Dynamic optical microcavity delay line based on optical Kerr tuning

Abstract

The invention discloses a dynamic optical microcavity delay line based on optical Kerr tuning, and provides a dynamic tunable system of an optical microcavity delay line. Comprising a laser A, an erbium-doped optical fiber amplifier, an attenuator, a band-pass filter A, a first optical fiber beam splitter, a laser B, a polarization controller A, a polarization controller B, a second optical fiber beam splitter, a photoelectric detector A, a photoelectric detector B, a band-pass filter B and an oscilloscope, wherein a conical optical fiber waveguide and a calcium fluoride SNAP microbottle cavity form a coupling system. The calcium fluoride SNAP microbottle cavity adopted by the invention has the characteristics of zero dispersion and high Q value, an optical Kerr tuning method is combined, an optical delay function with high response speed, large delay amount and lower loss is realized, the bandwidth-delay constant limitation of a traditional delay line is broken through, and powerful support is provided for the fields of optical signal processing, microwave photonics and the like.

Description

Technical Field

[0001] The invention belongs to the field of optoelectronic devices and photonics, and in particular relates to a dynamic optical microcavity delay line based on optical Kerr tuning. Background Art

[0002] In recent years, with the rapid development of optical communications, lidar, optical sensing and other fields, the demand for precise delay control of optical signals has become increasingly urgent. Tunable dynamic optical delay lines, as a key device that can achieve continuously adjustable delay time of optical signals, have broad application prospects in the above fields.

[0003] Traditional optical delay lines mainly use fixed-length optical fibers or waveguides to achieve the delay of optical signals. Their delay time is fixed and cannot meet the needs of dynamic adjustment in practical applications. In order to overcome this limitation, researchers have proposed a variety of tunable dynamic optical delay line schemes, such as optical delay lines based on mechanical scanning, optical delay lines based on acousto-optic effects, and tunable optical delay lines based on liquid crystal materials. However, the existing technologies generally face performance constraints such as delay, response speed, and system loss. Chinese invention patent, patent name: An optical delay line based on a reflective lens and its application, application number: 202211332813.1, publication date: 2024.08.27 patent, the light beam passes through the input fiber collimator and is emitted to the emission lens group, passes through the emission lens group and the emission lens group N times, and is emitted to the output fiber collimator. This scheme sacrifices the response speed in exchange for a large delay, and the response speed is slow. Chinese invention patent, patent name: A large-angle rotating optical delay line structure, application number: 202411018279.6, publication date: 2024.09.06. The patent uses an optical transmission device that changes the optical path or phase. The incident light passes through the center of the turntable and is incident on the Z-shaped right-angle reflector. After two reflections, it is emitted parallel to the incident light. The system is relatively complex to implement. The electro-acoustic-optical solution improves the response speed by increasing the operating frequency, but causes a sharp drop in the delay. The thermo-optical effect is difficult to break through the thermal relaxation bottleneck due to the limitations of the intrinsic physical mechanism. In view of the above technical defects, it is urgent to develop a new delay control mechanism to achieve a large range of delay adjustment of hundreds of picoseconds while maintaining a fast response at the sub-microsecond level, and significantly reduce the optical power loss and system complexity. Summary of the invention

[0004] In order to overcome the shortcomings and deficiencies of the prior art, the present invention provides a dynamic optical microcavity delay line based on optical Kerr tuning, which solves the technical problems of traditional optical delay lines such as large optical power loss, large dispersion, small delay, and slow response speed.

[0005] The present invention achieves the above-mentioned purpose through the following technical scheme: a dynamic optical microcavity delay line based on optical Kerr tuning, comprising A laser, an erbium-doped fiber amplifier, an attenuator, A bandpass filter, a first fiber beam splitter, B laser, A polarization controller, B polarization controller, a second fiber beam splitter, A photodetector, B photodetector, B bandpass filter, and an oscilloscope, wherein the coupling system is composed of a tapered fiber waveguide and a calcium fluoride SNAP microbottle cavity, the structures of A polarization controller and B polarization controller are the same; the structures of A photodetector and B photodetector are the same; the structures of A bandpass filter and B bandpass filter are the same; A laser and B laser are used to generate optical signals of different powers and frequencies; A laser and erbium-doped fiber amplifier are coupled to each other. The erbium-doped fiber amplifier is connected to the attenuator, the attenuator is connected to the A bandpass filter, the two input ends of the first fiber beam splitter are connected to the A bandpass filter and the B laser respectively, the output end of the first fiber beam splitter is connected to the A polarization controller, the light output by the A polarization controller enters the coupling system composed of the tapered fiber waveguide and the calcium fluoride SNAP microbottle cavity, the output end of the coupling system composed of the fiber waveguide and the calcium fluoride SNAP microbottle cavity is connected to the B polarization controller, the B polarization controller is connected to the input end of the second fiber beam splitter, the two outputs of the second fiber beam splitter are connected to the A photodetector and the B photodetector respectively, the A photodetector is connected to the oscilloscope, the B photodetector is connected to the B bandpass filter, and the B bandpass filter is connected to the oscilloscope.

