Integration of electronics and photonics for future applications requires an efficient conversion of electrical to optical signals. The excellent electronic and photonic properties of graphene make it a suitable material for integrated systems with extremely wide operational bandwidth. In this paper, we analyze the novel geometry of modulator based on the rib photonic waveguide configuration with a double-layer graphene placed between a slab and ridge. The theoretical analysis of graphene-based electro-absorption modulator was performed showing that a 3 dB modulation with ~ 600 nm-long waveguide is possible resulting in energy per bit below 1 fJ/bit. The optical bandwidth of such modulators exceeds 12 THz with an operation speed ranging from 160 GHz to 850 GHz and limited only by graphene resistance. The performances of modulators were evaluated based on the figure of merit defined as the ratio between extinction ratio and insertion losses where it was found to exceed 220.

We report preliminary results on the development of compact (length < 100 microm) fiber-coupled dielectric-loaded plasmonic waveguide components, including Mach-Zehnder interferometers (MZIs), waveguide-ring resonators (WRRs) and directional couplers (DCs), whose operation at telecom wavelengths is controlled via the thermo-optic effect by electrically heating the gold stripes of dielectric-loaded plasmonic waveguides. Strong output modulation (> 20%) is demonstrated with MZI- and WRR-based components, and efficient (approximately 30%) rerouting is achieved with DC switches.

Silicon based nonlinear photonics has been extensively researched at telecom wavelengths in recent years. However, studies of Kerr nonlinearity in silicon at mid-infrared wavelengths still remain limited. Here, we report the wavelength dependency of third-order nonlinearity in the spectral range from 1.6 μm to 6 μm, as well as multi-photon absorption coefficients in the same range. The third-order nonlinear coefficient n2 was measured with a peak value of 1.65 × 10(−13) cm2/W at a wavelength of 2.1 μm followed by the decay of nonlinear refractive index n2 up to 2.6 μm. Our latest measurements extend the wavelength towards 6 μm, which show a sharp decrement of n2 beyond 2.1 μm and steadily retains above 3 μm. In addition, the analysis of three-photon absorption and four-photon absorption processes are simultaneously performed over the wavelength range from 2.3 μm to 4.4 μm. Furthermore, the effect of multi-photon absorption on nonlinear figure of merit in silicon is discussed in detail.

A waveguiding configuration for surface plasmon polaritons (SPPs) featuring simultaneously a tight mode confinement and long propagation (several millimeters) at telecom wavelengths is proposed and analyzed using the finite-element method. The configuration represents a long-range dielectric-loaded SPP waveguide (LR-DLSPPW), in which a thin and narrow metal stripe is sandwiched between a square dielectric ridge and a dielectric film supported by a low-index substrate. Considering optical polymers, for example, we calculated that a 15-nm-thick and 500-nm-wide gold stripe placed on a 460 nm thick medium-index (1.49) layer supported by a low-index (1.34) substrate and topped by a 850 × 850 nm(2) high-index (1.535) ridge supports a fundamental LR-DLSPPW mode having width of 1.6 μm and propagating over 3.1 mm at the wavelength λ = 1.55 μm. The proposed configuration allows for easy connection to electrodes enabling, e.g., thermo- or electro-optic control, and is technologically simple being compatible with planar fabrication using UV-lithography.

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