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

Abstract

The present invention provides an M-DBR nonlinear laser limiting structure based on optical Tamm state, wherein the nonlinear laser limiting structure is formed by stacking three optical media in a certain order. Assuming that the three media are A, B and M, the nonlinear laser limiting structure is M(AB) 4 , medium A and B are nonlinear optical materials, medium M is a metal material, and the superscript 4 indicates that the medium layer AB alternates four cycles. This structure realizes high transmission of 1064nm weak signal laser based on the optical Tamm state, and for stronger laser, the nonlinear refraction effect is used to move the transmission spectrum center of the limiter structure, thereby realizing nonlinear limiting of 1064nm strong laser. The present invention can be effectively applied to limiting the 1064nm wavelength laser, and at the same time achieve high transmission of weak light.

Description

Technical Field

[0001] The invention relates to the fields of optical Tamm states, photonic crystals and nonlinear optics, and in particular to an M-DBR nonlinear laser limiting structure based on optical Tamm states, which can be applied to lasers at a wavelength of 1064nm and achieve high transmittance for weak light and high attenuation for strong light. Background Art

[0002] With the development of laser technology, lasers with lower energy can be used as signal light for laser ranging and laser warning, while lasers with higher energy can be used as attack light to interfere with, blind, or even damage personnel or optoelectronic equipment. For example, the common wavelength of 1064nm laser, when the laser power density reaches 58mw / mm 2 When the retina is exposed to a short period of time, it will cause irreversible damage to the retina. Therefore, it is necessary to limit the high-power laser, while the low-power laser as the signal input of the instrument does not need to be limited.

[0003] The commonly used laser limiting technologies can be divided into three categories according to their principles: optical limiting technology based on phase change principle, optical limiting technology based on linear optics principle, and optical limiting technology based on nonlinear optics principle. Among them, the optical limiting technology based on phase change principle requires a certain recovery time for the material used to transform from a metal state to a semiconductor state. During this period of time, the phase change material is in a low transmittance state, and the photoelectric sensor cannot receive signals normally. The laser limiting technology based on the linear optics principle also has many disadvantages. It is difficult to protect multi-wavelength lasers, and its transmittance cannot be dynamically adjusted according to the intensity of the incident laser. It is difficult to meet the high transmittance of weak signal light in the same band and the high attenuation of strong attack light. The existing YAG laser protective goggles based on one-dimensional photonic crystal band gap reflection design apply the linear optics principle and have the disadvantage of not being able to dynamically control the laser transmittance according to the intensity of the laser.

[0004] The optical Tamm state is a lossless optical surface state, which is a strong localization phenomenon of photons on the dielectric surface of an optical crystal. Compared with the photon localization phenomenon produced by ordinary photonic crystals, the photon localization of the optical Tamm state can be one or even multiple orders of magnitude higher, making it easier to stimulate the nonlinear effect of the medium and achieve a better limiting effect. The design of a nonlinear laser limiter based on the optical Tamm state does not require strict azimuth control of the incident light; and the response speed is extremely fast, reaching the nanosecond level, which has significant advantages over previous limiting methods.

[0005] In summary, in order to solve the existing technical defects, this invention designs a new M-DBR nonlinear limiting structure based on the optical Tamm state, which achieves high transmittance for weak light and high attenuation for strong light. Summary of the invention

[0006] The present invention aims at the deficiencies in the prior art and provides an M-DBR nonlinear laser limiting structure based on optical Tamm state.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] An M-DBR nonlinear laser limiting structure based on optical Tamm state, the nonlinear laser limiting structure is formed by stacking three optical media in a certain order, assuming that the three media are A, B and M, then the nonlinear laser limiting structure is M(AB) 4 , medium A and B are nonlinear optical materials, medium M is a metal material, and the superscript 4 indicates that the medium layers AB alternate for four periods.

