Method and device for realizing human body safety measurement of crystal electro-optic coefficient

Abstract

The invention discloses a method and a device for realizing human body safety measurement of a crystal electro-optic coefficient, and belongs to the technical field of photoelectric measurement, and the method comprises the following steps: constructing a crystal electro-optic coefficient measurement light path which comprises a wavelength tunable light source, a polarizer, a true zero-order half-wave plate, an electro-optic crystal to be measured, an analyzer and a power meter which are sequentially arranged along a light path propagation direction; connecting the electro-optical crystal to be measured with an adjustable direct-current low-voltage power supply; adjusting the wavelength of the light source and the voltage on the to-be-measured electro-optical crystal, judging the extinction state through a power meter, and fitting according to the wavelength voltage data corresponding to multiple groups of extinction states to obtain the electro-optical coefficient of the to-be-measured electro-optical crystal. The precision of the electro-optical coefficient obtained through fitting of multiple groups of data is equivalent to that of a traditional high-voltage method, meanwhile, only extremely small phase delay needs to be generated each time in the multiple extinction processes, the measurement voltage is greatly reduced, and potential safety hazards and crystal breakdown risks caused by high voltage are effectively avoided.

Description

Technical Field

[0001] This invention relates to the field of photoelectric measurement technology, and more specifically to a method and apparatus for safely measuring the electro-optic coefficient of a crystal. Background Technology

[0002] Electro-optic crystals are core materials for high-speed electro-optic switches, modulators, and pulsed lasers. Their electro-optic coefficient directly determines the performance and stability of the devices and is a key parameter for evaluating material quality. Currently, methods for measuring the electro-optic coefficient of crystals include the half-wave voltage method, the elliptic apparatus method, the interferometric compensation method, and the electro-optic effect comparison method. Among these, the elliptic apparatus method is complex and requires high precision, which is difficult for domestically produced equipment to achieve, resulting in high testing costs and limited usage. The interferometric compensation method and the electro-optic effect comparison method are both indirect measurement methods, based on the inverse piezoelectric effect or electro-optic effect of the reference sample. The measurement results are heavily dependent on the type and quality of the reference sample, resulting in limited accuracy and insufficient reliability. Overall, the half-wave voltage method remains the most direct, commonly used, mature, and authoritative method for measuring the electro-optic coefficient, offering advantages such as economy, accuracy, and convenience.

[0003] The fundamental principle of the half-wave voltage method is to calculate the electro-optic coefficient by using the voltage required to generate a λ / 2 optical path difference (i.e., phase difference) in an orthogonally polarized optical path and applying theoretical formulas. The half-wave voltage of most electro-optic crystals can reach several kilovolts, placing stringent requirements on the performance of high-voltage power supplies. This not only increases equipment costs but also imposes strict requirements on the measurement environment, posing serious safety hazards to measurement personnel. For crystals with smaller electro-optic coefficients, tens of thousands of volts are required. For some crystals with even smaller electro-optic coefficients or low resistivity, which are prone to overheating or breakdown under high voltage, the half-wave voltage method may even be insufficient to obtain results.

[0004] In summary, how to develop new methods for measuring electro-optic coefficients that are simple, economical, direct, and accurate, while strictly controlling the operating voltage below 36 V for human safety, has become an urgent problem to be solved in the field of electro-optic crystal research. Summary of the Invention

[0005] In view of the above problems, the present invention is proposed to provide a method and apparatus for safely measuring the electro-optic coefficient of a crystal to overcome or at least partially solve the above problems.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, embodiments of the present invention provide a method for safely measuring the electro-optic coefficient of a crystal, comprising the following steps: Step 1: Construct the optical path for measuring the electro-optic coefficient of the crystal, including a wavelength-tunable light source, a polarizer, a true zero-order half-wave plate, the electro-optic crystal under test, an analyzer, and a power meter arranged sequentially along the propagation direction of the optical path; Step 2: Connect the electro-optic crystal under test to an adjustable DC low-voltage power supply; Step 3: Adjust the output wavelength of the wavelength-tunable light source. When the output wavelength is fixed, adjust the voltage applied to the electro-optic crystal under test by the adjustable DC low-voltage power supply until the reading of the power meter reaches a minimum value. Determine that the measurement optical path is in an extinction state and record a set of wavelength and voltage values ​​at this time. Step 4: Repeat step 3 to obtain multiple sets of wavelength and voltage values; Step 5: Perform linear fitting on the obtained multiple sets of wavelength values ​​and voltage values, and obtain the electro-optic coefficient of the electro-optic crystal under test based on the fitting results.

