Laser power detector based on surface plasmon enhanced photo-thermoelectric effect and preparation method thereof

Abstract

The invention discloses a laser power detector based on a surface plasmon enhanced photo-thermoelectric effect and a preparation method thereof, and the detector is provided with a lower nanometer metal film layer, a lower photo-thermal conversion layer, a middle heat transfer layer, an upper oxide insulating film layer, an upper metal thermoelectric function layer and an upper oxide protection layer from bottom to top in sequence. And the positive electrode lead and the negative electrode lead are connected to the upper metal thermoelectric functional layer to serve as output ports of the detector. When laser irradiates the front face of the detector, metal nanoparticles in the lower photothermal conversion layer greatly enhance light absorption through the local surface plasmon resonance effect, generated heat enables the upper metal thermoelectric function layer to generate temperature difference in a heat conduction mode, and then thermoelectric force is generated at the two ends of the electrode due to the Seebeck effect. Therefore, laser power detection is realized. The device has the characteristics of simple structure, high sensitivity, wide spectral response, insensitivity to a detection angle and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of detection and sensing, and particularly relates to a laser power detector based on surface plasmon enhanced optothermoelectric effect. Background Art

[0002] Absorbing the energy of incident light and converting it into thermoelectric potential through heat conduction is the main working principle of a thermopile type laser power detector. Common laser power meters include photoelectric type laser power meters, pyroelectric type laser power meters, and thermopile type laser power meters. In the development process of modern laser power detectors, the cost of devices is getting lower and lower, the manufacturing cost is even lower, and the sensitivity and responsivity of devices are also gradually increasing. The traditional thermopile type laser power meter absorbs the heat of the laser through a photothermal conversion layer and transfers it to the thermopile layer, causing a temperature difference at both ends of the thermopile. Due to the Seebeck effect, a thermoelectric potential is generated, and thus the laser power is measured.

[0003] In current mainstream thermopile laser power meters, the response time of the detector is generally on the order of seconds, and the sensitivity is on the order of mV / W. However, there are still many limitations in terms of consumable costs, manufacturing processes, etc. The limited absorption bandwidth corresponding to the traditional structure is also the main factor restricting its wide application. Therefore, developing new and efficient laser power detection devices is of great significance.

[0004] In recent years, the application of surface plasmon effects in optoelectronic devices has attracted wide attention. Metal nanostructures can significantly enhance the absorption of light through the local surface plasmon resonance (LSPR) effect. For example, patent CN202411478010 discloses introducing microstructures into an infrared photomultiplier tube to utilize the plasmon effect to enhance the infrared absorption of the device, thereby increasing its photoelectric sensitivity. Similarly, the plasmon enhanced absorption effect can also be used for photothermal conversion. For example, patent CN202411452509 utilizes the plasmon effect of nanoparticles themselves to enhance light absorption and generate heat, thereby promoting the photocatalytic performance of the nanoparticles. This also provides a new idea for improving the performance of thermopile type laser power meters. Summary of the Invention

[0005] The purpose of the present invention is to provide a laser power detector based on surface plasmon enhanced optothermoelectric effect and its preparation method. This device simultaneously has the characteristics of simple structure, high sensitivity, wide spectral response, and insensitivity to detection angles.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A laser power detector based on surface plasmon enhanced optothermoelectric effect, the detector is sequentially provided with a lower nano-metal film layer, a lower optothermal conversion layer, an intermediate heat transfer layer, an upper oxide insulating film layer, an upper metal thermoelectric functional layer, and an upper oxide protective layer from bottom to top, and further includes a positive electrode wire and a negative electrode wire connected to the upper metal thermoelectric functional layer as the output port of the detector.

[0008] When the laser irradiates the front of the detector, the metal nanoparticles in the lower optothermal conversion layer greatly enhance the absorption of light through the local surface plasmon resonance effect, and the generated heat generates a temperature difference on the upper metal thermoelectric functional layer through heat conduction, and then a thermoelectric potential is generated at both ends of the electrode due to the Seebeck effect, thereby realizing the detection of the laser power.

