Silicon Mode-Selective Switch via Horizontal Metal-Oxide-Semiconductor Capacitor Incorporated With ENZ-ITO

Weifeng Jiang,Tao Li,Jinye Miao

doi:10.1038/s41598-019-54332-6

Weifeng Jiang, Tao Li + Show 1 more

Open Access

https://doi.org/10.1038/s41598-019-54332-6

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Abstract

A silicon mode-selective switch (MSS) is proposed by using a horizontal metal-oxide-semiconductor (MOS) capacitor incorporated with the epsilon-near-zero (ENZ) indium-tin-oxide (ITO). The carrier concentration of the double accumulation-layers in ITO can be adjusted via the applied gate-voltage to achieve the desired switching state. The MOS-type mode of the central MOS-capacitor based triple-waveguide coupler is introduced and optimised by using the full-vectorial finite element method to switch the “OFF” and “ON” states. The thickness of the accumulation layer and the optimal design are studied by using the 3D full-vectorial eigenmode expansion method. The optimised quasi-TE0 and quasi-TE1 modes based MSSes are with the extinction ratios of 28.52 dB (19.05 dB), 37.29 dB (17.8 dB), and 37.29 dB (23.7 dB), at “OFF” (“ON”) states for the accumulation-layer thicknesses of 1.5, 5.0, and 10.0 nm, respectively. The operation speed can achieve to be 6.3 GHz, 6.2 GHz, and 6.2 GHz for these three accumulation-layer thicknesses, respectively. The performance of the proposed MSS with a 2.5 V gate-voltage is also studied for preventing the oxide breakdown. The proposed MSS can be applied in the mode-division-multiplexing networks for signal switching and exchanging.

Highlights

Mode division multiplexing (MDM) technology is of great promise to overcome the communication bottleneck and to achieve a dramatic capacity-enhancement for optical transmission networks[1,2]
In order to increase the light-matter-interaction (LMI) inside the silicon switch, the triple-waveguide couplers (TWCs) based configurations incorporated with phase-change materials (PCMs) and transparent conducting oxides (TCOs), including Ge2Sb2Te5 (GST)[26], Ge2Sb2Se4Te1 (GSST)[19], indium-tin-oxide (ITO)[20], have been emerging as a promising approach to achieve an ultra-compact, broadband, and low-loss mode-selective switch (MSS)
The schematic diagram of the proposed MSS based on a silicon TWC is shown in Fig. 1(a), consisting of a central horizontal-MOS-capacitor incorporated with epsilon-near-zero indium-tin-oxide (ENZ-ITO), an input WG with input port I1 and output port O1, and a bus WG with input/output ports I2/O2

Summary

Introduction

Mode division multiplexing (MDM) technology is of great promise to overcome the communication bottleneck and to achieve a dramatic capacity-enhancement for optical transmission networks[1,2]. In order to increase the light-matter-interaction (LMI) inside the silicon switch, the TWC based configurations incorporated with phase-change materials (PCMs) and transparent conducting oxides (TCOs), including Ge2Sb2Te5 (GST)[26], Ge2Sb2Se4Te1 (GSST)[19], indium-tin-oxide (ITO)[20], have been emerging as a promising approach to achieve an ultra-compact, broadband, and low-loss MSS. Benefitting from the unique property of the epsilon-near-zero (ENZ) effect of the ITO-TCO, a reconfigurable mode (De)MUX/switch was numerically proposed by using a silicon TWC incorporated with a vertical metal-oxide-semiconductor (MOS) capacitor and an ITO layer[20].

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