Electron emission device of high current density and high operational frequency
An electric device operable with a THz-range frequency of the device output is presented. The device comprises a photocathode installed in either one of a diode, triode and tetrode configuration, and is exposed to illumination. In some embodiments of the invention, the device is configured as a diode and photomixing is used for illumination of the photocathode with light in the THz range, the diode converting this input light signal into an electrical output in the THz range, which operates a signal transmitter/receiver. In some other embodiments of the invention, the device is configured as a triode or tetrode, where the electrodes have small dimensions (about 1 micron or less) and are spaced from one another a distance not exceeding 1 micron. The photocathode is kept under certain illumination, and electrical signal applied to one of the electrodes results in the THz output at one of the other electrodes.
1. An electric device operable with a THz-range frequency of a device output, the electric device comprising:
an electrodes' arrangement comprising at least a photocathode electrode and an associated anode electrode with a free space between them where the photocathode electrode is exposed to illumination of a predetermined wavelength range thereby creating electrons' emission from the photocathode electrode and a photocurrent through the electric device;
a voltage supply unit for supplying an input electrical signal onto one electrode of said electrodes' arrangement,
an output electrical signal indicative of the photocurrent being readable on at least the one electrode of said electrodes' arrangement;
and a signal transmitter/receiver comprising an antenna circuit electrically connected to the at least the one electrode at which the output electrical signal is read to thereby radiate an output signal of the electric device in the THz-range in response to the output electrical signal on the at least the one electrode of the electrodes' arrangement.
2. The device of claim 1 , further comprising
an illumination source operable to illuminate the photocathode electrode with light of a certain fixed intensity, wherein
said predetermined wavelength range is selected in accordance with a photocathode electrode material for extracting electrons therefrom.
3. The device of claim 1 , wherein the electrodes' arrangement is configured as a triode structure comprising the photocathode electrode, the associated anode electrode and gate electrodes, the gate electrodes being located in a plane between photocathode and anode planes.
4. The device of claim 3 , wherein the gate electrodes are located in a plane spaced from each of the photocathode and anode planes by a gap of less than 1 micron.
5. The device of claim 4 , wherein the gap between the photocathode electrode and the associated anode electrode is about 0.1 micron and 0.3 microns, respectively.
6. The device of claim 5 , wherein said gate electrodes have a thickness of 01 micron 0.1 micron and a dimension across a space between the photocathode electrode and the associated anode electrode of about 0.1 micron.
7. The device of claim 3 , wherein the electrodes' arrangement is configured as a tetrode structure comprising the photocathode electrode, the associated anode electrode, the gate electrodes and screen grid electrodes, the screen grid electrodes being located between the gate electrodes and the anode planes.
8. The device of claim 7 , wherein the electrodes in the electrodes' arrangement are spaced from one another by a gap of less than 1 micron.
9. The device of claim 8 , wherein the gap between the gate electrode and the photocathode electrode is 0.1 micron, the gap between the gate electrode and screen grid electrodes is 0.3 microns, and the gap between the screen grid electrodes and the associated anode electrode is 0.3 microns.
10. The device of claim 9 , wherein the thickness of the gate electrodes and of the screen grid electrodes is 0.1 micron.
11. The device of claim 1 , wherein a photocathode electrode layer is patterned to form an array of spaced-apart regions of photocathode electrode material and higher electrically conductive material within the spaces between the photocathode electrode material regions.
12. An electric device operable with a THz-range frequency of a device output, the electric device comprising
a diode structure comprising a photocathode electrode and an anode electrode;
an illumination source configured and operable to generate a light beam in a form of a superposition of two light components of slightly different frequencies to thereby illuminate the photocathode electrode by an amplitude modulated wave and cause a corresponding photocurrent to be received at the anode electrode; and
a signal transmitter/receiver unit comprising an antenna circuit electrically connected to the anode and being operable by an electric signal induced by said photocurrent at the anode electrode for receiving and transmitting radiation with the THz-ranoe frequency.
13. The device of claim 12 , wherein the illumination source comprises two light emitters generating said two light components of slightly different frequencies, respectively.
14. The device of claim 13 , wherein one of said two light components is of 800 nm wavelengths.
15. The device of claim 13 , wherein said two light emitters are laser diodes.
16. The device of claim 13 , wherein one of said two light components is of 800 nm wavelengths and the other of said two light components is of 801 nm wavelengths.
17. The device of claim 12 , wherein the photocathode electrode and anode electrode are spaced from each other by a gap of up to a few microns.
18. The device of claim 12 , wherein a photocathode electrode layer and an anode electrode layer are located to be facing each other on spaced-apart surfaces of first and second substrates, respectively.
19. The device of claim 18 , wherein the first substrate is substantially transparent for said light beam.
20. The device of claim 18 , wherein the second substrate is formed with an electrical connector from the anode electrode layer to an outer surface of said second substrate for coupling to the signal transmitter/receiving unit.
21. The device of claim 20 , wherein the antenna circuit is printed on an outer surface of said second substrate.
22. A THz transmitter device comprising
a diode structure comprising a photocathode electrode and an anode electrode;
an illumination source configured and operable to generate a light beam in a form of a superposition of two light components of slightly different frequencies to thereby illuminate the photocathode electrode by an amplitude modulated wave and cause a corresponding photocurrent to be received at the anode electrode; and
an antenna circuit electrically connected to the anode electrode and operable an electric signal induced by said photocurrent at the anode electrode for transmitting radiation with a THz-range frequency.
23. A THz transmitter device comprising
an electrodes' arrangement comprising at least a photocathode electrode and an associated anode electrode where the photocathode electrode is exposed to illumination of a predetermined wavelength range thereby creating electrons' emission from the photocathode electrode and a photocurrent through the THz transmitter device;
a voltage supply unit for supplying an input electrical signal onto one of the electrodes of the electrodes' arrangement,
an output electrical signal corresponding to the photocurrent being readable on one or more electrodes of the electrodes' arrangement; and
a signal transmitter/receiver comprising an antenna circuit electrically connected to the electrode at which the output electrical signal is readable, said antenna circuit being therefore operable by the output electric signal to generate radiation in a THz-range frequency.
24. The device of claim 1 , wherein said electrodes' arrangement further comprises at least one gate electrode located in a plane between photocathode and anode planes.
25. The device of claim 1 , wherein the electrodes of the electrodes' arrangement are spaced from one another a distance not exceeding a few microns, thereby allowing the electric device to operate with a voltage supply of a few tens of volts or less to the at least the one electrode of the electrodes' arrangement.