A device and method for detecting the deuterium doping concentration of a deuterium-doped KDP crystal

Abstract

A device and method for detecting the deuterium doping concentration of a deuterium-doped KDP crystal are disclosed. The device comprises a fundamental frequency laser, a second-harmonic deuterium-doped KDP crystal arranged sequentially along the laser output direction of the fundamental frequency laser, a frequency doubling adjuster acting on the second-harmonic deuterium-doped KDP crystal, a first second-harmonic laser color separator, a second second-harmonic laser color separator, and an energy meter. The angle at which two fundamental frequency beams of different wavelengths output from the fundamental frequency laser are incident on the second-harmonic deuterium-doped KDP crystal is controlled by the frequency doubling adjuster. Based on the reading of the energy meter, the second-harmonic deuterium-doped KDP crystal is adjusted to a position corresponding to the phase matching angle. The deuterium doping concentration of the second-harmonic deuterium-doped KDP crystal is obtained by comparing the difference in the measured phase matching angles of the two laser beams with the difference in the phase matching angle calculated according to an empirical formula and the relationship between the phase matching angle difference and the deuterium doping concentration of the crystal. This invention has the advantages of stable device and simple and accurate detection method.

Description

Technical Field

[0001] This invention relates to the field of optical material performance testing technology, specifically a device and method for detecting the deuterium concentration in deuterated potassium dihydrogen phosphate (KDP) crystals. The device and method aim to conveniently and efficiently measure the deuterium atom concentration in deuterated KDP crystals to meet the precise control requirements for performance parameters of deuterated KDP crystals in fields such as laser technology, nonlinear optical material development, and high-power laser systems. Background Technology

[0002] KDP crystal is a crucial nonlinear optical material with wide applications in laser technology and frequency conversion, particularly in high-power laser systems where it is frequently used as an electro-optic modulator and nonlinear frequency conversion crystal. Deuterium doping of KDP crystals primarily aims to enhance the crystal's stability and damage resistance in frequency conversion systems, thereby ensuring the efficient operation of high-power laser systems. By reducing birefringence and increasing the laser damage threshold, deuterium-doped KDP crystals can further enhance frequency conversion efficiency. Monitoring the deuterium doping concentration in KDP crystals effectively improves the consistency and accuracy of deuterium doping concentration during processing, providing stable fundamental data support for material development. It also helps verify theoretical models in nonlinear frequency conversion systems, enabling further optimization of crystal design. Summary of the Invention

[0003] The main technical problem solved by this invention is to provide a device and method for detecting the deuterium doping concentration in deuterated KDP crystals. The detection method is based on the fact that KDP crystals with different deuterium doping concentrations have different nonlinear optical properties. A single wavelength has a corresponding phase matching angle in a KDP crystal with a specific deuterium doping concentration. By incident two laser beams with different wavelengths onto the deuterated KDP crystal to be tested, the difference in phase matching angles between the two laser beams can be obtained. The relationship between the difference in phase matching angles and the deuterium doping concentration of the crystal can be obtained through theoretical calculation. Then, the difference in phase matching angles between the two laser beams obtained experimentally is compared with the theoretical calculation to obtain the deuterium doping concentration of the crystal to be tested.

[0004] The technical solution of the present invention is as follows:

[0005] A device for detecting the deuterium doping concentration of a deuterium-doped KDP crystal is characterized in that it comprises a fundamental frequency laser, a second-harmonic deuterium-doped KDP crystal arranged sequentially along the output direction of the fundamental frequency laser, a frequency doubling regulator for fixing the second-harmonic deuterium-doped KDP crystal and capable of multi-dimensional control, a first second-harmonic laser color separator, a second second-harmonic laser color separator, and an energy meter. The first and second second-harmonic laser color separators are both placed at 45° to the optical path, and the angle at which the laser output from the fundamental frequency laser is incident on the second-harmonic deuterium-doped KDP crystal is controlled by the frequency doubling regulator.

[0006] A third frequency-harmonic laser color separator is also provided between the second frequency-harmonic laser color separator and the energy meter along the optical path.

[0007] The wavelengths of the laser output by the fundamental frequency laser are 1030nm and 1053nm, respectively.

[0008] This invention also provides a detection method for a deuterium doping concentration detection device for deuterium-doped KDP crystals, the method mainly including the following steps:

[0009] S1: Set the output wavelength of the fundamental frequency laser, and precisely adjust the angle at which the fundamental frequency light is incident on the deuterium-doped KDP crystal of the second harmonic through the frequency doubling adjuster. At the same time, observe the energy meter to make the second harmonic laser output reach the maximum value, and record the rotation angle of the frequency doubling adjuster at this time.

[0010] S2: Change the output wavelength of the fundamental frequency laser and adjust the frequency doubling regulator again so that the second harmonic laser measured by the energy meter reaches the maximum value. Record the rotation angle of the frequency doubling regulator at this time.

[0011] S3: The difference in phase matching angle between the second-harmonic deuterated KDP crystal and the two wavelength lasers is calculated. By comparing the theoretical calculation relationship between the deuterium doping concentration of the second-harmonic deuterated KDP crystal and the difference in phase matching angle between the two wavelength lasers, the deuterium doping concentration in the second-harmonic deuterated KDP crystal is obtained.