[0009] The surface of the DBR structure composed of medium M alternating with A and B meets the phase matching condition and forms an optical Tamm state, which causes the optical Tamm state-induced transmission enhancement phenomenon to occur in the band that was originally the bandgap of the DBR photonic crystal, so that weaker incident light can also have high transmittance; as the incident light power density continues to increase, the optical Tamm state has a localized effect on the light field, which increases the refractive index of the nonlinear optical media A and B, resulting in a red shift in the center of the transmission spectrum, and gradually returns to the original photonic crystal bandgap at 1064nm. Therefore, for the strong laser of 1064nm, the transmittance will continue to decrease, thereby achieving high attenuation under strong light.

[0010] To optimize the above technical solutions, the specific measures taken also include:

[0011] Furthermore, in a nonlinear laser limiting structure suitable for a laser wavelength of 1064 nm, the material of medium M is metallic silver (Ag), the material of medium A is barium titanate doped with nano-copper and nano-iron (nano-Au:(nano-Fe:BaTiO3)), and the material of medium B is polymethyl methacrylate (PMMA); the thicknesses of the three media A, B and M are 108 nm, 141 nm and 24 nm, respectively.

[0012] Furthermore, in a nonlinear laser limiting structure suitable for a laser wavelength of 1064 nm, the linear refractive index of medium A is 2.4, and the nonlinear refractive index is 2.1×10 -8 cm 2 / W; the linear refractive index of medium B is 1.48, and the nonlinear refractive index is 5.78×10 -12 cm 2 / W; background dielectric constant ε of medium M ∞ =3.7, plasma frequency ω p =1.38×10 16 / s, damped collision frequency

[0013] Furthermore, it is suitable for nonlinear laser limiting structures with a laser wavelength of 1064nm, and the optical power density is less than 0.15MW / cm 2 When the light transmittance is greater than 70.52%, the light power density is 1.27MW / cm 2 When the light transmittance is 60.71%, the light power density is greater than 6MW / cm 2 When , the light transmittance is 9.61%.

[0014] The beneficial effects of the present invention are as follows: the present invention provides an M-DBR nonlinear laser limiting structure based on the optical Tamm state by using dielectric silver, barium titanate doped with nano-copper and nano-iron, and polymethyl methacrylate, which can achieve high transmittance for weak light and high attenuation for strong light. The optical Tamm state is a lossless optical surface state. Compared with the photon localization phenomenon produced by ordinary photonic crystals, the optical Tamm state excitation can be several orders of magnitude higher, which can better excite the nonlinearity of the photonic crystal and more easily achieve the nonlinear limiting effect. Since both TM and TE light can excite the optical Tamm state, the nonlinear limiter designed based on the optical Tamm state is insensitive to the polarization of the incident light. The optical Tamm state has no requirements for the incident angle of the incident light, so wide-angle nonlinear limiting can be achieved. In addition, the use of the M-DNR structure can have a higher reflection of strong light, reduce the absorption of strong light by the dielectric layer itself, and greatly improve the laser damage threshold of the nonlinear limiter. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a cross-sectional view of the M-DBR nonlinear limiting structure of the present invention;

[0016] Figure 2 This is the internal electric field distribution diagram of the M-DBR nonlinear limiting structure of the present invention;

[0017] Figure 3 It is a schematic diagram showing that the transmission peak of the M-DBR nonlinear limiting structure of the present invention red-shifts as the incident light power density increases;

[0018] Figure 4 This is a graph showing the relationship between the transmittance of the limiting structure and the incident light power density when the incident light wavelength is 1064nm. DETAILED DESCRIPTION

[0019] The present invention will now be described in further detail with reference to the accompanying drawings.

[0020] like Figure 1As shown, an M-DBR nonlinear laser limiting structure based on optical Tamm state is formed by stacking three optical media in a certain order. Assuming that the three media are A, B and M, the nonlinear laser limiting structure is M(AB) 4 , medium A and B are nonlinear optical materials, medium M is a metal material, and the superscript 4 indicates that the medium layers AB alternate for four periods.

