A device and a method for preparing a disk-shaped crystal whispering gallery cavity

Abstract

The application discloses a kind of preparation device and preparation method of disc type crystal echo wall cavity, belong to optical material processing technical field.The device includes processing tool, the upper surface of processing tool is provided with recess for processing crystal echo wall sample, the curvature radius of groove bottom is slightly smaller than the radius of crystal echo wall sample, for grinding and polishing processing of crystal echo wall cavity, crystal echo wall sample has completed milling and grinding molding;Grinding, polishing crystal echo wall sample to be placed in the recess of processing tool, the top of crystal echo wall cavity sample is vertically provided with sample fixing rod for fixing itself, the bottom of processing tool is connected with coaxial motor through transmission shaft;Crystal echo wall cavity is finely ground, rough polished and fine polished using processing tool, to realize the processing of crystal echo wall cavity.It is convenient to use, and the application range of material is large, which can significantly reduce the preparation cost and shorten the preparation period.

Description

Technical Field

[0001] This invention relates to a fabrication apparatus and method for a disc-type crystal sound-alley cavity, belonging to the field of optical material processing technology. Background Technology

[0002] In recent years, optical resonators based on whispering gallery mode (WGM) have become a research hotspot due to their extremely high quality factor (Q value), extremely small mode volume, extremely narrow spectral linewidth, simple fabrication, and integrability. They are widely used in linear and nonlinear optical research, such as optical filtering, nonlinear optics, cavity quantum electrodynamics, high-sensitivity sensing, and low-threshold lasers. WGM-based optical resonators have demonstrated high academic value and broad application prospects in optics, biomedicine, chemistry, and many other fields, becoming a current focus in optical research and application.

[0003] Optical whispering cavities can be fabricated from various materials. For example, early droplet-type optical whispering cavities, due to the surface tension of the liquid, formed an extremely smooth whispering cavity surface, thus achieving a very high Q value. However, the development of droplets as optical whispering cavities has encountered some problems: rapid liquid evaporation, poor size and shape control, instability of the formed whispering cavity, and low practicality, significantly hindering the practical application of droplet-based resonant whispering mode optical cavities. In recent years, various solid-state optical whispering cavity fabrication technologies have developed rapidly. For example, by using electrode discharge or CO2 lasers to melt quartz optical fibers or quartz rods, different types of optical whispering cavities such as microspheres, micropillars, and microbubbles can be fabricated. These fabrication methods are relatively simple and can achieve reusability of the whispering cavity while maintaining a high Q value, making the practical application of optical whispering cavities possible in various fields. However, the morphology of whispering cavities fabricated using electrode discharge or CO2 laser melting methods is difficult to control, and they are prone to problems such as complex and dense mode spectra. Furthermore, the small size of whispering cavities makes them susceptible to environmental factors such as temperature and vibration, leading to a series of problems in practical applications. In recent years, with the development of micro-nano fabrication and semiconductor chip manufacturing technologies, waveguide-type WGM optical whispering cavities made of SiN, Si, SiO2, and LiNbO3 can be fabricated using the ultra-high processing precision of semiconductor CMOS (Complementary Metal Oxide Semiconductor) technology and single-crystal silicon as the substrate material. This type of whispering cavity can achieve highly integrated chip-level photonic devices with other on-chip optical components, enabling mass production. However, inherent material losses and fabrication process issues limit the device's quality factor (Q value) to 10. 4 ~10 7The fabrication of ultra-high Q-value sound-gallery cavities is difficult due to their large scale. Furthermore, the equipment and processes required for current CMOS technology are complex and the investment costs are extremely high, posing certain challenges to its large-scale application.

