WO2021170112A1 - 基于黑碳化硅陶瓷的热电型光探测器、光功率计和光能量计 - Google Patents

基于黑碳化硅陶瓷的热电型光探测器、光功率计和光能量计 Download PDF

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WO2021170112A1
WO2021170112A1 PCT/CN2021/078269 CN2021078269W WO2021170112A1 WO 2021170112 A1 WO2021170112 A1 WO 2021170112A1 CN 2021078269 W CN2021078269 W CN 2021078269W WO 2021170112 A1 WO2021170112 A1 WO 2021170112A1
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silicon carbide
pyroelectric
black silicon
optical
thermopile
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PCT/CN2021/078269
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English (en)
French (fr)
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李德龙
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山东芯源光电科技有限公司
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Priority to JP2022552250A priority Critical patent/JP2023525432A/ja
Priority to EP21759552.9A priority patent/EP4113079A4/en
Publication of WO2021170112A1 publication Critical patent/WO2021170112A1/zh
Priority to US17/822,778 priority patent/US20220412806A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
    • G01J1/4257—Photometry, e.g. photographic exposure meter using electric radiation detectors applied to monitoring the characteristics of a beam, e.g. laser beam, headlamp beam
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
    • G01J5/10—Radiation pyrometry, e.g. infrared or optical thermometry using electric radiation detectors
    • G01J5/12—Radiation pyrometry, e.g. infrared or optical thermometry using electric radiation detectors using thermoelectric elements, e.g. thermocouples
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
    • G01J1/44—Electric circuits
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
    • G01J5/02—Constructional details
    • G01J5/0215—Compact construction
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
    • G01J5/02—Constructional details
    • G01J5/08—Optical arrangements
    • G01J5/0853—Optical arrangements having infrared absorbers other than the usual absorber layers deposited on infrared detectors like bolometers, wherein the heat propagation between the absorber and the detecting element occurs within a solid
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
    • H10N10/01—Manufacture or treatment
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
    • H10N10/10—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects operating with only the Peltier or Seebeck effects
    • H10N10/17—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects operating with only the Peltier or Seebeck effects characterised by the structure or configuration of the cell or thermocouple forming the device
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
    • G01J1/44—Electric circuits
    • G01J2001/4446—Type of detector

Definitions

  • the invention relates to a pyroelectric optical detector, in particular to a pyroelectric optical detector based on black silicon carbide ceramics, and also relates to a pyroelectric optical power meter/pyroelectric optical energy meter using the pyroelectric optical detector .
  • a pyroelectric laser detector such as a pyroelectric optical power meter or a laser detector used in a pyroelectric optical energy meter produced by Optronics, Coherent, Gentec-EO, Laserpoint, etc.
  • Figure 1 Show. They generally use an aluminum alloy substrate as the thermal conductive plate 100, and a dark optical absorption coating 101 is provided on one side of the thermal conductive plate 100 to achieve a high rate of absorption of the optical incident surface.
  • the other side of the thermal conductive plate 100 is first provided with an insulating layer 102 ( Or directly generate an insulating oxide layer on the surface of the aluminum alloy), and then set a thermopile 103 on the surface of the insulating layer 102 (ie, multiple thermocouples are connected in series and attached to the surface of the insulating layer 102) to detect the temperature difference generated during heat conduction , And then realize the measurement of incident light power or light pulse energy.
  • the existing pyroelectric laser detectors have many defects, such as short life span, high failure rate, and poor durability, resulting in frequent replacement and maintenance by users.
  • the existing pyroelectric laser detectors have the following problems: 1.
  • the dark optical absorption coating 101 arranged on the surface of the optical incident surface of the aluminum alloy substrate is extremely easy to be damaged by the high-energy laser, resulting in optical absorption rate Once exposed, the surface of the aluminum alloy substrate used as the thermal conductive plate 100 will have a higher optical reflectivity, which will cause the laser detector to be misaligned; 2.
  • the surface of the dark optical absorption coating 101 is easily contaminated by humans and is difficult to clean.
  • the aluminum alloy substrate is not resistant to high temperatures, and its melting point is 500 to 660°C, the high temperature resistance limit of laser detectors based on aluminum alloy substrates generally does not exceed 300°C, so they cannot withstand higher average power optical measurements.
  • the damage of the dark optical absorption coating 101 is the main reason for the failure and failure of a large number of pyroelectric laser detectors, and the pyroelectric laser detectors with such failures can only be replaced and cannot be repaired, and the use cost is very high. high.
  • the primary technical problem to be solved by the present invention is to provide a pyroelectric photodetector based on black silicon carbide ceramics, which is used for light power measurement and light pulse energy measurement.
  • Another technical problem to be solved by the present invention is to provide a pyroelectric optical power meter/pyroelectric optical energy meter using the above pyroelectric optical detector.
  • a pyroelectric photodetector including a thermally conductive plate made of black silicon carbide ceramics, the thermally conductive plate as a whole as a light absorber; one side surface of the thermally conductive plate is optical Absorbing surface; a thermopile is provided on either side of the heat conducting plate.
  • thermopile forms a closed curve around the optical incident area.
  • thermopile and the adiabatic edge jointly surround the optical incident area to form a closed curve.
  • a pyroelectric photodetector which includes a thermally conductive plate made of black silicon carbide ceramics, and also includes a series-connected conductive metal layer and a heat-dissipating ceramic plate;
  • the heat conduction plate as a whole is a light absorber; one side surface of the heat conduction plate is an optical absorption surface, and the series conductive metal layer is arranged on the other side surface of the heat conduction plate, and is far away from the series conductive metal layer.
  • a heat-dissipating ceramic plate is arranged on one side surface of the heat conducting plate.
  • the series-connected conductive metal layer includes a thermocouple group composed of a plurality of series-connected thermocouples, the thermocouple group includes a plurality of semiconductor groups and a plurality of copper electrode plates, and the semiconductor group includes an N-type semiconductor and a P Type semiconductor, a plurality of semiconductor groups are connected in series through a plurality of copper electrode plates, and the copper electrode plates at both ends of the head and tail form a positive electrode and a negative electrode.
  • the surface of the heat dissipation ceramic plate on the side away from the series conductive metal layer is metalized.
  • a heat sink is provided on the side surface of the heat dissipation ceramic plate away from the series conductive metal layer.
  • the black silicon carbide ceramic is sintered from black silicon carbide powder.
  • the black silicon carbide ceramic is sintered from black silicon carbide powder through any one of pressureless sintering, high temperature isostatic pressing sintering, hot pressing sintering, recrystallization, reaction sintering, and chemical vapor deposition. become. Among them, a higher pressure sintering environment will lead to higher density and higher thermal conductivity.
  • the density of the black silicon carbide ceramic is between 2.6 and 3.2 g/cm 3.
  • the higher the density the better the thermal conductivity.
  • the optical absorption surface of the black silicon carbide ceramic is non-mirror surface.
  • the surface roughness Ra of the optical absorption surface of the black silicon carbide ceramic is between 0.8 and 6.3 um.
  • the laser damage threshold of the black silicon carbide ceramic is greater than 3 GW/cm 2 under a narrow pulse and high peak power and at least 200-500 J/cm 2 under a wide pulse and high energy.
  • a pyroelectric optical power meter/pyroelectric optical energy meter using the above pyroelectric optical detector is provided.
  • the pyroelectric photodetector based on black silicon carbide ceramic provided by the present invention includes a heat conducting plate made of black silicon carbide ceramic.
  • the whole heat-conducting plate serves as a light absorber; one side of the heat-conducting plate is an optical absorption surface.
  • a thermopile is arranged on either side surface (optical absorption surface or the surface opposite to the optical absorption surface) of the heat conducting plate to form a pyroelectric photodetector.
  • a pyroelectric photodetector is formed by arranging a series conductive metal layer and a heat dissipation ceramic plate on the back of the heat conducting plate.
  • the black silicon carbide ceramics as the heat-conducting plate and light absorber at the same time, it replaces the three-layer structure in the existing pyroelectric photodetector (including aluminum alloy substrate, dark optical absorption coating and Insulation layer), the black silicon carbide ceramic is directly combined with the thermopile or the series conductive metal layer to form a pyroelectric photodetector, which simplifies the structure of the pyroelectric photodetector.
  • Fig. 1 is a schematic structural diagram of a pyroelectric photodetector using an aluminum alloy substrate as a heat conducting plate in the prior art
  • Fig. 2 is a schematic structural diagram of a pyroelectric photodetector using black silicon carbide ceramics as a heat conducting plate provided by the present invention
  • Figure 3 is a schematic view of the structure of a thermopile provided on the surface of the heat conducting plate
  • 4a to 4h are structural schematic diagrams of various pyroelectric optical detectors provided by embodiments of the present invention.
  • FIG. 5 is a schematic structural diagram of a thermoelectric optical power meter/pyroelectric optical energy meter according to an embodiment of the present invention
  • Fig. 6 is a schematic structural diagram of another pyroelectric photodetector using black silicon carbide ceramics as a heat conducting plate provided by the present invention.
  • the pyroelectric photodetector based on black silicon carbide ceramic provided by the embodiment of the present invention includes a heat conducting plate 21 made of black silicon carbide ceramic.
  • the surface on one side of the light 10 (the surface with a larger area) is the optical absorption surface 211.
  • a thermopile 22 is provided on either side of the heat conducting plate 21 to form a pyroelectric photodetector.
  • the thermopile 22 can be arranged on the optical absorption surface 211 of the heat conducting plate 21, or on the other side surface 212 (the surface opposite to the optical absorption surface 211, also called the back surface 212) of the heat conducting plate 21.
  • thermopile 22 is arranged on the back 212 of the heat conducting plate 21 to prevent the thermopile 22 from being contaminated.
  • the heat 15 absorbed in the detection process of the pyroelectric photodetector passes through the thermopile 22 and then diffuses outward from the side surface 213 of the heat conducting plate 21.
  • a heat sink in contact with the heat conducting plate 21 is needed to dissipate heat.
  • thermopile 22 is composed of a plurality of thermocouples connected in series.
  • the thermopile 22 has a series of bimetallic junctions (including the hot end 22A and the cold end 22B). The temperature difference between any two adjacent junctions will be This causes a voltage to form between the two junctions. Since multiple nodes are connected in series, the hot end 22A is always inside, the hotter side, the cold end 22B is outside, and the colder side. Therefore, the radial heat flow through the thermopile 22 will cause the output of the thermopile 22 Terminal 22C generates a voltage proportional to the power input.
  • the incident light 10 irradiates the optical incident area 25 (ie, the center of the area enclosed by the thermopile 22 with a closed curve shape), and the heat absorbed by the heat conducting plate 21 flows radially and is dissipated from the outer area of the thermopile 22.
