A frequency-domain selective optical absorption electro-optic modulation device

Abstract

The present invention relates to the field of light absorption technology, and particularly relates to a frequency-domain selective light absorption electro-optic modulation device, which includes a substrate, a metal mirror layer, a nonlinear dielectric layer, and a light absorption superstructure layer. The metal mirror layer is disposed on the substrate, the nonlinear dielectric layer is disposed on the metal mirror layer, and the light absorption superstructure layer is disposed on the nonlinear dielectric layer. The light absorption superstructure layer includes periodically distributed light absorption superstructures. The light absorption superstructure layer forms a relatively wide absorption spectral band; the upper surfaces of the metal mirror layer and the nonlinear dielectric layer, and the upper surfaces of the metal mirror layer and the light absorption superstructure layer respectively form optical microcavities to form narrow-band absorption. By applying an electric field on both sides of the nonlinear dielectric layer, the resonance wavelengths of the two optical microcavities are changed, thereby forming tunable narrow-band absorption. In the present invention, the light absorption superstructure layer is not only used to achieve wide-band absorption, but also serves as the interface of the optical microcavity for narrow-band absorption, improving the system integration degree.

Description

Technical Field

[0001] The present invention relates to the technical field of light absorption, and particularly relates to a frequency-domain selective light absorption electro-optic modulation device. Background Art

[0002] Light absorption has very important application values in the fields of energy, optics, and optoelectronic functional materials and devices.

[0003] Frequency-domain selective light absorption has high application values in realizing functional selection and design and its application to light absorption and optical operations within a specific frequency range. For example, realizing light absorption within a specific working wavelength range under different requirements by using frequency-domain selective light absorption has important applications: in nonlinear optics, by adopting frequency-domain selective light absorption, high absorption can be achieved within the working wavelength range of nonlinear crystal materials, while low absorption in other frequency domains, thereby avoiding the serious problem that the nonlinear crystal materials absorb too much light energy and cause performance changes and failures. Specifically, in optoelectronic functional devices, the technologies in optical harmonics in nonlinear optics, including second harmonics and third harmonics, etc., involve two different frequency bands - the excitation frequency band and the harmonic generation frequency band. It is necessary to maintain high absorption in the absorption frequency band of the nonlinear optical crystal itself while changing the absorption or transmission efficiency of other frequency bands through external conditions, which has very important value for device applications. In addition, this selective optoelectronic functional technology also has important application values in the field of optobiomedicine.

[0004] In the existing literature, mostly only broadband absorption or narrowband absorption is achieved singly, and it is impossible to achieve both broadband absorption and narrowband absorption at the same time, especially impossible to achieve both broadband and tunable narrowband absorption at the same time. The integration degree of the device is poor, which hinders the application of nonlinear crystal materials. Summary of the Invention

[0005] To solve the above problems, the present invention provides a frequency-domain selective light absorption electro-optic modulation device, which includes a substrate, a metal mirror layer, a nonlinear dielectric layer, and a light absorption superstructure layer. The metal mirror layer is disposed on the substrate, the nonlinear dielectric layer is disposed on the metal mirror layer, and the light absorption superstructure layer is disposed on the nonlinear dielectric layer.

[0006] Furthermore, the material of the nonlinear dielectric layer is 4-dimethylamino-N-methyl-4-stilbazolium p-toluenesulfonate.

[0007] Furthermore, the material of the metal mirror layer is metal.

[0008] Furthermore, the substrate is a flexible transparent material.

[0009] Further, the light absorption superstructure layer includes periodically arranged microstructural units and a transparent conductive film layer. The transparent conductive film layer is disposed on the nonlinear dielectric layer, and the microstructural units are disposed on the nonlinear dielectric layer within the transparent conductive film layer.

[0010] Further, the period is a square array.

[0011] Further, the material of the transparent conductive film layer is indium tin oxide.

[0012] Further, the distance between adjacent microstructural units is greater than 100 nanometers.

[0013] Further, the material of the microstructural units is gold or silver.

[0014] Further, the microstructural units are conical.

