CN114706255A - M-DBR nonlinear laser amplitude limiting structure based on optical Tamm state - Google Patents

Abstract

The invention provides an optical Tamm state-based M-DBR nonlinear laser amplitude limiting structure, which is formed by stacking three optical media according to a certain sequence, wherein the three media are respectively A, B and M, and the nonlinear laser amplitude limiting structure is M (AB)⁴Media a and B are nonlinear optical materials, media M is a metal material, and superscript 4 indicates that media layer AB alternates for four periods. The structure realizes high transmission to 1064nm weak signal laser based on an optical Tamm state, and utilizes a nonlinear refraction effect to stronger laser, so that the transmission spectrum center of the limiter structure moves, and further realizes nonlinear limiting to 1064nm strong laser. The invention can be effectively applied to amplitude limiting of 1064nm wavelength laser and realizes high transmission of weak light.

Description

M-DBR nonlinear laser amplitude limiting structure based on optical Tamm state

Technical Field

The invention relates to the field of optical Tamm state, photonic crystal and nonlinear optics, in particular to an M-DBR nonlinear laser amplitude limiting structure based on an optical Tamm state, which can be applied to laser at a 1064nm wavelength, and can realize high transmission on weak light and high attenuation on strong light.

Background

With the development of laser technology, laser with lower energy can be used as signal light for laser ranging and laser warning of own party, while laser with higher energy can be used as attack light for interfering, blinding and even damaging own forming personnel or photoelectric equipment. For example, common laser with the wavelength of 1064nm, when the laser power density reaches 58mw/mm²In time, a brief exposure may cause irreversible damage to the retina. Therefore, the high-power laser needs to be subjected to amplitude limiting protection, and the low-power laser is used as the signal input of the instrument, so that amplitude limiting is not needed.

Currently commonly used laser clipping techniques can be divided into three major categories by principle: the optical amplitude limiting technology based on the phase change principle, the optical amplitude limiting technology based on the linear optical principle and the optical amplitude limiting technology based on the nonlinear optical principle. In the optical amplitude limiting technology based on the phase change principle, a certain recovery time is required in the process of converting a used material from a metal state to a semiconductor state, and in the period of time, the phase change material is in a low transmission state, and a photoelectric sensor cannot normally receive signals. The laser amplitude limiting technology based on the linear optical principle also has a plurality of defects, is difficult to protect multi-wavelength laser, cannot dynamically adjust the transmittance according to the intensity of incident laser, and is difficult to meet the requirements of high transmittance of weak signal light in the same waveband and high attenuation of strong attack light. The existing YAG laser protective mirror design based on one-dimensional photonic crystal band gap reflection applies a linear optical principle and has the defect that the laser transmittance cannot be dynamically controlled according to the intensity of laser.

The optical Tamm state is a lossless optical surface state and is a strong local phenomenon of photons on the dielectric surface of an optical crystal. Compared with the photon local phenomenon generated by a common photonic crystal, the photon local of an optical Tamm state can be higher by one or even more orders of magnitude, the nonlinear effect of a medium is easier to excite, and a better amplitude limiting effect is realized. The design of the nonlinear laser limiter is carried out based on the optical Tamm state, and the strict azimuth angle control of incident light is not needed; and the response speed is very fast and can reach nanosecond order of magnitude, and the method has obvious advantages compared with the prior amplitude limiting method.

In summary, in order to solve the technical defects in the prior art, the invention designs a novel M-DBR nonlinear amplitude limiting structure based on the optical Tamm state, which realizes high transmittance for weak light and high attenuation for strong light.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides an M-DBR nonlinear laser amplitude limiting structure based on an optical Tamm state.

In order to achieve the purpose, the invention adopts the following technical scheme:

an optical Tamm state-based M-DBR nonlinear laser amplitude limiting structure is formed by stacking three optical media according to a certain sequence, wherein the three media are A, B and M respectively, and the nonlinear laser amplitude limiting structure is M (AB)⁴Media a and B are nonlinear optical materials, media M is a metal material, and superscript 4 indicates that media layer AB alternates for four periods.

