Yujia Yang

Yujia Yang’s research innovatively combines integrated photonic chips with electron microscopy.

He explored the interaction between free electrons and nonlinear optical states inside electron microscopes by leveraging nonlinear integrated photonic chips. Using soliton frequency combs, he achieved ultrafast electron-beam modulation with sub-100 femtosecond pulses at a 200 GHz repetition rate.

This technology matches femtosecond-laser electron-beam control using continuous-wave lasers, increasing repetition rate and beam current by more than four orders of magnitude. It opens new possibilities for low-cost, high-performance ultrafast electron microscopy and compact electron accelerators, while also highlighting the unique role of electron microscopy in advancing nonlinear optics.

Yujia also co-developed correlated free-electron and photon pairs in photonic microresonators, revealing single-photon and single-electron energy-time correlations and their use in low-noise, high-dynamic-range electron imaging. Subsequent work verified quantum optical states from free electrons.

In precision measurement, he used photonic-chip light fields for free-electron phase modulation, creating a microwave-optical-free-electron frequency link. This bridges frequencies differing by 1013, combining electromagnetic and free-electron-matter-wave spectroscopy.

Moreover, he developed a new calibration method for free-electron spectrometers using this technology, enhancing accuracy 20-fold and enabling precise irregularity measurement, crucial for ultrahigh-precision electron spectroscopy.