[0007] Furthermore, in step three, when the power meter reading reaches its minimum value, the phase difference generated by the electro-optic effect due to the applied voltage in the electro-optic crystal compensates for the dispersive phase difference caused by the wavelength change in the half-wave plate, resulting in a total phase difference in the optical path for measuring the crystal's electro-optic coefficient. .

[0008] Furthermore, in the crystal electro-optic coefficient measurement optical path constructed in step one, the maximum output voltage of the adjustable DC low-voltage power supply is no higher than 36V.

[0009] Furthermore, in the crystal electro-optic coefficient measurement optical path constructed in step one, the transmission directions of the polarizer and the analyzer are parallel to each other.

[0010] Furthermore, the electro-optic crystal under test includes one of BBO crystal, DKDP crystal, or KDP crystal.

[0011] Furthermore, when the electro-optic crystal under test is a BBO crystal, the transverse electro-optic coefficient of the electro-optic crystal under test is measured; When the electro-optic crystal under test is a DKDP crystal or a KDP crystal, the longitudinal electro-optic coefficient of the electro-optic crystal under test is measured.

[0012] Secondly, embodiments of the present invention provide a device for safely measuring the electro-optic coefficient of a crystal, comprising a crystal electro-optic coefficient measurement optical path and a data control and processing module. The crystal electro-optic coefficient measurement optical path includes a wavelength-tunable light source, a polarizer, a true zero-order half-wave plate, the electro-optic crystal under test, an analyzer, and a power meter arranged sequentially along the propagation direction of the optical path; wherein the electro-optic crystal under test is connected to an adjustable DC low-voltage power supply. The data control and processing module is connected to the wavelength-tunable light source, the adjustable DC low-voltage power supply, and the power meter, respectively. It is used to adjust the wavelength of the wavelength-tunable light source and the voltage of the adjustable DC low-voltage power supply, and to measure the optical path in an extinction state based on the minimum value of the power meter reading when the wavelength is fixed. It records multiple sets of wavelength and voltage data, and performs linear fitting based on the recorded multiple sets of wavelength and voltage data to obtain the electro-optic coefficient of the electro-optic crystal under test.

[0013] Preferably, the wavelength of the wavelength-tunable light source is continuously adjustable within the range of 500-560 nm.

[0014] Preferably, the true zero-order half-wave plate comprises a true zero-order half-wave plate made of quartz.

[0015] Preferably, the electro-optic crystal to be tested is processed into a hexahedral shape.

[0016] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects: Improved operational safety: This invention employs a novel measurement mechanism that alters the wavelength and compensates for low voltage, significantly reducing the required measurement voltage from thousands of volts in existing technologies to below 36V, a safe voltage range for the human body. This fundamentally eliminates the serious safety hazards posed to measurement personnel by high-voltage operation. Traditional half-wave voltage methods are characterized by single extinction... Phase delay often requires voltages of several kilovolts; this invention achieves phase delay through multiple extinction processes, each requiring only a very small phase delay (approximately 0.01 volts). This reduces the measurement voltage to a level safe for the human body, ensuring the personal safety of the measurement personnel.

[0017] Expanding the scope of application: Due to the extremely low operating voltage, this invention avoids the crystal heating or breakdown problems that may be caused by strong electric fields, making this embodiment applicable to the measurement of special electro-optic crystals that are difficult to handle by traditional high-voltage methods, such as those with low resistivity and easy breakdown, thus broadening the application range of electro-optic coefficient measurement.

[0018] The system is simple and economical: the optical path structure of this invention is simple, consisting of basic optical components, and is easy to adjust. Furthermore, since it only requires a low-cost DC low-voltage power supply, compared to traditional methods that require high-performance high-voltage power supplies, this invention is more economical while ensuring safety and accuracy. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the electro-optic coefficient measuring device disclosed in an embodiment of the present invention.