  • the optical incident area 25 ie, the center of the area enclosed by the thermopile 22 with a closed curve shape
  • a single-layer material (specifically, a light absorber made of black silicon carbide ceramics and a heat-conducting plate integrated structure) is used instead of the traditional The three-layer structure of the pyroelectric photodetector (specifically, the aluminum alloy substrate 100, the dark optical absorption coating 101 and the insulating layer 102 shown in FIG. 1).
  • the black silicon carbide ceramic is used as the heat conducting plate 21 and the light absorber at the same time, which fundamentally eliminates the existing three-layer structure.
  • the dark optical absorption coating 101 is damaged, the aluminum alloy substrate 100 with high optical reflectivity is exposed, which is easy to cause The problem of inaccurate test results.
  • the installation of the insulating layer is omitted, and the problem of the electric heating pile falling off due to the mismatch of the thermal expansion rate of the heat conducting plate and the insulating layer is avoided.
  • the black silicon carbide ceramic used in the above structure is formed from black silicon carbide powder through a sintering process.
  • black silicon carbide ceramics are made by sintering black silicon carbide powder through any one of pressureless sintering, high-temperature isostatic pressing sintering, hot pressing sintering, recrystallization, reaction sintering, and chemical vapor deposition.
  • a higher pressure sintering environment will result in higher density and higher thermal conductivity.
  • the purpose of the technical solution provided by the embodiments of the present invention is to protect the pyroelectric photodetector made of black silicon carbide ceramics as a heat conducting plate and light absorber, rather than black silicon carbide ceramic sintering process or black silicon carbide sintering process.
  • the ceramic itself. Therefore, even if the existing sintering process is improved to obtain a denser or more uniform black silicon carbide ceramic, as long as it is used to manufacture the pyroelectric photodetector provided by the embodiment of the present invention, it belongs to the protection claimed by the present invention. Scope.
  • Black silicon carbide ceramics are sintered from black silicon carbide powder.
  • preparation methods to synthesize black silicon carbide powder such as Acheson synthesis method, laser method, organic precursor method and so on.
  • Acheson synthesis method which prepares black silicon carbide powder by adding quartz sand and coke into the furnace body, and adding an appropriate amount of wood chips as additives. Since the volume of the furnace body of the reaction furnace is often large, this makes the temperature distribution in the furnace body uneven to a certain extent, so the synthesized silicon carbide powder may have a certain difference in performance.
  • the quartz sand and coke used as raw materials for the reaction are often not very pure, and they may contain some metal impurities such as iron and aluminum. Therefore, there may be impurities in the obtained silicon carbide powder.
  • Even pure silicon carbide powder is often colorless, while silicon carbide doped with a small amount of metal impurities appears green. When the content of metal impurities increases, the color of silicon carbide powder will deepen and appear black.
  • the toughness of black silicon carbide is higher than that of green silicon carbide, and it is mainly used for processing ceramics, refractory materials and non-ferrous metals. Silicon carbide ceramics sintered from black silicon carbide powder will also appear black, so it is called black silicon carbide ceramics.
  • black silicon carbide ceramics sintered from silicon carbide powder with a darker color are selected as the heat conducting plate 21 and the light absorber of the pyroelectric photodetector.
  • the black silicon carbide ceramic mentioned in the embodiment of the present invention is to distinguish from the lighter green silicon carbide ceramic, and may include but not limited to dark blue, dark gray, and black gray carbonized Silicon ceramics are used to ensure a high light absorption rate, and the color of the silicon carbide ceramics used is not limited to black.
  • pure silicon carbide material has certain electrical conductivity, poor insulation, and is suitable for use as a semiconductor. Therefore, it is not suitable for use as a connection matrix for thermopile, and therefore is not suitable for the pyroelectric photodetector provided by the embodiment of the present invention. Used in. In addition, the compactness and thermal conductivity of ordinary silicon carbide materials are also insufficient; therefore, it is not suitable for making the heat conducting plate 21 and the light absorber of the pyroelectric photodetector. Silicon carbide ceramics have poor electrical conductivity and are suitable for use as a substrate for setting thermopiles. In addition, silicon carbide ceramics have high compactness and thermal conductivity, and are suitable for use as the heat-conducting plate 21 and the light absorber of the pyroelectric photodetector.
  • black silicon carbide ceramic as a spectroscopic optical absorption material is more suitable as a thermal conductive plate 21 and a light absorber of a pyroelectric photodetector.
  • black silicon carbide ceramics have a larger impurity content, and have greater resistivity, thermal conductivity and light absorption.
  • the surface reflectivity is lower than that of pure silicon carbide materials and green silicon carbide materials.
  • Silicon carbide ceramics are more suitable for making pyroelectric optical detectors.
  • black silicon carbide ceramic is used as the heat conducting plate 21.
  • black has an irreplaceable advantage as an optical absorption medium.
  • the optical absorption surface 211 of the black silicon carbide ceramic is not a mirror surface. It has a certain surface roughness, such as controlling Ra between 0.8 and 6.3um, which can ensure better optical absorption.
  • the particle size of the diamond abrasive paste used also needs to match the surface roughness.
  • Using a diamond abrasive paste with a certain particle size to clean the optical absorption surface of the thermal conductive plate 21 can repair the surface roughness of the optical absorption surface, which is conducive to optical absorption.
  • the surface roughness of the detection area ie, the optical incident area 25
  • thermopile 22 when black silicon carbide ceramics are used to make the heat conducting plate 21 and the light absorber, the amount of impurities contained therein should ensure that the resistance of the black silicon carbide ceramic is much higher than that of the thermopile 22 (R black silicon carbide ceramic>> R thermopile) to minimize the interference of the black silicon carbide ceramic conductivity to the thermopile 22, and the low conductivity of the existing black silicon carbide ceramic material can meet this requirement. Therefore, the thermopile 22 can be directly mounted on the back of the black silicon carbide ceramic 21 without an additional insulating layer.
  • the density of the pure silicon carbide crystal is 3.16-3.2 g/cm 3
  • the density of the black silicon carbide ceramic obtained by the sintering process is between 2.6-3.2 g/cm 3.
  • the density of the dense black silicon carbide ceramic can reach more than 98% of the theoretical density of the silicon carbide ceramic.
  • the higher the density of black silicon carbide ceramics the better its thermal conductivity, and the more suitable it is to make pyroelectric optical detectors.
  • the black silicon carbide ceramic that meets the requirements of the embodiments of the present invention also meets the following characteristics: the black silicon carbide ceramic itself is a black body, can absorb laser light without coating, and has consistent and good optics on both the surface and the interior.
  • black silicon carbide ceramics have good insulation properties and low electrical conductivity, and can be in direct physical contact with the thermopile 22 without causing short circuits or electrical interference; black silicon carbide ceramics have good thermal conductivity and can quickly dissipate heat, thereby Avoid burning caused by high-power laser; black silicon carbide ceramic has a low thermal expansion coefficient, so it is tightly combined with the thermopile, is not prone to thermal expansion and cracking, and prevents the thermopile from falling off; and, black silicon carbide ceramic has a higher The laser damage threshold (see below for details) can withstand high temperature and does not melt. Therefore, the black silicon carbide ceramic is suitable for making the pyroelectric photodetector provided by the embodiment of the present invention. In addition, the black silicon carbide ceramic has reasonable density and specific heat capacity, which can ensure that the pyroelectric photodetector has sufficient response speed.
  • Table 1 is a comparison table of related parameters between common black silicon carbide ceramics and common aluminum alloys. After comparison, it can be seen that the thermal conductivity, density, and specific heat capacity of black silicon carbide ceramics are similar to aluminum alloys; at the same time, the characteristics of working temperature, thermal expansion coefficient, light reflectivity, and resistivity are more obvious than aluminum alloys. Application advantages. Therefore, the inventor believes that black silicon carbide ceramics have more advantages than aluminum alloys as the heat-conducting plate and light absorber of laser detectors.
  • the ceramic density is 3.15g/cm 3
  • the silicon carbide content is about 98%
  • the optical absorption rate for 635nm wavelength is about 80%
  • the thermal conductivity is about 150W/(m ⁇ K)
  • the ceramic thickness is 2mm
  • the surface roughness Ra 0.8um
  • the first experiment was a short pulse, high peak power test.
  • the test light source selects a pulsed laser with a wavelength of 1064nm, a pulse width of 500ps, and a single pulse energy of 200mJ, to irradiate the surface of the black silicon carbide ceramic sample under circular spots of different diameters.
  • the spot diameter is 2mm and 3mm, the surface of the silicon carbide ceramic is slightly damaged, and when the spot diameter is 4mm and 5mm, the surface of the silicon carbide ceramic has no obvious damage except for the slight white spots in the color. Based on this, it is judged that the laser damage threshold is between 3.2GW/cm 2 and 5.6GW/cm 2 .
  • the laser damage threshold of aluminum alloy detectors with optical absorption coatings is generally within 30MW/cm 2.
  • the laser damage threshold of Optronics laser detectors is about 3 MW/cm 2, while the laser damage threshold of Laserpoint laser detectors The threshold is about 30MW/cm 2 . It can be said that the laser damage threshold of black silicon carbide ceramics has been increased by more than 100 times.
  • the second experiment is a wide pulse, high energy test: at room temperature 20°C, under the state of 2ms wide pulse, using a 200J 808nm semiconductor laser, on a 10mm ⁇ 10mm spot area, the thickness of black silicon carbide ceramics is 2mm. Surface irradiation, measured the highest local temperature of the irradiated area reached about 300 °C, but no material damage occurred. This shows that in the wide pulse state, the energy damage threshold is greater than 200J/cm 2 .
  • the energy density of the laser at this time reached 534 J/cm 2 . That is, its theoretical laser damage threshold is greater than 500J/cm 2 .
  • the laser damage threshold of an aluminum alloy substrate with an optical absorption coating is generally within 50J/cm 2.
  • the damage threshold of the laser detector of Optronics is about 10J/cm 2
  • the damage threshold of the laser detector of Laserpoint is about 36J. /cm 2 Detector loss. It can be considered that the damage threshold of silicon carbide ceramics under the condition of wide pulse and high energy is increased by about 10 times.
  • the use of black silicon carbide ceramics as the thermal conductive plate and light absorber of the pyroelectric photodetector can greatly increase the optical damage threshold of the laser detector, thereby increasing its life and durability. It is extremely suitable for detecting ultra-high power light or Pulse energy.
  • the structure of the pyroelectric photodetector provided by the embodiment of the present invention will be schematically introduced below in conjunction with FIG. 2 to FIG. 4h.
  • the following embodiments are only used to illustrate the structure of the pyroelectric photodetector, and do not constitute a specific structural limitation.
