Silicon-Based Optical Switch with Ge2Sb2Te5-Enabled Phase-Shifting Region

With the rapid development of communication networks and computing, optical switches as an important elementary unit are highly needed. In this article, a silicon-based optical switch with Ge2Sb2Te5$\left(\text{Ge}\right)_{2} \left(\text{Sb}\right)_{2} \left(\text{Te}\right)_{5}$ (GST)-enabled phase-shifting region is proposed. This optical switch is based on contra-directional couplers composed of two phase-shifted Bragg gratings. To minimize the impact of GST absorption loss, GST is only used in the phase-shifting area, and the switching function is achieved by changing the state of GST. In the results, it is shown that the proposed device has a 3 dB operation bandwidth of about 163.2 GHz (1.394 nm) and an extinction ratio of about 19.06 dB for the drop port and about 20.25 dB for the through port. The loss at the central operational wavelength is about 1.3 and 1.04 dB for the through port and the drop port, respectively, and the largest loss over the entire operation bandwidth for these two ports is 1.66 and 2.35 dB. Furthermore, the optical switch is shown to be bidirectional, achieving similar performance when light propagates in the opposite direction. Compared with previous works, the proposed optical switch realizes wider operation bandwidth, higher extinction ratio, and lower loss.