[0004] Compared to materials like quartz glass and silicon, optical crystal materials possess superior optical properties such as high optical transmittance and a wide transmission spectrum, making them one of the ideal materials for ultra-high Q-value optical whispering-gallery resonators. Optical crystal whispering-gallery cavities use high-optical-quality crystals as materials, commonly such as fluoride crystals (CaF2, MgF2, etc.), lithium niobate, and sapphire. Through precision optical processing methods, the surface morphology of the whispering-gallery resonator can be precisely controlled during fabrication, achieving a smooth surface with nanometer-level roughness. Currently, crystal whispering-gallery cavities can achieve a roughness greater than 10... 9 The extremely high Q-value of crystal whispering cavities (CVCs) enables them to achieve a powerful field enhancement effect, typically increasing the optical power density within the cavity by tens of thousands to millions of times compared to the incident light. Therefore, CVCs can significantly reduce the threshold of various optical nonlinear effects. Furthermore, the excellent intrinsic thermomechanical properties of the crystal material can greatly alleviate thermal instabilities caused by high power densities within the CVC and the disturbances to the optical field by mechanical modes, making CVCs highly valuable in optics, physics, chemistry, and many other fields. Currently, the main method for fabricating ultra-high Q-value CVCs is using a single-point diamond ultra-precision lathe. Under strict control of the machine tool and processing environment, a disc-shaped CVC with nanometer-level precision and meeting certain optical quality requirements is directly machined using diamond tools. The advantage of this method is that it allows for precise control of the cavity's surface morphology and the ability to design parameters according to different needs. However, the surface roughness of the crystal after single-point diamond machining is approximately in the tens of nanometer range, and it is still impossible to achieve a roughness greater than 10. 9 The fabrication of ultra-high Q-value crystal sounding cavities requires further surface polishing using precision optical polishing after turning, to achieve nanoscale low-roughness ultra-high Q-value crystal sounding cavities. However, the high cost of single-point diamond ultra-precision lathes and the stringent environmental requirements of the machining process significantly hinder the fabrication of ultra-high Q-value disc-type crystal sounding cavities, resulting in high costs per device and limiting their widespread application. Summary of the Invention

[0005] To address the shortcomings of existing technologies, a fabrication apparatus and method for a disc-type crystal sounding wall cavity are provided. This method overcomes the high requirements of existing fabrication technologies for equipment and environment, while reducing processing costs, and produces a disc-type crystal sounding wall cavity with low roughness and a high quality factor (Q value).

[0006] To achieve the above-mentioned technical objectives, the present invention provides a fabrication apparatus and method for a disc-shaped crystal soundbar cavity, comprising a processing tool. The upper surface of the processing tool is provided with a groove for processing a crystal soundbar sample. The radius of curvature at the bottom of the groove is slightly smaller than the radius of the crystal soundbar sample. The groove is used for grinding and polishing the crystal soundbar cavity. The crystal soundbar sample has been milled and shaped. The crystal soundbar sample to be polished is placed in the groove of the processing tool. A sample fixing rod is vertically arranged at the top of the crystal soundbar cavity sample to fix itself. The bottom of the processing tool is connected to a coaxial motor through a drive shaft.

[0007] Furthermore, the machining tools are made of stainless steel, brass, or aluminum alloy;

[0008] A method for preparing a disc-type crystal sound-alley cavity includes the following steps:

[0009] First, the crystal echo chamber sample is milled and shaped.

[0010] After molding, the crystal sound wall cavity sample is placed in the groove of the processing tool through a fixing rod. The processing tool is fixed to the coaxial motor through a drive shaft. Different grit sizes of diamond are replaced in the processing tool in sequence. The coaxial motor is turned on, and the processing tool is rotated through the drive shaft to achieve fine grinding of the sound wall cavity.

[0011] After fine grinding, the diamond abrasive is removed and polishing adhesive is applied to the inner wall of the groove of the small processing tool. Then, the finely ground crystal sound wall cavity sample is rough and finely polished using a polishing liquid prepared with diamond micro powder.

[0012] After fine polishing, the polished crystal sounding cavity sample was cleaned with deionized water, acetone, and anhydrous ethanol, ultimately yielding a high-quality factor disc-shaped crystal sounding cavity with low surface roughness and a quality factor Q value greater than 10. 12 .

[0013] Furthermore, the crystal sounding wall cavity sample is made of CaF2, MgF2, YAG, silicon carbide, diamond, or sapphire.

[0014] Furthermore, the polishing adhesive is prepared by compression molding of asphalt and rosin in a 4:6 ratio.

[0015] Furthermore, the diamond used for fine grinding of the sound wall cavity was successively polished using three types of diamond abrasive: W14, W10, and W7.