  • the pyroelectric photodetector based on black silicon carbide ceramics includes a heat conducting plate 21 made of black silicon carbide ceramics, and the entire heat conducting plate 21 serves as a light absorber;
  • One side surface of the plate 21 is an optical absorption surface 211;
  • a thermopile 22 is arranged on one side surface of the heat conducting plate 21 to form a pyroelectric photodetector.
  • the thermopile 22 may be arranged on the optical absorption surface 211 of the heat conducting plate 21, and the thermopile 22 may also be arranged on the other side surface 212 (the surface opposite to the optical absorption surface 211, also called the back surface) of the heat conducting plate 21.
  • the thermopile 22 is arranged on the back 212 of the heat conducting plate 21 to prevent the thermopile 22 from being contaminated.
  • thermopile 22 is arranged on the outside of the optical incident area 25 of the heat conducting plate 21, and the outside of the thermopile 22 is the heat dissipation area 24 (see the area marked c in FIGS. 4a to 4h); the optical incident area 25
  • the absorbed heat is dissipated to the outside through the thermopile 21 (in FIGS. 4a to 4h, the diffusion direction of the heat inside the optical incident area 25 is marked with black arrows).
  • thermopile 22 The hot end 22A of the thermopile 22 is arranged on the inner side of the area where the thermopile 22 is located (the side close to the optical incident area 25), and the cold end 22B of the thermopile 22 is arranged on the outer side of the area where the thermopile 22 is located (close to the heat dissipation area 24). Side), the two ends of the thermopile 22 are led out to form an output end 22C.
  • the thermopile 22 is formed by connecting multiple nodes in series to increase its output voltage. The output voltage is proportional to the temperature difference generated by the heat flowing through the hot end 22A and the cold end 22B of the thermopile 22; by detecting the output voltage, The power and energy of incident light can be detected.
  • thermopile 22 and the insulating edge 23 are enclosed in a closed shape; wherein the insulating edge 23 is used to prevent the heat absorbed by the optical incident area 25 from diffusing outward from the position of the insulating edge 23. This is achieved by making the heat conducting plate 21 at this position not contact the heat sink, so that all the heat flows through the thermopile 22.
  • thermopile 22 is enclosed in a closed shape to ensure that all the heat flows through the thermopile 22.
  • thermopile 22 Since all the heat absorbed by the heat conducting plate 21 flows through the thermopile 22 (as long as the incident light 10 illuminates the inner circle of the thermal junction 22A), the response of the pyroelectric photodetector is almost independent of the size and position of the incident light beam. If the beam is near the edge of the inner circle, some thermocouples will be hotter than others, but since the sum of all thermocouples is measured, the reading remains the same.
  • the shape of the heat conducting plate 21 is not limited to a circle, a rectangle, and a regular polygon, and may also be other shapes not shown, and may be a regular pattern or an irregular pattern;
  • the thermopile 22 forms a closed curve around the optical incident area 25, or the thermopile 22 and the adiabatic edge 23 surround a closed curve; the thermopile 22 (or the thermopile 22 and the adiabatic edge 23) arranged on the heat conducting plate 21 forms a closed curve
  • the topological figure of the curve does not necessarily correspond to the shape of the heat conducting plate 21 either.
  • thermopile 22 is not limited to the center position of the heat-conducting plate 21; when some sides of the heat-conducting plate 21 are set as the insulating edges 23, the location of the thermopile 22 can be set close to the edge or corner.
  • the shape of the heat conducting plate 21 is circular, and the thermopile 22 is a ring-shaped thermopile 220 formed by connecting a plurality of thermocouples in series.
  • the ring-shaped thermopile 220 is distributed around the center of the heat conducting plate 21 to form Close the curve.
  • the gray area represents the optical incident area 25
  • the ring-shaped thermopile 220 is arranged in a circle around the optical incident area 25
  • the symbol c represents the heat dissipation area 24 on the outside of the ring-shaped thermopile 220, in the optical incident area
  • the black arrow in 25 indicates the diffusion direction of the heat, and the heat absorbed by the optical incident area 25 is dissipated outward through the annular thermopile 220.
  • the shape of the heat conducting plate 21 is circular
  • the thermopile 22 is a box-shaped thermopile 221 formed by a plurality of thermocouples connected in series
  • the box-shaped thermopile 221 surrounds the heat conducting plate 21. Distributed in the center, forming a closed curve.
  • the optical incident area 25 defined by the box-shaped thermopile 221 is represented by a gray area.
  • the box-shaped thermopile 221 is arranged in a box shape around the optical incident area 25, on the outside of the box-shaped thermopile 220
  • the symbol c represents the heat dissipation area 24, and the black arrow in the optical incident area 25 represents the diffusion direction of heat.
  • the heat absorbed by the optical incident area 25 is dissipated outward through the box-shaped thermopile 221.
  • the shape of the heat conducting plate 21 is square, and the thermopile 22 is a box-shaped thermopile 221 formed by a plurality of thermocouples connected in series.
  • the box-shaped thermopile 221 surrounds the center of the heat conducting plate 21. Distribution, forming a closed curve.
  • the optical incident area 25 defined by the box-shaped thermopile 221 is represented by a gray area.
  • the box-shaped thermopile 221 is arranged in a box shape around the optical incident area 25, on the outside of the box-shaped thermopile 221
  • the symbol c represents the heat dissipation area 24, and the black arrow in the optical incident area 25 represents the diffusion direction of heat.
  • the heat absorbed by the optical incident area 25 is dissipated outward through the box-shaped thermopile 221.
  • the shape of the heat conducting plate 21 is a hexagon
  • the thermopile 22 is a triangular thermopile 222 formed by a plurality of thermocouples connected in series
  • the triangular thermopile 222 is distributed around the center of the heat conducting plate 21, Form a closed curve.
  • the gray area represents the optical incident area 25 defined by the triangular thermopile 222
  • the triangular thermopile 222 is arranged in a triangle around the optical incident area 25, and the symbol c is used to denote the heat dissipation area 24 on the outside of the triangular thermopile 222.
  • the black arrows in the optical incident area 25 indicate the diffusion direction of the heat, and the heat absorbed by the optical incident area 25 is dissipated outward through the triangular thermopile 222.
  • the shape of the heat-conducting plate 21 is rectangular, a heat-insulating edge 23 is provided on one or two sides of the heat-conducting plate 21, and the thermopile 22 is arranged on the periphery of the optical incident area 25 There is no area enclosed by the adiabatic edge 23, and the adiabatic edge 23 and the thermopile 22 together form a closed curve.
  • the insulating edge 23 is set close to the side or corner. Therefore, the closed area enclosed by the thermopile 22 and the insulating edge 23 is also set close to the side or corner.
  • the heat absorbed from the optical incident area 25 is only from the thermopile 22. The direction in which it is located spreads outward.
  • the heat-insulating edge 23 is arranged on the upper side of the heat conducting plate 21, and the heat-insulating edge 23 occupies the middle part of the upper side; the U-shaped electric heating pile 223 and the heat-insulating edge 23 are enclosed in a box-shaped closed shape, The inside is an optical incident area 25, and the heat absorbed by the optical incident area 25 is dissipated from the U-shaped thermopile 223 arranged on the left, lower, and right sides to the heat dissipation area 24 located outside the U-shaped thermopile 223.
  • the thermal insulation edge 23 is provided on the left side, the upper side and the lower side of the heat conducting plate 21 at the same time, and the thermal insulation edge 23 occupies the left half of the upper and lower sides;
  • the linear thermopile 224 is provided In a position close to the right side of the heat conducting plate 21, the heat conducting plate 21 is divided into a light incident area 25 on the left and a heat dissipation area 24 on the right; the heat absorbed by the optical incident area 25 is directed from the linear thermopile 224 to The heat dissipation area 24 on the right side is scattered.
  • the thermal insulation edge 23 is provided on the left side and the upper side of the heat conducting plate 21 at the same time, and the thermal insulation edge 23 occupies the left part of the left side and the upper part of the upper side; the broken line type thermopile 225 and The adiabatic edge 23 is surrounded by a box-shaped closed shape, and its interior is the optical incident area 25.
  • the optical incident area 25 is located near the upper left corner of the heat conducting plate 21.
  • the optical incident area 25 absorbs heat from the folded-line thermopile 225 to the outside (Specifically, the lower and right sides of the broken line thermopile 225), the heat dissipation area 24 is scattered.
  • thermopile 226 includes two linear thermopiles 226a and 226b, the left thermopile 226a and the right thermopile 226b, respectively It is arranged on both sides of the insulation edge 23, and one end of the left thermopile 226a and the right thermopile 226b (the lower end as shown in the figure) are connected as a whole by wires, and the other end of the left thermopile 226a and the right thermopile 226b (as shown in the figure) Shown as the upper end) lead out as the output end 22C.
  • the left side area of the left thermopile 226a and the right side area of the right thermopile 226b are the heat dissipation area 24, so that the heat absorbed by the optical incident area 25 passes through the left thermopile 226a and the right thermopile 226b, respectively.
  • the heat dissipation areas 24 on both sides of the conductive plate 21 are scattered.
  • thermopile 22 set on the surface of the black silicon carbide ceramic 21 can choose different thermoelectrics such as bismuth-silver, nickel-chromium-nickel silicon, copper-constantan, platinum-rhodium, etc. according to different applications such as application temperature, measurement accuracy, and use environment. Even combination.
  • thermoelectric optical power meter (or thermoelectric optical energy meter).
  • the pyroelectric optical power meter/pyroelectric optical energy meter mainly includes the above-mentioned pyroelectric optical detector and the voltmeter 8, and may also include other well-known supporting components. Among them, the output terminal 22C of the pyroelectric photodetector is connected to the voltmeter 8.
  • the voltmeter 8 is used to measure the voltage value output by the pyroelectric optical detector in a predetermined ratio to the actual power of the laser to be measured.
  • the voltmeter 8 can be realized by a digital multimeter.
  • the digital multimeter can directly display the voltage value output by the pyroelectric photodetector in a predetermined ratio to the actual power of the laser to be measured. According to the voltage value in a predetermined ratio to the actual power of the laser to be measured, Deduct the actual power of the laser to be measured.
  • the heat generated by the incident light 10 can make the temperature difference detected by the thermopile 22 disposed on the surface of the heat conducting plate 21 remain stable for a long time, correspondingly
  • the curve of the output voltage of the thermopile maintains a certain peak value for a long period of time.
  • the above-mentioned pyroelectric photodetector can obtain the optical power of the incident light 10 by measuring the constant voltage generated by the thermopile 22 over a period of time.
  • the incident light 10 is a light pulse that lasts for a short time
  • the heat generated by the light pulse can cause the temperature difference detected by the thermopile 22 disposed on the surface of the heat conducting plate 21 to fluctuate in a short time.