[0021] Figure 2 The factory-designed wavelength disclosed in the embodiments of the present invention =532 nm quartz half-wave plate and The diagram illustrates the linear dependence between them, with a slope of approximately -0.1 in the 520-540 nm band.

[0022] Figure 3 This is a schematic diagram of the wavelength voltage data measurement results in Embodiment 1 of the present invention.

[0023] Figure 4 This is a schematic diagram of the wavelength voltage data measurement results in Embodiment 2 of the present invention.

[0024] Figure 5 This is a schematic diagram of the wavelength voltage data measurement results in Embodiment 3 of the present invention.

[0025] The components represented by each number in the diagram are listed below: 1-Tunable wavelength light source, 2-Polarizer, 3-True zero-order half-wave plate, 4-Electro-optic crystal under test, 5-Adjustable DC low-voltage power supply, 6-Analyzer, 7-Power meter. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] This invention discloses a method for safely measuring the electro-optic coefficient of a crystal, achieved through multiple extinction cycles. The method includes the following steps: Step 1: Construct the optical path for measuring the electro-optic coefficient of the crystal, including a wavelength-tunable light source, a polarizer, a true zero-order half-wave plate, the electro-optic crystal under test, an analyzer, and a power meter arranged sequentially along the propagation direction of the optical path; Step 2: Connect the electro-optic crystal under test to the adjustable DC low-voltage power supply; Step 3: Adjust the output wavelength of the wavelength-tunable light source. When the output wavelength is fixed, adjust the voltage applied to the electro-optic crystal under test by the adjustable DC low-voltage power supply until the reading of the power meter reaches a minimum value. Determine that the measurement optical path is in an extinction state and record a set of wavelength and voltage values ​​at this time. Step 4: Repeat step 3 to obtain multiple sets of wavelength and voltage values; Step 5: Perform linear fitting on the obtained multiple sets of wavelength values ​​and voltage values, and obtain the electro-optic coefficient of the electro-optic crystal under test based on the fitting results.

[0028] In the above method, when the power meter reading reaches its minimum value, the phase difference generated by the electro-optic effect caused by the applied voltage in the electro-optic crystal under test compensates for the dispersive phase difference caused by the wavelength change of the true zero-order half-wave plate, so that the total phase difference of the optical path for measuring the electro-optic coefficient of the crystal is p.

[0029] By adjusting the wavelength of the tunable light source and the voltage applied to the electro-optic crystal by the adjustable DC low-voltage power supply, multiple sets of wavelength and voltage values ​​that meet the extinction state of the optical path for measuring the electro-optic coefficient of the crystal are recorded, and the final electro-optic coefficient is obtained by fitting.

[0030] The inventive principle and specific testing steps of the present invention will be further explained below through different embodiments.

[0031] Example 1

[0032] Example 1 discloses the measurement of the electro-optic coefficient of BBO crystal using the present invention. The method and measuring device are the same. Figure 1 As shown. The wavelength-tunable light source 1 is a tunable optical parametric oscillator (OPO) laser (Horizon), with an output wavelength continuously tunable in the range of 500-560 nm. Both polarizer 2 and analyzer 6 are 12.7 mm aperture Glan-Taylor prisms. The true zero-order half-wave plate 3 is a true zero-order half-wave plate made of quartz, with a working wavelength... It is 532 nm. The electro-optic crystal 4 under test is a commercially available electro-optic Pockel cell (CASTECH, BPA-3AS-L), and the electro-optic material used is... The crystal is processed into a hexahedral shape, with the manufacturer's nominal dimensions being... The light transmission direction is along the Z-axis, and the electric field direction is along the X-axis. The two Z-side faces of the light transmission are polished and coated with an anti-reflection film, while the two X-side faces of the electric field are coated with silver electrodes. The adjustable low-voltage DC power supply 5 is a commercially available low-voltage DC power supply with continuously adjustable output voltage up to 36V. Its positive and negative terminals are connected via power lines to... A human-safe voltage between -36 and 36V can be applied to the crystal's side electrodes via electrode swapping. The power meter 7 consists of a 3A probe and a power meter head, with a minimum resolution of microwatts, capable of adequately determining the system's extinction state.