[0006] Among them, the preparation process of the calcium fluoride SNAP micro-bottle cavity is as follows: step a-1, the calcium fluoride crystal sample is initially cut at a specific distance from the top by a program-controlled diamond tool, and the cutting depth is the bottle handle distance of the calcium fluoride SNAP micro-bottle cavity, step a-2, the cut sample is roughly ground until its surface reaches a flat state; step a-3, the diamond tool is used again to cut the sample for the second time, and two wedge angles are accurately cut at both ends; step a-4, rough grinding is performed to make the sample initially formed. Then enter the ultra-smooth surface preparation stage, step b-1 first uses diamond grinding paste to rough polish the sample, step b-2, fine polish the sample with a suspension, and each step is completed. The ethanol solution needs to be placed in the water circulation system to thoroughly clean the particles generated by grinding to prevent large particles from affecting subsequent processing. After each level of polishing, it is necessary to observe in real time with a microscope or observe the interference fringes with a white light interferometer. After reaching the standard, proceed to the next step, and finally obtain a high-quality calcium fluoride crystal microcavity.

[0007] The axial length and radial diameter of the calcium fluoride SNAP micro-bottle cavity are in the order of 200 micrometers to 2 millimeters, the effective radius variation size is between 50 nanometers and 400 nanometers, and the effective radius variation is parabolic along the axial direction. The parabolic shape makes the axial modes of the micro-bottle cavity almost equally spaced, and can achieve near-zero dispersion.

[0008] Among them, the dynamic optical microcavity delay line based on optical Kerr tuning adopts optical Kerr nonlinear effect tuning, uses strong pump light to generate polarization in the weak detection light field, causes the cavity refractive index to change based on the pump light intensity, and achieves tuning by changing the effective radius of the cavity surface at the nanometer level. Compared with traditional delay lines, the response time of Kerr effect tuned delay lines is shorter and the response speed is faster, which enables the dynamic optical delay line based on optical Kerr nonlinear effect tuning to respond quickly to changes in optical signals, track and process high-speed changing optical information in real time, realize high-speed modulation of optical signals, and ensure accurate and fast transmission of data.

[0009] The calcium fluoride SNAP microbottle cavity is an axially symmetrical device, high in the middle and low at both ends, that is, approximately bottle-shaped, and supports a variety of tuning methods to control the cavity equivalent radius, thereby tuning the delay line in real time. Compared with the ring resonator, this type of microcavity has a larger equivalent diameter and a very high quality factor Q value. The Q value of the calcium fluoride SNAP microbottle cavity exceeds 10^9. The high Q value enhances the storage time of light in the cavity. Compared with the traditional delay line, the Kerr effect tuned delay line has a larger delay.

[0010] Among them, the mode volume of the calcium fluoride SNAP micro-bottle cavity is relatively large. The mode of the calcium fluoride SNAP micro-bottle cavity has a long extension in the axial direction. The light continuously travels back and forth between the two "turning points", which greatly increases the travel distance of the light in the cavity. This feature is very advantageous in delay line applications. The near-parabolic shape makes the axial modes of the micro-bottle cavity almost equally spaced. The micro-bottle cavity of a specific shape can achieve near-zero dispersion. This feature can achieve lower losses compared to traditional delay lines.

