Atomic-Scale Optical Microscopy with Continuous-Wave Mid-Infrared Radiation

Area of Science:

• Physics
• Materials Science
• Optical Microscopy

Background:

• High spatial resolution is crucial for understanding matter at fundamental levels.
• Scanning near-field optical microscopy (SNOM) circumvents the diffraction limit but is restricted to nanometer scales by tip geometry.

Purpose of the Study:

• To achieve optical imaging resolution on the Ångstrom length scale.
• To explore light emission from atomically confined tunneling currents.
• To enable high-resolution imaging with standard optical setups.

Main Methods:

• Utilized a conventional continuous-wave mid-infrared laser and intensity-based detection.
• Observed optical signals modulated on Ångstrom length scales.
• Investigated near-field optical tunneling emission (NOTE) under continuous-wave driving.

Main Results:

• Demonstrated optical signals modulated on Ångstrom length scales, indicating light emission from atomically confined tunneling currents.
• Observed NOTE, a strong-field excitation process, under continuous-wave driving, which is typically pulse-dependent.
• Identified anharmonic tip oscillation as a factor influencing the signal.

Conclusions:

• Developed a pathway to optical imaging with unprecedented resolution using tunneling-mediated contrast.
• Established the feasibility of NOTE with standard optical setups.
• Opened new avenues for fundamental studies of matter with Ångstrom-scale resolution.