A simple configuration for achieving a radio frequency transparent 90° hybrid, for broadband QAM wireless systems
using silicon photonics is proposed. The device consists of a high Q ring resonator which induces an optical 90° phase
shift between two adjacent resonant wavelengths. When these optical carriers are modulated by an RF carrier the
resulting device behaves as an RF 90° hybrid. Numerical simulations of the phase shift were performed on a 40 GHz
carrier, and to demonstrate the frequency transparency phase shift simulations was also performed at a carrier frequency
of 60 GHz. One of the main applications of such a device is the generation of millimeter wave 10 Gb/s wireless based on
quadrature amplitude modulation.
We prove theoretically that it is possible to build embedded reflectionless squeezers/expanders using transformation
optics. We illustrate the potential of this finding by proposing an application in which the squeezer is a key element: an
ultra-short perfect coupler for high-index nanophotonic waveguides.
Generic packaging concepts for silicon photonics have been developed in the frame of EU-funded Network of
Excellence ePIXnet (FP6). Three approaches for Silicon photonic packaging will be presented within this paper. Two
concepts provide solutions for fiber array coupling to high-index contrast photonic wire waveguide gratings. Third
concept is the integration of inverted taper-based fiber coupling structure with silicon etched V-grooves. Using
standardized SOI chip designs and commercial available assembly parts, the packaging concepts allow for small
footprint or flexible use in an R&D environment. The work presented here has resulted from cooperation within the
European Network of Excellence ePIXnet.
Optical nonlinear effects have been widely studied in III-V semiconductor photonics. However, nonlinear performance
in silicon photonics is still inefficient. An alternative silicon-based waveguide configuration, which is known as slot
waveguide, has been recently proposed to improve the nonlinear performance in a very efficient way. In the slot
waveguide, the fundamental mode light is highly confined in a very small region, which is called slot, of a low index
contrast material between two silicon high index contrast layers. This enables the introduction of new silicon photonic
devices in which the characteristics of active optical materials can be efficiently exploited for modulation, switching,
sensing, and other applications. Horizontal and vertical slot waveguides for optimum nonlinear performance have been
recently proposed. However, the horizontal slot waveguide is more feasible for nonlinear applications. To increase
nonlinear performance in the horizontal slot region, silicon nanocrystals (Si-nc) embedded in silica (SiO<sub>2</sub>) have been
proposed to fill the slot region between the two silicon layers. It is achievable nonlinear performance in the horizontal
slot region for down to 50nm thick slots. However, the lower the slot thickness is, the more difficult the coupling to fiber
results. One of the most developed silicon photonics efficient vertical coupling techniques is the grating coupler. We
demonstrate grating couplers for efficient coupling between horizontal slot waveguides and standard single mode fibers.
Broadband and highly efficient horizontal slot waveguide grating couplers have been obtained by means of simulations.
These grating couplers configuration are suitable for nonlinear performance in silicon photonics. It is achieved 61%
maximum coupling efficiency for λ=1550 nm and TM polarization. Furthermore, a 35 nm 1dB-bandwidth is achievable
for the designed grating couplers.