  • thermoelectric The curve of the output voltage of the stack 22 fluctuates in a relatively short period of time.
  • the energy of the light pulse can be obtained, so that the energy measurement of the light pulse can be performed.
  • the optical signal measured by the photodetector/optical power meter/optical energy meter of the present invention is mainly laser, and can also include other types of optical signals, such as ultraviolet light, infrared light, and X-ray. , Even including the fluorescence emitted by weak light sources.
  • the pyroelectric photodetector provided by the embodiment of the present invention includes: a thermally conductive plate 301 made of black silicon carbide ceramic, and also includes a conductive metal layer 302 and a heat-dissipating ceramic plate 303 in series.
  • the heat-conducting plate 301 as a whole serves as a light absorber; one side surface of the heat-conducting plate 301 is an optical absorption surface (the upper surface as shown in FIG. 6), incident light 10 is irradiated to this surface, and the heat-conducting plate 301 absorbs heat.
  • the series conductive metal layer 302 is provided on the other side surface of the heat conducting plate 301 (the lower surface as shown in FIG.
  • the heat conduction plate 301, the series conductive metal layer 302 and the heat dissipation ceramic plate 303 form a three-layer structure.
  • the thermal conductive plate 301 is made of black silicon carbide ceramics.
  • the black silicon carbide ceramic serves as a thermal conductive plate and a light absorber at the same time, replacing the three-layer structure in the existing pyroelectric photodetector (including aluminum alloy substrate, dark Optical absorption coating and insulating layer), the black silicon carbide ceramic is directly combined with the series conductive metal layer to form a pyroelectric photodetector with a vertical structure, which simplifies the structure of the pyroelectric photodetector.
  • the series-connected conductive metal layer 302 includes a thermocouple group composed of a plurality of series-connected thermocouples 320, the first end 321 of the thermocouple group is a positive electrode, and the second end 322 of the thermocouple group is a negative electrode.
  • the thermocouple group includes multiple semiconductor groups and multiple copper electrode plates.
  • the semiconductor group includes an N-type semiconductor and a P-type semiconductor.
  • the positive and negative electrodes are formed.
  • the thermocouple group uses paired general thermocouple materials such as pure copper-constantan, nickel-chromium-nickel silicon, or P-type and N-type bismuth telluride semiconductor-type thermocouple materials.
  • the heat dissipation ceramic plate 303 can be selected from various types of insulating and thermally conductive ceramics such as alumina, aluminum nitride, silicon carbide, and silicon nitride, or black silicon carbide ceramics.
  • insulating and thermally conductive ceramics such as alumina, aluminum nitride, silicon carbide, and silicon nitride, or black silicon carbide ceramics.
  • the use of ceramic materials with good thermal conductivity ensures the heat conduction effect between the heat conducting plate 301 and the heat dissipation ceramic plate 303. So as to realize the integrated conversion effect of light-heat-electricity.
  • a heat sink is provided on the surface of the heat dissipation ceramic plate 303 far away from the series conductive metal layer 302 to realize heat dissipation.
  • the side surface of the heat dissipation ceramic plate 303 away from the series conductive metal layer 302 is metalized to facilitate welding to an external heat sink for heat dissipation.
  • the heat dissipation element (not shown) is arranged on the side of the heat dissipation ceramic plate 303 away from the series conductive metal layer 302, and is used to absorb the heat conducted from the heat conduction plate 301 to the heat dissipation ceramic plate 303 so as to quickly cool the heat dissipation ceramic plate 303.
  • the above-mentioned pyroelectric photodetector uses the heat conducting plate 301 to absorb the incident light 10 and convert it into heat, and then conducts the heat to the series conductive metal layer 302, and the heat is dissipated by the heat-dissipating ceramic plate 303; During the process, an induced voltage (that is, an output voltage) is generated at both ends of the series conductive metal layer 302 through the Seebeck effect. After stable heat conduction is achieved, the induced voltage of the series conductive metal layer 302 is roughly proportional to the incident light power.
  • the pyroelectric photodetector with the vertical structure has a faster response time and can withstand higher incident light power.
  • the thermal conductivity of the pyroelectric photodetector can be greatly improved by using a thermocouple with high thermal conductivity and increasing the ratio of the cross section of the thermocouple to the area of the silicon carbide ceramic on the incident surface, thereby increasing the incident light power.
  • the high-power and fast response characteristics of the pyroelectric optical detector are particularly suitable for real-time power measurement and volatility monitoring of current kilowatt-level, 10,000-watt-level or even higher power fiber lasers. If a semiconductor thermocouple material with a higher ZT value (Thermoelectric figure of merit) is used, the thermoelectric photodetector can be used as an excellent photoelectric conversion device for solar power generation and other occasions.
  • the present invention also provides a preparation method of the pyroelectric photodetector shown in FIG. 6, which includes the following steps:
  • S1 Grind and polish the optical incident surface of the black silicon carbide ceramic to meet the roughness requirements
  • thermocouple pad S2
  • electroplating S3
  • etching the surface of the black silicon carbide ceramic facing away from the optical incident surface to form a thermocouple pad and a series connection line on the first side;
  • thermocouple pad on the second side and a corresponding series link line
  • thermocouples Coating solder on the surfaces of thermocouples on both sides, assemble and arrange the black silicon carbide ceramics, heat sink ceramic sheets and thermocouples neatly, and place them on the heating plate steadily;
  • step S2 the following sub-steps are included:
  • S21 Magnetron sputtering Ti-Cu or Cr-Cu plating on the welding surface of black silicon carbide ceramics (that is, the surface facing away from the optical incident surface), where the Ti layer or Cr layer is used to enhance the bonding of the metal layer
  • the thickness of the overall magnetron sputtering is generally ⁇ 2um.
  • the sputtered black silicon carbide ceramic is electroplated with Cu in water to thicken the copper layer to 10-50um, and then the surface can be optionally plated with a layer of gold (generally ⁇ 1um in thickness) to facilitate subsequent welding.
  • thermocouple pads and series link lines are formed on the first side (ie, the first side) thermocouple pads and series link lines.
  • step S3 on one side of the heat-dissipating ceramic plate, the same methods as in steps S21 to S23 can be used to perform sputtering, electroplating and etching to form the other side (ie, the second side) pads and corresponding Serial link line.
  • the heat-dissipating ceramic plate can be selected from various types of insulating and thermally conductive ceramics such as alumina, aluminum nitride, silicon carbide, and silicon nitride. If alumina ceramic is used for the heat dissipation ceramic plate, the pad and circuit can also be prepared directly by using the DBC process.
  • metallization can also be used to support the welding and heat dissipation between the heat sink and the heat sink.
  • step S4 the two matched thermocouples are processed into particles of the same height (different shapes such as cubes, cuboids, cylinders, etc. can be used). According to different materials, pickling or other cleaning processes are carried out to remove surface stains and oxide layers to ensure the cleanliness of the upper and lower welding surfaces.
  • step S5 apply solder paste, evaporate solder, or use soldering pads between the pads and circuits of the ceramic plates on both sides. You can also apply a certain liquid flux to remove the upper and lower ceramics (including black silicon carbide ceramics and heat sink ceramics). Plate) and thermocouple are assembled neatly and placed on the heating plate steadily.
  • gold-tin solder such as Au80/Sn20 or Au85/Sn15
  • the pads on the ceramic surface be gold-plated, so that after the fusion of the gold-tin solder and the electroplated gold layer, the proportion of gold in the solder will increase. In turn, the melting point for re-melting is increased.
  • step S6 a heating plate is used to heat and reflow the assembled ceramic, solder, and thermocouple.
  • Different temperature curves and atmosphere environments can be set for different solders, such as nitrogen or vacuum environment.
  • applying certain pressure to the ceramic can improve the welding quality and reliability.
  • step S7 spot welding is used to weld the two output terminals of the thermocouple group to lead wires.
  • thermocouple is required to be moisture-proof, after step S7 is completed, the gap between the two ceramics (black silicon carbide ceramic and thermal conductive ceramic plate) can be edge-sealed with silica gel, epoxy resin and other materials to insulate water vapor.
  • the pyroelectric photodetector provided by the embodiment of the present invention uses a heat-conducting plate made of black silicon carbide ceramic as the light absorber, so that even if the surface of the light absorber is damaged, the laser absorption rate will not be affected.
  • the invention overcomes the problem in the prior pyroelectric photodetector that once the metal thermally conductive substrate is exposed to the irradiating laser, strong optical reflection will be generated, thereby causing the detector to be misaligned.
  • thermopile or series conductive metal layer can be directly arranged on the surface of the light absorber to avoid the thermal expansion of the heat conducting plate causing the thermopile or series conductive metal layer to fall off, and the thermopile or series conductive metal layer is conductive
  • the direct contact between the metal layer and the heat conducting plate is more reliable, heat conduction is faster, and the response is more sensitive.
  • black silicon carbide ceramic has the advantages of high thermal conductivity, low thermal expansion coefficient, high temperature resistance, high laser damage threshold, and the optical absorption surface can be cleaned by grinding, it can quickly dissipate heat, and can avoid the thermal expansion of the heat conducting plate causing the thermopile to fall off. As well as reducing the damage of the optical absorption surface of the heat conducting plate, the failure rate of the pyroelectric optical detector is reduced, and the service life of the pyroelectric optical detector is greatly prolonged. During use, even if the optical absorption surface of the black silicon carbide ceramic is slightly damaged, the light spot traces on the surface of the black silicon carbide ceramic can be easily cleaned up by simple cleaning, such as grinding with diamond paste.
  • the pyroelectric optical detector provided by the embodiment of the present invention has simple structure, low cost, reliable performance, and long life. It is especially suitable for power measurement of lasers or other light sources or energy measurement of light pulses, and has great economic value.

