Blue light source. — Image by © Tim Sandle.
Scientists have created a chip that turns a single laser into a “frequency comb,” producing dozens of powerful light channels at once. By using a special locking mechanism to clean messy laser light, the researchers achieved high precision on a small silicon device.
This discovery could significantly improve data centre efficiency and fuel innovations in sensing, quantum tech, and LiDAR.
The discovery came about when scientists from the Columbia University School of Engineering and Applied Science were working on a project to improve LiDAR (which uses lightwaves to measure distance). The scientists were designing highpower chips that could produce brighter beams of light.
As the researchers more and more power through a chip, they noticed that it was creating a frequency comb – a special type of light that contains many colours lined up next to each other in an orderly pattern, similar to a rainbow.
Dozens of colours — or frequencies of light — shine brightly, while the gaps between them remain dark. Viewed via a spectrogram, these bright frequencies appear as spikes, or teeth on a comb. This offers an opportunity to send dozens of streams of data simultaneously. Since different colours of light do not interfere with each other, each tooth acts as its own channel.
The need for frequency combs
Data centers have created tremendous demand for powerful and efficient sources of light that contain many wavelengths. By creating a powerful frequency comb conventionally requires large and expensive lasers and amplifiers. Now, with the discovery, the same thing is possible on a single chip.
Developing the process
To develop the new technology, the scientists developed a multimode laser diode of a similar type to diodes used in applications like medical devices and laser cutting tools. These lasers can produce enormous amounts of light, but the beam is “messy,” which makes it hard to use for precise applications.
By integrating a laser into a silicon photonics chip, where the light pathways are just a few microns — even hundreds of nanometers — wide, required careful engineering using a locking mechanism to purify the source of light.
This method relied on silicon photonics to reshape and clean up the laser’s output, producing a much cleaner, more stable beam, a property called high coherence.
Once the light is purified, the chip’s nonlinear optical properties take over, splitting that single powerful beam into dozens of evenly spaced colors, a defining feature of a frequency comb. The result is a compact, highefficiency light source that combines the raw power of an industrial laser with the precision and stability needed for advanced communications and sensing.
The advantage of the new discovery
The new technology takes a very powerful laser and turns it into dozens of clean, highpower channels on a chip. That means technologists should be able to replace racks of individual lasers with one compact device, cutting cost, saving space, and opening the door to much faster, more energyefficient systems.
By making highpower, multiwavelength combs small enough to fit directly on a chip, the researchers have made it possible to have dozens of beams running in parallel through the same fibre. A similar technology, using multiple fibres is termed wavelengthdivision multiplexing (WDM), which is the technology that turned the Internet into a global highspeed network in the late 1990s.
Hence, it shouldbe possible to bring this capability into the most compact, costsensitive parts of modern computing systems. Beyond data centres, the same chips could enable portable spectrometers, ultraprecise optical clocks, compact quantum devices, and even advanced LiDAR systems.
The research appears in the journal Nature Photonics, titled “Highpower electrically pumped microcombs.”
