The digital future can count on optical electronics and ultra-fast computers

If you’ve ever wished you had a faster phone, computer, or internet connection, you’ve come across the personal experience of reaching a technology limit. But there may be help on the way.

Over the past few decades, scientists and engineers like myself have worked to develop faster transistors, the electronic components underpinning modern electronic and digital communication technologies. These efforts have relied on a class of materials called semiconductors that have special electrical properties. Silicon is perhaps the best known example of this type of material.

But about a decade ago, scientific efforts reached the speed limit of semiconductor-based transistors. Researchers simply can’t make electrons move faster through these materials. One way engineers are trying to address the speed limitations inherent in moving a current through silicon is by designing shorter physical circuits that essentially give electrons less distance to travel. The increase in a chip’s computing power reduces as the number of transistors increases. However, even if the researchers could get very small transistors, they wouldn’t be fast enough for the faster processing and data transfer speeds that people and businesses will need.

My research group’s work aims to develop faster ways to move data, using ultrafast laser pulses in free space and optical fiber. The laser light travels through the optical fiber with almost no loss and very low noise.

In our most recent study, published in February 2023 in Science Advances, we took a step in this direction, demonstrating that it is possible to use laser-based systems equipped with optical transistors, which depend on photons rather than voltage to move electrons and transfer information much more quickly than current systems and do so more effectively than the previously reported optical switches.

Ultrafast optical transistors

At their most basic level, digital broadcasts involve turning a signal on and off to represent ones and zeros. Electronic transistors use voltage to send this signal: when voltage causes electrons to flow through the system, they signal a 1; when there are no electrons flowing, this signals a 0. This requires a source to emit the electrons and a receiver to detect them.

Our ultra-fast optical data transmission system relies on light rather than voltage. Our research group is one of many working with optical communication at the transistor level, the building blocks of modern processors, to circumvent the current limitations of silicon.

Our system controls reflected light to convey information. When light hits a piece of glass, most of it passes through, although some may be reflected. This is what you experience as glare when you drive into sunlight or look through a window.

We use two laser beams transmitted from two sources passing through the same piece of glass. One beam is constant, but its transmission through the glass is controlled by the second beam. By using the second beam to shift the properties of the glass from transparent to reflective, we can start and stop the transmission of the constant beam, very quickly switching the optical signal from on to off and back again.

With this method, we can change the properties of glass much faster than current systems can send electrons. So we can send a lot more zero and one on and off signals in less time.

one hand holds a bundle of optical fibers between thumb and forefinger
The authors’ research team has developed a way to turn beams of light, such as those that pass through these optical fibers, on and off 1 trillion times per second.
Mediacolors/Construction Photography/Avalon via Getty Images

How fast are we talking?

Our studio took the first step to transmitting data 1 million times faster than if we used typical electronics. With electrons, the maximum speed for data transmission is one nanosecond, one billionth of a second, which is very fast. But the optical switch we built was able to transmit data a million times faster, which only took a few hundred attiseconds.

We were also able to transmit those signals securely so that an attacker attempting to intercept or modify messages would fail or be detected.

Using a laser beam to carry a signal and adjusting the signal strength with glass controlled by another laser beam allows information to travel not only faster, but also much greater distances.

For example, the James Webb Space Telescope recently broadcast stunning images from far out in space. These images were transferred as data from the telescope to the Earth base station at a rate of one every 35 nanoseconds using optical communications.

A laser system like the one being developed could accelerate the transfer rate a billion times, allowing for faster and clearer exploration of deep space, revealing the secrets of the universe more quickly. And computers themselves may one day run on light.

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Image Source : theconversation.com

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