New light-to-microwave converting tech could revolutionize GPS, radars
The new microchip effectively shrinks a tabletop’s worth of components, making it energy efficient and practical for everyday use.
National Institute of Standards and Technology (NIST) researchers have developed a revolutionary time-keeping microchip. Able to seamlessly convert light to microwaves, this new chip could dramatically improve global position systems (GPS), phone and internet connections, and radar accuracy.
In fact, it could improve any technology that relies on high-precision time-keeping and communication. This is achieved by reducing “timing jitter,” which is small, random changes in the timing of microwave signals.
Like a musician struggling to keep a steady beat during a musical rendition, the timing of these signals can sometimes waver over time. However, to be precise, NIST researchers have reduced this to a tiny fraction of a second: 15 femtoseconds.
By the way, a femtosecond is one quadrillionth of a second. That is very impressive in anyone’s books.
Timing jitter is no longer a problem
This new technology is a significant upgrade from conventional microwave sources. It enhances the stability and accuracy of signals, which can increase radar sensitivity, improve analog-to-digital converters’ accuracy, and capture clearer astronomical images using groups of telescopes.
What’s more, the new NIST technology is also very compact. It normally takes a tabletop-size system to achieve a similar feat, but the NIST team has also managed to shrink much of it into a compact chip.
The chip is roughly the same size as a digital camera memory card. By reducing timing jitter and miniaturizing it into a small chip, the NIST team has reduced its power usage while simultaneously making it more usable in everyday devices.
The components required for NIST’s chip are currently situated outside the chip to test their efficiency. But, the team now plans to merge all the different parts, including lasers, modulators, detectors, and optical amplifiers, onto a single chip.
This will reduce the size and power usage and make it possible to include the system in small devices without extensive training or significant energy input.
Not just a NIST effort
“The current technology takes several labs and many Ph. D.s to make microwave signals happen,” said NIST physical scientist Frank Quinlan. A lot of this research is about how we utilize the advantages of optical signals by shrinking the size of components and making everything more accessible,” he added.
“The goal is to make all these parts work together effectively on a single platform, which would greatly reduce the loss of signals and remove the need for extra technology,” said Quinlan. “Phase one of this project was to show that all these individual pieces work together. Phase two is putting them together on the chip,” he added.
A team of researchers from several prestigious institutions helped NIST with this amazing achievement. These included the University of Colorado Boulder, the NASA Jet Propulsion Laboratory, the California Institute of Technology, the University of California Santa Barbara, the University of Virginia, and Yale University.
“I like to compare our research to a construction project. There are a lot of moving parts, and you need to make sure everyone is coordinated so the plumber and electrician show up at the right time in the project,” said Quinlan. We all work together really well to keep things moving forward,” he added.
You can view the study for yourself in the journal Nature.
Study abstract:
Numerous modern technologies are reliant on the low-phase noise and exquisite timing stability of microwave signals. Substantial progress has been made in the field of microwave photonics, whereby low-noise microwave signals are generated by the down-conversion of ultrastable optical references using a frequency comb.
Such systems, however, are constructed with bulk or fiber optics and are difficult to further reduce in size and power consumption. In this work, we address this challenge by leveraging advances in integrated photonics to demonstrate low-noise microwave generation via two-point optical frequency division. Narrow-linewidth self-injection-locked integrated lasers are stabilized to a miniature Fabry–Pérot cavity and the frequency gap between the lasers is divided with an efficient dark soliton frequency comb.
The stabilized output of the microcomb is photodetected to produce a microwave signal at 20 GHz with phase noise of −96 dBc Hz−1 at 100 Hz offset frequency that decreases to −135 dBc Hz−1 at 10 kHz offset—values that are unprecedented for an integrated photonic system. All photonic components can be heterogeneously integrated on a single chip, providing a significant advance for the application of photonics to high-precision navigation, communication, and timing systems.
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