[0033] The general measurement steps in this embodiment are as described above. Specifically, regarding the measurement data in this embodiment, the derivation process of the fitting formula is as follows: The phase delay calculation formula for the 532 nm true zero-order half-wave plate 3 made of quartz crystal is: The refractive index dispersion equation described in "Optics Communications, 163, 95-102, 1999" can be used to obtain the refractive index dispersion of quartz crystals at the working wavelength. Birefringence at =532 nm The value is 0.009191199, thus yielding a thickness d1 of 28.9 μm for the true zero-order half-wave plate 3. When the wavelength of the light emitted by the wavelength-tunable light source 1 is... When the design wavelength of the true zero-order half-wave plate 3 is deviated from by 532 nm, the true zero-order half-wave plate will... A new additional phase difference is generated based on the existing phase difference. Size is ,in Assuming Then the numerator term in the above equation becomes For quartz crystals (true zero-order half-wave plates), the following pattern exists in the experimental wavelength range of 520-540 nm. (like Figure 2 As shown in the figure, this linear dependency is the fundamental basis of the calculation method of this invention. Therefore, it can be seen that... ,and , This takes into account the true zero-order half-wave plate of a 532 nm quartz crystal. Therefore, it can be concluded that when =532 nm, in this embodiment Within a measurement range of 6 nm, the additional phase difference caused by the change in detection wavelength This refers to the phase delay range on the electro-optic crystal sample that needs to be compensated for by applying voltage. Compared to the p-phase delay required by the traditional half-wave voltage measurement method, this is reduced by two orders of magnitude, resulting in a crystal voltage reduction of approximately 100 times, reaching a level safe for the human body. The phase delay generated on the electro-optic crystal BBO under test... Wavelength Electro-optic coefficient The function of voltage V has different expressions for different crystal types and cuts, but can be uniformly written as... For the BBO crystal with the cut described in this embodiment, the phase difference caused by the electro-optic effect... , where n o Let be the o-ray refractive index of the BBO crystal, and l2 and d2 be the length of the BBO crystal in the light transmission direction and the thickness in the electric field direction (i.e., the electrode spacing), respectively. The extinction conditions can be used to further obtain the extinction voltage. This serves as the basis for fitting the measurement data.

[0034] The specific measurement process is as follows: Turn on the wavelength-tunable light source 1 (tunable optical parametric oscillator laser) to output 532nm laser light. Adjust polarizer 2 and analyzer 6 so that their transmission directions are perpendicular to each other. Place the BBO crystal (used as the electro-optic crystal 4 to be tested) between polarizer 2 and analyzer 6, and finely adjust the crystal angle to extinct the light path. At this time, the laser light is incident along the principal axis of the BBO crystal. Rotate analyzer 6 until the system output light intensity reaches its maximum. At this time, the transmission directions of analyzer 6 and polarizer 2 are parallel to each other. Insert a true zero-order half-wave plate 3 between polarizer 2 and the BBO crystal. Place the true zero-order half-wave plate 3 perpendicular to the light path. Rotate the true zero-order half-wave plate 3 until the system is extinct. At this time, the true zero-order half-wave plate 3 generates light on the laser light. Phase difference: The electro-optic crystal under test generates a zero phase difference with the laser. The wavelength of the tunable light source 1 is changed by equal amplitude from the initial wavelength towards shorter and longer wavelengths, respectively. Simultaneously, an adjustable low-voltage DC power supply is used to gradually increase the forward or reverse voltage on the BBO crystal from 0, so that the phase difference generated by the BBO crystal gradually cancels out the phase difference caused by dispersion in the half-wave plate. In addition to the phase difference, the reading on power meter 7 will gradually decrease. When the reading on power meter 7 reaches its lowest point, the entire optical path system is in an extinction state. Record the extinction voltage values ​​for each wavelength. Measurement results are attached. Figure 3 The independent black dots shown represent the measured fitting data of the extinction voltage of the BBO crystal under test as a function of wavelength.

