Design of a novel nanoscale high-performance phase-change silicon photonic switch

摘要

We report the design of a novel high static performance on-off photonic switch by embedding the nanoscale phase-change material Ge2Sb2Te5 into a silicon-on-insulator waveguide. The state of the proposed switch can be changed using electrical/optical pulses, and no electrical bias is needed to maintain a particular state. The fundamental mode propagating through the silicon waveguide drastically alters its properties because of the large index change at the Si-Ge2Sb2Te5 interface and absorption in Ge2Sb2Te5. The photonic switch made of the silicon waveguide embedded with Ge2Sb2Te5 of volume 400 nm x 180 nm x 450 nm (length x height x width) provides a high extinction ratio of 43 dB with a low insertion loss of 2.76 dB in ON state at the communication wavelength of 1550 nm. There is a trade-off between the insertion loss and the extinction ratio. For 10 dB extinction ratio, the insertion loss can be as low as 1.2 dB with an extremely low active volume of 400 nm x 30 nm x 450 nm (length x height x width). Further, spectral response investigations reveal that this switch maintains an extinction ratio of more than 30 dB in the wavelength range of 1500-1600 nm. The high static performance of the photonic switch reported here is a direct consequence of the proper dimensions of the active volume of Ge2Sb2Te5 and its incorporation into the silicon-on-insulator waveguide. We also propose figure-of-merit for bias-free (nonvolatile) photonic switches that considers relevant parameters of static performance.