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Abstract

一种基于黑碳化硅陶瓷的热电型光探测器，采用热电型光探测器的热电型光功率计/热电型光能量计，包括由黑碳化硅陶瓷制作的导热板（21），导热板（21）的一侧表面是光学吸收面（211）；在导热板（21）的任一侧表面设置热电堆（22）或串联导电金属层（302），组成热电型光探测器。在热电型光探测器中，通过使用黑碳化硅陶瓷同时作为导热板（21）和光吸收体，并使黑碳化硅陶瓷直接与热电堆（22）或串联导电金属层（302）结合组成热电型光探测器，简化了热电型光探测器的结构；同时，由于黑碳化硅陶瓷导热系数高、热膨胀系数小、耐高温、激光损伤阈值高、光学吸收面可采用研磨方式清洁，降低了热电型光探测器的故障率，并大幅度延长了热电型光探测器的使用寿命。

Description

基于黑碳化硅陶瓷的热电型光探测器、光功率计和光能量计 技术领域
本发明涉及一种热电型光探测器，尤其涉及一种基于黑碳化硅陶瓷实现的热电型光探测器，同时也涉及采用该热电型光探测器的热电型光功率计/热电型光能量计。
背景技术
现有技术中，热电型激光探测器(例如Ophir Optronics、Coherent、Gentec-EO、Laserpoint等厂商出品的热电型光功率计或热电型光能量计中使用的激光探测器)的结构如图1所示。它们普遍采用铝合金基板作为导热板100，在导热板100的一面设置深色光学吸收涂层101，以实现光学入射面的高比率吸收，导热板100的另外一面先设置一层绝缘层102(或者在铝合金表面直接生成绝缘的氧化层)，然后再在绝缘层102表面设置热电堆103(即多个热电偶串联并贴附于绝缘层102表面)，以探测热量传导时产生的温度差，进而实现对入射光功率或者光脉冲能量的测量。
然而，现有的热电型激光探测器因自身有诸多缺陷，存在寿命短、故障率高的问题，耐用性较差，导致用户需要频繁更换和维修。具体来说，现有的热电型激光探测器存在如下几个方面的问题：1，设置在铝合金基板光学入射面表面的深色光学吸收涂层101极其容易被高能激光破坏，导致光学吸收率下降，而作为导热板100的铝合金基板表面一旦暴露则会有较高的光学反射率，导致激光探测器失准；2，深色光学吸收涂层101表面容易被人为污染而很难清洁，导致光学吸收率变化，激光探测器失准；3，因为导热板100、深色光学吸收涂层101和绝缘层102三层材料的不同，且铝合金基板的热膨胀系数较大，导热板100与绝缘层102材料不匹配，因此使用过程中容易因背面绝缘层102的热胀冷缩导致热电堆103从导热板100脱落，致使激光探测器故障；4，铝合金基板不耐高温，其熔点为500～660℃，一般基于铝合金基板的激光探测器的耐高温极限不超过300℃，因此无法耐受较高平均功率的光学测量。
在上述问题中，深色光学吸收涂层101的损坏是大量热电型激光探测器失效和故障的最主要原因，而且出现此类故障的热电型激光探测器只能更换、不可修复，使用成本很高。
发明内容
本发明所要解决的首要技术问题在于提供一种基于黑碳化硅陶瓷的热电型光探测器，用于光功率测量和光脉冲的能量测量。
本发明所要解决的另一技术问题在于提供一种采用上述热电型光探测器的热电型光功率计/热电型光能量计。
为了实现上述目的，本发明采用下述的技术方案：
根据本发明实施例的第一方面，提供一种热电型光探测器，包括由黑碳化硅陶瓷制作的导热板，所述导热板整体作为光吸收体；所述导热板的一侧表面是光学吸收面；在所述导热板的任一侧表面设置热电堆。
其中较优地，所述热电堆围绕光学入射区域形成闭合曲线。或者，所述热电堆和绝热边共同围绕光学入射区域形成闭合曲线。
根据本发明实施例的第二方面，提供一种热电型光探测器，包括由黑碳化硅陶瓷制作的导热板，还包括串联导电金属层和散热陶瓷板；
所述导热板整体作为光吸收体；所述导热板的一侧表面是光学吸收面，所述串联导电金属层设置在所述导热板的另一侧表面，并在所述串联导电金属层远离所述导热板的一侧表面设置散热陶瓷板。
其中较优地，所述串联导电金属层包括由多个串联的热电偶组成的热电偶组，热电偶组包括多个半导体组和多个铜电极片，半导体组包括一个N型半导体和一个P型半导体，多个半导体组通过多个铜电极片依次串联，且首尾两端的铜电极片形成正极和负极。
其中较优地，所述散热陶瓷板远离串联导电金属层的一侧表面被金属化。
其中较优地，所述散热陶瓷板远离串联导电金属层的一侧表面设置有散热器。
在上述两种热电型光探测器中，所述黑碳化硅陶瓷由黑碳化硅粉体烧结而成。
其中较优地，所述黑碳化硅陶瓷由黑碳化硅粉体通过无压烧结、 高温等静压烧结、热压烧结、重结晶、反应烧结以及化学气相沉积等工艺中的任意一种烧结而成。其中，压力较高的烧结环境将导致更高的致密性和更高的导热性能。
其中较优地，所述黑碳化硅陶瓷的密度在2.6～3.2g/cm 3之间，一般而言，密度越高，其导热性能越好。
其中较优地，所述黑碳化硅陶瓷的光学吸收面非镜面。
其中较优地，所述黑碳化硅陶瓷的光学吸收面的表面粗糙度Ra在0.8～6.3um之间。
其中较优地，所述黑碳化硅陶瓷的激光损伤阈值为窄脉冲高峰值功率下大于3GW/cm 2且宽脉冲高能量下至少200～500J/cm 2。
根据本发明实施例的第三方面，提供一种采用上述热电型光探测器的热电型光功率计/热电型光能量计。
本发明所提供的基于黑碳化硅陶瓷的热电型光探测器，包括由黑碳化硅陶瓷制作的导热板。导热板整体作为光吸收体；导热板的一面是光学吸收面。在本发明提供的一种结构的热电型光探测器中，在导热板的任一侧表面(光学吸收面或与光学吸收面相对的面)设置热电堆，组成热电型光探测器。在本发明提供的另一种结构的热电型光探测器中，通过在导热板的背面设置串联导电金属层和散热陶瓷板，组成热电型光探测器。
在上述热电型光探测器中，通过使用黑碳化硅陶瓷同时作为导热板和光吸收体，取代了现有热电型光探测器中的三层结构(包括铝合金基板、深色光学吸收涂层和绝缘层)，使黑碳化硅陶瓷直接与热电堆或串联导电金属层结合，组成热电型光探测器，简化了热电型光探测器的结构。同时，由于黑碳化硅陶瓷导热系数高、热膨胀系数小、耐高温、激光损伤阈值高、光学吸收面可采用研磨方式清洁，降低了热电型光探测器的故障率，并大幅度延长了热电型光探测器的使用寿命。
附图说明
图1是现有技术中以铝合金基板作为导热板的热电型光探测器的结构示意图；
图2是本发明所提供的以黑碳化硅陶瓷作为导热板的一种热电型 光探测器的结构示意图；
图3为在导热板的表面设置热电堆的结构示意图；
图4a至图4h为本发明实施例提供的多种热电型光探测器的结构示意图；
图5为本发明实施例提供的热电型光功率计/热电型光能量计的结构示意图；
图6为本发明所提供的以黑碳化硅陶瓷作为导热板的另一种热电型光探测器的结构示意图。
具体实施方式
下面结合附图和具体的实施例对本发明的技术方案进行进一步地详细描述。
如图2所示，本发明实施例所提供的基于黑碳化硅陶瓷的热电型光探测器包括由黑碳化硅陶瓷制作的导热板21，导热板21整体作为光吸收体，导热板21朝向入射光10的一侧表面(面积较大的表面)是光学吸收面211。同时，在导热板21的任意一侧表面设置热电堆22，组成热电型光探测器。其中，热电堆22可以设置在导热板21的光学吸收面211上，也可以设置在导热板21的另一侧表面212(与光学吸收面211相对的面，也称背面212)上。优选地，将热电堆22设置在导热板21的背面212，可以防止热电堆22被污染。热电型光探测器检测过程中所吸收的热量15经过热电堆22后从导热板21的侧面213向外扩散，通常需要借助与导热板21接触的散热体进行散热。
如图3所示，热电堆22由多个热电偶串联而成，热电堆22具有一系列双金属结(包括热端22A和冷端22B)，任何两个相邻结之间的温度差会导致在两个结之间形成电压。由于多个结点是串联的，热端22A始终在内部，较热的一侧，冷端22B在外部，较冷的一侧，因此通过热电堆22的径向热流会使热电堆22的输出端22C产生与功率输入成比例的电压。入射光10照射在光学入射区域25(即具有封闭曲线形状的热电堆22所围合区域的中心)内，导热板21所吸收的热量径向流动并从热电堆22的外侧区域散去。
如图2所示，在本发明实施例所提供的热电型光探测器中，使用一种单层材料(具体为由黑碳化硅陶瓷制作的光吸收体与导热板一体 式结构)，替代传统热电型光探测器的三层结构(具体为图1所示的铝合金基板100、深色光学吸收涂层101和绝缘层102)。黑碳化硅陶瓷同时用作导热板21和光吸收体，从而从根本上杜绝了现有三层结构中，深色光学吸收涂层101被损坏后露出具有高光学反射率的铝合金基板100，容易引起检测结果失准的问题。并且，省去了绝缘层的设置，避免了由于导热板和绝缘层的热膨胀率不匹配导致电热堆脱落的问题。
在上述结构中所使用的黑碳化硅陶瓷，由黑碳化硅粉体经过烧结工艺形成。具体来说，黑碳化硅陶瓷由黑碳化硅粉体通过无压烧结、高温等静压烧结、热压烧结、重结晶、反应烧结以及化学气相沉积等工艺中的任意一种烧结而成。其中，较优地，压力较高的烧结环境将导致更高的致密性和更高的导热性能。需要说明的是，本发明实施例所提供的技术方案的目的在于保护由黑碳化硅陶瓷作为导热板和光吸收体制造的热电型光探测器，而不在于黑碳化硅陶瓷烧结工艺或黑碳化硅陶瓷本身。因此，即使通过对现有烧结工艺进行改进，获得更致密或更均匀的黑碳化硅陶瓷，只要其用于制造本发明实施例所提供的热电型光探测器，均属于本发明所主张的保护范围。
