Coherent and tunable light radiation from nanoscale surface plasmons array via an exotic Smith-Purcell effect

Area of Science:

• Condensed Matter Physics
• Nanophotonics
• Plasmonics

Background:

• Surface plasmons are collective electron oscillations on metal surfaces.
• The Smith-Purcell effect describes electron-beam-induced radiation from a grating.
• Existing methods for nanoscale light generation face limitations in coherence and tunability.

Purpose of the Study:

• To demonstrate the transformation of surface plasmons into coherent radiation using a nanoscale metallic array.
• To investigate the characteristics of this novel radiation and compare it to ordinary Smith-Purcell radiation.
• To explore the potential of this phenomenon for developing advanced nanoscale light sources.

Main Methods:

• Fabrication of a nanoscale metallic array.
• Excitation of surface plasmons on the array.
• Analysis of the emitted radiation properties, including frequency, direction, and spectral density.
• Tuning of radiation by adjusting array material and structure.

Main Results:

• Surface plasmons were successfully converted into coherent radiation waves.
• The radiation exhibited specified directions and satisfied the Smith-Purcell relation.
• The spectral density of the coherent radiation was an order of magnitude higher than ordinary Smith-Purcell radiation.
• Radiation frequency was tunable from infrared to ultraviolet regions.

Conclusions:

• The demonstrated effect is an exotic variant of the Smith-Purcell effect, producing coherent radiation.
• This technique offers significant advantages in intensity, coherence, tunability, and miniaturization.
• It opens new prospects for developing compact and efficient nanoscale light sources.