As the world’s demand for faster internet and more powerful computing continues to grow, scientists are looking for new ways to send larger amounts of information using light instead of electricity.
Now, researchers have developed a tiny device that could make optical communication faster and more efficient by controlling light in a completely new way.
The study, published in Light: Advanced Manufacturing, was carried out by researchers from Skoltech and several collaborating institutions.
Modern optical communication systems transmit information through pulses of light traveling along optical fibers.
Besides brightness and color, light also has another important property called polarization.
Polarization describes the direction in which light waves vibrate, and it can be used to carry extra information without requiring additional light signals.
By using polarization, communication systems can send more data through the same optical fiber, increasing capacity without building entirely new infrastructure.
However, controlling light polarization has traditionally been slow and mechanically complicated. Many existing devices physically rotate tiny optical components many times every second to change the polarization of light. Although effective, these moving parts limit speed and consume energy.
The new device removes the need for mechanical movement altogether.
Instead of rotating parts, the researchers designed a tiny optical modulator that changes light polarization simply by heating a special material called GST. GST is made from germanium, antimony and tellurium and is already widely used in rewritable Blu-ray discs and DVDs to store digital information.
One reason GST is so useful is that it can exist in two different forms. It can have an ordered crystal structure or a disordered glass-like structure called an amorphous state. Once it changes from one state to the other, it remains stable until heated again.
The researchers created a microscopic patterned layer, known as a grating, using GST. Depending on whether the material is in its crystalline or amorphous form, the grating changes how light is polarized as it passes through.
The prototype is extremely small, covering less than one-hundredth of a square centimeter, yet it can perform the work that currently requires mechanically rotating optical components.
In this first demonstration, the researchers used relatively slow heating methods, including a furnace and laser heating, because they wanted to carefully measure the device’s optical performance rather than maximize its speed.
They believe much faster operation will be possible by adding tiny transparent electrical heaters directly beneath the GST layer. Similar heating methods have already been shown to switch GST materials in less than a millionth of a second, making them fast enough for many practical applications.
The team also believes further improvements in material design and heat control could make the switching even faster.
Previous experimental polarization devices often relied on another material called vanadium dioxide. While it performs similarly in some ways, vanadium dioxide has an important drawback. It requires continuous heating to remain in one of its operating states, making it less energy efficient.
GST avoids this problem because it stays in either state without needing a constant supply of heat. Another advantage is that GST functions as a polarizer in both of its stable states, producing two different polarization effects in a single device. Many other materials lose their ability to control polarization in one of their operating states.
Although the technology is still at the prototype stage, the researchers believe it could eventually replace slower mechanical systems inside optical communication equipment. In the future, devices like this could become part of optical transceivers that convert electrical signals into light for high-speed internet, data centers and advanced optical computers.
By eliminating moving parts while increasing data capacity, this tiny heat-controlled device could help build the faster, more energy-efficient communication networks needed for tomorrow’s digital world.