[0015] Advantages of the present invention: The present invention provides a frequency-domain selective light absorption electro-optic modulation device, including a substrate, a metal mirror layer, a nonlinear dielectric layer, and a light absorption superstructure layer. The metal mirror layer is disposed on the substrate, the nonlinear dielectric layer is disposed on the metal mirror layer, and the light absorption superstructure layer is disposed on the nonlinear dielectric layer. The light absorption superstructure layer includes periodically distributed light absorption superstructures. During application, incident light is incident from one side of the light absorption superstructure layer, and the light absorption superstructure layer forms a relatively wide absorption spectral band; the upper surfaces of the metal mirror layer and the nonlinear dielectric layer, and the upper surfaces of the metal mirror layer and the light absorption superstructure layer respectively form optical microcavities. These optical microcavities resonate and couple with the incident light field to form narrow-band absorption. An electric field is applied on both sides of the nonlinear dielectric layer to adjust the dielectric constant of the nonlinear dielectric layer, thereby changing the resonance wavelengths of the above two optical microcavities, and thus forming adjustable narrow-band absorption. In the present invention, the light absorption superstructure layer is not only used to achieve wide-band absorption, but also serves as the interface of the optical microcavities for narrow-band absorption, improving the system integration. In addition, the present invention designs an electro-optic modulation device that simultaneously satisfies wide-band absorption and adjustable narrow-band absorption according to the absorption requirements of different bands in the nonlinear optical crystal, and has high application value.

[0016] The following will further describe the present invention in detail with reference to the accompanying drawings. Description of the Drawings

[0017] Figure 1 is a schematic diagram of a frequency-domain selective light absorption electro-optic modulation device.

[0018] Figure 2 is a schematic diagram of another frequency-domain selective light absorption electro-optic modulation device.

[0019] Figure 3 is an absorption spectral diagram at different voltages.

[0020] Figure 4 It is a line graph showing the change in the position of the long - wavelength absorption peak with the applied voltage.

[0021] Figure 5 It is a schematic diagram of another frequency - domain selective optical absorption electro - optic modulation device.

[0022] Figure 6 They are absorption spectra at different voltages.

[0023] In the figure: 1. Substrate; 2. Metal mirror layer; 3. Non - linear dielectric layer; 4. Optical absorption superstructure layer; 5. Micro - structure unit; 6. Transparent conductive film layer; 51. Top of the micro - structure; 52. Transparent conductive part; 53. Bottom of the micro - structure. Specific implementation mode

[0024] To make the purpose, technical solution and advantages of this application clearer, the following takes examples with reference to the attached drawings and further elaborates on this application in detail.

[0025] Example 1

[0026] The present invention provides a frequency - domain selective optical absorption electro - optic modulation device, as Figure 1 shown, which includes a substrate 1, a metal mirror layer 2, a non - linear dielectric layer 3, and an optical absorption superstructure layer 4. The metal mirror layer 2 is placed on the substrate 1, the non - linear dielectric layer 3 is placed on the metal mirror layer 2, and the optical absorption superstructure layer 4 is placed on the non - linear dielectric layer 3. The optical absorption superstructure layer 4 includes periodically arranged optical absorption superstructures. The material of the non - linear dielectric layer 3 is 4 - dimethylamino - N - methyl - 4 - stilbazolium tosylate. The material of the metal mirror layer 2 is a metal. Preferably, the material of the metal mirror layer 2 is gold. The substrate 1 is a flexible transparent material to facilitate attaching the substrate 1 to other substrates.

[0027] During application, the incident light enters from one side of the optical absorption superstructure layer 4, and the optical absorption superstructure layer 4 forms a relatively wide - band absorption spectral band; the upper surfaces of the metal mirror layer 2 and the non - linear dielectric layer 3, and the upper surfaces of the metal mirror layer 2 and the optical absorption superstructure layer 4 respectively form optical micro - cavities. These optical micro - cavities resonate and couple with the incident light field to form narrow - band absorption. An electric field is applied on both sides of the non - linear dielectric layer 3 to adjust the dielectric constant of the non - linear dielectric layer 3, thereby changing the resonance wavelengths of the above two optical micro - cavities, and thus forming adjustable narrow - band absorption. In the present invention, the optical absorption superstructure layer 4 not only realizes wide - band absorption, but also serves as the interface of the optical micro - cavities for narrow - band absorption, improving the system integration.

