Novel Phonon Technology Shrinks Wireless Filters

Researchers in the US have made a groundbreaking advancement in wireless technology by developing semiconductor–piezoelectric heterostructures that can integrate multiple front end filters in wireless systems. The team at the University of Arizona Wyant College of Optical Sciences and Sandia National Laboratories successfully combined lithium niobate and indium gallium arsenide on a silicon substrate, enabling stronger interactions between phonons than ever seen before in conventional materials used for front end filters on a single chip.

This innovative approach led to the creation of nonlinear phononic interactions that have the potential to revolutionize classical and quantum information processing at radio frequencies, similar to the impact of nonlinear photonic interactions at optical frequencies. By utilizing a semiconductor, the conversion efficiency can be further enhanced through the application of semiconductor bias fields that amplify the phonons. The theoretical model developed accurately predicts three-wave mixing efficiencies and extends these nonlinearities to smaller dimensions in waveguides, optimizing the properties of the semiconductor material.

"Most people would probably be surprised to hear that there are something like 30 filters inside their cell phone whose sole job is to transform radio waves into sound waves and back," said Matt Eichenfield, a researcher at the UArizona College of Optical Sciences and Sandia National Laboratories. The group is working on integrating all the components required for radio frequency signal processors using acoustic wave technologies on a single chip, making it compatible with standard microprocessor manufacturing.

"Now, you can point to every component in a diagram of a radiofrequency front-end processor and say, 'Yeah, I can make all of these on one chip with acoustic waves,'" Eichenfield explained. "We're ready to move on to making the whole system in the acoustic domain." Having all the necessary components on a single chip could potentially reduce the size of devices like cell phones and wireless communication gadgets significantly, possibly by a factor of 100.

The researchers demonstrated that one beam of phonons can alter the frequency of another beam and manipulate the phonons, showcasing the newfound capabilities of the developed heterostructures. "Normally, phonons behave linearly, meaning they don't interact with each other," Eichenfield noted. "When we combined the materials in the right way, we accessed a new realm of phononic nonlinearity, paving the way for high-performance technology for sending and receiving radio waves in a smaller form factor than ever before."

By incorporating the indium-gallium arsenide semiconductor, Eichenfield's team created an environment where acoustic waves influence the distribution of electrical charges in the semiconductor film, allowing for controlled mixing of acoustic waves and opening up a range of potential applications. "The effective nonlinearity achievable with these materials is orders of magnitude larger than previously possible, which is truly remarkable," Eichenfield emphasized. "If similar advancements could be made in nonlinear optics, it would revolutionize the entire field."

Sources: Nature Article, University of Arizona