[0011] Among them, the micro-bottle cavity tunable dynamic optical delay line adopts ultra-precision processing technology to cut, grind, polish and other operations on calcium fluoride crystal to prepare SNAP micro-bottle cavity, specifically, using a programmable diamond tool to cut, grind, re-cut and make wedge angles at specific depths and positions on the calcium fluoride crystal sample, and then using diamond grinding paste and diamond suspension to perform rough and fine polishing processes on the cut sample, and finally cleaning it with alcohol.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] (1) High-speed dynamic response capability: Based on the refractive index tuning mechanism of the optical Kerr nonlinear effect, the strong pump light induces nanoscale deformation of the microcavity surface, achieving a sub-nanosecond response time. The optical Kerr effect tuned delay line has a response time of 1ps, which is 3 times faster than the traditional delay line. The tuning method has a shorter response time and a faster response speed. In addition, the pump light and the detection light are isolated by wavelength to avoid interference, ensuring the stability of high-speed signal processing.

[0014] (2) Longer delay transmission: The unique bottle-shaped structure and ultra-high quality factor of the calcium fluoride SNAP micro-bottle cavity, with a Q value greater than 10 9 , which extends the photon lifetime to the microsecond level, has a higher Q value and higher optical path accumulation efficiency than the traditional silicon-based ring cavity. With the same tuning power, the delay time of the traditional optical delay line is 3ns, and the delay time of the optical Kerr effect tuning is 6ns. The delay time of the optical Kerr effect tuning is approximately twice that of the traditional optical delay line, indicating that the optical Kerr effect tuning delay line has a larger delay.

[0015] (3) Near-zero dispersion and low loss: Combined with the near-zero dispersion characteristics of the near-parabolic axial profile, while achieving a delay of hundreds of picoseconds, the total system loss is lower, maintaining the integrity of the high-speed optical signal. Compared with traditional delay lines, the loss is lower, significantly improving the energy efficiency and signal fidelity, meeting the needs of high-speed optical communication systems above 100 Gbps for real-time delay compensation, and improving the timeliness of signal processing.

[0016] The dynamic optical microcavity delay line based on optical Kerr tuning provided by the present invention is mainly used in fields such as optical signal processing, microwave photonics, nonlinear optics, and lidar that require precise delay control of optical signals. It solves the technical problems of traditional optical delay lines, such as large optical power loss, large dispersion, small delay, and slow response speed. It has the beneficial effects of achieving a wide range of delay adjustment of hundreds of picoseconds while maintaining a fast response at the sub-microsecond level, and significantly reducing optical power loss and system complexity. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0018] Figure 1 Schematic diagram of the optical Kerr effect tuning system.

[0019] Figure 2 This is the basic structure of the calcium fluoride SNAP micro-bottle cavity optical delay line.

[0020] Figure 3 Transmission spectrum and Q value of calcium fluoride microbottle cavity.

[0021] Figure 4 This is a comparison chart of the optical Kerr effect tuning response time.

[0022] Figure 5 This is a comparison chart of the optical Kerr effect tuning delay.

[0023] Figure 6 Field distribution of the SNAP micro-bottle cavity mode.

[0024] Figure 7 This is the process flow chart for the precision machining of calcium fluoride micro-bottle cavities.

[0025] Figure 8 This is a microscopic photo of a calcium fluoride crystal microcavity.

[0026] Figure numerals: 1-A laser; 2-Er-doped fiber amplifier; 3-Attenuator; 4-A bandpass filter; 5-B laser; 6-first fiber beam splitter; 7-A polarization controller; 8-tapered fiber waveguide; 9-calcium fluoride SNAP microbottle cavity; 10-B polarization controller; 11-second fiber beam splitter; 12-A photodetector; 13-B photodetector; 14-B bandpass filter; 15-oscilloscope. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] See also Figures 1 to 8A dynamic optical microcavity delay line based on optical Kerr tuning includes an A laser 1, an erbium-doped fiber amplifier 2, an attenuator 3, an A bandpass filter 4, a first optical fiber splitter 6, a B laser 5, an A polarization controller 7, a coupling system consisting of a tapered optical fiber waveguide 8 and a calcium fluoride SNAP microbottle cavity 9, a B polarization controller 10, a second optical fiber splitter 11, an A photodetector 12, a B photodetector 13, a B bandpass filter 14, and an oscilloscope 15. The coupling system consists of a tapered optical fiber waveguide 8 and a calcium fluoride SNAP microbottle cavity 9. The structures of the A polarization controller 7 and the B polarization controller 10 are the same; the structures of the A photodetector 12 and the B photodetector 13 are the same; the structures of the A bandpass filter 4 and the B bandpass filter 14 are the same; the A laser 1 and the B laser 5 are used to generate optical signals of different powers and frequencies. A laser 1 is connected to erbium-doped fiber amplifier 2. After the optical signal power is amplified by erbium-doped fiber amplifier 2, it is transmitted to attenuator 3 for light intensity adjustment, and then enters A bandpass filter 4 to filter out stray light. The two input ends of the first optical fiber splitter 6 are respectively connected to the optical signals output by A bandpass filter 4 and B laser 5. After coupling, its output end is connected to A polarization controller 7 to adjust the polarization state of light. The light output by A polarization controller 7 enters the coupling system composed of tapered optical fiber waveguide 8 and calcium fluoride SNAP microbottle cavity 9. The light output by the coupling system is then connected to the second optical fiber splitter 11 after the polarization state is adjusted by B polarization controller 10. The second optical fiber splitter 11 divides the optical signal into two paths, one of which is connected to A photodetector 12 and then connected to oscilloscope 15; the other path is first filtered by B bandpass filter 14, then converted into an electrical signal by B photodetector 13 and connected to oscilloscope 15, so as to realize the monitoring and analysis of the characteristics of the optical signal.