[0012] Furthermore, the output wavelength of the fundamental frequency laser in step S1 is set to 1030 nm.

[0013] Furthermore, the output wavelength of the fundamental frequency laser in step S2 is set to 1053 nm.

[0014] The aforementioned deuterium-doped KDP crystal doubles the fundamental frequency laser to produce a frequency-doubled laser.

[0015] The first and second frequency-doubled laser color separators can separate the fundamental frequency laser and the frequency-doubled laser, with the fundamental frequency laser being transmitted and the frequency-doubled laser being reflected.

[0016] The frequency doubling adjuster is a crystal control device that is tunable in three dimensions: azimuth (the crystal rotates about an axis parallel to the platform), pitch (the crystal rotates about an axis perpendicular to the platform), and rotation (the crystal rotates about its own optical axis). It can adjust the state of the fundamental frequency light incident on the deuterium-doped KDP crystal in three dimensions.

[0017] The advantages of the present invention are as follows:

[0018] 1. Compared with general chemical detection methods, physical methods using nonlinear frequency conversion do not damage the sample and are more convenient and efficient.

[0019] 2. By using the difference in phase matching angle between two fundamental frequency laser beams, the instability caused by a single wavelength can be effectively eliminated, and the experimental and theoretical calculations of deuterium doping concentration can be more accurately correlated.

[0020] 3. The three-dimensional tunable frequency multiplier has high precision and can be applied to deuterated KDP crystals of different concentrations. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the deuterium-doped KDP crystal concentration detection device of the present invention;

[0022] Figure 2 This is a graph showing the theoretical relationship between the deuterium doping concentration and the difference in phase matching angle between the two laser beams, calculated according to the Sellmeier empirical formula in this invention. Detailed Implementation

[0023] The present invention will be further described below with reference to examples and accompanying drawings, but this should not be construed as limiting the scope of protection of the present invention.

[0024] Please see Figure 1 , Figure 1 This is a schematic diagram of the deuterium doping concentration detection device for deuterium-doped KDP crystals according to the present invention. As shown in the figure, the detection device for detecting the deuterium doping concentration of deuterium-doped KDP crystals according to the present invention includes a fundamental frequency laser 1, and along the output direction of the fundamental frequency laser 1 are a second-harmonic deuterium-doped KDP crystal 3, a first second-harmonic laser color separator 4, a second second-harmonic laser color separator 5, and an energy meter 6. The first second-harmonic laser color separator 4 and the second second-harmonic laser color separator 5 are both placed at 45° to the optical path. The angle at which the laser output from the fundamental frequency laser 1 is incident on the second-harmonic deuterium-doped KDP crystal 3 is controlled by a frequency doubling adjuster 2.

[0025] The method for detecting the deuterium doping concentration of KDP crystals includes the following steps:

[0026] 1) Set the output wavelength of the fundamental frequency laser 1 to 1030nm, and precisely adjust the angle of the fundamental frequency laser incident on the deuterium-doped KDP crystal by the frequency doubling tuner 2. The direction of rotation is determined by the axis of the deuterium-doped KDP crystal and the polarization state of the fundamental frequency laser. At the same time, observe the energy meter 6 to make the output of the frequency doubling laser reach its maximum.

[0027] 2) Set the output wavelength of the fundamental frequency laser 1 to 1053nm, adjust the frequency doubling regulator 2 again, and observe the energy meter 6 until the second-harmonic laser output reaches its maximum again.

[0028] 3) By using two laser beams of different wavelengths output by the fundamental frequency laser 1, the difference in phase matching angle between the two laser beams and the second harmonic deuterated KDP crystal under test is obtained. Then, it is compared with the theoretical calculation to obtain the deuterium doping concentration of the second harmonic deuterated KDP crystal under test.

[0029] Please see Figure 2 . Figure 2 This is a graph showing the theoretically calculated relationship between the difference in phase matching angles between the two laser beams and the deuterium doping concentration in this invention. Figure 2 The horizontal axis represents the deuterium doping concentration, and the vertical axis represents the angle difference between the phase matching angle corresponding to the 1053nm wavelength and the phase matching angle corresponding to the 1030nm wavelength. As shown in the figure, the difference in phase matching angles between two laser beams with wavelengths of 1030nm and 1053nm in a frequency-doubled deuterium-doped KDP crystal with different deuterium doping concentrations can be obtained through theoretical calculation. The difference in phase matching angles between the two laser beams in the frequency-doubled deuterium-doped KDP crystal under test is obtained by adjusting the crystal control device, and then the obtained phase matching angle difference is compared with... Figure 2 The deuterium doping concentration of the second harmonic-doped KDP crystal to be tested is obtained by corresponding to the relationship curve in the figure.

[0030] The fundamental frequency laser is a laser capable of generating fundamental frequency lasers of 1030nm and 1053nm.