[0028] The frequency-domain selective optical absorption electro-optic modulation device provided by the present invention can apply an external electric field to the nonlinear dielectric layer 3 with electro-optic response characteristics to adjust the dielectric constant of the nonlinear dielectric layer 3, thereby causing a change in the spectrum of the reflection detector directly above the device, forming a specific optical absorption that changes with the external electric field. This optical absorption stems from the resonance coupling between the optical microcavity formed by the upper surface of the nonlinear dielectric layer 3, the upper surface of the optical absorption superstructure layer 4, and the metal mirror layer 2 and the incident light field, and thus is very sensitive to the change in the dielectric constant of the nonlinear dielectric layer 3 caused by the applied external electric field.

[0029] In addition, the optical absorption superstructure layer 4 of the device itself has the resonance structure characteristics of generating optical absorption. Relative to the above optical microcavity, a relatively wide absorption spectral band is formed in the short wavelength band of the spectrum. The absorption spectrum in this part has a low correlation with the properties of the nonlinear dielectric layer 3 and is not affected by the behavior of the applied voltage. Therefore, the present invention forms the optical absorption resonance characteristics with spatial three-dimensional distribution and the consequent frequency-domain selective optical absorption and its differential electro-optic modulation response.

[0030] This device with significantly different absorption spectrum responses generated by the external voltage regulation has a series of novel optoelectronic characteristics: (1) selective optical absorption in the frequency domain that is correlated with the structural spatial characteristics; (2) the characteristic of generating differential optical absorption responses under the action of an external electric field. Among them, (1) is reflected in the wide-band optical absorption in the short wavelength band and the narrow-band optical absorption in the long wavelength band; (2) corresponds to the fact that the wide-band optical absorption does not change with the external electric field, and the narrow-band optical absorption in the long wavelength band changes with the external electric field and has a linear frequency shift law.

[0031] Example 2

[0032] Based on Example 1, as Figure 2As shown, the light-absorbing superstructure layer 4 includes periodically arranged microstructural units 5 and a transparent conductive film layer 6. The transparent conductive film layer 6 is disposed on the nonlinear dielectric layer 3, and the microstructural units 5 are disposed within the transparent conductive film layer 6 and on the nonlinear dielectric layer 3. The microstructural units 5 are arranged in a square array with a period. The distance between adjacent microstructural units 5 is greater than 100 nanometers. The material of the transparent conductive film layer 6 is indium tin oxide. The material of the microstructural units 5 is gold or silver. Further, the microstructural units 5 are conical, and the radius of the circle at the top of the cone is smaller than the radius of the circle at the bottom. In this way, between adjacent microstructural units 5, the interval between the bottoms is smaller, which is conducive to guiding the incident light into the vicinity of the bottoms of adjacent microstructural units 5, thereby achieving stronger absorption of the incident light. Both the metal mirror layer 2 and the transparent conductive film layer 6 are provided with electrode contact points, facilitating connection to an external power supply to apply a voltage, thereby forming an electric field on the nonlinear dielectric layer 3. By connecting the electrode contact points of the transparent conductive film layer 6 and the metal mirror layer 2 through an external circuit, a voltage is applied to the nonlinear dielectric layer 3 to adjust the dielectric constant of the nonlinear dielectric layer 3, causing a change in the spectrum of the reflection detector directly above the device, forming a specific light absorption that changes with the external voltage. This light absorption results from the resonance coupling between the optical microcavity formed by the upper surface of the nonlinear dielectric layer 3, the upper surface of the microstructural units 5, and the metal mirror layer 2 and the incident light field, and thus is very sensitive to the change in the dielectric constant of the nonlinear dielectric layer 3 caused by the applied external voltage. In addition, the metal conical array structure in the light-absorbing superstructure layer 4 itself of the device also has the resonance structure characteristics of generating light absorption, thereby forming a relatively wide absorption spectral band in the short wavelength band of the spectrum. The absorption spectrum in this part has a low correlation with the properties of the nonlinear dielectric layer 3 and is not affected by the behavior of the applied external voltage. Thus, a light absorption resonance characteristic with a spatial three-dimensional distribution and the consequent frequency-domain selective light absorption and its differential electro-optic regulation response are formed.

[0033] In this embodiment, on the one hand, the transparent conductive film layer 6 is not only used to connect the electrodes; on the other hand, the microstructural units 5 are filled in the transparent conductive film layer 6, and the transparent conductive film layer 6 limits the light scattering of the microstructural units 5, further improving the light absorption ability of the light-absorbing superstructure layer 4.