[0035] The operating wavelength of the quartz half-wave plate =532 nm, obtained above The thickness d1 = 28.9 μm, the electrode spacing d2 = 3 mm, the light transmission length l2 = 20 mm of the BBO sample mentioned above, and the o-ray refractive index n of the BBO crystal at 532 nm obtained from the literature "IEEE JQE, 22, 1013-1014, 1986" are all specified. o =1.6742 Substituted into the formula , combined Figure 3 The measured data can be used to analyze the wavelength change using the extinction voltage V. The straight line fitting yielded =3.03 pm / V.

[0036] Example 2 Example 2 discloses the measurement of the electro-optic coefficient of a DKDP crystal using the present invention. The method. The measuring device is also as follows. Figure 1 As shown. The difference is that in Example 2, the electro-optic crystal 4 under test is a DKDP crystal with a deuterium content of 98% that has been processed into a hexahedral shape, and its size is... The light transmission direction is along the Z-axis, and transparent electrodes and voltages are applied to the two light-transmitting end faces of the DKDP crystal.

[0037] The general measurement steps in this embodiment are the same as in Embodiment 1, and the measurement results are as follows: Figure 4 The independent black dots shown represent the measured data of the extinction voltage of the DKDP crystal under test as a function of wavelength.

[0038] Will d1=28.9μm, n o =1.5087, =532 nm Substituting into the formula , combined Figure 4 The measured data can be expressed as a function of voltage V and wavelength change. The straight line fitting yielded =26.19 pm / V. For the same sample, we measured its 532 nm half-wave voltage as 2970 V using the traditional half-wave voltage method. It can be seen that this embodiment reduces the measurement voltage by approximately 100 times, obtaining electro-optic coefficient measurement results similar to the traditional half-wave voltage method while fully ensuring personnel safety, with a difference of only 0.4%. Furthermore, the value obtained in this embodiment is also very close to the standard value reported in previous literature (26.4 pm / V), with a difference of 0.8%. These comparisons confirm the reliability of this technique.

[0039] Example 3 Example 3 discloses the measurement of the electro-optic coefficient of a KDP crystal using the present invention. The method and measuring device are the same. Figure 1 As shown. The difference is that in Example 2, the electro-optic crystal 4 under test is a KDP crystal processed into a hexahedral shape, with a size of... The light transmission direction is along the Z-axis, and transparent electrodes and voltages are applied to the front and rear light transmission end faces of the crystal.

[0040] The general measurement steps in this embodiment are the same as in Embodiment 1, and the measurement results are as follows: Figure 5 The independent black dots shown represent the actual measured data of the extinction voltage of the KDP crystal under test as a function of wavelength.

[0041] Will d1=28.9μm, n o =1.5129, =532 nm Substitute , combined Figure 5 The actual measurement data shown can be expressed by varying the wavelength through voltage V. The straight line fitting yielded =10.07 pm / V.

[0042] For the same sample, we measured its 532 nm half-wave voltage using the traditional half-wave voltage method to be 7720 V, corresponding to... =9.95 pm / V. It can be seen that this embodiment reduces the measurement voltage by approximately 200 times, achieving an electro-optic coefficient measurement result similar to the traditional half-wave voltage method while fully ensuring personnel safety, with a difference of only 1.2%. Furthermore, the value obtained in this embodiment is also very close to the previously reported value (10.3 pm / V), with a difference of only 2.2%. These comparisons confirm the reliability of this technology.

[0043] Secondly, this invention also discloses a device for safely measuring the electro-optic coefficient of a crystal, comprising a crystal electro-optic coefficient measurement optical path and a data control and processing module, as shown in the reference. Figure 1 The optical path for measuring the electro-optic coefficient of a crystal includes a wavelength-tunable light source 1, a polarizer 2, a true zero-order half-wave plate 3, the electro-optic crystal under test 4, an analyzer 6, and a power meter 7 arranged sequentially along the propagation direction of the optical path; wherein, the electro-optic crystal under test 4 is connected to an adjustable DC low-voltage power supply 5. The data control and processing module (not shown in the figure) is connected to the wavelength-tunable light source, the adjustable DC low-voltage power supply, and the power meter, respectively. It is used to adjust the wavelength of the wavelength-tunable light source and the voltage of the adjustable DC low-voltage power supply, and to measure the optical path in an extinction state based on the minimum value of the power meter reading when the wavelength is fixed. It records multiple sets of wavelength and voltage data, and performs linear fitting based on the recorded multiple sets of wavelength and voltage data to obtain the electro-optic coefficient of the electro-optic crystal under test.