[0016] Furthermore, the finely ground crystal echo chamber is placed in the processing tool of the preparation device, and a polishing slurry prepared with diamond micro powder with an average particle size of 2μm is selected for rough polishing to remove obvious defects such as large pits and scratches on the crystal surface. At the same time, the speed of the coaxial motor is selected to be 20-60r / min during the polishing process.

[0017] Furthermore, the coarsely polished crystal sounding wall cavity was finely polished with diamond micron polishing slurry with an average particle size of approximately 1 μm and 0.5 μm, respectively. At the same time, the speed of the coaxial motor was set to 10-50 r / min. During the polishing process, the polishing angle of the crystal sounding wall cavity was adjusted slightly by manual means or by controlling the swing shaft.

[0018] Beneficial effects:

[0019] Based on traditional optical processing techniques, a fabrication apparatus and method for disc-shaped crystal sounding cavities have been developed, capable of producing disc-shaped crystal sounding cavities with low surface roughness and high quality factor (Q value). Unlike the current mainstream single-point diamond ultra-precision lathe machining method, this invention utilizes small processing tools in the fabrication apparatus combined with abrasive materials such as different grades of diamond abrasive and polishing materials such as diamond micropowder to perform abrasive and precision optical polishing on the milled crystal sounding resonator. This overcomes the high requirements of existing fabrication technologies on equipment and environment, has low requirements on processing equipment and operator skills, and is applicable to a wide range of materials. It can significantly reduce fabrication costs and shorten the fabrication cycle, which is conducive to promoting and realizing the application of high-quality factor crystal sounding cavities in various fields such as optical nonlinearity research, ultra-narrow linewidth light sources, high-precision sensing, and optoelectronic countermeasures. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the preparation device of the present invention.

[0021] Figure 2 Figure 1 shows the MgF2 crystal echo-gallery cavity prepared in the embodiments of the present invention and the roughness measurement results; Figure 2a is a picture of the processed MgF2 crystal echo-gallery cavity; Figure 3b is an interference pattern of the crystal echo-gallery cavity under a white light interferometer; Figure 4c is the surface roughness data.

[0022] Reference numerals: 1. Machining tool, 2. Drive shaft, 3. Coaxial motor, 4. Fixing rod, 5. Crystal sounding wall sample. Detailed Implementation

[0023] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings:

[0024] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0025] To obtain a crystal sounding wall cavity with low roughness and a high quality factor (Q value), this invention provides a fabrication apparatus and method for a disc-type crystal sounding wall cavity, comprising the following steps:

[0026] The preparation device includes a small processing tool 1, a drive shaft 2, a coaxial motor 3, and a sample fixing rod 4. The small processing tool 1 is a groove-type processing tool based on brass, with the radius of curvature at the bottom of the groove being slightly smaller than the radius of the crystal sounder cavity material. It is used for the grinding and polishing process of the crystal sounder cavity.

[0027] The crystal sound wall material 5 is milled and shaped.

[0028] The milled crystal sound wall cavity is placed in the processing tool 1 of the preparation device through the fixing rod 4. The processing tool 1 is fixed on the coaxial motor 3 through the transmission shaft 2. The sound wall cavity is finely ground in the processing tool 1 using three types of diamond abrasive: W14, W10 and W7.

[0029] The finely ground crystal sound wall cavity is cleaned and dried;

[0030] A polishing adhesive, prepared by mixing asphalt and rosin in a ratio of 4:6, is applied to the inner wall of the groove of the small processing tool 1 in the preparation device. The polishing adhesive is prepared by compression molding. After the polishing adhesive is applied, the radius of curvature at the bottom of the groove is slightly smaller than the radius of the crystal sounding wall cavity.

[0031] The finely ground crystal echo cavity is placed in the processing tool 1 of the preparation device. A polishing slurry made of diamond micro powder with an average particle size of 2μm is selected for rough polishing to remove obvious defects such as large pits and scratches on the crystal surface. At the same time, the speed of the coaxial motor 3 is selected to be 20-60r / min during the polishing process.