黑碳化硅陶瓷由黑碳化硅粉体烧结而成。目前有多种制备方法来合成黑碳化硅粉体，如Acheson合成法、激光法、有机前驱体法等。其中，在工业上最常用的是Acheson合成法，通过将石英砂和焦炭加入到炉体内，并加入适量木屑作为添加剂，制备黑碳化硅粉体。由于反应炉的炉体体积往往很大，这就一定程度上使得炉体内的温度分布不均匀，因此合成出的碳化硅粉体可能在性能上具有一定的差异。另外一点就是，用作反应原料的石英砂和焦炭往往不是非常纯净的，里面可能会含有一些铁和铝的金属杂质。因此，获得的碳化硅粉体中可能会存在杂质。绝对纯净的碳化硅粉体往往是无色的，而掺杂有少量的金属杂质时的碳化硅呈现绿色，当金属杂质的含量增多时，碳化硅粉体的颜色会加深，从而呈现黑色。黑碳化硅韧性高于绿碳化硅，主要用于加工陶瓷、耐火材料和有色金属。由黑碳化硅粉体烧结出的碳化硅陶瓷也会呈现黑色，因此称为黑碳化硅陶瓷。在本发明实施例中选取由颜色较深的碳化硅粉体烧结而成的黑碳化硅陶瓷，同时作为热 电型光探测器的导热板21和光吸收体。需要说明的是，本发明实施例所提到的黑碳化硅陶瓷，是为了与颜色较浅的绿碳化硅陶瓷进行区分，可以包括但不限于颜色较深的深蓝色、深灰色和黑灰色碳化硅陶瓷，用以保证较高的光吸收率，并不限定所使用的碳化硅陶瓷的颜色必须为黑色。
发明人经过深入研究，认为纯碳化硅材料具有一定的导电性能，绝缘性差，适合作为半导体，因此不适合作为热电堆的连接基体，从而不适合在本发明实施例所提供的热电型光探测器中使用。并且，普通碳化硅材料的致密性和热导率也不足；因此，也不适合用于制作热电型光探测器的导热板21和光吸收体。而碳化硅陶瓷导电性较差，适合作为设置热电堆的基体，并且，碳化硅陶瓷具有较高的致密性和热导率，适合作为热电型光探测器的导热板21和光吸收体。
另一方面，在碳化硅材料中，较为纯净的绿碳化硅的颜色不适合做光学吸收，光学吸收率不佳，并具有较高的光学反射率。黑碳化硅的光学吸收率明显高于绿碳化硅，并且黑碳化硅的光学反射率低于绿碳化硅。因此，黑碳化硅陶瓷作为光谱光学吸收材料，更适合作为热电型光探测器的导热板21和光吸收体。
总之，与纯碳化硅材料和绿碳化硅陶瓷相比，黑碳化硅陶瓷杂质含量较大，并具有更大的电阻率、热导率和光吸收率，表面反射率低于纯碳化硅材料和绿碳化硅陶瓷，更适合制作热电型光探测器。
在本发明的实施例中，使用黑碳化硅陶瓷作为导热板21，一方面黑色作为光学吸收介质具有不可替代的优势，另一方面，黑碳化硅陶瓷的光学吸收面211不是镜面，经过加工使其具备一定的表面粗糙度，例如将Ra控制在0.8～6.3um之间，可以保证较好的光学吸收。当对由黑碳化硅陶瓷制作的光吸收体的表面进行清洁时，所使用的金刚石研磨膏的粒度，也需要和此表面粗糙度相匹配。使用具有一定粒度的金刚石研磨膏清洁导热板21的光学吸收面，可以修复光学吸收面的表面粗糙度，有利于光学吸收。在对黑碳化硅陶瓷的光学吸收面211的光学入射区域25的表面进行加工或清洁时，应使探测区域(即，光学入射区域25)的表面粗糙度保持一致，以确保光学吸收的均匀性。
需要强调的是，采用黑碳化硅陶瓷制成导热板21和光吸收体时， 其中所含杂质的量应保证黑碳化硅陶瓷的电阻远高于热电堆22的电阻(R黑碳化硅陶瓷>>R热电堆)，以使黑碳化硅陶瓷导电性对热电堆22的干扰降到最小，而现有的黑碳化硅陶瓷材料的低导电性可以满足此要求。因此，黑碳化硅陶瓷21背面无需额外的绝缘层即可直接贴装热电堆22。
纯碳化硅晶体的密度为3.16～3.2g/cm 3，通过烧结工艺获得的黑碳化硅陶瓷的密度在2.6～3.2g/cm 3之间。较佳地，致密的黑碳化硅陶瓷的密度可以达到碳化硅陶瓷理论密度的98％以上。一般而言，黑碳化硅陶瓷的密度越大，其导热性能越好，越适合制作热电型光探测器。
经过深入研究，满足本发明实施例要求的黑碳化硅陶瓷同时满足以下特性：黑碳化硅陶瓷本身为黑色本体、无须涂层即可吸收激光，无论是表面还是内部均具有一致的、良好的光学吸收特性；黑碳化硅陶瓷绝缘性较好，具有较低的电导率，可以和热电堆22直接物理接触而不造成短路或电学干扰；黑碳化硅陶瓷具有良好的导热性能，可以快速散热，从而避免大功率激光造成的灼烧；黑碳化硅陶瓷具有较低的热膨胀系数，因此，与热电堆结合紧密，不易发生热膨胀开裂，避免了热电堆的脱落；并且，黑碳化硅陶瓷具有较高的激光损伤阈值(具体参见下文)，可以耐高温、不熔化，因此，黑碳化硅陶瓷适合制作本发明实施例所提供的热电型光探测器。此外，黑碳化硅陶瓷具有合理的密度和比热容，可以保证热电型光探测器具有足够的响应速度。
表1是常见的黑碳化硅陶瓷与常见的铝合金的相关参数对照表。经过对比可知，黑碳化硅陶瓷的导热系数、密度、比热容等方面，具有和铝合金相似的特性；同时在工作温度、热膨胀系数、光反射率、电阻率上的特性，较铝合金有明显的应用优势。因此，发明人认为黑碳化硅陶瓷相较于铝合金，作为激光探测器的导热板和光吸收体，更具有优势。
表1 黑碳化硅陶瓷与铝合金的相关参数对照表：
Figure PCTCN2021078269-appb-000001
Figure PCTCN2021078269-appb-000002
下面，详细介绍发明人对黑碳化硅陶瓷的激光损伤阈值所进行的实验测量和理论计算。
选择无压烧结的黑色碳化硅陶瓷制备热电型光探测器，陶瓷密度为3.15g/cm 3，碳化硅含量约98％，对635nm波长的光学吸收率约80％，导热系数约150W/(m·K)，陶瓷厚度2mm，表面粗糙度Ra＝0.8um，进行实验如下。
第一次实验为短脉冲、高峰值功率测试。测试光源选择波长1064nm、脉宽500ps、单脉冲能量200mJ的脉冲激光，在不同直径的圆形光斑下对黑碳化硅陶瓷样品表面进行冲击照射。光斑直径选择2mm、3mm时，碳化硅陶瓷表面产生轻微破损，而光斑直径选择4mm、5mm时，碳化硅陶瓷表面除了颜色产生轻微发白色斑之外，没有明显损伤。据此判断其激光损伤阈值在3.2GW/cm 2到5.6GW/cm 2之间。而具有光学吸收涂层的铝合金探测器所能承受的激光损伤阈值一般在30MW/cm 2以内，如Ophir Optronics的激光探测器损伤阈值约3MW/cm 2，而Laserpoint的激光探测器的激光损伤阈值约30MW/cm 2。可以说，黑碳化硅陶瓷的激光损伤阈值较之提高了100倍以上。
在上述实验结束之后，使用粒度600目数的金刚石研磨膏，对经过冲击照射的黑碳化硅陶瓷片表面进行手工研磨之后，4mm和5mm光斑位置的色斑可以轻易去除掉，而3mm光斑处仍有轻微表层损伤，2mm光斑处有一定深度的损伤。这进一步印证了我们对激光损伤阈值的判断。另外，这也表明，使用简单的研磨工艺，可以将被强激光污损的黑碳化硅陶瓷表面清理和复原，进而提高了激光探测器的复用性和长期使用的经济性。而传统的热电型光探测器中，设置在铝合金基板表 面的涂层一旦被污损则无法清理和复原，只能维修更换整个激光探测器。
第二次实验为宽脉冲、高能量测试：在室温20℃时，在2ms的宽脉冲状态下，使用200J的808nm半导体激光器，在10mm×10mm光斑面积上，对厚度2mm的黑碳化硅陶瓷进行表面照射，测量得到被照射区域的局部温度最高值达到约300℃，但并未产生材料损伤。这说明，在宽脉冲状态下，其能量损伤阈值大于200J/cm 2。从理论上计算，如使用10mm×10mm×2mm的碳化硅陶瓷，假定其密度为3.15g/cm 3，比热容为800J/(kg·K)，光学吸收率为85％，则升高900℃的情况下(此时碳化硅仍然不会有材料损伤)，其理论上可以接收的光学脉冲能量E＝900×(800/1000)×(1×1×0.2×3.15)/85％＝534J。此时的激光的能量密度达到534J/cm 2。即其理论激光损伤阈值大于500J/cm 2。而具有光学吸收涂层的铝合金基板所能承受的激光损伤阈值一般在50J/cm 2以内，如Ophir Optronics的激光探测器损伤阈值约10J/cm 2，而Laserpoint的激光探测器损伤阈值约36J/cm 2探测器损。可以认为，碳化硅陶瓷在宽脉冲、高能量情况下的损伤阈值较之提高约10倍。
因此，使用黑碳化硅陶瓷作为热电型光探测器的导热板和光吸收体，可以大幅提高激光探测器的光学损伤阈值，进而提高其寿命和耐用性，极其适合用于检测超高功率的光或脉冲能量。
下面结合图2至图4h，对本发明实施例所提供的热电型光探测器的结构进行示意性介绍。下述实施例仅用于说明热电型光探测器的结构，并不构成具体的结构限制。
如图2和图3所示，本发明实施例所提供的基于黑碳化硅陶瓷的热电型光探测器，包括由黑碳化硅陶瓷制作的导热板21，导热板21整体作为光吸收体；导热板21的一侧表面是光学吸收面211；在导热板21的一侧表面设置热电堆22，组成热电型光探测器。热电堆22可以设置在导热板21的光学吸收面211上，热电堆22也可以设置在导热板21的另一侧表面212(与光学吸收面211相对的面，也称背面)上。其中优选地，将热电堆22设置在导热板21的背面212，可以防止热电堆22被污染。
在本发明的实施例中，热电堆22设置在导热板21的光学入射区 域25的外侧，热电堆22外侧为散热区24(参见图4a至图4h中标注c的区域)；光学入射区域25吸收的热量经过热电堆21向外侧散去(在图4a至图4h中用黑色的箭头标注了光学入射区域25内部热量的扩散方向)。热电堆22的热端22A布置在热电堆22所在区域的内侧(靠近光学入射区域25的一侧)，热电堆22的冷端22B布置在热电堆22所在区域的外侧(靠近散热区24的一侧)，热电堆22的两端导出，形成输出端22C。热电堆22由多个结点串联而成，以增加其输出电压，输出电压与热量流经热电堆22的热端22A和冷端22B所产生的温度差成正比；通过对输出电压进行检测，可以对入射光的功率和能量进行探测。
