Abstract
We demonstrate the potential of a graphene capacitor structure on silicon-rich nitride micro-ring resonators for multitasking operations within high performance computing. Capacitor structures formed by two graphene sheets separated by a 10 nm insulating silicon nitride layer are considered. Hybrid integrated photonic structures are then designed to exploit the electro-absorptive operation of the graphene capacitor to tuneably control the transmission and attenuation of different wavelengths of light. By tuning the capacitor length, a shift in the resonant wavelength is produced giving rise to a broadband multilevel photonic volatile memory. The advantages of using silicon-rich nitride as the waveguiding material in place of the more conventional silicon nitride (Si3N4) are shown, with a doubling of the device's operational bandwidth from 31.2 to 62.41 GHz achieved while also allowing a smaller device footprint. A systematic evaluation of the device's performance and energy consumption is presented. A difference in the extinction ratio between the ON and OFF states of 16.5 dB and energy consumptions of <0.3 pJ/bit are obtained. Finally, it has been demonstrated that increasing the permittivity of the insulator layer in the capacitor structure, the energy consumption per bit can be reduced even further. Overall, the resonance tuning enabled by the novel graphene capacitor makes it a key component for future multilevel photonic memories and optical routing in high performance computing.
Highlights
Photonic integrated circuits (PICs) overcome the major drawbacks that electronics faces today, in terms of the limited transmission speed and high power consumption, by using light to process, transmit and store information [1]
PICs based on silicon-rich nitride (SRN) waveguide platforms demonstrate enhanced operation [2] due to their: tuneable non-linearity and refractive index; low temperature sensitivity; low optical losses; stronger mode confinement than Si3N4 while maintaining a better interaction with the deposited materials than silicon-on-insulator (SOI); and most importantly, broadband transparency spanning infrared and visible wavelength ranges [3,4]
In addition to the active tuning already discussed, a passive tuneability of the devices is inherent in the fabrication process
Summary
Photonic integrated circuits (PICs) overcome the major drawbacks that electronics faces today, in terms of the limited transmission speed and high power consumption, by using light to process, transmit and store information [1]. The density of states of carriers near the Dirac points is low, and as a consequence, graphene’s Fermi energy can be tuned significantly with relatively low electrical energy required [23] This Fermi level tuning changes the refractive index (RI) of the graphene. Combining graphene with integrated silicon waveguides opens great possibilities for the design of tuneable components in PICs. we propose a graphene capacitor as the key component for future volatile multilevel photonic memories (VMPM). We propose a graphene capacitor as the key component for future volatile multilevel photonic memories (VMPM) Volatile memories find their main applications in general-purpose random-access memories, and in data security systems for the protection of sensitive information [24]. Design and modelling of a reconfigurable graphene capacitor based on electric field effect in SRN micro-ring resonators
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