We demonstrate the first silicon waveguides in the mid-infrared regime, based on a Silicon-on-Sapphire (SOS) geometry. Single-mode waveguiding occurs at 4.5 microns, with losses of 10.4+/-1.2 dB/cm. Our waveguides are expected to work at even longer wavelengths, and should continue to exhibit low loss to around 6.2 microns. Our results suggest that the many recent developments in near-infrared silicon-based integrated optics can be applied to an entirely new wavelength regime.

Ultrafast all-optical computation with silicon photonic devices is still a dream. New research, which combines organic nonlinear polymers with silicon waveguides, is now bringing that dream closer to reality.

Working together with collaborators at Yale, we build and test a nanomechanical (NEMS) resonator which also serves as an optical waveguide. This device is used in order to demonstrate both actuation and measurement of the mechanical structure, using the optical gradient force to drive the motion and optical interferometry to measure the resulting displacement. This approach offers remarkable sensitivity to small displacements at room temperature, and is a new methodology for driving and interrogating NEMS systems. Applications are likely to include sensing, metrology, materials science, and a range of new optomechanical systems.

Here we demonstrate all-optical modulation in a damaged silicon waveguide based on absorption by mid-bandgap states. Our work suggests that it may be possible to build mid-bandgap based all-optical modulators operating at extremely low optical switching powers, providing a path towards practical all-optical logic and computation.

This paper proposes some possible applications for silicon-polymer hybrid systems, including mid-infrared parametric amplifiers with exceptional performance. This is made possible by the combination of the high optical nonlinearity exhibited by modern synthetic polymers and the sharp mode confinement of nano-scale silicon waveguides.

Using slot waveguides and nonlinear electrooptic polymers, we demonstrate a modulator with a halfwave drive voltage of 0.25 V, one of the lowest values obtained anywhere. This result highlights the benefits that can be obtained with the close integration of nonlinear polymers and silicon waveguides.

We demonstrate that the surface states of silicon waveguides can absorb photons near 1.55 microns in a single photon process, even though the bandgap of silicon exceeds the photon energy. A photocurrent results through an as yet undetermined mechanism, allowing the creation of a photodetector with quantum effeciency 2.8%.

A reconfigurable optical add/drop multiplexer (ROADM) is built, based on a silicon ridge waveguide, with planar electrodes and electrooptic polymers.

Using the extremely large nonlinearity found in modern nonlinear polymers, we project that it will soon be possible to generate moderate amounts of terahertz and mid-infrared radiation directly through difference frequency mixing of two CW near-infrared optical signals. Until now, this method of generating terahertz radiation required pulsed lasers due to lower nonlinearities.

We demonstrate that in a single lithographic step, slotted and segmented waveguides can be defined which have both a slot geometry, and nearly transparent optical electrical contacts. This is a vital piece of photonics infrastructure needed to fully explot electroopic modulation with slot waveguides. Exceptionally low losses of 4 dB/cm are shown.

We discuss the theoretical performance of a number of different slot waveguide based electrooptic modulators. When used with the exceptionally active polymers that have recently been demonstrated, we predict that extremely low drive voltage modulators should become possible.

We demonstrate that a Terahertz bandwidth all-optical modulator can be built with silicon ridge waveguides and a nonlinear polymer cladding. This all-optical modulator demonstrates performance beyond what can be done with silicon alone; it is a good example of the benefits that can be achieved by using a silicon and nonlinear polymer hybrid system.

We demonstrate a waveguide design that involves a periodic series of arms connected to a silicon ridge waveguide. The arms are optically transparent, allowing both electrical contact and optical waveguiding to be achieved in a single lithographic step. The propagation loss of the segmented waveguide is -16 dB/cm.

We demonstrate modulation using electrooptic polymers in slotted silicon waveguides. We achieve exceptionally 5.2 GHz/V of tunability for resonators based on these waveguides. Further, we show that even with no bias voltage, direct conversion from the optical signal to electrical power can be obtained through optical rectification.

We develop a semi-analytic formalism that can be used to predict the tunability of resonators based on the waveguide geometry and the modal pattern. We then perform experiments that confirm the accuracy of our models through temperature variation and also changing the indices of the cladding materials of the resonators.

We design and fabricate slotted waveguides in silicon-on-insulator. Ring resonators based on these waveguides are also built and characterized, and Q values of 27,000 are obtained, corresponding to a waveguide loss of -10 dB/cm.

We design and fabricate surface-plasmon based waveguides that are readily integrated with ridge silicon waveguides. Our waveguides have 1.2 dB/micron loss and can guide light around 0.5 micron bends. We also show that light can be effeciently coupled between these waveguides and more conventional silicon ridge waveguides.

We fabricate high Q microrings from thin silicon-on-insulator SOI layers, and achieve Q values of 45,000. This corresponds to around 7 dB/cm of loss.

An electrically tuned liquid crystal based photonic crystal laser is demonstrated.

Designs for the effecient coupling of light from a slab mode to a photonic crystal mode are presented. The proposed designs are fabricated, and the performance is characterized.

We propose a new photonic crystal cavity design that supports a dipole mode with a quality factor greater than 20,000, in InGaAsP. The cavities are fabricated, and lasing is achieved.

The propagating mode of a photonic crystal waveguide is simulated, the losses are determined.

Porous alumina membranes are used as stable electron transparent windows for atmospheric electron spectroscopy applications.

Micromachined, micron-thick porous alumina membranes with closed pore endings show high electron transparency above an energy of 5 keV.