Design of an electric-driven nonvolatile low-energy-consumption phase change optical switch

Traditional optical switches relying on the weak, volatile thermo-optic or electro-optic effects of Si or SiN waveguides show a high consumption and large footprint. In this paper, we reported an electric-driven phase change optical switch consisting of a Si waveguide, Ge2Sb2Te5 (GST) thin film and graphene heater suitable for large-scale integration and high-speed switching. The reversible transition between the amorphous and crystalline states was achieved by applying two different voltage pulses of 1.4 V (SET) and 4 V (RESET). The optical performance of the proposed switch showed a high extinction ration of 44-46 dB in a wide spectral range (1525-1575 nm), an effective index variation of Delta n (eff) = 0.49 and a mode loss variation of Delta alpha = 15 dB mu m(-1) at the wavelength of 1550 nm. In thermal simulations, thanks to the ultra-high thermal conductivity of graphene, the proposed switch showed that the consumption for the SET process was only 3.528 pJ with a 1.4 V pulse of 5 ns, while a 4 V pulse of 1.5 ns was needed for RESET process with a consumption of 1.05 nJ. Our work is helpful to analyze the thermal-conduction phase transition process of on-chip phase change optical switches, and the design of the low-energy-consumption switch is conducive to the integrated application of photonic chips.

Automated summary

This study presents an electric-driven phase change optical switch composed of a Si waveguide, GST thin film, and graphene heater, suitable for large-scale integration and high-speed switching, with high extinction ratio and wide spectral range adaptability. Thermal simulations show that the switch has low energy consumption during both SET and RESET processes, which is beneficial for integrated applications of photonic chips.