A step toward optical transistors? Study demonstrates new way to control light in semiconductor nanocrystals

April 9, 2013

(Phys.org) —As demand for computing and communication capacity surges, the global communication infrastructure struggles to keep pace, since the light signals transmitted through fiber-optic lines must still be processed electronically, creating a bottleneck in telecommunications networks.

While the idea of developing an optical transistor to get around this problem is alluring to scientists and engineers, it has also remained an elusive vision, despite years of experiments with various approaches. Now, McGill University researchers have taken a significant, early step toward this goal by showing a new way to control light in the semiconductor known as "quantum dots."

In results published online recently in the journal Nano Letters, PhD candidate Jonathan Saari, Prof. Patanjali (Pat) Kambhampati and colleagues in McGill's Department of Chemistry show that all-optical modulation and basic Boolean logic functionality – key steps in the processing and generation of signals – can be achieved by using laser-pulse inputs to manipulate the quantum mechanical state of a semiconductor nanocrystal.

"Our findings show that these nanocrystals can form a completely new platform for optical logic," says Saari. "We're still at the nascent stages, but this could mark a significant step toward optical transistors."

Quantum dots already are used in applications ranging from photovoltaics, to light-emitting diodes and lasers, to biological imaging. The Kambhampati group's latest findings point toward an important new area of potential impact, based on the ability of these nanocrystals to modulate light in an optical gating scheme.

"These results demonstrate the proof of the concept," Kambhampati says. "Now we are working to extend these results to integrated devices, and to generate more complex gates in hopes of making a true optical transistor."

The findings build on a 2009 paper by Kambhampati's research group in Physical Review Letters. That work revealed previously unobserved light-amplification properties unique to quantum dots, which are nanometer-sized spheroids with size-dependent optical properties, such as absorption and photoluminescence.

Explore further: Scientists create new type of nanocrystal

More information: pubs.acs.org/doi/abs/10.1021/nl3044053

Related Stories

'Squeezing' light into quantum dots

April 1, 2009

(PhysOrg.com) -- “Quantum wells have been instrumental in telecommunications, enabling light amplification,” Patanjali Kambhampati tells PhysOrg.com, “but theory has suggested that a very small - colloidal - quantum ...

Physicists lay the groundwork for cooler, faster computing

December 14, 2009

University of Toronto quantum optics researchers Sajeev John and Xun Ma have discovered new behaviours of light within photonic crystals that could lead to faster optical information processing and compact computers that ...

Recommended for you

Reshaping the solar spectrum to turn light to electricity

July 28, 2015

When it comes to installing solar cells, labor cost and the cost of the land to house them constitute the bulk of the expense. The solar cells—made often of silicon or cadmium telluride—rarely cost more than 20 percent ...

Meet the high-performance single-molecule diode

July 29, 2015

A team of researchers from Berkeley Lab and Columbia University has passed a major milestone in molecular electronics with the creation of the world's highest-performance single-molecule diode. Working at Berkeley Lab's Molecular ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

EyeNStein
1 / 5 (3) Apr 09, 2013
Sounds good. Hard to agree/disagree with such vague details.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.