当在导热板21上设置绝热边23时，热电堆22与绝热边23围绕成闭合形状；其中，绝热边23用于阻止光学入射区域25吸收的热量从绝热边23的位置向外扩散，可以通过使该位置处的导热板21不与散热体接触实现，从而使得热量全部流经热电堆22。当没有在导热板21上设置绝热边时，热电堆22围绕成闭合形状，以保证全部热量流经热电堆22。由于导热板21所有吸收的热量都流过热电堆22(只要入射光10照射在热结22A的内圈内)，热电型光探测器的响应几乎与入射光束的大小和位置无关。如果光束靠近内圆的边缘，则某些热电偶会比其他热电偶更热，但是由于测量了所有热电偶的总和，因此读数保持不变。
具体来说，如图4a至图4h所示，导热板21的形状不限于圆形、矩形和规则的多边形，还可以是其他未示出的形状，可以是规则图形也可以是不规则图形；热电堆22围绕光学入射区域25成闭合曲线，或者热电堆22和绝热边23围绕成闭合曲线；在导热板21上设置的热电堆22(或热电堆22和绝热边23)所围绕成的闭合曲线的拓扑图形也不一定与导热板21的形状对应。而热电堆22的设置位置也不限于导热板21的中心位置；当导热板21的某些侧边设置为绝热边23时，热电堆22的设置位置可以靠近边缘或角部设置。
在图4a所示的实施例中，导热板21的形状为圆形，热电堆22是由多个热电偶串联而成的环形热电堆220，环形热电堆220围绕导热板21的中心分布，形成闭合曲线。其中，如图4a所示，以灰色区 域表示光学入射区域25，环形热电堆220围绕光学入射区域25布置成圆形，在环形热电堆220的外侧用符号c表示散热区24，在光学入射区域25中以黑色箭头表示热量的扩散方向，由光学入射区域25吸收的热量均通过环形热电堆220向外散去。
在图4b所示的实施例中，导热板21的形状为圆形，热电堆22是由多个热电偶串联而成的方框形热电堆221，方框形热电堆221围绕导热板21的中心分布，形成闭合曲线。如图4b所示，以灰色区域表示由方框形热电堆221限定的光学入射区域25，方框形热电堆221围绕光学入射区域25布置成方框形，在方框形热电堆220的外侧用符号c表示散热区24，在光学入射区域25中以黑色箭头表示热量的扩散方向，由光学入射区域25吸收的热量均通过方框形热电堆221向外散去。
在图4c所示的实施例中，导热板21的形状为方形，热电堆22是由多个热电偶串联而成的方框形热电堆221，方框形热电堆221围绕导热板21的中心分布，形成闭合曲线。如图4c所示，以灰色区域表示由方框形热电堆221限定的光学入射区域25，方框形热电堆221围绕光学入射区域25布置成方框形，在方框形热电堆221的外侧用符号c表示散热区24，在光学入射区域25中以黑色箭头表示热量的扩散方向，由光学入射区域25吸收的热量均通过方框形热电堆221向外散去。
在图4d所示的实施例中，导热板21的形状为六边形，热电堆22是由多个热电偶串联而成的三角形热电堆222，三角形热电堆222围绕导热板21的中心分布，形成闭合曲线。如图4d所示，以灰色区域表示由三角形热电堆222限定的光学入射区域25，三角形热电堆222围绕光学入射区域25布置成三角形，在三角形热电堆222的外侧用符号c表示散热区24，在光学入射区域25中以黑色箭头表示热量的扩散方向，由光学入射区域25吸收的热量均通过三角形热电堆222向外散去。
在图4e至图4h所示的实施例中，导热板21的形状为矩形，在导热板21的一个侧边或两个侧边设置有绝热边23，热电堆22布置在光学入射区域25外围没有被绝热边23所围合的区域，绝热边23和热电 堆22共同围绕成闭合曲线。绝热边23靠进侧边或角部设置，因此，热电堆22和绝热边23所围合的闭合区域也靠进侧边或角部设置，从光学入射区域25吸收的热量仅从热电堆22所在的方向向外散去。
其中，在图4e中，绝热边23设置在导热板21的上侧边，绝热边23占据上侧边的中间部分；U型的电热堆223和绝热边23围绕成方框形的闭合形状，其内部为光学入射区域25，光学入射区域25吸收的热量从布置在左侧、下侧和右侧的U型热电堆223向位于U型热电堆223外侧的散热区24散去。
在图4f中，绝热边23同时设置在导热板21的左侧边、上侧边和下侧边，绝热边23占据上侧边和下侧边的左半部分；直线型的热电堆224设置在导热板21中靠近右侧的位置，从而将导热板21分为位于左侧的光线入射区域25和位于右侧的散热区24；光学入射区域25吸收的热量从直线型的热电堆224向右侧的散热区24散去。
在图4g中，绝热边23同时设置在导热板21的左侧边和上侧边，绝热边23占据左侧边的左侧部分和上侧边的上半部分；折线型的热电堆225和绝热边23围绕成方框形的闭合形状，其内部为光学入射区域25，光学入射区域25设置在靠近导热板21左上角的位置，光学入射区域25吸收的热量从折线形热电堆225向外侧(具体为折线形热电堆225的下侧和右侧)的散热区24散去。
在图4h中，绝热边23同时设置在导热板21的上侧边和下侧边的中部；热电堆226包括两条直线型的热电堆226a和226b，左热电堆226a和右热电堆226b分别设置在绝热边23的两侧，并且左热电堆226a和右热电堆226b的一端(如图所示为下端)通过导线连接成整体，左热电堆226a和右热电堆226b的另一端(如图所示为上端)引出，作为输出端22C。在该实施例中，左热电堆226a的左侧区域和右热电堆226b的右侧区域是散热区24，从而，光学入射区域25吸收的热量通过左热电堆226a和右热电堆226b分别向位于导电板21两侧的散热区24散去。
在黑碳化硅陶瓷21表面设置的热电堆22，可以根据应用温度、测量精度、使用环境等不同应用，选择铋-银、镍铬-镍硅、铜-康铜、铂-铑等不同的热电偶组合。
进一步地，如图5所示，本发明还提供了一种热电型光功率计(或热电型光能量计)。该热电型光功率计/热电型光能量计主要包括上述的热电型光探测器和电压表8，还可以包括其它公知的配套元件。其中，热电型光探测器的输出端22C与电压表8连接。电压表8用于测量热电型光探测器输出的与待测激光实际功率呈预定比例的电压数值。电压表8可以采用数字万用表实现，通过数字万用表可以直接显示出热电型光探测器输出的与待测激光实际功率呈预定比例的电压数值，根据与待测激光实际功率呈预定比例的电压数值可以反推出待测激光的实际功率。
例如，当入射光10为持续较长时间的激光时，入射光10所产生的热量可使设置在导热板21表面的热电堆22所检测到的温度差在较长时间内保持稳定，相应地，热电堆的输出电压的曲线在较长时间内保持一定的峰值，上述热电型光探测器通过测量热电堆22在一段时间内所产生的恒定电压，可以获得入射光10的光功率。当入射光10为持续较短时间的光脉冲时，光脉冲所产生的热量可引起设置在导热板21表面的热电堆22所检测到的温度差在短时间内发生起伏变化，相应地，热电堆22的输出电压的曲线在较短时间内发生起伏变化，通过对短时间内热电堆22所输出的电压进行积分，可以获得光脉冲的能量，从而进行光脉冲的能量测量。
需要说明的是，本发明中的光探测器/光功率计/光能量计所测量的光信号以激光为主，还可以包括其他各种类型的光信号，例如紫外光、红外光、X射线，甚至包括弱光源发射的荧光等。
下面结合图6对本发明提供的另一种热电型光探测器的结构进行描述。
参照图6所示，本发明实施例所提供的热电型光探测器，包括：由黑碳化硅陶瓷制作的导热板301，还包括串联导电金属层302和散热陶瓷板303。其中，导热板301整体作为光吸收体；导热板301的一侧表面是光学吸收面(如图6所示的上表面)，入射光10照射到该表面，导热板301吸收热量。串联导电金属层302设置在导热板301的另一侧表面(如图6所示的下表面)，并在串联导电金属层302远离导热板301的一侧表面设置散热陶瓷板303。导热板301、串联导电 金属层302和散热陶瓷板303组成三层结构。
如图6所示，导热板301由黑碳化硅陶瓷制作，黑碳化硅陶瓷同时作为导热板和光吸收体，取代了现有热电型光探测器中的三层结构(包括铝合金基板、深色光学吸收涂层和绝缘层)，使黑碳化硅陶瓷直接与串联导电金属层结合，组成垂直结构的热电型光探测器，简化了热电型光探测器的结构。同时，由于黑碳化硅陶瓷导热系数高、热膨胀系数小、耐高温、激光损伤阈值高、光学吸收面可采用研磨方式清洁，降低了热电型光探测器的故障率，并大幅度延长了热电型光探测器的使用寿命。关于黑碳化硅陶瓷的制备工艺及其所能带来的有益效果，在上文已详细讲述，在此不再赘述。
串联导电金属层302包括由多个串联的热电偶320组成热电偶组，热电偶组的第一端321为正极，热电偶组的第二端322为负极。其中，热电偶组包括多个半导体组和多个铜电极片，半导体组包括一个N型半导体和一个P型半导体，多个半导体组通过多个铜电极片依次串联，且首尾两端的铜电极片形成正极和负极。本实施例中，热电偶组使用如纯铜-康铜，镍铬-镍硅等成对的通用热电偶材料或P型和N型碲化铋半导体型热电偶材料。
散热陶瓷板303可选择氧化铝、氮化铝、碳化硅、氮化硅等各类绝缘导热的陶瓷均可，也可以选用黑碳化硅陶瓷。利用导热性较好的陶瓷材料保证了热量在导热板301和散热陶瓷板303之间的热传导效果。从而实现了光-热-电的集成转化效果。
散热陶瓷板303远离串联导电金属层302的一侧表面设置有散热器，用于实现散热。优选地，散热陶瓷板303远离串联导电金属层302的一侧表面被金属化，以便于焊接到外部散热器上进行散热。
散热件(未图示)设置在散热陶瓷板303上远离串联导电金属层302的一侧，用于吸收从导热板301传导到散热陶瓷板303上的热量以使散热陶瓷板303快速冷却。
具体使用时，上述热电型光探测器，利用导热板301吸收入射光10并转化为热量，然后，将热量传导给串联导电金属层302，并被散热陶瓷板303将热量散发出去；在上述热传导的过程中，通过塞贝克效应在串联导电金属层302的两端产生感应电压(即输出电压)。当 达成稳定的热传导之后，串联导电金属层302的感应电压与入射光功率大致成正比。
