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CN-116609953-B - Graphical wave front regulating and controlling method of terahertz spin emitter

CN116609953BCN 116609953 BCN116609953 BCN 116609953BCN-116609953-B

Abstract

The invention belongs to the technical field of terahertz wave pulse source generation, and provides a patterned wave front regulating and controlling method of a terahertz spin emitter. According to the method, a plurality of sequential terahertz spin thin film units and a plurality of reverse-sequence terahertz spin thin film units in the terahertz spin emitter are spatially distributed according to a graphical design, so that terahertz light beams with expected forms are obtained, space phase encoding of a terahertz light field is realized, and wave front regulation and control are completed. Compared with the prior art, the method has the advantages of strong operability, wide applicability, low cost and the like.

Inventors

  • CHEN SAI
  • WU XIAOJUN

Assignees

  • 北京航空航天大学

Dates

Publication Date
20260512
Application Date
20230428

Claims (9)

  1. 1. A graphical wavefront regulation method of a terahertz spin emitter is characterized in that a plurality of sequential terahertz spin thin film units and a plurality of reverse-sequence terahertz spin thin film units in the terahertz spin emitter are spatially distributed according to graphical design so as to obtain terahertz light beams in expected forms and realize the spatial phase coding of a terahertz light field; The sequential terahertz spin thin film unit and the material layer stacking sequence in the reverse-sequence terahertz spin thin film unit are opposite.
  2. 2. The patterned wavefront manipulation method of a terahertz spin emitter according to claim 1, wherein the sequential terahertz spin thin film unit includes at least a ferromagnetic material and a non-magnetic material stacked from bottom to top, and the reverse-sequential terahertz spin thin film unit includes at least a non-magnetic material and a ferromagnetic material stacked from bottom to top.
  3. 3. The patterned wavefront manipulation method of a terahertz spin emitter according to claim 1, wherein the sequential terahertz spin thin film unit at least includes a nonmagnetic material, a ferromagnetic material, and a nonmagnetic material stacked from bottom to top, and the terahertz spin thin film is composed of at least two layers of different materials, and is stacked in a specific order to form a heterojunction on the surface of the fused quartz crystal.
  4. 4. The patterned wavefront manipulation method of a terahertz spin emitter according to claim 1, wherein the sequential terahertz spin thin film unit includes at least an antiferromagnetic material, a ferromagnetic material and a nonmagnetic material stacked from bottom to top, and the reverse sequential terahertz spin thin film unit includes at least a nonmagnetic material, a ferromagnetic material and an antiferromagnetic material stacked from bottom to top.
  5. 5. A method of patterned wavefront manipulation of a terahertz spin emitter according to any one of claims 2-3, wherein the non-magnetic material is tungsten or platinum.
  6. 6. A method of patterned wavefront manipulation of a terahertz spin emitter according to any one of claims 2-3, wherein the ferromagnetic material is cobalt-iron-boron or iron-nickel.
  7. 7. The patterned wavefront manipulation method of a terahertz spin emitter according to claim 4, the anti-ferromagnetic material is iridium manganese or tungsten.
  8. 8. The method of claim 1, wherein the terahertz light field is a dual beam, a focused terahertz light beam, or a focused terahertz vortex light beam.
  9. 9. The patterned wavefront control method of the terahertz spin emitter according to claim 1, characterized in that the sequential terahertz spin thin film unit and the reverse-sequential terahertz spin thin film unit are prepared by using a magnetron sputtering technology.

Description

Graphical wave front regulating and controlling method of terahertz spin emitter Technical Field The invention belongs to the technical field of terahertz wave pulse source generation, and particularly relates to a patterned wave front regulating and controlling method of a terahertz spin emitter. Background The frequency range of terahertz waves is generally defined as 0.1-10 thz, and is an electromagnetic wave between microwaves and infrared light. The terahertz wave is in a transition frequency band between low-energy electronics and high-energy photonics, is an electromagnetic wave band with excellent characteristics, has the advantages of wide frequency band, low photon energy, strong coherence, high measurement signal-to-noise ratio, good safety and the like, is widely applied to various fields of communication, radar, security inspection, substance identification, biological detection and the like, and has important application value in national economy and national defense construction. In recent 20 years, the academic world at home and abroad has developed a great deal of researches on the transmission mechanism of terahertz waves, key materials and device technologies thereof, and has made a great breakthrough in the principles of terahertz generation, modulation, detection and the like and device technologies, thereby laying an important foundation for the development of terahertz application technology. The development of terahertz sources for time-domain spectroscopy at present has achieved many achievements, in which a method for generating terahertz radiation based on a spintronic thin film has both higher electric field intensity and better stability, and simultaneously has better compatibility for pump lasers with high or low repetition frequency, which is favored by researchers and becomes a typical method for realizing terahertz wave emission. The basic principle is that spin flow is injected into a heavy metal material to cause spin-charge conversion by exciting the super-diffusion transport process of thermal electrons in a ferromagnetic material and the heavy metal material through femtosecond laser pulse, so that sub-picosecond spin flow is converted into charge flow, and terahertz radiation is realized. However, the existing terahertz pulse often lacks a space structure, and cannot meet the requirements of various application scenes on a structural light field. In the early stage, the optical field regulation and control of the terahertz wave mainly depends on artificial electromagnetic microstructures such as a super surface and the like, and the terahertz optical field is controlled on a terahertz wave transmission path. However, due to the self dimension of the terahertz wave, the device cannot achieve higher integration level in an actual system, tends to have larger loss, and is difficult to realize effective regulation. Disclosure of Invention The terahertz pulse generated by the existing terahertz emission source lacks a space structure, and is difficult to realize a structure light beam based on light field regulation and control in the terahertz frequency band, so that the front edge cross application in the fields of advanced spectroscopy, high-resolution imaging, high-speed communication and the like is difficult to achieve. In order to overcome the defects in the prior art, the invention provides a graphical wavefront regulation and control method of a terahertz spin emitter, which is based on a spin electronic film subjected to graphical design to generate a space structured terahertz pulse field, thereby completing wavefront regulation and control and being applicable to compact terahertz spectrum and imaging systems of various applications. The technical scheme of the invention is as follows: According to a graphical design, a plurality of sequential terahertz spin thin film units and a plurality of reverse-sequence terahertz spin thin film units in the terahertz spin emitter are spatially distributed to obtain terahertz light beams in expected forms, and space amplitude and phase encoding of a terahertz light field are realized; The sequential terahertz spin thin film unit and the material layer stacking sequence in the reverse-sequence terahertz spin thin film unit are opposite. Preferably, the sequential terahertz spin thin film unit at least includes a ferromagnetic material and a non-magnetic material stacked from bottom to top, and the reverse sequential terahertz spin thin film unit at least includes a non-magnetic material and a ferromagnetic material stacked from bottom to top. Preferably, the sequential terahertz spin film unit at least comprises a nonmagnetic material, a ferromagnetic material and a nonmagnetic material stacked from bottom to top. Preferably, the sequential terahertz spin thin film unit includes at least an antiferromagnetic material, a ferromagnetic material and a nonmagnetic material stacked from bottom to top, and the reverse sequential t