Optical waveguide switch based on a negative-index metamaterial load.

An optical switch concept is presented which involves moving a negative-index metamaterial (NIM) load, possibly with loss, close to one waveguide in a two-waveguide directional coupler. The NIM load limits the number of optical modes in the switch, creating a system where the single waveguide mode propagation constant is far from other mode propagation constants. The wide spacing in propagation constants, not possible with positive-index media (PIM) loads, permits a small switch size.

Plasmonic distributed feedback lasers at telecommunications wavelengths.

We investigate electrically pumped, distributed feedback (DFB) lasers, based on gap-plasmon mode metallic waveguides. The waveguides have nano-scale widths below the diffraction limit and incorporate vertical groove Bragg gratings. These metallic Bragg gratings provide a broad bandwidth stop band (~500 nm) with grating coupling coefficients of over 5000/cm.

A top-down approach to fabrication of high quality vertical heterostructure nanowire arrays.

We demonstrate a novel top-down approach for fabricating nanowires with unprecedented complexity and optical quality by taking advantage of a nanoscale self-masking effect. We realized vertical arrays of nanowires of 20-40 nm in diameter with 16 segments of complex longitudinal InGaAsP/InP structures. The unprecedented high quality of etched wires is evidenced by the narrowest photoluminescence linewidth ever produced in similar wavelengths, indistinguishable from that of the corresponding wafer.

Lasing in metal-insulator-metal sub-wavelength plasmonic waveguides.

We demonstrate lasing in Metal-Insulator-Metal (MIM) waveguides filled with electrically pumped semiconductor cores, with core width dimensions below the diffraction limit. Furthermore these waveguides propagate a transverse magnetic (TM0) or so called gap plasmon mode [1-4]. Hence we show that losses in sub-wavelength MIM waveguides can be overcome to create small plasmon mode lasers at wavelengths near 1500 nm.

Carrier recovery time in semiconductor optical amplifiers that employ holding beams.

An analytical expression for the carrier recovery time in semiconductor optical amplifiers (SOAs) that employ holding beams is presented. The amplifier model from which the expression is derived assumes a uniform carrier density along the SOA's length and that the signal and the holding beams both receive amplification. Simulations and experiments show that the expression predicts the recovery time well over a wide range of amplifier gains, holding beam powers, and configurations.

Coupled Mach-Zehnder interferometer memory element.

Two active Mach-Zehnder interferometers are integrated in a monolithic InP/InGaAsP photonic integrated circuit. Together they form a crucial component for optical signal processing: an optical memory element or set-reset flip-flop. The switching time for this initial device is approximately 200 ps.

A fast low-power optical memory based on coupled micro-ring lasers.

The increasing speed of fibre-optic-based telecommunications has focused attention on high-speed optical processing of digital information. Complex optical processing requires a high-density, high-speed, low-power optical memory that can be integrated with planar semiconductor technology for buffering of decisions and telecommunication data. Recently, ring lasers with extremely small size and low operating power have been made, and we demonstrate here a memory element constructed by interconnecting these microscopic lasers.