The University of Michigan-Shanghai Jiao Tong University Joint Institute (UM-SJTU JI, JI hereafter) Professor Lei Shao and his collaborators have published a research article “Femtometer-amplitude imaging of coherent super high frequency vibrations in micromechanical resonators” in Nature Communications.

The article proposed a new technology to image super-high frequency super-small amplitude vibrations in micromechanical resonators using a femtosecond laser interferometer. Corresponding authors of the paper are Professor Lei Shao and Dr. Jason Gorman from the US National Institute of Standards and Technology. Professor Wen-Ming Zhang from SJTU and Professor Amit Lal from Cornell University also made significant contributions to the research.

Inside every cellphone lies a tiny mechanical heart, beating several billion times a second. These micromechanical resonators play an essential role in cellphone communication. Buffeted by the cacophony of radio frequencies in the airways, these resonators select just the right frequencies for transmitting and receiving signals between mobile devices. With the growing importance of these resonators for communications and their potential applications in quantum computing and biomedical sensing, scientists need a reliable and efficient way to make sure the devices are working properly. That’s best accomplished by carefully studying the tiny vibrations that these resonators generate. The challenge of measuring these vibrations is now grand as those super-high frequency resonators, required for 5G networks and quantum information, are generating even tinier vibrations.

In the research conducted by Professor Shao and his collaborators, a breakthrough was achieved in development of instrument for imaging super-high frequency vibrations by proposing a femtosecond laser interferometry technology. The research team measured vibrations as rapid as 12 gigahertz (GHz, or billions of cycles per second) and as small as 55 femtometers (quadrillionths of a meter) in amplitude or height, which is about one-five-hundredth the diameter of a hydrogen atom. The measurements are expected to be extended above 25 GHz, providing the necessary frequency coverage for 5G communications as well as for potentially powerful future applications in quantum information. The researchers also produced “movies” of these resonators with unprecedented detail.



Personal Profile

Lei Shao is currently a tenure-track assistant professor at the UM-SJTU Joint Institute. He received his bachelor degree from Shanghai Jiao Tong University in 2009, master and doctorate degrees from University of Michigan in 2011 and 2014, respectively. After postdoctoral research at the US National Institute of Standards and Technology from 2014 to 2018, he joined the UM-SJTU Joint Institute. Lei Shao’s research focuses on microelectromechanical systems (MEMS), sensors and actuators.