[0021] For the laser with an attack wavelength of 1064 nm, in the M-DBR nonlinear laser limiting structure based on the optical Tamm state, the material of the medium M is metallic silver (Ag), with a thickness of 108 nm, and the background dielectric constant ε ∞ =3.7, plasma frequency ω p =1.38×10 16 / s, damped collision frequency The material of medium A is barium titanate doped with nano-copper and nano-iron (nano-Au:(nano-Fe:BaTiO3)), with a thickness of 141nm, a linear refractive index of 2.4, and a nonlinear refractive index of 2.1×10 - 8 cm 2 / W; the material of medium B is polymethyl methacrylate (PMMA), with a thickness of 24nm, a linear refractive index of 1.48, and a nonlinear refractive index of 5.78×10 -12 cm 2 / W. When the incident light power density is less than 0.15MW / cm 2 When the light transmittance is greater than 70.52%, the light power density is 1.27MW / cm 2 When the light transmittance is 60.71%, the light power density is greater than 6MW / cm 2 When , the light transmittance is 9.61%.

[0022] For the M-DBR nonlinear laser limiting structure based on the optical Tamm state provided by the present invention, the finite element analysis software COMSOL Multiphysics is used for simulation calculation, and the electromagnetic wave frequency domain physical field in the wave optics module is added to perform steady-state analysis, and the internal electric field distribution of the M-DBR nonlinear limiting structure of the present invention can be obtained. Figure 2 As shown in the figure, the incident light field oscillates and changes along the working direction of the M-DBR structure. Due to the optical Tamm state generated by the medium M (metal layer) and the DBR structure, the light 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. Figure 3As shown in the figure, since medium A and B are made of nonlinear optical materials, as the incident laser power density continues to increase, due to the optical Kerr effect, the refractive index of medium A and B increases, resulting in the red shift of the original transmission peak and the corresponding decrease in the transmittance at 1064nm, achieving the optical limiting effect under high incident light power density. Figure 4 For incident laser with wavelength of 1064nm, the M-DBR structure based on optical Tamm state of the present invention has an incident light power density of less than 0.15MW / cm 2 When the incident light power density increases to 6MW / cm 2 When the light transmittance is gradually reduced to 9.61%, the nonlinear limiting of 1064nm laser is achieved.

[0023] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. An M-DBR nonlinear laser limiting structure based on optical Tamm state, characterized in that: The nonlinear laser limiting structure is formed by stacking three optical media in a certain order. Assuming that the three media are A, B and M, the nonlinear laser limiting structure is M(AB) 4 , medium A and B are nonlinear optical materials, medium M is a metal material, and the superscript 4 indicates that the medium layers AB alternate for four periods; The material of medium M is metallic silver, the material of medium A is barium titanate doped with nano-copper and nano-iron, and the material of medium B is polymethyl methacrylate; the thicknesses of the three media A, B and M are 108nm, 141nm and 24nm respectively.

2. The M-DBR nonlinear laser limiting structure based on optical Tamm state according to claim 1, characterized in that: Applicable to the nonlinear laser limiting structure with a laser wavelength of 1064nm. The linear refractive index of medium A is 2.4 and the nonlinear refractive index is 2.1×10 -8 cm 2 / W; the linear refractive index of medium B is 1.48, and the nonlinear refractive index is 5.78×10 -12 cm 2 / W; background dielectric constant ε of medium M ∞ =3.7, plasma frequency ω p =1.38×10 16 / s, damped collision frequency ћγ=0.0018eV.

3. The M-DBR nonlinear laser limiting structure based on optical Tamm state according to claim 2, characterized in that: Applicable to nonlinear laser limiting structures with a laser wavelength of 1064nm, and the optical power density is less than 0.15MW / cm 2 When the light transmittance is greater than 70.52%, the light power density is 1.27MW / cm 2 When the light transmittance is 60.71%, the light power density is greater than 6MW / cm 2 When the light transmittance is 9.61%.

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