CW) signal at 1555 nm with an optical power of 20.41 mW generated by a tuneable laser source was converted into a variable frequency square-wave-modulated switching signal using a mechanical shutter/modulator. This modulated switching signal was then applied to the Eu2O3-PVA-based SA thin film with a CW signal at 1545 nm with an optical power of 3.47 mW provided by another tuneable laser source to switch the absorption characteristics of the SA between high-loss and low-loss cases. It has been shown that the 1545 nm CW signal was optically ON--OFF switched due to nonlinear absorption loss variations in SA generated by the saturating switching light at 1555 nm. In the experiments, all-optical switching in Eu2O3-PVA-based saturable absorber thin film succeeded for switching frequencies up to 4 KHz. The rise and fall times of the modulated light measured at 302 Hz were 500 µs and 350 µs on average, respectively.