Abstract: A device for providing electrons and its method of making. The device includes an optical fiber with a tip and a metallic arrangement arranged at the tip. The metallic arrangement is arranged to be excited by an energy source to emit electrons or electron beams.

Abstract: An electron gun and an apparatus incorporating the electron gun. The electron gun includes an electron emission element, an electrode, a control element, and a control circuit. The electron emission element is arranged to be activated to emit electron beam. The electrode is arranged to be electrically connected with a power supply to accelerate the emitted electron beam. The control element may be arranged between the electron emission element and the electrode. The control element is arranged to be electrically connected with the power supply to provide an electric field to control emission of electron beams from the electron emission element. The control circuit is electrically connected with the control element for changing the electric field provided by the control element.

Abstract: A waveguide for guiding terahertz waves with wavelength ranging 0.1 mm-3 mm, includes a cladding tube made of a metal-free dielectric material, and a core filling a transmission space defined by the cladding tube. The core has a minimum width or diameter larger than the wavelength of the terahertz wave guided by the waveguide. The thickness of the cladding tube is smaller than the radius or one half of the width of the core. The core has an attenuation constant for the terahertz waves lower than that of the cladding tube. The waveguide guides terahertz waves mainly inside the core, and has a simple construction.