Scientists Creates A Tsunami Of Light On A Silicon Chip

For the first time, scientists have managed to form a tsunami of light within a silicon chip. But rather than causing an untold amount of destruction, this tsunami can mean smaller, faster signals as well as provide the basis for more energy efficient processors.

Tsunamis In A Silicon Chip

Tsunamis are just a natural example of soliton. In short, it is a pulse of energy in a waveform that can keep its original shape as it travels without spreading out.

Aside from this amazing property, solitons can be harnessed for complicated signal processing, which includes a range of advanced techniques like creating systemic ‘trains’ of pulses, pulse shaping, and pulse compression.

Of course, according to Ben Eggleton from the University of Sydney, if researchers can crack the code of solitons and put them into practical use, it would open up a completely new toolkit for pulse manipulation. Light pulses practically made up the modern communications infrastructure, such as high-bandwidth Internet connection with optical fibers.

Eggleton was one of the leading researchers behind the achievement. The results, in collaboration with the Singapore University of Technology and Design, was published in the scientific journal Laser and Photonics Reviews.

Photonics

As said, optical fibers can be used to transfer a large amount of data through vast distances. Nonetheless, the majority of the phases in such connection (Signal processing, transmitting, and receiving of data) are still done using conventional electronics. The project’s aim is to find a way for us to directly process light signals instead of having to ‘translate’ light signals into electricity so that computers can process them. This is a field formally known in science as photonics.

Although the dynamics of soliton for signal processing has been a feasible process for quite some time, it can only be done when the signal is sent through a very long length of optic fiber. Practically eliminating all of the advantages in speed that light processing could have.

How to Make A Soliton 101

In order to create a soliton for a silicon chip, you must first get the refractive index, technically a measurement of the wave’s speed, to vary in a certain way that the center of pulse, where the pulse’s intensity is the strongest (And thus, fastest), travels slightly slower than the edges of the pulse. This will allow the slower edges to keep up with the faster center, creating an even pulse that will not spread out over long distances.

Of course, doing this is not easy. It will require a very exact balance between two things: The intensity dependence of the speed (Or non-linearity) and the frequency dependence of the speed (Dispersion).

There aren’t a lot of materials that can keep up with such specific requirements. But such a thing can be done within optic fiber by covering it in a structure known as a Bragg grating.

The high intensity that the technique necessitates made things quite difficult. Silicon, while it is the most common material used in photonics, absorb too much energy when the signal reaches the intensity that is needed to create a soliton. So silicon is not a feasible venue.

A Chance Discovery

During Eggleton’s trip to Singapore, he witnessed Ezgi Sahin created Bragg gratings in an unusual way via lithography. Instead of using pure silicon as the primary material, he instead utilized silicon nitride. Silicon nitride does not voraciously consume excess energy like silicon.

Commenting about the chance discovery, Eggleton said: “It was a real Eureka moment.”

Joining hands with his Singaporean co-workers, they went on to establish the project to try and demonstrate soliton generation in silicon nitride. Delivering the final, glorious result being the discovery of silicon-rich silicon nitride being the perfect material for soliton generation.

Eggleton said that by using this knowledge, a signal processor based on soliton can now be created in such scale that it could sit on a tiny chip to be integrated into specialized photonic equipment like lasers and detectors.