Interfacial Cherenkov radiation from ultralow-energy electrons

Area of Science:

• Physics
• Materials Science
• Optoelectronics

Background:

• Cherenkov radiation requires charged particles to exceed the speed of light in a medium.
• Generating Cherenkov radiation with low-energy electrons is a significant challenge due to momentum mismatch.
• On-chip light sources are desirable but hindered by the need for high-energy particles.

Purpose of the Study:

• To overcome the challenge of generating Cherenkov radiation from ultralow-energy electrons.
• To enable the development of on-chip light sources using low-energy particle interactions.
• To investigate a novel mechanism combining interfacial Cherenkov radiation and umklapp scattering.

Main Methods:

• Exploiting the combined effect of interfacial Cherenkov radiation and umklapp scattering.
• Utilizing constructive interference from sequential particle-interface interactions.
• Designing specific (umklapp) momentum-shifts for particle interactions.

Main Results:

• Successfully generated interfacial Cherenkov radiation from electrons with kinetic energies down to the electron-volt scale.
• Demonstrated a mechanism overcoming the high-energy particle requirement for Cherenkov radiation.
• Observed unique features in the radiation, including spatially separated wave and group cone apexes due to umklapp scattering.

Conclusions:

• The combined effect of interfacial Cherenkov radiation and umklapp scattering provides a viable pathway for generating Cherenkov radiation from ultralow-energy electrons.
• This mechanism has significant implications for developing compact and efficient on-chip light sources.
• The unique radiation characteristics offer new avenues for controlling light emission at the nanoscale.