We propose an active plasmonic device based on graphene. Highly confined plasmonic waves in monolayer graphene are efficiently excited using an etched diffractive grating on silicon. The guided-wave resonance of the combined structure creates a sharp notch on the normal-incidence transmission spectra, as the incident optical wave couples to the graphene plasmonic wave. This structure can be used as a highly tunable optical filter or a broad-band modulator because the resonant wavelength can be quickly tuned over a wide wavelength range by a small change in the Fermi energy level of the graphene. In this paper, we analyze the performance of this device with finite-difference time-domain simulations. We compare the proposed structure with recently demonstrated graphene nanoribbons based on bound plasmonic oscillations.

The gate-controllability of the Fermi-edge onset of interband absorption in graphene can be utilized to modulate near-infrared radiation in the telecommunication band. However, a high modulation efficiency has not been demonstrated to date, because of the small amount of light absorption in graphene. Here, we demonstrate a ~40% amplitude modulation of 1.55 µm radiation with gated single-layer graphene that is coupled with a silicon micro-ring resonator. Both the quality factor and resonance wavelength of the silicon micro-ring resonator were strongly modulated through gate tuning of the Fermi level in graphene.These results promise an efficient electro-optic modulator, ideal for applications in large-scale on-chip optical interconnects that are compatible with complementary metal-oxide-semiconductor technology.

Silicon photonics has attracted tremendous interest from academia and industry, as the fabrication of the silicon family of photonic devices is mostly compatible with the microelectronics process using complementary metal‐oxide semiconductors (CMOS). Herein, three silicon‐family materials are discussed: silicon, silicon nitride, and silica. In addition, hybrid integration with a 2D material, graphene, is examined. First, the material and waveguide properties are reviewed. Second, typical fabrication processes for waveguide devices are introduced. Subsequently, a variety of passive waveguide devices, operating at different physical dimensions covering wavelength, polarization, and mode, are discussed. They correspond to fixed and tunable filters, polarization beam splitters and rotators, and mode conversion and multiplexing devices. These passive waveguide devices play important roles in a wide range of applications including telecom, interconnects, computing, sensing, quantum information processing, bio‐photonics, and energy.

We propose and experimentally demonstrate an on-chip all-optical differential-equation solver capable of solving second-order ordinary differential equations (ODEs) characterizing continuous-time linear time-invariant (LTI) systems. The photonic device is implemented by a self-coupled micro-resonator on a silicon-on-insulator (SOI) platform with mutual coupling between the cavity modes. Owing to the mutual mode coupling within the same resonant cavity, the resonance wavelengths induced by different cavity modes are self-aligned, thus avoiding precise wavelength alignment and unequal thermal wavelength drifts as in the case of cascaded resonators. By changing the mutual mode coupling strength, the proposed device can be used to solve second-order ODEs with tunable coefficients. System demonstration using the fabricated device is carried out for 10-Gb/s optical Gaussian and super-Gaussian input pulses. The experimental results are in good agreement with theoretical predictions of the solutions, which verify the feasibility of the fabricated device as a tunable second-order photonic ODE solver.

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We propose and experimentally demonstrate an all-optical temporal differential-equation solver that can be used to solve ordinary differential equations (ODEs) characterizing general linear time-invariant (LTI) systems. The photonic device implemented by an add-drop microring resonator (MRR) with two tunable interferometric couplers is monolithically integrated on a silicon-on-insulator (SOI) wafer with a compact footprint of ~60 μm × 120 μm. By thermally tuning the phase shifts along the bus arms of the two interferometric couplers, the proposed device is capable of solving first-order ODEs with two variable coefficients. The operation principle is theoretically analyzed, and system testing of solving ODE with tunable coefficients is carried out for 10-Gb/s optical Gaussian-like pulses. The experimental results verify the effectiveness of the fabricated device as a tunable photonic ODE solver.

In this work, a novel soft-hard template method towards the direct fabrication of graphene films on silicon/silica substrate is developed via a tri-constituent self-assembly route. Using cetyl trimethyl ammonium bromide (CTAB) as a soft template, silica (SiO2) from tetramethoxysilane as a hard template, and pyrene as a carbon source, the self-assembly process allows the formation of a sandwich-like SiO2/CTAB/pyrene composite, which can be further converted to high quantity graphene films with a thickness of ~1 nm and a size of over 5 μm by thermal treatment. The morphology and thickness of the graphene films can be effectively controlled through the adjustment of the ratio of pyrene to CTAB. Furthermore, a high nonlinear refractive index n2 of ~10−12 m2 W−1 is measured from graphene/silica hybrid film, which is six orders of magnitude larger than that of silicon and comparable to the graphene from chemical vapor deposition process.

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