Reviewed by Frances BriggsOct 8 2025
A new chip-based light source can generate dozens of powerful, stable wavelengths at once, an advancement from Columbia Engineering researchers that could facilitate a new era in data center hardware and portable sensing technologies. The study was published in Nature Photonics.
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The discovery began almost by accident, while experimenting with lasers to improve LiDAR (a light-based distance-measuring technology), researchers in Michal Lipson's laboratory noticed that their chip was creating a frequency comb.
A frequency comb is a unique form of light encompassing numerous colors arranged systematically, resembling a rainbow. A multitude of colors, or light frequencies, radiate vividly, while the spaces in between stay dark. When observed on a spectrogram, these luminous frequencies manifest as spikes, like the teeth of a comb.
Traditionally generating such combs has required bulky, expensive lasers and amplifiers. Lipson's group in Columbia Engineering, however, has shown how to create a powerful, stable comb on a chip smaller than a fingernail.
Data centers have created tremendous demand for powerful and efficient sources of light that contain many wavelengths. The technology we’ve developed takes a very powerful laser and turns it into dozens of clean, high-power channels on a chip. That means you can replace racks of individual lasers with one compact device, cutting cost, saving space, and opening the door to much faster, more energy-efficient systems.
Gil-Molina, Principal Engineer, Xscape Photonics
As silicon photonics becomes increasingly important to critical infrastructure and our daily lives, this kind of progress is essential to ensuring that data centers are as efficient as possible.
The work started with a basic challenge: how to integrate an extremely powerful laser onto a chip. The team selected a multimode laser diode, commonly used in medical equipment and laser cutting instruments. These lasers can generate substantial quantities of light; however, the beam is considered "messy," complicating its use in precise applications.
Incorporating such a laser into a silicon photonics chip, where the light pathways measure only a few microns and in some cases, even hundreds of nanometers, required meticulous engineering.
We used something called a locking mechanism to purify this powerful but very noisy source of light.
Gil-Molina, Principal Engineer, Xscape Photonics
The technique uses silicon photonics to modify and enhance the laser's output, resulting in a significantly cleaner and more stable beam, a characteristic scientists refer to as high coherence.
The nonlinear optical characteristics of the chip come into play when the light has been purified, dividing that singular intense beam into numerous evenly distributed colors, which is a hallmark of a frequency comb. The outcome is a compact, highly efficient light source that merges the substantial power of an industrial laser with the accuracy and stability required for sophisticated communications and sensing.
Why It Matters Now
The breakthrough is timely: With the rapid expansion of artificial intelligence, the infrastructure within data centers is struggling to transfer information quickly enough, particularly between processors and memory. Cutting-edge data centers are currently using fiber optic connections to convey data; however, the majority of these still depend on single-wavelength lasers.
Frequency combs offer a way forward. Rather than a single beam transmitting one data stream, multiple beams can operate simultaneously through the same fiber. This concept is the foundation of wavelength-division multiplexing (WDM), the technology that transformed the internet into a global high-speed network in the late 1990s.
By integrating high-power, multi-wavelength combs directly into silicon hardware, Lipson's team has opened up new possibilities for compact and cost-sensitive systems. In addition to data centers, these chips could facilitate portable spectrometers, ultra-precise optical clocks, compact quantum devices, and even sophisticated LiDAR systems.
This is about bringing lab-grade light sources into real-world devices. If you can make them powerful, efficient, and small enough, you can put them almost anywhere.
Gil-Molina, Principal Engineer, Xscape Photonics
Journal Reference:
Gil-Molina, A., et al. (2025) High-power electrically pumped microcombs. Nature Photonics. doi.org/10.1038/s41566-025-01769-z