Abstract: A terahertz (THz) cross-correlation device for material characterization of a sample comprising an optical source for outputting a continuous-wave (CW) optical signal: THz antennas providing a THz transmitter and a THz receiver optically coupled to the optical source, and an optical delay setup configured to adjust a synchronization of the THz receiver to the THz transmitter by the CW optical signal. The optical source is configured to provide a CW optical signal having an at least substantially continuous broadband spectrum and the optical paths for the CW signal are provided by optical waveguides such as optical fibres or integrated waveguides. The optical delay setup comprises a double-pass polarization-conserving fibre stretcher comprising a circulator, a fibre stretcher, and a Faraday mirror; and/or a variable solid state optical delay (SSOD).

Abstract: An electron tube includes a housing that is internally held in a vacuum and has a window transmitting an electromagnetic wave, an electron emitting unit that is disposed in the housing and has a meta-surface emitting electrons in response to incidence of the electromagnetic wave, an electron multiplying unit that is disposed in the housing and multiplies the electrons emitted from the electron emitting unit, and an electron collecting unit that is disposed in the housing and collects the electrons multiplied by the electron multiplying unit. The window contains at least one selected from quartz, silicon, germanium, sapphire, zinc selenide, zinc sulfide, magnesium fluoride, lithium fluoride, barium fluoride, calcium fluoride, magnesium oxide, and calcium carbonate.

Abstract: In a photoelectric conversion device, the meta-surface includes a first antenna portion, a first bias portion, a second antenna portion, and a second bias portion. The first antenna portion extends in a first direction and emits an electron in response to incidence of the electromagnetic wave. The first bias portion faces the first antenna portion and is configured to generate an electric field having a component in the first direction between the first bias portion and the first antenna portion. The second antenna portion extends in a second direction intersecting the first direction and emits an electron in response to incidence of the electromagnetic wave. The second bias portion faces the second antenna portion and is configured to generate an electric field having a component in the second direction between the second bias portion and the second antenna portion.

Abstract: In a photoelectric conversion device, the potential control unit controls electric potentials applied to the meta-surface. The meta-surface includes a plurality of patterns which are space away from each other. The plurality of patterns include an antenna portion and at least one bias portion. The antenna portion extends in a predetermined direction and emits the electron in response to incidence of the electromagnetic wave. The potential control unit switches a first state and a second state by controlling the electric potentials applied to the plurality of patterns. In the first state, a component of an electric field from the bias portion toward the antenna portion in a predetermined direction is positive. In the second state, a component of an electric field from the bias portion toward the antenna portion in the predetermined direction is negative.

Abstract: A photoelectric conversion device is provided with an electron emitter including a meta-surface emitting an electron in response to incidence of an electromagnetic wave. The meta-surface includes a plurality of photoelectric conversion units having a sensitivity for electromagnetic waves having mutually different wavelength regions. The plurality of photoelectric conversion units respectively include patterns having mutually different configurations.

Abstract: In an electron tube, the meta-surface emits an electron in response to an incidence of the electromagnetic wave. The first and second electrodes are spaced away from each other, and apply potentials different from each other to the meta-surface. A holder is disposed in the housing and holds the electron emitter. A first conductive line of the meta-surface is electrically connected to the first electrode. A second conductive line of the meta-surface is spaced away from the first conductive line, and is electrically connected to the second electrode. The first conductive line extends from the first electrode to the second conductive line. The second conductive line extends from the second electrode to the first conductive line.

Abstract: An electron tube includes a housing that is internally held in a vacuum and has a window transmitting an electromagnetic wave, an electron emitting unit that is disposed in the housing and has a meta-surface emitting electrons in response to incidence of the electromagnetic wave, an electron multiplying unit that is disposed in the housing and multiplies the electrons emitted from the electron emitting unit, and an electron collecting unit that is disposed in the housing and collects the electrons multiplied by the electron multiplying unit. The window contains at least one selected from quartz, silicon, germanium, sapphire, zinc selenide, zinc sulfide, magnesium fluoride, lithium fluoride, barium fluoride, calcium fluoride, magnesium oxide, and calcium carbonate.

Abstract: This invention concerns a photo-cathode for a vacuum system, wherein the photo-cathode is configured for receiving electromagnetic radiation having an incoming wavelength and for emitting electrons in response thereto. The photo-cathode comprises a conducting structure having a geometry, the geometry comprising a tip section. The tip section is adapted to provide field enhancement, ?, when the conducting structure is illuminated with the electromagnetic radiation, wherein ? is greater than about 102. The photo-cathode further comprising a substrate, the substrate being or comprising a dielectric substrate, the substrate supporting the conducting structure.