Bistable transistor laser to boost processing speeds

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An upgrade to the transistor laser developed at the University of Illinois at Urbana-Champaign could boost computer processor speeds through the formation of two stable energy states and the ability to switch between them quickly.

According to the team, having two stable energy states within a transistor allows the device to form an optical-electric switch which could act as the primary building block for development of optical logic.

Professor Milton Feng, pictured, said: “Building a transistor with electrical and optical bistability into a chip will significantly increase processing speeds because the devices can communicate without the interference that occurs when limited to electron-only transistors.”

In their study, the researchers describe how optical and electrical bistable outputs are constructed from a single transistor. The addition of an optical element using electron tunneling creates a feedback loop that controls the transmission of light.

Prof Feng noted: “You cannot remove electronics entirely because you need to plug into a current and convert that into light. That’s the problem with the all-optical computer concept some people talk about; it just is not possible because there is no such thing as an all-optical system.”

The new transistor could enable new devices and applications that have not been possible with traditional transistor technology. “This is a single device that provides bistability for electrical and optical functions with one switch,” Prof Feng contined. “It is totally new and we are working hard to find more new applications for the device.”

However, the team has only demonstrated electro-optical bistability at -50°C. The next step will be to prove that the device can work at room temperature – something Prof Feng says has been achieved, with details to be published shortly.