[0031] The deuterium-doped KDP crystal to be tested is a deuterium-doped KDP crystal that can double the frequency of a 1030nm laser to a 515nm laser, or double the frequency of a 1053nm laser to a 526.5nm laser.

[0032] The frequency doubling adjuster can precisely adjust each dimension of the deuterium-doped KDP crystal under test, so that the angle at which the fundamental frequency laser is incident on the deuterium-doped KDP crystal under test is the phase matching angle.

[0033] The first and second frequency-harmonic laser color separation mirrors are color separation mirrors with high reflectivity of frequency-harmonic laser and high transmittance of fundamental laser coated on their surfaces. They are placed at 45° along the laser transmission direction and can reflect frequency-harmonic laser perpendicular to the original laser transmission direction while transmitting fundamental laser, thus obtaining pure frequency-harmonic laser.

[0034] The working process of this invention is as follows:

[0035] The fundamental frequency laser first outputs a 1030nm wavelength fundamental frequency laser. This fundamental frequency laser passes through the deuterium-doped KDP crystal under test to generate a second-harmonic laser, which is then separated by two second-harmonic laser color separators before reaching the energy meter. The angle at which the fundamental frequency laser is incident on the deuterium-doped KDP crystal under test is adjusted by a frequency doubling tuner. Adjustment is stopped when the energy measured by the energy meter reaches its maximum. At this point, the angle at which the 1030nm wavelength fundamental frequency laser is incident on the deuterium-doped KDP crystal under test is the phase matching angle. The fundamental frequency laser is adjusted to output a fundamental frequency laser with a wavelength of 1053nm. The frequency doubling regulator is repeatedly adjusted to maximize the energy measured by the energy meter. At this point, the angle at which the 1053nm fundamental frequency laser is incident on the deuterated KDP crystal under test is the corresponding phase matching angle. The difference between the phase matching angles of the two laser beams in the deuterated KDP crystal under test is calculated. Then, the relationship between the difference in phase matching angles and the deuterium doping concentration is obtained through theoretical calculation, thus obtaining the deuterium doping concentration of the deuterated KDP crystal under test.

[0036] Analysis shows that the method for detecting the deuterium doping concentration of deuterium-doped KDP crystals in this invention has the advantages of high efficiency and stability, simple debugging method, low equipment requirements and high detection accuracy, and has high application value.

Claims

1. A device for detecting the deuterium doping concentration in deuterated KDP crystals, characterized in that, The device comprises a fundamental frequency laser (1), a second-harmonic deuterium-doped KDP crystal (3) arranged sequentially along the optical path, a frequency doubling adjuster (2) for fixing the second-harmonic deuterium-doped KDP crystal (3) and capable of multi-dimensional control, a first second-harmonic laser color separator (4), a second second-harmonic laser color separator (5), and an energy meter (6). The frequency doubling adjuster (2) is used to control the angle at which the fundamental frequency light generated by the fundamental frequency laser (1) is incident on the second-harmonic deuterium-doped KDP crystal (3). The first second-harmonic laser color separator (4) and the second second-harmonic laser color separator (5) are both placed at 45° to the optical path.

2. The deuterium doping concentration detection device for deuterium-doped KDP crystals as described in claim 1, characterized in that, A third frequency-harmonic laser color separator (7) is also provided between the second frequency-harmonic laser color separator (5) and the energy meter (6) along the optical path direction.

3. The deuterium doping concentration detection device for deuterium-doped KDP crystals as described in claim 1, characterized in that, The fundamental frequency laser (1) can output lasers with wavelengths of 1030nm and 1053nm respectively.

4. A detection method for the deuterium doping concentration detection device for deuterium-doped KDP crystals as described in claim 1, characterized in that, This method mainly includes the following steps: S1: Set the output wavelength of the fundamental frequency laser (1), and precisely adjust the angle of the fundamental frequency light incident on the second-harmonic deuterium-doped KDP crystal (3) through the frequency doubling adjuster (2). At the same time, observe the energy meter (6) to make the second-harmonic laser output reach the maximum value, and record the rotation angle corresponding to the frequency doubling adjuster (2) at this time. S2: Change the output wavelength of the fundamental frequency laser (1), and adjust the frequency doubling regulator (2) again so that the second harmonic laser measured by the energy meter (6) reaches the maximum value. Record the rotation angle of the frequency doubling regulator (2) at this time. S3: The difference in phase matching angle between the second-harmonic deuterated KDP crystal (3) and the two wavelength lasers is calculated. By comparing the theoretical calculation relationship between the deuterium doping concentration of the second-harmonic deuterated KDP crystal and the difference in phase matching angle between the two wavelength lasers, the deuterium doping concentration in the second-harmonic deuterated KDP crystal (3) is obtained.

5. The detection method for a deuterium doping concentration detection device for deuterium-doped KDP crystals as described in claim 4, characterized in that, The output wavelength of the fundamental frequency laser (1) in step S1 is set to 1030nm.

6. The detection method for a deuterium doping concentration detection device for deuterium-doped KDP crystals as described in claim 4, characterized in that, The output wavelength of the fundamental frequency laser (1) in step S2 is set to 1053nm.

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