[0009] Further, the thickness of the lower nano-metal film layer is 20 - 50 nm.

[0010] Further, the lower optothermal conversion layer is a thermal sprayed silicon layer presenting a Lambertian reflection surface, and its thickness is about 100 - 200 μm.

[0011] Further, the upper oxide insulating film layer is alumina, and the thickness is 20 - 50 μm.

[0012] Further, the thickness of the upper metal thermoelectric functional layer is 200 - 500 nm.

[0013] Further, the thickness of the upper oxide protective layer is 200 - 500 nm.

[0014] Further, the material of the intermediate heat transfer layer is selected from one of aluminum alloy, copper alloy or quartz.

[0015] Further, the material of the lower nano-metal film layer is selected from one of gold, silver and copper, and the material of the upper metal thermoelectric functional layer is selected from two of nickel-chromium, nickel-copper, nickel-silicon and copper.

[0016] Further, the materials of the upper oxide insulating film layer and the upper oxide protective layer are selected from silicon dioxide or alumina, and the materials in the lower optothermal conversion layer are selected from silicon or silicon carbide.

[0017] A preparation method of a laser power detector based on surface plasmon enhanced optothermoelectric effect, comprising the following steps:

[0018] 1) Subject the intermediate heat transfer layer to a standard cleaning process;

[0019] 2) Spray the lower optothermal conversion layer on the lower surface of the intermediate heat transfer layer by thermal spraying;

[0020] 3) Prepare the lower nano-metal film layer on the surface of the lower optothermal conversion layer by thermal evaporation, and control the evaporation rate and time to control the average particle size;

[0021] 4) The upper oxide insulating film layer is grown on the upper surface of the intermediate heat transfer layer by using the plasma enhanced chemical vapor deposition method;

[0022] 5) The upper metal thermoelectric functional layer is deposited on the upper oxide insulating film layer by using the magnetron sputtering method;

[0023] 6) The upper oxide protective layer is grown on the upper metal thermoelectric functional layer by using the PECVD method;

[0024] 7) The positive electrode wire and the negative electrode wire of the electrode are prepared at both ends of the upper metal functional layer through the metallization process.

[0025] Due to the adoption of the above technical solutions, the present invention has the following beneficial effects:

[0026] 1) The local surface plasmon resonance effect of metal nanoparticles is used to enhance light absorption, significantly improving the sensitivity of the device.

[0027] 2) The device has a simple structure, is convenient for processing and preparation, and has a low cost.

[0028] 3) The response time can reach the millisecond level, meeting the requirements of rapid measurement.

[0029] 4) It has a wide spectral response range and can be used for the power detection of lasers with different wavelengths.

[0030] 5) It is insensitive to the polarization state and incident angle of the incident light, improving the practicability. Description of the Drawings

[0031] The present invention will be further described below in conjunction with the drawings and embodiments:

[0032] Figure 1 It is a schematic structural diagram of the laser power detector in the present invention.

[0033] Figure 2 It is a scanning electron microscope image of the lower nano-metal layer in the lower photothermal conversion layer.

[0034] Figure 3 It is the enhancement effect of the lower nano-metal layer on the absorption spectrum of the lower photothermal conversion layer.

[0035] Figure 4 It is the response curve of the detector to the 1106nm high-power laser.

[0036] Figure 5 It is the response curve of the detector under the irradiation of lasers with different wavelengths.

[0037] Figure 6 It is the response curve of the detector at different incident angles.

[0038] Among them, Figure 11. Upper oxide protection layer; 2. Upper metal thermoelectric functional layer; 3. Upper oxide insulating layer; 4. Intermediate heat transfer layer; 5. Lower photothermal conversion layer; 6. Lower nano metal film layer; 101. Positive electrode wire; 102. Negative electrode wire. Detailed implementation mode

[0039] As Figure 1 shown, a laser power detector based on surface plasmon enhanced photothermal-electric effect, the detector is successively provided with a lower nano metal film layer 6, a lower photothermal conversion layer 5, an intermediate heat transfer layer 4, an upper oxide insulating film layer 3, an upper metal thermoelectric functional layer 2, and an upper oxide protection layer 1 from bottom to top, and further includes a positive electrode wire 101 and a negative electrode wire 102 connected to the upper metal thermoelectric functional layer as the output ports of the detector.

