Dielectric/Antiferromagnetic/Metal Sandwich Structure Difference Frequency Effect

Terahertz(THz) radiation covers the spectral range between 0.1 and 10 THz(3 mm – 30 μm) and is gathering an increasing interest both for spectroscopic applications and as a playground for fundamental studies e.g. on nonlinear and extreme-nonlinear optical effects. Since the resonant frequencies of typical the antiferromagnet(AF) materials are distributed over the far-infrared and millimeter ranges, the nonlinear response of AFs has been paid a great deal of attention. The nonlinear magnetic polaritons, bi-stability and sum-frequency of AF film or superlattice have been discussed. According to the expectation of Almeida and Mills and Kahn et al., the magnetic component of the plane electromagnetic wave should reach a few ten gauss, corresponding to the laser power of 100.0MW/m2, so a free-electron laser may be necessary to induce the nonlinear response of AF film. Therefore, how to increase the nonlinear outputs is an interesting subject.The difference and sum-frequency(DF and SF) generations are the second-order nonlinear response of AF film. DF or SF generation, as a method of frequency conversion, is widely used to generate the new light. The three-wave mixing processes, also as known as frequency upconversion or downconversion, are typically very sensitive to the incoming frequencies, due to the requirement of phase matching. An excellent review of four-wave mixing and phase conjugation in plasmas has been given by Federici. The SF outputs of a single AF film have been discussed in which the continuous SF output windows versus the infrared signal wave frequencies are shown. However, the SF generation, the second-order nonlinear response of AF, is much weaker which leads to the lower SF conversion efficiency. Therefore, to increase the conversion efficiency at a fixed intensity is discussed from several ways. Wang presented a method to increase the second-harmonic generation(SHG) by an AF film for a fixed input power, in which the film is put between two different dielectrics or in one-dimensional photonic crystals. The results show that the SH outputs are raised to a few hundred times that of the single film. A simple AF sandwich structure, dielectric/AF/Ag, was proposed in ref, in which Ag has a relative higher dielectric constant and lower optical losses. If Ag is thick enough, the electromagnetic waves cannot penetrate it. The reflected electromagnetic waves will heighten the field strength in the AF film. Thus, the SF outputs from the above film are enhanced a few times than those of a single AF film when the thickness of AF film is one quarter of the vacuum wavelength.Voigt were studied in this paper, using the transfer matrix method a type antiferromagnetic sandwich structure under difference frequency effect, developed more reults below:1.The presence of outfield antiferromagnetic difference frequency magnetic susceptibility, and to study the properties of the antiferromagnetic difference frequency laid a theoretical foundation.2.The type research in Voigt antiferromagnetic sandwich structure under difference frequency effect.We through the antiferromagnetic layer below the layer of silver plated to enhance antiferromagnetic film difference frequency effect.This and previous research difference is bigger, the metallized structure at the bottom of the antiferromagnetic layer is one of the main innovation point of this article, through the difference frequency with antiferromagnetic monolayer membrane structure effect, we found that the output of the sandwich structure with metal strength significantly higher than the antiferromagnetic nude model.We put forward a sandwich structure of dielectric/antiferromagnetic/silver, when the input energy is a certain value, the effective method to increase the difference frequency output.At the same time with two beams of incident light on the medium surface.Through the numerical simulation of SiO2/MnF2/Ag sandwich structure, the results show that in the upper film output can improve at least two orders of magnitude, and the difference frequency output energy will change with the change of incident Angle3. We also discussed the influence of the external magnetic field on the difference frequency output.Found that when the external magnetic field changes, the difference frequency output will also change accordingly.