[0044] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0045] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for safely measuring the electro-optic coefficient of a crystal, characterized in that, Includes the following steps: Step 1: Construct the optical path for measuring the electro-optic coefficient of the crystal, including a wavelength-tunable light source, a polarizer, a true zero-order half-wave plate, the electro-optic crystal under test, an analyzer, and a power meter arranged sequentially along the propagation direction of the optical path; Step 2: Connect the electro-optic crystal under test to an adjustable DC low-voltage power supply; Step 3: Adjust the output wavelength of the wavelength-tunable light source. When the output wavelength is fixed, adjust the voltage applied to the electro-optic crystal under test by the adjustable DC low-voltage power supply until the reading of the power meter reaches a minimum value. Determine that the measurement optical path is in an extinction state and record a set of wavelength and voltage values ​​at this time. Step 4: Repeat step 3 to obtain multiple sets of wavelength and voltage values; Step 5: Perform linear fitting on the obtained multiple sets of wavelength values ​​and voltage values, and obtain the electro-optic coefficient of the electro-optic crystal under test based on the fitting results.

2. The method for safely measuring the electro-optic coefficient of a crystal as described in claim 1, characterized in that, In step three, when the power meter reading reaches its minimum value, the phase difference generated by the electro-optic effect due to the applied voltage in the electro-optic crystal compensates for the dispersion phase difference caused by the wavelength change in the half-wave plate, resulting in a total phase difference in the optical path for measuring the crystal's electro-optic coefficient. .

3. The method for safely measuring the electro-optic coefficient of a crystal as described in claim 1, characterized in that, In the crystal electro-optic coefficient measurement optical path constructed in step one, the maximum output voltage of the adjustable DC low-voltage power supply is no higher than 36V.

4. The method for safely measuring the electro-optic coefficient of a crystal as described in claim 1, characterized in that, In the crystal electro-optic coefficient measurement optical path constructed in step one, the transmission directions of the polarizer and the analyzer are parallel to each other.

5. The method for safely measuring the electro-optic coefficient of a crystal as described in claim 1, characterized in that, The electro-optic crystal to be tested includes one of BBO crystal, DKDP crystal, or KDP crystal.

6. The method for safely measuring the electro-optic coefficient of a crystal as described in claim 5, characterized in that, When the electro-optic crystal under test is a BBO crystal, the transverse electro-optic coefficient of the electro-optic crystal under test is measured. When the electro-optic crystal under test is a DKDP crystal or a KDP crystal, the longitudinal electro-optic coefficient of the electro-optic crystal under test is measured.

7. A device for safely measuring the electro-optic coefficient of a crystal, characterized in that, The device includes a crystal electro-optic coefficient measurement optical path and a data control and processing module. The crystal electro-optic coefficient measurement optical path includes a wavelength-tunable light source, a polarizer, a true zero-order half-wave plate, the electro-optic crystal under test, an analyzer, and a power meter arranged sequentially along the optical path propagation direction. The electro-optic crystal under test is connected to an adjustable DC low-voltage power supply. The data control and processing module is connected to the wavelength-tunable light source, the adjustable DC low-voltage power supply, and the power meter, respectively. It is used to adjust the wavelength of the wavelength-tunable light source and the voltage of the adjustable DC low-voltage power supply, and to measure the optical path in an extinction state based on the minimum value of the power meter reading when the wavelength is fixed. It records multiple sets of wavelength and voltage data, and performs linear fitting based on the recorded multiple sets of wavelength and voltage data to obtain the electro-optic coefficient of the electro-optic crystal under test.

8. The device for safely measuring the electro-optic coefficient of a crystal as described in claim 7, characterized in that, The wavelength of the wavelength-tunable light source can be continuously adjusted within the range of 500-560 nm.

9. The device for safely measuring the electro-optic coefficient of a crystal as described in claim 7, characterized in that, The true zero-order half-wave plate includes a true zero-order half-wave plate made of quartz.

10. The device for safely measuring the electro-optic coefficient of a crystal as described in claim 7, characterized in that, The electro-optic crystal to be tested is processed into a hexahedral shape.

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