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

Abstract

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, Ge 2 Sb 2 Te 5 (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 Δn eff =0.49 and a mode loss variation of Δα=15 dB μm −1 at the wavelength of 1550 nm. In thermal simulations, thanks to the ultrahigh 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 thermalconduction 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.

A Review of Silicon‐Based Integrated Optical Switches

“…[102] While more detailed studies are required to develop and demonstrate a fully functional silicon-integrated device, the non-volatile property of VO 2 at room temperature using the first major transition between insulator state and oscillating state reported for the first time paves the foundation to unleash the latching property of VO 2 -based integrated optical switches. [102] An electrical-driven phase change optical switch consisting of a Si waveguide and GST film with ITO or graphene heaters was reported by Li et al [97] in 2021. Different from the previous works, [92,93,100] which use VO 2 as the PCM and use Ti heater or square optical pump pulse to trigger the phase transition, this optical switch uses GST as PCM and uses ITO or graphene heaters to trigger the phase transition.…”

“…On top of the corrugated waveguide, GST nano-strips is integrated. The straight silicon waveguide has a width (W 1 ) of 370 nm, and the grating-assisted waveguide (loaded with GST) has a basic width [97] Copyright 2022, IOP Publishing Ltd.…”

“…In addition to the straight waveguide structure, Hu et al [95] presented a 1 × 2 wavelength-selective optical switch based on the Si-GST grating assisted waveguide structure in 2020. Different from the other waveguide-based works using PCM, [92,93,97,100] this optical switch further introduces the grating structure, thereby enabling the function of path selection instead of simple on-off switch. The structure is shown in Figure 19, and it is consisted of two parallel silicon strip waveguides.…”

Impact of GST thickness on GST-loaded silicon waveguides for optimal optical switching

“…Such appealing properties have led to developing high-performance and new kinds of waveguide-based photonic integrated devices such as modulators 26 – 30 , pass polarizers 31 , photonic memories 32 – 37 , reconfigurable devices 38 – 40 , switches 41 – 47 , or synapses 48 . Thereby, enabling new applications based on non-von Neumann architectures such as arithmetic 49 and logic 50 operations, in-memory computing 51 , neuromorphic computing 52 , 53 , or photonic tensor cores 54 .…”

On-Chip Photonic Synapses with All-Optical Memory and Neural Network Computation

“…With further research, more and more new materials and structures have been discovered, such as inorganic perovskite [ 14 ], black phosphorus [ 15 ] and phase-change materials [ 16 ], etc. Among them, phase-change materials (PCMs) are one of the ideal candidates in the field of integrated photonics and have become a hot topic in the research of optical switches [ 17 ], optical modulators [ 18 ], optical computing [ 19 , 20 ] and optical neural networks [ 21 ]. Cheng et al [ 22 ] demonstrated a photonic synapse based on an integrated PCMs-Si waveguide in 2017, where the weight of the synapse can be set by the light pulse.…”