[0034] Embodiment 3

[0035] Based on Example 2, a comparison diagram of the absorption spectral lines of a frequency-domain selective optical absorption electro-optic modulation device at different voltages is provided. This result is obtained by using the finite element numerical calculation method. The relevant structural parameters are as follows: the thickness of the metal mirror layer 2 is 150 nanometers and the material is gold; the thickness of the nonlinear dielectric layer 3 is 100 nanometers; the microstructure unit 5 is conical: the radii of the top circle and the bottom circle are 50 nanometers and 175 nanometers respectively, and the height is 500 nanometers; the microstructure unit 5 array is a square array and the array period is 350 nanometers; the thickness of the transparent conductive film layer 6 above the microstructure unit 5 is 100 nanometers; the substrate 1 is a flexible polystyrene material with a thickness of 20 micrometers.

[0036] As Figure 3 shown, when there is no input voltage value, the device generates absorption in two frequency bands. One is the short-wave band absorption, covering a relatively wide band from 0.38 micrometers to 0.69 micrometers, with the lowest absorption rate being 0.9 and the highest absorption rate reaching 0.993; there is another absorption band in the long-wave band, presenting an absorption peak with an absorption rate of 0.98 centered at 0.845 micrometers. This dual-band optical absorption with selectivity in the spectral frequency domain mainly comes from two resonance modes of the device structure. The short-wave band optical absorption is the resonance absorption of the metal conical array structure itself; the long-wave band optical absorption is the optical absorption of the metal-dielectric-metal optical microcavity formed by the metal conical array structure and the metal mirror layer 2.

[0037] An external circuit is connected at the electrode contact points of the optical absorption superstructure layer 4 and the metal mirror layer 2, and a voltage is applied to the nonlinear dielectric layer 4, thereby adjusting the dielectric constant of the nonlinear dielectric layer 4, causing a change in the spectrum of the reflection detector directly above the device, and forming a specific optical absorption that changes with the external voltage. By selecting a voltage of 10 volts, the absorption spectral lines in the presence of an external voltage are tested. As Figure 3 shown by the dashed line in

[0038] Example 4

[0039] Based on Example 3, as Figure 4As shown, by changing the voltage of the external circuit from -10 volts to 10 volts, with an interval of 1 volt, 21 electro-optical modulation experiments were continuously carried out. The spectral position changes of the long-wavelength absorption peak were recorded in sequence, plotted, and a dot-line graph of the wavelength position of this absorption peak changing with voltage was obtained. Further, through the linear fitting operation of the origin software, the linear fitting line of the 21 test results was obtained. Through fitting calculations, the linear relationship between this absorption peak and the external circuit voltage was obtained as that for every 1-volt change in voltage, the wavelength position of the absorption peak moves 7.1 nanometers. This not only indicates that there are differential responses during the electro-optical modulation process of this device within a large range, but also there is a quantitative linear relationship. Therefore, it is very beneficial for artificial regulation and the design and application of optoelectronic functional devices.

[0040] Example 5

[0041] Based on Example 2, as Figure 5 shown, the microstructure unit 5 is cylindrical. The microstructure unit 5 includes a microstructure top 51, a transparent conductive part 52, and a microstructure bottom 53. The microstructure bottom 53, the transparent conductive part 52, and the microstructure top 51 are arranged in sequence from bottom to top along the axis of the microstructure unit 5. That is to say, the microstructure bottom 53, the transparent conductive part 52, and the microstructure top 51 are all disk-shaped. The materials of the microstructure bottom 53 and the microstructure top 51 are gold, and the material of the transparent conductive part 52 is indium tin oxide. In this embodiment, the transparent conductive part 52 is inserted into the microstructure unit 5. On the one hand, multiple optical microcavity interfaces are created in the light absorption superstructure layer 4 to facilitate the formation of multiple narrow-band absorptions in the reflection spectrum; on the other hand, under the action of an external electric field or an external voltage, the refractive index of the transparent conductive part 52 also changes, changing the dielectric environment around the microstructure top 51 and the microstructure bottom 52; during electric field regulation or voltage regulation, the narrow-band resonance peak moves more, thus realizing more sensitive narrow-band regulation.

[0042] Furthermore, the thickness of the transparent conductive part 52 is less than 60 nanometers. In this way, strong coupling is formed between the microstructure top 51 and the microstructure bottom 53, and the optical microcavity between the interface formed by the microstructure unit 5 and the interface formed by the metal mirror layer 2 can achieve stronger light absorption.