较传统平面扩散型热电型光探测器，该垂直结构的热电型光探测器具有更快的响应时间，可以承受更高的入射光功率。可以通过采用高导热的热电偶、增加热电偶截面与入射面碳化硅陶瓷面积比值，来大幅提高热电型光探测器的热传导能力，进而提高入射光功率。该热电型光探测器的高功率、快速响应特性，尤其适合目前千瓦级、万瓦级甚至更高功率的光纤激光器的实时功率测量和波动性监测。如采用较高ZT值(Thermoelectric figure of merit，热电优值)的半导体型热电偶材料，该热电型光探测器可以作为优异的光电转换器件，用于太阳能发电等场合。
本发明同时提供了图6所示热电型光探测器的制备方法，包括如下步骤：
S1，对黑色碳化硅陶瓷的光学入射表面进行磨抛，使之达到粗糙度的要求；
S2，对黑色碳化硅陶瓷背对光学入射面的一侧表面进行溅射、电镀和蚀刻，形成第一侧的热电偶焊盘和串联链接线路；
S3，对散热陶瓷板的一侧表面进行溅射、电镀和蚀刻，形成第二侧的热电偶焊盘及对应的串联链接线路；
S4，将两种匹配的热电偶加工成高度相同的颗粒；
S5，在两侧热电偶表面涂装焊料，将黑碳化硅陶瓷、散热陶瓷片和热电偶组装排列整齐，平稳置于加热盘上；
S6，使用加热盘，将组装排列好的陶瓷、焊料、热电偶组进行加热回流焊接；
S7，使用点焊的方式，将热电偶组的两个输出端焊接上引线。
具体来说，在步骤S1中，对黑色碳化硅陶瓷的光学入射表面进行磨抛，达到均匀的粗糙度(建议Ra＝0.8左右，并避免镜面抛光)，以保证光学吸收的均匀性。
在步骤S2中，包括如下子步骤：
S21，对黑色碳化硅陶瓷的焊接面(即，背对光学入射面的一侧表面)进行磁控溅射镀Ti-Cu或者Cr-Cu，其中Ti层或者Cr层用于增 强金属层的结合力，整体磁控溅射厚度一般≤2um。
S22，将溅射后的黑色碳化硅陶瓷进行水电镀Cu，加厚铜层至10～50um，然后表面可以选择镀一层金(厚度一般≤1um)，以利于后续焊接。
S23，制作掩膜板，对水电镀之后的黑色碳化硅陶瓷的金属层进行蚀刻，形成一侧(即第一侧)热电偶焊盘和串联链接线路。
在步骤S3中，对散热陶瓷板的一侧表面，可以采用与步骤S21～S23中相同的方法，进行溅射、电镀和蚀刻，形成另外一侧的(即第二侧)焊盘及对应的串联链接线路。
散热陶瓷板可选择氧化铝、氮化铝、碳化硅、氮化硅等各类绝缘导热的陶瓷均可。如散热陶瓷板选择使用氧化铝陶瓷，也可以采用DBC工艺直接实现焊盘和线路制备。
另外，对于散热陶瓷板的另外一面，也可以采用金属化，以支持和散热器之间的焊接散热。
在步骤S4中，将两种匹配的热电偶加工成高度相同的颗粒(可采用立方体、长方体、圆柱体等不同形状)。根据材料不同，进行酸洗或其他清洁工艺，除去表面污渍和氧化层，保证上下焊接面的清洁。
在步骤S5中，在两侧陶瓷片的焊盘和线路之间涂装焊膏、蒸发焊料或者使用焊片，也可以涂抹一定的液体助焊剂，将上下陶瓷(包括黑碳化硅陶瓷和散热陶瓷板)和热电偶组装排列整齐，平稳置于加热盘上。
如采用金锡焊片，如Au80/Sn20或者Au85/Sn15等型号，推荐对陶瓷表面的焊盘进行镀金处理，以使得金锡焊料和电镀金层融合后，焊料中金的组分比例提高，进而提高了再次熔化的熔点。
在步骤S6中，使用加热盘，将组装排列好的陶瓷、焊料、热电偶进行加热回流焊接。针对不同的焊料可以设置不同的温度曲线和气氛环境，如氮气或者真空环境等。焊接过程中，对陶瓷施加一定的压力可以提高焊接质量和可靠性。
在步骤S7中，使用点焊的方式，将热电偶组的两个输出端焊接上引线。
最后，对焊接完成的热电型光探测器进行清洁，可以使用三氯乙 烯或者三氯甲烷进行浸泡和冲洗，以除去助焊剂残留或者其他焊接生成的有机污渍。
如对热电偶防潮有要求，可以在步骤S7完成后，对两片陶瓷(黑碳化硅陶瓷和导热陶瓷板)之间的缝隙使用硅胶、环氧树脂等材料进行封边处理，以绝缘水汽。
综上所述，本发明实施例所提供的热电型光探测器采用由黑碳化硅陶瓷制成的导热板作为光吸收体，使得即便光吸收体表面产生破损，也不影响激光吸收率。本发明克服了现有热电型光探测器中，一旦金属导热基体暴露给照射激光，将产生强烈的光学反射，从而导致探测器失准的问题。同时，由于黑碳化硅陶瓷具有绝缘性，可以通过在光吸收体表面直接设置热电堆或串联导电金属层，避免导热板热膨胀导致热电堆或串联导电金属层的脱落，并且，热电堆或串联导电金属层和导热板直接接触更加可靠，导热更加迅速，反应更加灵敏。
由于黑碳化硅陶瓷具有导热系数高、热膨胀系数小、耐高温、激光损伤阈值高、光学吸收面可采用研磨方式清洁的优点，从而可以快速散热，并且可以避免导热板热膨胀导致热电堆的脱落，以及减少导热板的光学吸收面的损坏，降低了热电型光探测器的故障率，并大幅度延长了热电型光探测器的使用寿命。在使用过程中，即使黑碳化硅陶瓷的光学吸收面有轻微损坏，也可以通过简单清洁，例如使用金刚石研磨膏进行研磨，即可轻松地将黑碳化硅陶瓷表面的光斑痕迹清理干净。本发明实施例所提供的热电型光探测器的结构简单、成本低廉、性能可靠、寿命持久，尤其适用于激光或者其他光源的功率测量或光脉冲的能量测量，具有巨大的经济价值。
以上对本发明所提供的基于黑碳化硅陶瓷的热电型光探测器进行了详细的说明。对本领域的一般技术人员而言，在不背离本发明实质内容的前提下对它所做的任何显而易见的改动，都将构成对本发明专利权的侵犯，将承担相应的法律责任。

Claims (19)

  1. 一种热电型光探测器，其特征在于包括由黑碳化硅陶瓷制作的导热板，所述导热板的一侧表面是光学吸收面。
  2. 如权利要求1所述的热电型光探测器，其特征在于，还包括热电堆，所述光学吸收面或另一侧表面上设置所述热电堆。
  3. 如权利要求2所述的热电型光探测器，其特征在于：
    所述热电堆围绕光学入射区域形成闭合曲线。
  4. 如权利要求2所述的热电型光探测器，其特征在于：
    所述热电堆和绝热边共同围绕光学入射区域形成闭合曲线。
  5. 如权利要求1所述的热电型光探测器，其特征在于，还包括串联导电金属层和散热陶瓷板；
    所述导热板的一侧表面是光学吸收面，所述串联导电金属层设置在所述导热板的另一侧表面，并在所述串联导电金属层远离所述导热板的一侧表面设置散热陶瓷板。
  6. 如权利要求5所述的热电型光探测器，其特征在于：
    所述串联导电金属层包括由多个串联的热电偶组成的热电偶组，热电偶组包括多个半导体组和多个铜电极片，半导体组包括一个N型半导体和一个P型半导体，多个半导体组通过多个铜电极片依次串联，且首尾两端的铜电极片形成正极和负极。
  7. 如权利要求6所述的热电型光探测器，其特征在于：
    所述散热陶瓷板远离串联导电金属层的一侧表面被金属化。
  8. 如权利要求6所述的热电型光探测器，其特征在于：
    所述散热陶瓷板远离串联导电金属层的一侧表面设置有散热器。
  9. 如权利要求1所述的热电型光探测器，其特征在于：
    所述光学吸收面采用研磨方式清洁。
  10. 如权利要求1所述的热电型光探测器，其特征在于：
    所述黑碳化硅陶瓷由黑碳化硅粉体烧结而成。
  11. 如权利要求10所述的热电型光探测器，其特征在于：
    所述黑碳化硅陶瓷由黑碳化硅粉体在加压环境中烧结而成。
  12. 如权利要求1所述的热电型光探测器，其特征在于：
    所述黑碳化硅陶瓷的密度在2.6～3.2g/cm 3之间。
  13. 如权利要求1所述的热电型光探测器，其特征在于：
    所述黑碳化硅陶瓷的光学吸收面非镜面。
  14. 如权利要求13所述的热电型光探测器，其特征在于：
    所述黑碳化硅陶瓷的光学吸收面的表面粗糙度Ra在0.8～6.3um之间。
  15. 如权利要求1所述的热电型光探测器，其特征在于：
    所述黑碳化硅陶瓷的激光损伤阈值为窄脉冲高峰值功率下大于3GW/cm 2且宽脉冲高能量下至少200～500J/cm 2。
  16. 如权利要求1所述的热电型光探测器，其特征在于：
    所述黑碳化硅陶瓷包括但不限于颜色较深的深蓝色、深灰色和黑灰色碳化硅陶瓷。
  17. 一种热电型光功率计，其特征在于包括电压表及权利要求1所述的热电型光探测器，所述电压表与所述热电型光探测器的输出端连接。
  18. 一种热电型光能量计，其特征在于包括电压表及权利要求1所述的热电型光探测器，所述电压表与所述热电型光探测器的输出端连接。
  19. 一种热电型光探测器的制造方法，用于制造如权利要求5所述的热电型光探测器，其特征在于包括如下步骤：
    S1，对黑色碳化硅陶瓷的光学入射表面进行磨抛，使之达到粗糙度的要求；
    S2，对黑色碳化硅陶瓷背对光学入射面的一侧表面进行溅射、电镀和蚀刻，形成第一侧的热电偶焊盘和串联链接线路；
    S3，对散热陶瓷板的一侧表面进行溅射、电镀和蚀刻，形成第二侧的热电偶焊盘及对应的串联链接线路；
    S4，将两种匹配的热电偶加工成高度相同的颗粒；
    S5，在两侧热电偶表面涂装焊料，将黑碳化硅陶瓷、散热陶瓷片和热电偶组装排列整齐，平稳置于加热盘上；
    S6，使用加热盘，将组装排列好的陶瓷、焊料、热电偶组进行加热回流焊接；
    S7，使用点焊的方式，将热电偶组的两个输出端焊接上引线。
PCT/CN2021/078269 2020-02-28 2021-02-26 基于黑碳化硅陶瓷的热电型光探测器、光功率计和光能量计 WO2021170112A1 (zh)

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