[0032] After rough polishing, the crystal sounding wall cavity was finely polished with diamond micro powder polishing slurry with an average particle size of about 1μm and 0.5μm respectively. At the same time, the speed of coaxial motor 3 was set to 10-50r / min. During the polishing process, the polishing angle of the crystal sounding wall cavity was adjusted slightly by manual means or by controlling the swing shaft.

[0033] The polished crystal sounding wall cavity is cleaned at least three times with deionized water, acetone, and anhydrous ethanol to finally obtain a disc-shaped crystal sounding wall cavity with low surface roughness and a high quality factor Q value.

[0034] Example 1

[0035] In this embodiment, the disc-type crystal sound wall cavity is made of MgF2.

[0036] First, prepare MgF2 crystal 5 with a diameter of 5.5 mm and a thickness of 0.8 mm. Then, mill the crystal to its desired shape, with each milling pass having a feed rate of approximately 0.02 mm. The center thickness and accuracy of the milled crystal should be controlled within ±0.1 mm. However, this is not the only acceptable method. Those skilled in the art can adjust the feed rate during milling according to the actual situation to avoid breakage due to the relatively high hardness of the crystal during the milling process.

[0037] Next, a groove is machined on the surface of the brass machining tool 1. The groove has a diameter of 6 mm and a bottom radius of curvature slightly smaller than the radius of the crystal sounding wall cavity. The MgF2 crystal sounding wall cavity 5 is placed inside the machining tool 1 of the preparation device via a fixing rod 4. Then, the machining tool 1 is fixed to the drive shaft 2 of the coaxial motor 3. Inside the machining tool 1, the MgF2 crystal is finely ground using three types of diamond abrasive: W14, W10, and W7. After the fine grinding is completed, the crystal sounding wall cavity is cleaned and dried. However, this is not the only method of fine grinding. Those skilled in the art can adjust the selection of diamond abrasive type according to actual conditions.

[0038] Next, a groove is machined on the surface of the small brass machining tool 1, and polishing adhesive is applied to the inner wall of the groove. After applying the polishing adhesive, the groove diameter is 5.6 mm, and the radius of curvature at the bottom of the groove is slightly smaller than the radius of the crystal sounding wall cavity. The polishing adhesive applied to the inner wall of the groove is prepared by a 4:6 ratio of asphalt and rosin, and is prepared by compression molding. However, this is not the only option. Those skilled in the art can adjust the ratio of asphalt and rosin to control the hardness of the polishing adhesive according to different polishing conditions and requirements, such as temperature and spindle speed, thereby further improving the polishing effect. At the same time, the preparation method of the polishing adhesive can be reasonably selected according to the actual situation to achieve a better match with the crystal edge contour.

[0039] Next, the finely ground MgF2 crystal sounding wall cavity 5 is placed in the processing tool 1 of the preparation device; the rotation speed of the coaxial motor 3 is selected to be 40 r / min according to the size and shape of the crystal sounding wall cavity; under the working environment of 20-25℃, the finely ground MgF2 crystal sounding wall cavity 5 is coarsely polished using polishing liquid prepared with diamond micro powder with an average particle size of 2μm.

[0040] After rough polishing, the MgF2 crystal whispering chamber 5 is then finely polished sequentially using polishing slurries prepared with diamond microparticles of average particle sizes of approximately 1 μm and 0.5 μm, respectively. The angle of the MgF2 crystal is adjusted slightly by manual operation or by controlling the pendulum shaft, with the spindle speed set at 20 r / min. However, this is not the only method of fine polishing. Those skilled in the art should adjust the spindle speed, temperature, sample angle, and other conditions appropriately during the fine polishing process based on the actual situation. Furthermore, due to the periodic structures that may be introduced during polishing, the crystal angle should be adjusted slightly by controlling the pendulum shaft according to the specific circumstances.

