
Researchers at EPFL and Max Planck have merged nonlinear optics with electron microscopy, unlocking new capabilities in material studies and the control of electron beams
When light goes through a material, it often behaves in unpredictable ways. This phenomenon is the subject of an entire field of study called “nonlinear optics”, which is now integral to technological and scientific advances from laser development and optical frequency metrology, to gravitational wave astronomy and quantum information science.
In addition, recent years have seen nonlinear optics applied in optical signal processing, telecommunications, sensing, spectroscopy, light detection and ranging. All these applications involve the miniaturization of devices that manipulate light in nonlinear ways onto a small chip, enabling complex light interactions chip-scale.
Now, a team of scientists at EPFL and the Max Plank Institute has brought nonlinear optical phenomena into a transmission electron microscope (TEM), a type of microscope that uses electrons for imaging instead of light. The study was led by Professor Tobias J. Kippenberg at EPFL and Professor Claus Ropers, Director of the Max Planck Institute for Multidisciplinary Sciences. It is now published in Science.
At the heart of the study are “Kerr solitons”, waves of light that hold their shape and energy as they move through a material, like a perfectly formed surf wave traveling across the ocean. This study used a particular type of Kerr solitons called “dissipative”, which are stable, localized pulses of light that last tens of femtoseconds (a quadrillionth of a second) and form spontaneously in the microresonator. Dissipative Kerr solitons can also interact with electrons, which made them crucial for this study.
The researchers formed dissipative Kerr solitons inside a photonic microresonator, a tiny chip that traps and circulates light inside a reflective cavity, creating the perfect conditions for these waves. “We generated various nonlinear spatiotemporal light patterns in the microresonator driven by a continuous-wave laser,” explains EPFL researcher Yujia Yang, who led the study. “These light patterns interacted with a beam of electrons passing by the photonic chip, and left fingerprints in the electron spectrum.” …. learn more