[0029] The tuning system of the dynamic optical microcavity delay line based on optical Kerr tuning adopts optical Kerr nonlinear effect tuning to control the change of the effective radius of the cavity along the axial direction to realize real-time regulation of the delay amount. The optical Kerr effect will cause the refractive index of light to change with the light intensity. The system generates pump light through A laser, and the erbium-doped fiber amplifier increases the intensity of light to provide strong pump light for the system. A polarization controller adjusts the initial polarization state of the optical signal to meet the optical Kerr effect excitation conditions, and fine-tunes the passband range of the bandpass filter to screen the target signal. The strong pump light generates polarization in the weak detection light field, causing the cavity refractive index to change based on the pump light intensity, and the photodetector is used to monitor the change of the optical signal.

[0030] The machining accuracy required for the calcium fluoride SNAP micro-bottle cavity 9 is nanometers in the radial direction and micrometers in the axial direction. At the same time, in order to achieve the best performance of the photonic delay device based on the ultra-high Q value SNAP micro-bottle cavity, the control of its resonance peak position must be less than or approximately equal to its resonance line width. Therefore, in order to obtain a high-performance delay line, ultra-precision machining technology is required. The preparation process is as follows: Figure 7In step a-1 of (a), a program-controlled diamond tool is used to make an initial cut at a specific distance from the top of the calcium fluoride crystal sample, and the cutting depth is the handle distance of the calcium fluoride SNAP micro-bottle cavity 9. In step a-2, the cut sample is roughly ground until its surface is flat; in step a-3, the diamond tool is used again to perform a secondary cut on the sample, and two wedge angles are accurately cut at both ends; in step a-4, a rough grinding process is performed to initially shape the sample. Then enter the ultra-smooth surface preparation stage such as Figure 7 (b), in step b-1, the sample is rough-polished with diamond paste, and in step b-2, the sample is fine-polished with suspension. After each step, the ethanol solution needs to be placed in the water circulation system to thoroughly clean the particles generated by grinding to prevent large particles from affecting subsequent processing. After each level of polishing, it is necessary to observe in real time with a microscope or observe the interference fringes with a white light interferometer. After meeting the standards, proceed to the next step, and finally obtain high-quality calcium fluoride crystal microcavities. Figure 8 , is a microscopic photo of a calcium fluoride crystal microcavity.

[0031] The principle of the dynamic optical microcavity delay line based on optical Kerr tuning is to achieve a large-scale delay adjustment of hundreds of picoseconds while maintaining a sub-microsecond fast response and significantly reducing optical power loss and system complexity.