[0041] After fine polishing, the prepared MgF2 crystal sounding cavity 5 was cleaned five times with deionized water, acetone, and anhydrous ethanol, ultimately yielding a disc-shaped MgF2 crystal sounding cavity 5 with low surface roughness and extremely high Q value, as shown below. Figure 2 As shown in figure a, the prepared crystal sound-gallery cavity was tested using a white light interferometer. Figure 2 b is a white light interference image of the edge of the MgF2 crystal whispering cavity 5 obtained under an optical profilometer. A clear and distinct interference elliptical ring can be observed in the image, and the elliptical ring has a large major axis / minor axis ratio, indicating that the finely polished MgF2 crystal whispering cavity 5 has a good roughness level. At the same time, the edge curvature radius is small, which is beneficial to suppressing higher-order mode oscillations. Figure 2 c represents the measured roughness data. After data fitting, the average surface roughness Ra of the MgF2 crystal sounding wall cavity 5 is approximately 2.0 nm. The roughness measurement results indicate that the machined MgF2 crystal sounding wall cavity 5 possesses good surface quality, and the theoretically achievable Q value is greater than 10. 12 The processing method proposed in this invention fully meets the processing quality requirements of ultra-high Q-value crystal sounding wall cavities, while reducing processing costs and improving processing efficiency.

[0042] Example 2

[0043] In this embodiment, the disc-type crystal sound wall cavity is made of CaF2.

[0044] First, prepare a CaF2 crystal 5 with a diameter of 5.5 mm and a thickness of 0.8 mm. The crystal is then milled to its desired shape, with each milling pass being 0.02 mm. The center thickness and accuracy of the milled crystal should be within ±0.1 mm. However, this is not the only requirement. Those skilled in the art can adjust the milling pass according to the actual situation to avoid breakage due to the relatively high hardness of the crystal during milling.

[0045] Next, a groove is machined on the surface of the brass machining tool 1. The groove has a diameter of 6 mm and a bottom radius of curvature slightly smaller than the radius of the crystal sounder cavity. The CaF2 crystal sounder cavity 5 is placed inside the machining tool 1 of the preparation device via a fixing rod 4. Then, the machining tool 1 is fixed to the drive shaft 2 of the coaxial motor 3. Inside the machining tool 1, the CaF2 crystal is finely ground using three types of diamond abrasive: W14, W10, and W7. After the fine grinding is completed, the crystal sounder cavity is cleaned and dried. However, this is not the only method of fine grinding. Those skilled in the art can adjust the selection of diamond abrasive type according to the actual situation.

[0046] Next, a groove is machined on the surface of the small brass machining tool 1, and polishing adhesive is applied to the inner wall of the groove. After applying the polishing adhesive, the groove diameter is 5.6 mm, and the bottom radius of curvature is slightly smaller than the radius of the crystal sounding wall cavity. The polishing adhesive applied to the inner wall of the groove is prepared by a 4:6 ratio of asphalt and rosin, and is prepared by compression molding. However, this is not the only option. Those skilled in the art can adjust the ratio of asphalt and rosin to control the hardness of the polishing adhesive according to different polishing conditions and requirements, such as temperature and spindle speed, thereby further improving the polishing effect. At the same time, the preparation method of the polishing adhesive can be reasonably selected according to the actual situation to achieve a better match with the crystal edge contour.

[0047] Then, the finely ground CaF2 crystal sounding wall cavity 5 is placed in the processing tool 1 of the preparation device. The rotation speed of the coaxial motor 3 is selected to be 60 r / min according to the size and shape of the crystal sounding wall cavity. Under the working environment of 20-25℃, the finely ground CaF2 crystal sounding wall cavity 5 is coarsely polished using polishing liquid prepared with diamond micro powder with an average particle size of 2μm.

[0048] Then, the rough-polished CaF2 crystal sounding wall cavity 5 is finely polished using polishing slurries prepared with diamond microparticles with average particle sizes of approximately 1 μm and 0.5 μm, respectively. The polishing angle of the CaF2 crystal sounding wall cavity 5 is adjusted slightly by manual operation or by controlling the swing shaft, with the spindle speed adjusted to 25 r / min. However, this is not the only method; those skilled in the art should adjust the spindle speed, temperature, sample angle, and other conditions appropriately during the fine polishing process according to the actual situation.

[0049] Finally, the CaF2 crystal sounding cavity 5, after fine polishing, was cleaned three times with deionized water, acetone, and anhydrous ethanol to obtain a high-Q disc-shaped CaF2 crystal sounding cavity.

