Silicon Photonics This research is motivated by the need on chip integration of various functionalities for communication and sensing applications. Based on silicon on insulator (SOI) platform, it is possible to realize nanoscale optical and electro-optical functionalities using CMOS compatible process. We are developing both passive and active nanoscale components in silicon. A recent achievement is the demonstration of a mode selector in silicon waveguide. This mode selector is realized by introducing a periodic structure into the waveguide. By doing so, the device supports the propagation of the second waveguide mode, while the propagation of the fundamental mode is forbidden. SEM image of the fabricated device Polarization Optics Polarization plays an important role in optics. In 2003, it was demonstrated that radially polarized light can produce a sharper spot in the focal plane under tight focusing conditions, compared with linearly or circularly polarized light. Radially polarized light is also useful for applications such as lithography, microscopy, optical memories and optical trapping. We generate special polarization patterns based on the form birefringence effect using subwavelength gratings made of dielectrics and semiconductors. In particular, we were the first to demonstrate such elements for Nd-YAG laser applications. Projection of radially polarized light on a linear polarizer Plasmonics Surface plasmons polaritons (SPPs) are charge density waves propagating along the interface between materials with free electrons (e.g. metals) and a dielectric medium. SPP wavelength can be extremely short, enabling the confinement of energy at the nanoscale. Triggered by the demonstration of super transmission in 1998, the research field of plasmonics is growing in exponential rate. Our group is active in plasmonic research, primarily for nanoimaging and nanoconfinement of electromagnetic waves at the nanoscale. We have recently demonstrated the focusing of radially polarized light by a plasmonic lens made by milling a subwavelength width annular aperture in a thin slab of metal on top of glass. Near field measurements of the plasmonic lens Optofluidics Optofluidics refers to the integration of miniaturized optical devices with microfluidic structures and assemblies. The optofluidic platform enables to enhance and diversify the functionalities of optical devices. This platform is attractive for variety of applications, including for example sensing, tunable optical devices, on-chip miniaturized light sources, optical trapping and nanoimaging. Recently, we have demonstrated an on-chip tunable optical filter based on the electrowetting effect. The "on" and "off" states of a tunable Optofluidic resonator Near Field Optics Since its invention in 1984, the near field scanning optical microscope (NSOM) is becoming a powerful tool for the investigation of near field interactions. The near field plays an important role in light matter interactions, and is the subject of extensive research. Our group is using NSOM in order to learn more about our component and devices. The NSOM allows an "in situ" measurement of light propagating through the device. This is in contrast to more "standard" approaches, which are based on measuring the transfer function of the device. In addition, we also study the coupling of light to NSOM tips in variety of configurations. Near field measurements of light propagating in a microring resonator