'Photonic transistor' switches light signals instead of electronic signals

April 23, 2014
‘Photonic transistor’ switches light signals instead of electronic signals
The realization of practical ‘photonic transistors’ could revolutionize optical signal processing in the same way as the invention of the electronic transistor in the 1950s did for microelectronics. Intel’s state-of-the-art coprocessor, the Xeon Phi (above), contains a staggering five billion electronic transistors. Credit: Intel Corporation

Electronic transistors, which act as miniature switches for controlling the flow of electrical current, underpin modern-day microelectronics and computers. State-of-the-art microprocessor chips contain several billion transistors that switch signals flowing in electrical wires and interconnects. With increasing data-processing speeds and shrinking chip sizes, however, wires and interconnects waste considerable energy as heat.

One alternative is to replace electrical interconnects with energy-efficient that carry data using . However, a practical analogue of the transistor for optical interconnects does not yet exist. Hence, Vivek Krishnamurthy from the A*STAR Data Storage Institute and co-workers in Singapore and the United States are developing a practical 'photonic transistor' for optical interconnects that can control light signals in a similar manner to electronic .

The researchers' latest photonic transistor design is based on prevalent semiconductor technology and offers attractive attributes of high switching gain, low switching power and high operating speed.

Importantly, the research team's design enables a switching gain of greater or equal to 2, which means the output signal is more than double the strength of the input signal. Hence, the transistor can be cascaded: the from one photonic transistor is sufficiently strong so that it can be split to feed several others. Known as 'fan-out', this functionality means the design can become a building block to be scaled up to form larger circuits with many such switching elements connected together for all-optical processing on an optical interconnect platform for data- and telecommunications. Furthermore, Krishnamurthy says that the design consumes 10–20 times less power than the conventional all-optical switching technologies and can operate at very fast speeds.

The team's design consists of a circuit of coupled silicon waveguides that guide infrared light with a wavelength of 1.5 micrometers. Some of the waveguides feature an optically active material, such as an indium gallium arsenide semiconductor, that can amplify or absorb signal light depending on whether or not it is optically excited. During operation, the intensity of a short-wavelength routing beam is used to control the strength of an output beam by altering the amount of absorption and gain in the circuit.

The researchers are now working to experimentally realize their optical transistor. "We are realizing it on a silicon chip so that it will be compatible with current microelectronic industry standards to enable commercial deployment," explains Krishnamurthy. "Once we experimentally verify the prototype, we could further integrate it into large-scale optical switching systems for optical ."

Explore further: Proposal for optical transistor uses light to control light

More information: Krishnamurthy. V., Chen. Y. & Ho S.-T. "Photonic transistor design principles for switching gain >=2." Journal of Lightwave Technology 31, 2086–2098 (2013). dx.doi.org/10.1109/JLT.2013.2262134

Related Stories

An optical switch based on a single nano-diamond

October 15, 2013

A recent study led by researchers of the ICFO (Institute of Photonic Sciences) demonstrates that a single nano-diamond can be operated as an ultrafast single-emitter optical switch operating at room temperature. The scientific ...

Low-cost multi-fiber optical connector developed

February 3, 2014

Fujitsu Laboratories and Furukawa Electric today announced that they have collaborated to develop a new multi-fiber optical connector that enjoins and aligns multiple optical fibers for optical interconnects.

Photonics: Enabling next-generation wireless networks

March 12, 2014

Wireless transmission at microwave frequencies is important for high-data-rate transmission applications, such as mobile phone networks, satellite links and remote imaging. Now, Xianshu Luo and colleagues from the A*STAR ...

Recommended for you

Perfectly accurate clocks turn out to be impossible

October 7, 2015

Can the passage of time be measured precisely, always and everywhere? The answer will upset many watchmakers. A team of physicists from the universities of Warsaw and Nottingham have just shown that when we are dealing with ...

The topolariton, a new half-matter, half-light particle

October 7, 2015

A new type of "quasiparticle" theorized by Caltech's Gil Refael, a professor of theoretical physics and condensed matter theory, could help improve the efficiency of a wide range of photonic devices—technologies, such as ...

Professor solves 140-year fluid mechanics enigma

October 7, 2015

A Purdue University researcher has solved a 140-year-old enigma in fluid mechanics: Why does a simple formula describe the seemingly complex physics for the behavior of elliptical particles moving through fluid?

Fusion reactors 'economically viable' say experts

October 2, 2015

Fusion reactors could become an economically viable means of generating electricity within a few decades, and policy makers should start planning to build them as a replacement for conventional nuclear power stations, according ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

4 / 5 (1) Apr 24, 2014
I have read this story every five or six years for the past 35

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.