Pavel Kornilovich

A High-Speed Optical Multi-Drop Bus for Computer Interconnections

Buses have historically provided a flexible communications structure in computer systems. However, signal integrity constraints of high-speed electronics have made multi-drop electrical busses infeasible. Instead, we propose an optical data bus for computer interconnections. It has two sets of optical waveguides, one as a fan-out and the other as a fan-in, that are used to interconnect different modules attached to the bus. A master module transmits optical signals which are received by all the slave modules attached to the bus. Each slave module in turn sends data back on the bus to the master module. Arrays of lasers, photodetectors, waveguides, microlenses, beamsplitters and Tx/Rx integrated circuits are used to realize the optical data bus. With 1 mW of laser power, we are able to interconnect 8 different modules at 10 Gb/s per channel. An aggregate bandwidth of over 25 GB/s is achievable with 10 bit wide signaling paths.

Photonic crystals from step and flash imprint lithography

Photonic crystals are structures which exhibit a band gap in the electromagnetic spectrum as a result of dielectric periodicity. These structures present the potential to control electromagnetic waves in a similar manner to the way electrons are controlled by semiconductors. To obtain a photonic band gap in a specific region of the spectrum, there are two important characteristics of the photonic crystal that must be considered. The first is the length scale of the periodicity of the crystal, which governs the frequency range in which the band gap falls. The second is the dielectric contrast between the two media which comprise the crystal, which controls the size of the bang gap. Therefore, to construct a photonic crystal which could be used as an optical device, such as a waveguide or filter, the features should be on the order of optical wavelengths, or nanometers. The dielectric contrast through the visible region should also be large enough to open a band gap. Lithography techniques are ideally suited to pattern such structures. This work focused on the use of step and flash imprint lithography as an ideal patterning technology for two dimensional photonic crystals because of its capability for sub-50 nm patterning. Another attractive aspect of using step and flash imprint lithography is the potential to pattern a functional polymer as the crystal. The feasibility of printing structures needed for photonic crystals using imprint lithography was first demonstrated. Then, a strategy to raise the index of refraction of imprint compatible polymer formulations for large dielectric contrast using metal oxide nanoparticles was investigated. A maximum index of n = 1.65 was achieved, but at the high nanoparticle concentrations needed to reach this value, the formulations would not photocure. At low concentrations, imprints were obtained and uses for the resulting moderate index polymer composites as partial band gap photonic crystals were suggested.

Fabrication of nanophotonic structures for information processing

Nanophotonic structures can be used to dramatically enhance interactions between light and matter. We describe some of our recent progress in fabricating optical nanostructures suitable for both classical and quantum information processing. In particular, we present our progress using nanoimprint lithography, a low cost nanoreplication method, to fabricate low loss photonic crystals.