Carbon Nanotubes Help Bridge The Gap to Optical Computing
Michael Alba posted on April 26, 2016 |
Optical computer chips could employ carbon nanotube waveguides.
Carbon nanotubes in conjunction with precisely tuned waveguides allow for nanoscale optical circuits. (Image courtesy of WWU).
Carbon nanotubes in conjunction with precisely tuned waveguides allow for nanoscale optical circuits. (Image courtesy of Western Washington University).
Engineering researchers recently developed carbon nanotube (CNT) light emitters that could potentially pave the way to fully optical computer chips.


Carbon Nanotube Waveguides

The CNTs, approximately 1 μm long and 1 nm in diameter, act as electrically driven light emitters. When a voltage is applied to the CNTs, they produce photons of near-infrared to visible wavelength. The intensity of the photons can be controlled by current modulation.

The high-speed nanotube emitters are integrated into a nanostructured waveguide. The waveguides are several micrometers long and engraved with cavities only a few nanometers in size using electron beam lithography. Processing of the waveguide determines the exact wavelength of the photons emitted by the carbon nanotubes, allowing for adjustability within the system.

The carbon nanotube (black, visible right) is placed transverse to the waveguide (purple). The nanotube is driven by electrical signals from the two electrodes (yellow) on either side. (Image courtesy of Nature Photonics).
The carbon nanotube (black, visible right) is placed transverse to the waveguide (purple). The nanotube is driven by electrical signals from the two electrodes (yellow) on either side. (Image courtesy of Nature Photonics).
To integrate the nanotubes, the researchers used dielectrophoresis. This process separates particles using inhomogeneous electric fields and is well suited for the deposition of nanoscale objects on carrier materials.

 

Building Optical Computer Chips

As computer processing requirements and worldwide data volume increase, traditional electronic integrated circuits may have to step aside. Integrated optical circuits, which make use of light as opposed to electrical signals, offer speed and energy advantages over traditional integrated circuits. However, stand-alone nanophotonic chips are not possible without light sources that can be easily tailored and integrated into an on-chip waveguide network.

This research demonstrates that carbon nanotube technology is a promising candidate for overcoming this hurdle. The optoelectronic components developed by the researchers enable modulation rates in the gigahertz range and are compatible with functional optical circuits.

The full results of this research can be found in Nature Photonics.

Recommended For You