Creating this rainbow effect — called a frequency comb — typically requires large and expensive lasers and amplifiers.
What is a frequency comb?
A frequency comb is a type of laser light made up of multiple colors or frequencies that are evenly spaced across the optical spectrum.
“The technology we’ve developed takes a very powerful laser and turns it into dozens of clean, high-power channels on a chip.
Rainbow-on-a-chip To create a frequency comb on a chip, the researchers needed to find a high-power laser that could be squeezed into a compact photonic circuit.
After a lab accident, engineers created a chip that emits a rainbow of potent laser beams, which may help data centers handle the rapidly increasing amounts of artificial intelligence (AI) data.
A carefully designed optical circuit and an industrial-grade laser source are combined in the new photonics chip to stabilize and shape light before dividing it into several evenly spaced colors.
The technology could allow data centers to transfer information much more quickly and efficiently than current optical networks like fiber, which use single-wavelength laser pulses to transmit data. This is because each color band represents an optical frequency that can carry its own distinct stream of data.
This frequency comb, or rainbow effect, is usually produced by large, costly lasers and amplifiers. However, while trying to boost lidar (light detection and ranging) technology, the researchers discovered a way to fit this potent photonics technology into a single, tiny chip.
By measuring how long it takes for laser pulses to reach an object and return, Lidar calculates distance. The group discovered the chip was dividing the light into several colors while working to create stronger lasers that could record fine details from a greater distance.
A frequency comb is what?
Multiple colors or frequencies evenly distributed throughout the optical spectrum make up a frequency comb, a type of laser light. These frequencies show up as spikes that resemble a comb’s teeth when plotted on a spectrogram.
Each of the “tooth”‘s peaks denotes a precise, stable wavelength that is capable of carrying information on its own. The wavelengths don’t interfere with one another because they are locked in both frequency and phase, which means that their peaks remain precisely aligned. This makes it possible for numerous data streams to pass through a single optical channel—like a fiber-optic cable—in parallel.
Following their accidental discovery of the effect, the scientists devised a method to deliberately and carefully replicate it. Additionally, they crammed the technology into a silicon chip, which allows light to pass through waveguides that are only a few micrometers wide. One micrometer (1 µm) is approximately one hundredth of a human hair’s width, or one thousandth of a millimeter (0.0001 cm).
The group released its results in October. 7 published in Nature Photonics. According to the researchers, the discovery is particularly significant now that AI is putting increasing demands on data center infrastructure’s resources.
In a statement, study co-author Andres Gil-Molina, a principal engineer at Xscape Photonics and a former researcher at Columbia Engineering, said, “Data centers have created tremendous demand for powerful and efficient sources of light that contain many wavelengths.”.
“With our technology, a very strong laser can be converted into dozens of high-power, clean channels on a chip. Thus, you can use a single small device to replace racks of separate lasers, saving money, space, and paving the way for faster, more energy-efficient systems. “.”.
A rainbow on a chip.
In order to develop a frequency comb on a chip, the scientists had to figure out how to fit a powerful laser into a small photonic circuit. They ultimately decided on a multimode laser diode, which is frequently found in laser cutting tools and medical equipment.
According to the study, multimode laser diodes are capable of producing strong laser light beams, but because the beam is “messy,” the researchers had to figure out how to stabilize and refine the light in order to make it practical.
They did this by incorporating resonators into the chip that return a tiny amount of light to the laser, a process known as self-injection locking. This produces a powerful and incredibly stable beam by filtering and stabilizing the light.
The chip divides the laser beam into a multicolored frequency comb after it has stabilized. According to the scientists, the end product is a compact yet effective photonics device that combines the strength of an industrial laser with the accuracy required for sensing and data transfer applications.
Outside of data centers, the new chip may make it possible to use advanced lidar systems, portable spectrometers, compact quantum devices, and ultra-precise optical clocks.
Gil-Molina stated, “This is about integrating lab-grade light sources into practical devices.”. “You can place them practically anywhere if you can make them strong, effective, and compact. “,”.
