Efficient Smith-Purcell Radiation Sources and Enhancement Methods

Applications

This light emitting technology improves upon the Smith-Purcell Effect by implementing a dielectric periodic structure. The light source shows promise in a range of Ultraviolet (UV), Extreme Ultraviolet (EUV), and soft X-ray applications, such as UV sterilization and forensics, EUV lithography, and soft X-ray tomography.

Problem Addressed

The Smith-Purcell Effect is a light emission method induced by free electrons coupled to the electromagnetic modes of a periodic structure that diffracts light into several wavelengths. The wavelength of radiation is dependent on the velocity of the free electrons and the geometry of the periodic structure. Smith-Purcell light sources typically use a metallic periodic structure and adjust emission wavelength through electron velocity. Unfortunately, the output of conventional light sources is too weak for realistic application due to a range of nanoscale technical issues, from phase mismatch between electrons and emitted photons to misalignment of the electron beam and the periodic structure.

Technology

This wavelength-tunable light emission technology enhances the monochromatic and directional nature of Smith-Purcell radiation through a dielectric periodic structure. The electron source comprises of a laser that illuminates a gated field emitter array (FEA) with light pulses, propagating free electrons as a beam. The dielectric periodic structure, situated a few wavelengths away from the electron source, interacts with the free electron beam, inducing Smith-Purcell radiation. The periodic structure defines at least one light wave that gets emitted. The technology’s light emission wavelength can be specified between the visible and X-ray range by tuning the electron source’s energy within a range of 0.5 to 40 keV.

Advantages

  • Enhances monochromatic and directional nature of Smith-Purcell radiation through dielectric periodic structure
  • Tunable emission wavelength between the visible and X-ray spectrum via FEA-based electron source
  • Improves output strength, allowing for realistic applications in UV, EUV, and soft X-ray technologies