Abstract
All-optical signal processing avoids the conversion between optical signals and electronic signals and thus has the potential to achieve a power efficient photonic system. Micro-scale all-optical devices for light manipulation are the key components in the all-optical signal processing and have been built on the semiconductor platforms (e.g., silicon and III-V semiconductors). However, the two-photon absorption (TPA) effect and the free-carrier absorption (FCA) effect in these platforms deteriorate the power handling and limit the capability to realize complex functions. Instead, silicon nitride (Si3N4) provides a possibility to realize all-optical large-scale integrated circuits due to its insulator nature without TPA and FCA. In this work, we investigate the physical dynamics of all-optical control on a graphene-on-Si3N4 chip based on thermo-optic effect. In the experimental demonstration, a switching response time constant of 253.0 ns at a switching energy of ~50 nJ is obtained with a device dimension of 60 μm × 60 μm, corresponding to a figure of merit (FOM) of 3.0 nJ mm. Detailed coupled-mode theory based analysis on the thermo-optic effect of the device has been performed.
Highlights
All-optical signal processing avoids the conversion between optical signals and electronic signals and has the potential to achieve a power efficient photonic system
The pump light generated by a continuous-wave (CW) laser source is either directly injected into an Erbium-doped fiber amplifier (EDFA) for CW pump experiment or modulated by a commercial LiNO3 intensity modulator before EDFA for pulsed pump experiment
Pump and probe light beams are combined through a wavelength division multiplexer (WDM) and coupled to the chip through a tapered lensed fiber
Summary
All-optical signal processing avoids the conversion between optical signals and electronic signals and has the potential to achieve a power efficient photonic system. Silicon and III-V semiconductors such as InP and GaAs, are promising platforms for photonic integration[1,2,3,4] Based on these semiconductor platforms, micro-scale all-optical devices for light manipulation have been reported with picosecond response time[1] or femto-joule energy consumption[2]. Which requires a buffer layer (e.g., SiO2 with very low thermal conductivity) to avoid the metal induced huge optical absorption, graphene can directly contact with waveguides since it has a low absorption rate[19] These two properties result in a highly efficient heat transfer from graphene to waveguides and allow the possibility to significantly enhance the efficiency of the all-optical control on a graphene-on-Si3N4 integrated platform based on thermo-optic effect
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