We demonstrate for the first time a fully integrated electro-optic modulator based on locally strained silicon rib-waveguides. By depositing a Si3N4 strain layer directly on top of the silicon waveguide the silicon crystal is asymmetrically distorted. Thus its inversion symmetry is broken and a linear electro-optic effect is induced. Electro-optic characterization yields a record high value χ(2)(yyz) = 122 pm/V for the second-order susceptibility of the strained silicon waveguide and a strict linear dependence between the applied modulation voltage V(mod) and the resulting effective index change Δn(eff). Spatially resolved micro-Raman and terahertz (THz) difference frequency generation (DFG) experiments provide in-depth insight into the origin of the electro-optic effect by correlating the local strain distribution with the observed second-order optical activity.

Silicon photonics offers tremendous potential for inexpensive high-yield photonic-electronic integration. Besides conventional dielectric waveguides, plasmonic structures can also be efficiently realized on the silicon photonic platform, reducing device footprint by more than an order of magnitude. However, neither silicon nor metals exhibit appreciable second-order optical nonlinearities, thereby making efficient electro-optic modulators challenging to realize. These deficiencies can be overcome by the concepts of silicon-organic hybrid (SOH) and plasmonicorganic hybrid (POH) integration, which combine silicon-oninsulator (SOI) waveguides and plasmonic nanostructures with organic electro-optic cladding materials.

The development of ultrahigh-quality-factor (Q) silicon-on-insulator (SOI) microring resonators based on silicon wire waveguides is presented. An analytical description is derived, illustrating that in addition to low propagation losses the critical coupling condition is essential for optimizing device characteristics. Propagation losses as low as 1.9 +/- 0.1 dB/cm in a curved waveguide with a bending radius of 20 microm and a Q factor as high as 139.000 +/- 6.000 are demonstrated. These are believed to be the highest values reported for a curved SOI waveguide device and for any directly structured semiconductor microring fabricated without additional melting-induced surface smoothing.

We present detailed investigations of the local strain distribution and the induced second-order optical nonlinearity within strained silicon waveguides cladded with a Si₃N₄ strain layer. Micro-Raman Spectroscopy mappings and electro-optic characterization of waveguides with varying width w(WG) show that strain gradients in the waveguide core and the effective second-order susceptibility χ(2)(yyz) increase with reduced w(WG). For 300 nm wide waveguides a mean effective χ(2)(yyz) of 190 pm/V is achieved, which is the highest value reported for silicon so far. To gain more insight into the origin of the extraordinary large optical second-order nonlinearity of strained silicon waveguides numerical simulations of edge induced strain gradients in these structures are presented and discussed.

Metal-halide perovskites are promising lasing materials for the realization of monolithically integrated laser sources, the key components of silicon photonic integrated circuits (PICs). Perovskites can be deposited from solution and require only low-temperature processing, leading to significant cost reduction and enabling new PIC architectures compared to state-of-the-art lasers realized through the costly and inefficient hybrid integration of III−V semiconductors. Until now, however, due to the chemical sensitivity of perovskites, no microfabrication process based on optical lithography (and, therefore, on existing semiconductor manufacturing infrastructure) has been established. Here, the first methylammonium lead iodide perovskite microdisc lasers monolithically integrated into silicon nitride PICs by such a top-down process are presented. The lasers show a record low lasing threshold of 4.7 μJcm–2 at room temperature for monolithically integrated lasers, which are complementary metal–oxide–semiconductor compatible and can be integrated in the back-end-of-line processes.

Organic materials combined with strongly guiding silicon waveguides open the route to highly efficient electro-optical devices. Modulators based on the so-called silicon-organic hybrid (SOH) platform have only recently shown frequency responses up to 100 GHz, high-speed operation beyond 112 Gbit/s with fJ/bit power consumption. In this paper, we review the SOH platform and discuss important devices such as Mach-Zehnder and IQmodulators based on the linear electro-optic effect. We further show liquid-crystal phase-shifters with a voltage-length product as low as V π L = 0.06 V·mm and sub-μW power consumption as required for slow optical switching or tuning optical filters and devices.

In this work, double-gated field effect transistors manufactured from monolayer graphene are investigated. Conventional top-down CMOS-compatible processes are applied except for graphene deposition by manual exfoliation. Carrier mobilities in single-and doublegated graphene field effect transistors are compared. Even in double-gated graphene FETs, the carrier mobility exceeds the universal mobility of silicon over nearly the entire measured range. At comparable dimensions, reported mobilities for ultra thin body siliconon-insulator MOSFETs can not compete with graphene FET values.

Strontium based complex perovskites are potential candidates for microwave integrated circuit applications. In the present article, we report on Raman scattering studies of cubic and noncubic structures of Sr(B0.5′Nb0.5)O3 [B′=Ga, In, Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Yb] based complex-perovskite materials for an improved understanding of structure-property relations. The spectral results are compared to some tantalum analogues of known crystal structure. The present study reveals a higher degree of ordering for the tantalum compounds compared to those of the niobium analogues. Vibrational studies show a correlation between the tolerance factor and symmetry of these materials.