[0040] Example 1

[0041] A preparation method of a laser power detector based on surface plasmon enhanced photothermal-electric effect is as follows:

[0042] 1) Select the Figure 1 shown structure, select aluminum alloy as the intermediate heat transfer layer (4), and after the standard cleaning process;

[0043] 2) Adopt the thermal spraying method to spray 100 μm thick silicon on the substrate as the lower photothermal conversion layer (5), and the thermal spraying temperature is 1200 °C.

[0044] 3) Adopt the thermal evaporation method to prepare a lower nano metal film layer (6) composed of gold nanoparticles on the lower photothermal conversion layer, and control the evaporation rate and time to control the average particle size to be Figure 2 shown 80 nm, and the density is about 20 particles / μm 2 ;

[0045] 4) Adopt the plasma enhanced chemical vapor deposition (PECVD) method to grow 20 μm thick alumina as the upper oxide insulating film layer (3);

[0046] 5) Adopt the magnetron sputtering method to deposit a 200 nm thick nickel-silicon and nickel-chromium metal film as the upper metal thermoelectric functional layer (2);

[0047] 6) Adopt the PECVD method to grow 300 nm thick SiO2 as the upper oxide protection layer (1);

[0048] 7) Finally, prepare a positive electrode wire (101) and a negative electrode wire (102) at both ends of the upper metal functional layer through the metallization process.

[0049] Figure 2It shows the morphology and distribution of metal nanoparticles deposited on the lower photothermal conversion layer observed under a scanning electron microscope. The size of the nanoparticles is 80 - 100 nm.

[0050] As Figure 3 shown, the light absorption of the probe containing gold nanoparticles is significantly enhanced between 250 and 650 nm, reaching an average of over 90%. Figure 3 It illustrates the response curve of the device under laser irradiation of different wavelengths, indicating that the device has good broadband response characteristics. In this embodiment, a laser with a maximum power of 300 W and a wavelength of 1106 nm is used to calibrate the detector. As Figure 4 shown, the sensitivity of the detector to the 1106 nm laser is 0.3 mV / W, and the response time is 500 ms.

[0051] Example 2

[0052] A preparation method of a laser power detector based on surface plasmon enhanced photothermal-electric effect is as follows:

[0053] 1) Select the Figure 1 shown structure, select quartz as the intermediate heat transfer layer (4), and after the standard cleaning process;

[0054] 2) Spray 100 μm thick silicon on the substrate as the lower photothermal conversion layer (5) by thermal spraying method, and the thermal spraying temperature is 1200 °C.

[0055] 3) Prepare the lower nano-metal film layer (6) composed of silver nanoparticles on the lower photothermal conversion layer by thermal evaporation method, and control the evaporation rate and time to control the average particle size to be Figure 2 the 50 nm shown, and the density is about 40 particles / μm 2 ;

[0056] 4) Grow 20 μm thick alumina as the upper oxide insulating film layer (3) by plasma enhanced chemical vapor deposition (PECVD) method;

[0057] 5) Deposit 200 nm thick nickel-silicon and nickel-chromium metal films as the upper metal thermoelectric functional layer (2) by magnetron sputtering method;

[0058] 6) Grow 400 nm thick SiO2 as the upper oxide protection layer (1) by PECVD method;

[0059] 7) Finally, prepare the positive electrode wire (101) and the negative electrode wire (102) at both ends of the upper metal functional layer through a metallization process.

