In 1956, American physicists John Bardeen, Walter Brattain, and William Shockley received the Nobel Prize in Physics for completely revolutionizing the field of electronics. They created one of the fundamental building blocks of modern electronics that allowed for the development of smaller and cheaper devices such as computers, radios, and calculators, spawning a $335 billion industry.
Their achievement is so crucial to the industry that it can be found in every modern electronics system. Some even consider it to be one of the greatest inventions of the 20th century. So what did these physicists develop? In 1947, while working at Bell Laboratories to create a new amplifier for the US telephone system, the team achieved practical implementation of the transistor.
The transistor is a miniature electronic component made from layers of silicon, a chemical element commonly found in sand. Although we could dive into the complexities of BJT versus MOSFET or even further with the quantum physics of NPN versus PNP, the gist is that transistors are very small devices that can act as electronic switches, digital logic, and signal amplifying circuits. Originally packaged as a single component, the transistor of today can be found packaged individually or more commonly interconnected and embedded in quantities of millions (sometimes even billions) within small chips that create microprocessors, computer memory, and other complex integrated circuits.
Since their inception, transistors have allowed electronic devices to drastically shrink. Computers have gone from entire rooms to desktops down to wearable devices. To give you an idea of just how small the internal components can get, Intel’s planned 2017 transistor release will showcase the smallest-ever transistor technology at a mere 10 nanometers. Eventually however it will no longer be economically efficient to reduce the size of transistors. Some have predicted this will happen as soon as 2021. If size reduction is no longer possible, what is the future of innovation for transistor technology?
At the same time, cloud computing and big data are growing at a pace that continues to demand increasing data transfer speeds from the infrastructure. Soon we will reach the switching limits of the diode laser used within the fiber optic interconnects, and users of data-rich data centers will be presented with speed challenges. Is there another option to increase switching speeds?
Enter the transistor laser. A team at the University of Illinois at Urbana-Champaign headed by Nick Holonyak, Jr. (inventor of the first LED and laser diode, and Ph.D student of John Bardeen) and Milton Feng created the first light-emitting transistor in 2004. Since then graduate students at the university have been focused on understanding and refining this unique technology. The team even had to extend one of Kirchoff’s laws to include conservation of energy as well as the balance of charge.
What is a transistor laser? Without diving headfirst into the quantum physics, a transistor laser has the standard two outputs of a transistor, but this time only one of them is electrical while the other emits infrared light that is focused into a laser beam. The advantage of an optical output is pure energy-efficient speed – the transistor laser is up to a hundred times faster than diode laser switching. This is huge! The current prototype at the University of Illinois can switch on and off at over 700 billion times per second. The output from the transistor laser can be modulated to send optical signals at the rate of 10 billion bits per second. If that doesn’t seem fast enough, the team believes they will eventually be able to send over 100 billion bits per second at room temperature. That’s the equivalent of sending three DVDs worth of data every second!
Never before have we had a device that can take an electrical input and simultaneously output both an electrical and optical signal. Although still considered in the research phase, the transistor laser has been the source of significant speculation on what the future of high-speed computing holds. This discovery was considered so potentially revolutionary that the team’s paper was ranked as one of the all-time top five for Applied Physics Letters and the transistor laser was named one of the top 100 discoveries by Discover magazine. Engineers and physicists believe the transistor laser could hold the key to the next generation of high-speed data transmission in both telecommunication networks and at the chip level. Not only will memory chips and graphics cards transfer data at faster rates, but with a direct electrical to optical signal conversion, other previously impractical designs such as optical communication computers are now a tangible reality. Supercomputers working to crunch data from the latest advanced particle accelerator could produce results in a matter of minutes instead of days. So what does this mean for the everyday consumer? If you think your Internet and gaming experiences are fast now, just wait until transistor-laser microprocessors are pushing the data! Beyond the known uses, there are probably thousands of possibilities for the transistor laser that we cannot presently imagine.
In a 1963 Reader’s Digest article Nick Holonyak predicted that his LED would eventually replace Thomas Edison’s incandescent light bulb. As his prediction becomes a reality, it begs the question of what the future holds for his latest groundbreaking invention. The transistor laser may very well usher in the next great computing frontier.