Bandwidth requirements continue to drive the need for low-power, high speed interconnects. Harnessing the mature CMOS technology for high volume manufacturing, Silicon Photonics is a top candidate for providing a viable solution for high bandwidth, low cost, low power, and high packing density, optical interconnects. The major drawback of silicon, however, is that it is an indirect bandgap material, and thus cannot produce coherent light. Consequently, different integration schemes of III/V materials on silicon are being explored. An integrated CMOS tunable laser is demonstrated as part of a composite-CMOS integration platform that enables high bandwidth optical interconnects. The integration platform embeds III-V into silicon chips using a metal bonding technique that provides low thermal resistance and avoids lattice mismatch problems. The performance of the laser including side mode suppression ratio, relative intensity noise, and linewidth is summarized.
Advances in nanoscale fabrication techniques in dielectric and metallic material systems has opened up new
opportunities in photonics and plasmonics for solving long standing problems in information systems and
telecommunication systems. In this talk, we discuss some of the metamaterials and devices that recently have been
demonstrated in our lab. These include metamaterials with space variant polarizability to realize on-chip, frequencyselective
resonators and Bragg gratings, as well as metal-semiconductor-dielectric nanolasers.
We discuss a new effect of optical forces, namely, the self-alignment or instability of two parts of a waveguide
broken by an offset and a gap. Using a mode matching technique, we investigate the case where there is no
gap and only an offset. It is shown that for a TE incident mode, self-alignment occurs for small values of the
waveguide thickness, whereas for large values, the system is unstable. For a TM incident mode, however, the
situation is reversed and the two parts tend to self-align for large values of the waveguide thickness. It is also
shown that the forces are due to the presence of both radiation modes, generated by the discontinuity, and
the guided mode. For a TM incident mode, polarization surface charges are formed, that may cause strong
self-alignment forces in both the transverse and longitudinal directions.
An add/drop filter based on coupled vertical gratings is presented on silicon. We analyze the device theoretically and
experimentally and show that the concept is easily extended to multi-channel add/drop filters. We demonstrate tunability
of the device bandwidth and operation wavelength. The free spectral range of the device exceeds the bandwidth used in
wavelength division multiplexing systems, which makes it ideally suited for use in such systems.
It is demonstrated that waveguide eigenmodes with a rotating phase may exert a longitudinal force, positive
or negative, as well as a torque on the guiding structure or part of it. A general formulation of the linear and
angular momentum currents flowing in the waveguide is given. Several examples are considered, including a
lossy dielectric cylinder bounded inside a hollow waveguide, and a lossy dielectric fiber. The results of this study
may be used for a novel type of light driven rotating machines.
Two mirrors guiding light experience attractive or repulsive forces according to the eigenmode type of symmetry,
but regardless of the specific details of the guiding structure. A transverse evanescent mode (TM or TE) that
has an anti-symmetric transverse field causes repulsion, while attraction occurs when the mode has a symmetric
transverse field. Transverse propagating modes, however, are always repulsive. One possible application for this
phenomenon is to use a symmetric mode supported, for instance, by two properly designed Bragg mirrors. By
varying the wavelength of the mode injected into the waveguide, it is possible to cross the light-line and switch
between attraction and repulsion. If the mirror is free to move in the transverse direction, then this is a scheme
for controlling its motion. Another possibility is to create a stable equilibrium with a superposition of transverse
evanescent symmetric and anti-symmetric modes. For this purpose, a more appealing configuration than Bragg
mirrors is a waveguide that consists of two dielectric slabs where the light is guided by total internal reflection.
Each slab is trapped in a potential well resulting in optical binding by eigenmodes.