Tuning silicon-rich nitride microring resonances with graphene capacitors for high-performance computing applications

This is the final version. Available from the Optical Society of America via the DOI in this record.We demonstrate the potential of a graphene capacitor structure on silicon-richnitride micro-ring resonators for multitasking operations within high performance computing.Capacitor structures formed by two graphene sheets separated by a 10 nm insulating siliconnitride layer are considered. Hybrid integrated photonic structures are then designed to exploitthe electro-absorptive operation of the graphene capacitor to tuneably control the transmissionand attenuation of different wavelengths of light. By tuning the capacitor length, a shift in theresonant 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 moreconventional silicon nitride (Si3N4) are shown, with a doubling of the device’s operationalbandwidth 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 energyconsumptions of<0.3 pJ/bit are obtained. Finally, it has been demonstrated that increasing thepermittivity of the insulator layer in the capacitor structure, the energy consumption per bit canbe reduced even further. Overall, the resonance tuning enabled by the novel graphene capacitormakes it a key component for future multilevel photonic memories and optical routing in highperformance computing.Engineering and Physical Sciences Research Council (EPSRC

O-band N-rich silicon nitride MZI based on GST

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordWe have experimentally demonstrated an O-band Mach-Zehnder interferometer (MZI) based on a N-rich silicon nitride platform combined with Ge2Sb2Te5 for future optical communication applications. The device operation relies on controlling the waveguide’s losses using a phase change material cell which can be changed from amorphous (lowloss) to crystalline (high-loss). An extinction ratio (ER) as high as 11 dB was obtained between the amorphous (ON) and the crystalline (OFF) states of the MZI optical building block. The insertion loss of the MZI structure per cell unit length was measured to be as high as 0.87 dB/µm in OFF state and as low as 0.064 dB/µm in ON state for TM polarisation.Engineering and Physical Sciences Research Council (EPSRC

Reconfigurable photonic integrated circuits (RPICs) based on functional materials for integrated optical communication applications

This is the final version. Available from the publisher via the DOI in this record.In this work we combine the already mature silicon and silicon nitride platforms with novel reconfigurable materials such as 2D materials, liquid crystals and phase change materials. An actively reconfigurable 1D photonic crystal multi-channel filter based on Si-on-insulator and liquid crystal platforms is demonstrated with extraordinary large quality factor, Q ∼ 104 . A complete study and design of an optical routing and multilevel volatile photonic memory based on graphene capacitor concept for future high performance computing using Silicon rich nitride is shown with a bandwidth of 64 GHz and energy power consumption per bit as low as 0.22 pJ. Finally, an optical switch based on germanium-antimony-tellurium phase change material (GST) is experimentally demonstrated for O-band operation with the extinction ratio as high as 10 dB between the amorphous and the crystalline statesEngineering and Physical Sciences Research Council (EPSRC

Performance characteristics of phase-change integrated silicon nitride photonic devices in the O and C telecommunications bands

This is the final version. Available on open access from the Optical Society via the DOI in this recordData Availability: Data relating to this manuscript can be obtained from the authors.The evaluation and comparison of the optical properties in the O and C bands of silicon nitride rib waveguides with integrated Ge2Sb2Te5 phase-change cells is reported. In straight rib waveguides, a high transmission contrast is observed in both bands when the Ge2Sb2Te5 cell is switched between states, being up to 2.5 dB/μm in the C-band and 6.4 dB/μm in the O-band. In the case of silicon nitride ring resonator waveguides, high quality factor resonances (Q ∼ 105) are found in both bands, leading to the provision of an ON-OFF switch characterized by an extinction ratio of 12 and 18 dB in O and C bands respectively. Finally, with the view to provide a comparison of the wavelength-dependent optical switching of the phase-change cell, a 3-dimensional finite-element method simulation is performed and a comparison of the optical-to-thermal energy conversion in both bands given.European Union Horizon 2020Engineering and Physical Sciences Research Council (EPSRC

Silicon CMOS photonics platform for enabling high-speed DQPSK transceivers

In this work we review the results obtained under the framework of FP7-HELIOS project for integrated DQPSK transceivers in silicon photonics. A differential DQPSK receiver with balanced zero biased Germanium photodiodes has been demonstrated at 10Gbit/s with an error floor around 10(-15). Furthermore, DPSK modulation up to 10Gbit/s with a bit error rate below 10(-9) is also demonstrated using a silicon push-pull operated dual-drive Mach-Zehnder modulator (MZM) based on carrier depletion. The results indicate the potential of the silicon CMOS photonics platform for boosting next-generation optical networks based on advanced modulation formats

Integration of high performance silicon optical modulators

We present our recent work on high speed silicon optical modulators developed within the UK silicon photonics and HELIOS projects. Examples of their integration with other photonic and electronic elements are also presented