[0050] In summary, based on the above embodiments, this invention develops a fabrication apparatus and method for disc-shaped crystal soundwall cavities using traditional optical processing techniques. This method can produce disc-shaped crystal soundwall cavities with low surface roughness and a high quality factor (Q). Unlike the current mainstream single-point diamond ultra-precision lathe machining method, this invention utilizes small tools in the fabrication apparatus combined with abrasive materials such as different grades of diamond abrasive and polishing materials such as diamond micron powder to perform abrasive and precision optical polishing on the milled crystal soundwall cavity. This overcomes the high requirements of existing fabrication technologies on equipment and environment, has low requirements on processing equipment and operator skills, and is applicable to a wide range of materials. It can significantly reduce fabrication costs and shorten the fabrication cycle, which is conducive to promoting and realizing the application of high quality factor crystal soundwall cavities in various fields.

[0051] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An apparatus for preparing a disc-type crystal sound-alley cavity, characterized in that: The tool includes a small processing tool (1). The upper surface of the small processing tool (1) is provided with a groove for processing the crystal sounding wall sample (5). The radius of curvature of the bottom of the groove is slightly smaller than the radius of the crystal sounding wall sample (5). The groove is used for grinding and polishing the crystal sounding wall sample (5). The crystal sounding wall sample (5) has been milled and shaped. The crystal sounding wall sample (5) to be polished is placed in the groove of the small processing tool (1). The top of the crystal sounding wall sample (5) is vertically provided with a sample fixing rod (4) to fix itself. The bottom of the small processing tool (1) is connected to a coaxial motor (3) through a drive shaft (2). The preparation method steps are as follows: First, the crystal whispering wall sample (5) was milled and shaped. After molding, the crystal sounding wall sample (5) is placed in the groove of the processing tool (1) by the fixing rod (4). The processing tool (1) is fixed on the coaxial motor (3) by the transmission shaft (2). Different types of diamond grit are replaced in the processing tool (1) in sequence. The coaxial motor (3) is turned on and the processing tool (1) is rotated by the transmission shaft (2) to achieve fine grinding of the sounding wall cavity. After fine grinding, after removing the diamond sand, apply polishing glue to the inner wall of the groove of the small processing tool (1), and then use the polishing liquid prepared with diamond micro powder to perform rough polishing and fine polishing on the finely ground crystal echo wall sample (5). After fine polishing, the polished crystal sounder sample (5) was cleaned with deionized water, acetone, and anhydrous ethanol to obtain a high-quality factor disc-shaped crystal sounder cavity with low surface roughness and a quality factor Q value greater than 10. 12 .

2. The apparatus for preparing a disc-type crystal sound-alley cavity according to claim 1, characterized in that, The machining tools (1) are made of stainless steel, brass, or aluminum alloy.

3. The apparatus for preparing a disc-type crystal sounding wall cavity according to claim 1, wherein the crystal sounding wall sample (5) is made of CaF2, MgF2, YAG, silicon carbide, diamond or sapphire material.

4. The apparatus for preparing a disc-type crystal sound-alley cavity according to claim 1, characterized in that, The polishing adhesive is made from asphalt and rosin and prepared by compression molding.

5. According to the apparatus for preparing a disc-type crystal soundwall cavity as described in claim 1, the diamond abrasive used for fine grinding of the crystal soundwall sample (5) is successively of three types: W14, W10, and W7 diamond abrasive.

6. According to the preparation device of the disc-type crystal soundwall cavity as described in claim 1, the finely ground crystal soundwall sample (5) is placed in the processing tool (1) of the preparation device, and a polishing liquid prepared with diamond micro powder with an average particle size of 2μm is selected for rough polishing to remove large pits and obvious scratches on the crystal surface. At the same time, the rotation speed of the coaxial motor (3) is selected to be 20-60r / min during the polishing process.

7. According to the device for preparing a disc-type crystal sounding wall cavity as described in claim 1, the crystal sounding wall sample (5) after rough polishing is polished with diamond micro powder polishing liquid with an average particle size of 1μm and 0.5μm respectively, and the rotation speed of the coaxial motor (3) is selected to be 10-50r / min. During the polishing process, the polishing angle of the crystal sounding wall cavity is adjusted slightly by controlling the swing shaft.

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