The ultimate goal of silicon photonics development is the monolithical integration of a photonic layer with optical functions onto silicon IC chips. This 3-D stacking can be obtained by wafer-to-wafer bonding leading to the photonic layers to be embedded into the last levels of metalization above the IC layer. We present a method that takes advantage of this integration process in order to realize enhanced fiber grating couplers. Indeed, grating structures are very attractive to couple the light between tiny silicon wires to the external world, which is dominated by optical fibers. Moreover, the insertion of a mirror below the grating is a well-known solution to increase significantly the coupling efficiency. We propose a method to obtain this bottom mirror by anticipating the grating coupler flip due to the wafer-to-wafer bonding. To this end, the mirror is formed above the encapsulation layer of the fiber grating coupler in order to appear below it after the optical layers integration onto an IC wafer. In this way, the thickness between the grating and the bottom mirror, which is a very sensitive parameter, remains under control whatever wafer-to-wafer bonding process tolerances. Experimental results with one single silicon layer as a bottom mirror exhibit coupling efficiency up to 69%.

We present a numerical method to accurately model the electro-optic interaction in anisotropic materials. Specifically, we combine a full-vectorial finite-difference optical mode solver with a radio-frequency solver to analyze the overlap between optical modes and applied electric field. This technique enables a comprehensive understanding on how electro-optic effects modify individual elements in the permittivity tensor of a material. We demonstrate the interest of this approach by designing a modulator that leverages the Pockels effect in a hybrid silicon-BaTiO₃ slot waveguide. Optimized optical confinement in the active BaTiO₃ layer as well as design of travelling-wave index-matched electrodes is presented. Most importantly, we show that the overall electro-optic modulation is largely governed by off-diagonal elements in the permittivity tensor. As most of active electro-optic materials are anisotropic, this method paves the way to better understand the physics of electro-optic effects and to improve optical modulators.

Optical waveguides on three material platforms of silicon-on-insulator (SOI), amorphous silicon (a-Si:H) and silicon nitride are analyzed for realization of an optical compact link compatible with CMOS technology. The three material properties are presented. The optical components on the three potential material platforms are put together for a comparison, in which, straight, bent waveguides, and multimode-interference beam splitters for an optical link are designed, fabricated, and measured. The comparison results of simulation and measurement show that a-Si:H has a similar performances with SOI material but lower cost and good feasibility of photonic integration on silicon.

Optical properties of the λ-router basic building block are simulated using a matrix method. Experiments are performed for the -router basic building block with multimode-interference (MMI) crossings, which shows large free spectral range (~35 nm) and more than 24 dB on/off contrast of the drop resonance. Theoretical and experimental results reveal that the λ-router basic building block with MMI crossings can suppress the crosstalk (defined as the difference between the drop efficiency and the throughput attenuation at resonance), offer relatively symmetric resonance, and increase the on/off contrast of the drop resonance, compared with a λ-router building block using conventional crossings.

We report on a system to control the emitted wavelength of a laser independently from its pump conditions. To illustrate the concept, it is applied to III-V microdisk lasers fabricated on a CMOS pilot line for application to multicolored optical interconnections. Two different control systems are experimentally studied. The first one requires two coupling areas between the resonator and its coupled waveguide while the second solution is based on a photonic crystal mirror and a single coupling area. In both cases, the independent tuning of their emission from the pump conditions is demonstrated with a very high compacity. A controlled multimode emission in microdisk lasers is obtained for the first time.

This paper reports on the design and characterization of a silicon nitride ring resonator-based device for biosensing manufactured with the STMicroelectronics 300 mm R&D Datacom Advanced PHotonic Nanoscale Environment (DAPHNE) industrial platform. The experimental results demonstrate a 300 nm/RIU bulk sensitivity and a 0.125 nm resonant peak shift per nanometer of biological adlayer thickness change. These results, comparable to the state of the art in ring resonator-based biosensors, demonstrate the potential of the DAPHNE industrial platform for manufacturing high-performance photonics biosensors at low cost.