[0043] Example 6

[0044] Based on Embodiment 5, this embodiment provides a point regulation device with specific structural parameters. The relevant structural parameters are as follows: the thickness of the metal mirror layer 2 is 250 nanometers, and the material is gold; the thickness of the nonlinear dielectric layer 3 is 90 nanometers; the diameter of the microstructure unit 5 is 250 nanometers; the heights of the top 51 and bottom 53 of the microstructure are both 280 nanometers; the height of the transparent conductive part 52 is 40 nanometers; above the upper surface of the microstructure unit 5, the thickness of the transparent conductive film layer 6 is 200 nanometers; the substrate 1 is made of silicon material with a thickness of 10 micrometers; the microstructure unit 5 array is a square array with an array period of 350 nanometers. The absorption spectrum of the above structure was calculated using finite element software. As Figure 6 shown, obvious differential electro-optic regulation responses are generated under the regulation of the applied voltage. When the applied voltage value is 0, the absorption rate spectrum shows that the short wavelength band is a wide-band light absorption region and the long wavelength band is a narrow-band light absorption region. Especially in the long wavelength band, under the structural characteristics of this embodiment, 3 obvious light absorption peaks are generated. This once again proves that the technology involved in the present invention can also generate frequency shift selective light absorption in a device composed of disk-shaped structure units. When the applied voltage value is 10 volts, there is no frequency shift in the light absorption region of the short wavelength band of the absorption rate spectrum, while obvious frequency shifts occur in the light absorption peaks of the long wavelength narrow band. For example, the left absorption peak moves from 0.754 micrometers to 0.784 micrometers; the wavelength position corresponding to the middle absorption peak moves from 0.878 micrometers to 0.972 micrometers; the wavelength position corresponding to the right absorption peak moves from 1.218 micrometers to 1.288 micrometers. This embodiment proves that after setting the transparent conductive part 52 in the microstructure unit 5, not only the number of narrow-band absorption peaks is increased, but also under the same voltage regulation, the absorption peaks move more, and more sensitive regulation of the absorption peak position can be achieved.

[0045] Embodiment 7

[0046] Based on Embodiment 5, the microstructure unit 5 is conical. The transparent conductive part 52 is arc-shaped. At the center position of the microstructure unit 5, the transparent conductive part 52 is low; at the edge position of the microstructure unit 5, the transparent conductive part 52 is high. In this way, the light field is not only restricted to the bottom of the microstructure unit 5, thus achieving a greater amplitude of light absorption, but also the light field is restricted to the area below the center position of the microstructure unit 5, concentrating the electric field more densely between the center of the microstructure unit 5 and the metal mirror layer 2, and enabling stronger absorption of the incident light.

[0047] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included within the scope of protection of the present application.

Claims

1. A frequency-domain selective optical absorption electro-optic modulation device, characterized in that, it includes a substrate, a metal mirror layer, a nonlinear dielectric layer, and an optical absorption superstructure layer. The material of the metal mirror layer is metal. The metal mirror layer is placed on the substrate. The nonlinear dielectric layer is placed on the metal mirror layer. The optical absorption superstructure layer is placed on the nonlinear dielectric layer. The optical absorption superstructure layer includes periodically arranged microstructure units and a transparent conductive film layer. The transparent conductive film layer is placed on the nonlinear dielectric layer. The microstructure units are placed on the nonlinear dielectric layer within the transparent conductive film layer. The microstructure units are conical.

2. The frequency-domain selective optical absorption electro-optic modulation device according to claim 1, characterized in that: the material of the nonlinear dielectric layer is 4-dimethylamino-N-methyl-4-stilbazolium p-toluenesulfonate.

3. The frequency-domain selective optical absorption electro-optic modulation device according to claim 1, characterized in that: the substrate is a flexible transparent material.

4. The frequency-domain selective optical absorption electro-optic modulation device according to claim 1, characterized in that: the period is a square array.

5. The frequency-domain selective optical absorption electro-optic modulation device according to claim 1, characterized in that: the material of the transparent conductive film layer is indium tin oxide.

6. The frequency-domain selective optical absorption electro-optic modulation device according to claim 1, characterized in that: the distance between adjacent microstructure units is greater than 100 nanometers.

7. The frequency-domain selective optical absorption electro-optic modulation device according to claim 1, characterized in that: the material of the microstructure units is gold or silver.

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