The surface of the DBR structure formed by the media M and A, B alternately meets the phase matching condition to form an optical Tamm state, so that the transmission enhancement phenomenon induced by the optical Tamm state occurs in the wave band originally serving as the forbidden band of the DBR photonic crystal, and thus weak incident light can have high transmission; with the continuous increase of the incident light power density, the optical Tamm state has the light field local effect, so that the refractive indexes of the nonlinear optical media A and B are increased, the red shift of the center of a transmission spectrum is caused, the 1064nm position is gradually restored to the original photonic crystal forbidden band region, the transmissivity is continuously reduced aiming at 1064nm strong laser, and the high attenuation under strong light is realized.

In order to optimize the technical scheme, the specific measures adopted further comprise:

further, the medium M is suitable for a nonlinear laser amplitude limiting structure with the laser wavelength of 1064nmThe material of the medium A is metal silver (Ag), and the material of the medium A is nano-copper and nano-iron doped barium titanate (nano-Au (nano-Fe: BaTiO)₃) The material of the medium B is polymethyl methacrylate (PMMA); the thicknesses of the three media A, B and M were 108nm, 141nm, and 24nm, respectively.

Furthermore, the medium A is suitable for a nonlinear laser amplitude limiting structure with the laser wavelength of 1064nm, the linear refractive index of the medium A is 2.4, and the nonlinear refractive index is 2.1 multiplied by 10^-8cm²W; the linear refractive index of medium B was 1.48, and the nonlinear refractive index was 5.78X 10^-12cm²W; background dielectric constant ε of Medium M_∞3.7, plasma frequency ω_p＝1.38×10¹⁶S, damping collision frequency

Furthermore, the optical power density is less than 0.15MW/cm in a nonlinear laser amplitude limiting structure with the laser wavelength of 1064nm²When, the light transmittance is greater than 70.52%; the optical power density is 1.27MW/cm²When the light transmittance is 60.71%; the optical power density is more than 6MW/cm²When the refractive index was too high, the light transmittance was 9.61%.

The invention has the beneficial effects that: the invention provides an optical Tamm state-based M-DBR nonlinear laser amplitude limiting structure by utilizing medium silver, nano-copper and nano-iron-doped barium titanate and polymethyl methacrylate, and realizes high transmission of weak light and high attenuation of strong light. The optical Tamm state is a lossless optical surface state, compared with a photon local phenomenon generated by a common photonic crystal, the excitation of the optical Tamm state can be higher by several orders of magnitude, the nonlinearity of the photonic crystal can be excited better, and the nonlinear amplitude limiting effect is easier to realize. Since both TM and TE light can excite the optical Tamm state, a nonlinear limiter designed based on the optical Tamm state is insensitive to the polarization of the incident light. The optical Tamm state has no requirement on the incident angle of incident light, so that wide-angle nonlinear amplitude limiting can be realized. In addition, the M-DNR structure can reflect strong light, reduce the absorption of the medium layer to the strong light and greatly improve the laser damage threshold of the nonlinear amplitude limiter.

Drawings

FIG. 1 is a cross-sectional view of the M-DBR nonlinear clipping structure of the present invention;

FIG. 2 is a diagram illustrating the distribution of the internal electric field of the M-DBR nonlinear limiter structure according to the present invention;

FIG. 3 is a schematic diagram of the red shift of the transmission peak of the M-DBR nonlinear clipping structure according to the present invention with the increase of the incident light power density;

fig. 4 is a graph showing the variation of the transmittance of the limiter structure with the incident light power density at 1064 nm.

Detailed Description

The present invention will now be described in further detail with reference to the accompanying drawings.

As shown in FIG. 1, the nonlinear laser limiter structure of M-DBR based on optical Tamm state is formed by stacking three optical media in a certain order, wherein the three media are A, B and M respectively, and the nonlinear laser limiter structure is M (AB)⁴Media a and B are nonlinear optical materials, media M is a metal material, and superscript 4 indicates that media layer AB alternates for four periods.

