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Home > Mall Dynamic > New Breakthrough: Tiny Photonic Chips Can Produce High-Precision Microwave Signals For Autonomous Driving
In a new study in the journal Nature, researchers at Columbia University's School of Engineering have created a photonic chip that can produce high-quality, ultra-low noise microwave signals using only a single laser. The chip is so small that it fits on the tip of a sharp pencil and is the lowest microwave noise observed to date on an integrated photon platform. The work offers a promising path to smaller, ultra-low noise microwave generators for applications such as high-speed communications, atomic clocks and self-driving cars.
Electronics used in global navigation, wireless communications, radar and precision timing require a stable microwave source as a clock and information carrier. To improve the performance of these devices, the key is to reduce the noise or random phase fluctuations that exist in microwaves.
Alexander Gaeta, the David M. Rickey Professor of Applied Physics and Materials Science and Professor of Electrical Engineering at Columbia University's School of Engineering, said: "Over the past decade, a technique known as optical frequency splitting has produced the lowest-noise microwave signals to date.
Typically, such systems require multiple lasers and a relatively large volume to accommodate all the components."
Optical frequency division, a method of converting high frequency signals into low frequency signals, is a recent innovation in the production of microwaves, in which noise has been greatly suppressed.
However, because optical frequency division systems take up a lot of desktop space, they cannot be used for micro sensing and communication applications, which require more compact microwave sources. "
We have achieved a device that can perform optical frequency division entirely on the chip in areas as small as 1 mm2, using only a single laser," Gaeta said. For the first time, we have demonstrated an optical frequency division process that requires no electronics, greatly simplifying device design.
Gaeta's research team specializes in quantum and nonlinear photonics, or how lasers interact with matter. Research focus areas include nonlinear nanophotonics, frequency comb generation, strong ultrafast pulse interactions, and the generation and processing of optical quantum states.
In the current study, his research team designed and manufactured an on-chip all-optical device that generates microwave signals at 16 GHz with the lowest frequency noise ever achieved on an integrated chip platform.
The device uses two micro-resonators made of silicon nitride that are coupled together by photons. A single frequency laser pumps two micro-resonators.
One of them is used to create optical parametric oscillators that convert input waves into two output waves - one with a higher frequency and one with a lower frequency. The frequency interval between the two new frequencies was adjusted to the terahertz frequency.
Due to the quantum correlation of the oscillator, the noise of this frequency difference is thousands of times smaller than the noise of the input laser. The second microresonator can be adjusted to produce an optical frequency comb with microwave intervals.
The small amount of light emitted by the oscillator is then coupled to the comb frequency generator, which synchronizes the microwave comb frequency with the terahertz oscillator, automatically achieving optical frequency division.
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