[0060] In this embodiment, quartz is used to replace aluminum alloy as the intermediate heat transfer layer, sacrificing the response speed and enhancing the sensitivity. As Figure 5As shown, a detector of this embodiment is calibrated using lasers of three wavelengths (450 nm, 628 nm, and 940 nm) with a power of 0.1 W. The sensitivity of the detector to the lasers of the three wavelengths is 2.2 mV / W, and the response time is 5 s. It can be seen that the sensitivity of the probe is weakly related to the wavelength. This is due to the fact that the photo-thermal conversion layer's light absorption is insensitive to the laser wavelength caused by the surface plasmon enhanced absorption effect. Figure 6 The response characteristic curves of the device at different incident angles are given. The sensitivity of the detector is tested using a 940 nm laser within the range of different incident angles from 0 to 30°. It is found that the change is less than 5%. It can be considered that the sensitivity of the detector is insensitive to the incident angle. This is due to the nanoarray effect formed by the microstructure of the metal nanoparticles.

[0061] The above are only specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on the present invention to solve substantially the same technical problems and achieve substantially the same technical effects are all covered by the protection scope of the present invention.

Claims

1. A laser power detector based on surface plasmon enhanced optothermoelectric effect, characterized in that: The detector is provided with a lower nano-metal film layer, a lower photo-thermal conversion layer, an intermediate heat transfer layer, an upper oxide insulating film layer, an upper metal thermoelectric functional layer, and an upper oxide protective layer in sequence from bottom to top. It also includes a positive electrode wire and a negative electrode wire connected to the upper metal thermoelectric functional layer as the output ports of the detector.

2. The laser power detector based on surface plasmon enhanced optothermoelectric effect according to claim 1, wherein: The thickness of the lower nano-metal film layer is 20 - 50 nm.

3. The laser power detector based on surface plasmon enhanced optothermoelectric effect according to claim 1, characterized in that: The lower photo-thermal conversion layer is a thermally sprayed silicon layer presenting a Lambertian reflecting surface, and its thickness is about 100 - 200 μm.

4. The laser power detector based on surface plasmon enhanced optothermoelectric effect according to claim 1, wherein: The upper oxide insulating film layer is alumina, and its thickness is 20 - 50 μm.

5. The laser power detector based on surface plasmon enhanced optothermoelectric effect according to claim 1, characterized in that: The thickness of the upper metal thermoelectric functional layer is 200 - 500 nm.

6. The laser power detector based on surface plasmon enhanced optothermoelectric effect according to claim 1, characterized in that: The thickness of the upper oxide protective layer is 200 - 500 nm.

7. The laser power detector based on surface plasmon enhanced optothermoelectric effect according to claim 1, characterized in that: The material of the intermediate heat transfer layer is selected from one of aluminum alloy, copper alloy or quartz.

8. The laser power detector based on surface plasmon enhanced optothermoelectric effect according to claim 1, wherein: The material of the lower nano-metal film layer is selected from one of gold, silver, and copper, and the material of the upper metal thermoelectric functional layer is selected from two of nickel-chromium, nickel-copper, nickel-silicon, and copper.

9. The laser power detector based on surface plasmon enhanced optothermoelectric effect according to claim 1, characterized in that: The materials of the upper oxide insulating film layer and the upper oxide protective layer are selected from silicon dioxide or alumina, and the materials in the lower photo-thermal conversion layer are selected from silicon or silicon carbide.

10. A method for preparing a laser power detector based on surface plasmon enhanced optothermoelectric effect as described in claim 1, characterized in that, It includes the following steps: 1) Subject the intermediate heat transfer layer to a standard cleaning process; 2) Spray the lower photo-thermal conversion layer on the lower surface of the intermediate heat transfer layer by thermal spraying; 3) Prepare the lower nano-metal film layer on the surface of the lower photo-thermal conversion layer by thermal evaporation, and control the evaporation rate and time to control the average particle size; 4) Grow the upper oxide insulating film layer on the upper surface of the intermediate heat transfer layer by plasma-enhanced chemical vapor deposition; 5) Deposit the upper metal thermoelectric functional layer on the upper oxide insulating film layer by magnetron sputtering; 6) Grow the upper oxide protective layer on the upper metal thermoelectric functional layer by PECVD; 7) Prepare the positive electrode wire and the negative electrode wire at both ends of the upper metal functional layer through a metallization process.

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