Aiming at laser with an attack wavelength of 1064nm, in an M-DBR nonlinear laser amplitude limiting structure based on an optical Tamm state, a medium M is made of metal silver (Ag), the thickness of the medium M is 108nm, and the background dielectric constant epsilon_∞3.7, plasma frequency ω_p＝1.38×10¹⁶S, damping collision frequency

The medium A is made of nano-copper and nano-iron doped barium titanate (nano-Au (nano-Fe: BaTiO))₃) 141nm in thickness, 2.4 in linear refractive index and 2.1X 10 in nonlinear refractive index)^{- 8}cm²W; the material of the medium B is polymethyl methacrylate (PMMA), the thickness is 24nm, the linear refractive index is 1.48, and the nonlinear refractive index is 5.78 multiplied by 10^-12cm²and/W. When the incident light power density is less than 0.15MW/cm²When, the light transmittance is greater than 70.52%; the optical power density is 1.27MW/cm²Time, light transmissionThe rate was 60.71%; the optical power density is more than 6MW/cm²When the refractive index was adjusted, the light transmittance was 9.61%.

Aiming at the M-DBR nonlinear laser amplitude limiting structure based on the optical Tamm state, finite element analysis software COMSOL Multiphysics is used for carrying out simulation calculation, an electromagnetic wave frequency domain physical field in a wave optical module is added, and steady state analysis is carried out, so that the distribution of an electric field in the M-DBR nonlinear amplitude limiting structure can be obtained. As shown in fig. 2, the incident optical field oscillates along the working direction of the M-DBR structure, and due to the optical Tamm state generated by the medium M (metal layer) and the DBR structure, the optical field is localized between the medium M (metal layer) and the DBR, so that the weaker 1064nm laser can also be induced to enhance transmission. As shown in fig. 3, since the media a and B are made of nonlinear optical materials, with the increasing of the incident laser power density, the refractive indexes of the media a and B increase due to the optical kerr effect, which results in the original red shift of the transmission peak and the corresponding decrease of the transmittance at 1064nm, thereby achieving the optical amplitude limiting effect at high incident light power density. Referring to FIG. 4, for an incident laser with a wavelength of 1064nm, the M-DBR structure based on the optical Tamm state of the invention has an incident light power density of less than 0.15MW/cm²When, the transmittance is greater than 70.52%; when the power density of incident light is continuously increased to 6MW/cm²When the laser is used, the light transmittance can be gradually reduced to 9.61%, so that the nonlinear amplitude limiting of 1064nm laser is realized.

The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may be made by those skilled in the art without departing from the principle of the invention.

Claims (4)

1. An optical Tamm state-based M-DBR nonlinear laser amplitude limiting structure is characterized in that the nonlinear laser amplitude limiting structure is formed by stacking three optical media according to a certain sequence, wherein the three media are A, B and M respectively, and the nonlinear laser amplitude limiting structure is M (AB)⁴Media A and B are nonlinear optical materialsMedium M is a metal material, and superscript 4 indicates that medium layer AB alternates for four periods.

2. The optical Tamm state-based M-DBR nonlinear laser amplitude limiting structure of claim 1, wherein the material of the medium M is silver, the material of the medium A is barium titanate doped with nano copper and nano iron, and the material of the medium B is polymethyl methacrylate, and the material of the medium A is silver, the material of the medium A is barium titanate doped with nano copper and nano iron; the thicknesses of the three media A, B and M were 108nm, 141nm, and 24nm, respectively.

3. The optical Tamm state-based M-DBR nonlinear laser limiting structure of claim 2, wherein the linear refractive index of medium A is 2.4 and the nonlinear refractive index is 2.1 x 10 for the nonlinear laser limiting structure with 1064nm laser wavelength^-8cm²W; the linear refractive index of medium B was 1.48, and the nonlinear refractive index was 5.78X 10^-12cm²W; background dielectric constant ε of Medium M_∞3.7, plasma frequency ω_p＝1.38×10¹⁶S, damping collision frequency

4. The optical Tamm state-based M-DBR nonlinear laser limiting structure of claim 3, wherein the optical power density is less than 0.15MW/cm for a nonlinear laser limiting structure with a laser wavelength of 1064nm²When, the light transmittance is greater than 70.52%; the optical power density is 1.27MW/cm²When the light transmittance is 60.71%; the optical power density is more than 6MW/cm²When the refractive index was adjusted, the light transmittance was 9.61%.

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