[0032] A laser provides the pump light required for tuning; the erbium-doped fiber amplifier amplifies the optical signal and increases the intensity of the light; the attenuator adjusts the optical signal to an appropriate level; A bandpass filter is used to filter out stray light to ensure that the light entering the subsequent optical path has a single spectral characteristic; the first fiber beam splitter is used to couple the two paths of light into one path; B laser provides detection light; A polarization controller is used to control the polarization state of the light entering the coupling system, and the effect of the optical Kerr effect can be optimized by adjusting the polarization state; the coupling system composed of the tapered fiber waveguide and the calcium fluoride SNAP microbottle cavity is the core area where the optical Kerr effect occurs; when the strong laser enters the microcavity, due to the high Q value and small mode volume characteristics of the microcavity, the light and As the material interaction increases, the refractive index of the medium will change with the change of light intensity. This change in refractive index will cause the propagation characteristics of light to change, thereby achieving tuning of the light; the tapered fiber waveguide couples light into the microcavity through the evanescent field, and can well couple the light out into the optical fiber; the second fiber beam splitter divides one path of light into two; the photodetector is used to convert the optical signal into an electrical signal, and obtains the information of the change of optical characteristics caused by the optical Kerr effect by detecting the change of the optical signal; the B bandpass filter filters the detection light to ensure that the light entering the oscilloscope is the light of the required wavelength; the oscilloscope displays the electrical signal converted by the photodetector, and then analyzes the effect of the optical Kerr effect.

[0033] When working, pump light is generated by A laser, the erbium-doped fiber amplifier increases the intensity of light and provides strong pump light for the system, A polarization controller adjusts the initial polarization state of the optical signal to meet the optical Kerr effect excitation conditions, fine-tunes the passband range of the bandpass filter to screen the target signal, and the strong pump light generates polarization in the weak detection light field, causing the cavity refractive index to change based on the pump light intensity, and the photodetector is used to monitor the change of the optical signal.

[0034] The optical Kerr effect is to use the strong pump light of ω2 to produce polarization in the weak detection light field ω1, and the polarization intensity is:

[0035] P(w1)=ε0(χ (1) +χ (3) (ω1,ω1,ω2,-ω2)|E(ω2)| 2 )E(ω1)

[0036] This results in an intensity-dependent polarization at ω1 and, therefore, a pump intensity-dependent change in the cavity refractive index:

[0037] n=n1+n2·I

[0038] Where, linear refractive index Nonlinear refractive index n2∝χ (3) This is the principle of tuning the effective refractive index of the cavity based on the optical Kerr effect. A composite micro-bottle cavity is processed on the crystal micro-cavity processing platform. The low-loss CaF2-cladding supports a high-Q whispering gallery mode, which can be tuned by the Kerr nonlinear effect of the crystal core layer. This tuning method has a fast response speed and can produce an effective radius change of the order of nm. For a cavity with a radius of 200μm, a laser is used as the pump light source. The Kerr nonlinear frequency domain generated by a 2mW change is 0.4nm, corresponding to a 5nm effective radius change, which is sufficient to achieve the control of the delay amount. Figure 4 As shown in the figure, according to the signal amplitude time domain waveform, the response time of the traditional delay line during the delay process is 3ps, and the response time of the delay line tuned by the optical Kerr effect is 1ps. Compared with the traditional delay line, the response speed of the optical Kerr effect tuned delay line is increased by 3 times. At the same time, the optical Kerr nonlinear effect can usually be realized in optical media with smaller sizes, such as calcium fluoride SNAP microbottle cavities, which makes it possible to build compact and miniaturized dynamic optical delay lines. Compared with traditional delay lines based on mechanical structures or large optical elements, the delay line tuning response speed based on the optical Kerr nonlinear effect is fast, which is easy to integrate into various miniaturized optical systems, such as portable optical detection equipment, micro optical communication modules, etc.

[0039] SNAP, also known as surface nano-axial photon microcavity, is a micro-bottle cavity based on the nanometer-scale tiny radius changes generated on the crystal surface. Its core feature is to utilize the axial symmetry of the structure, combined with nanometer-scale precision control, to achieve ultra-high quality factor and low mode volume light field confinement, and produce nanometer-scale tiny effective radius changes on the surface of the cylindrical SNAP microcavity. The SNAP micro-bottle cavity is a resonant cavity with a three-dimensional structure and is a device with axial symmetry. The SNAP microcavity prepared in the present invention has an axial length and radial diameter of 200 microns to 2 millimeters, and an effective radius change size of 50 nanometers to 400 nanometers. The nanometer-scale tiny effective radius change is parabolic along the axial direction, and the parabolic shape makes the axial modes of the micro-bottle cavity almost equally spaced, which can achieve near-zero dispersion. The light-guiding mode of traditional optical fibers is laterally confined, while the SNAP microcavity forms a standing wave resonance of the light field in the axial direction through an axial periodic structure. Through ultra-precision machining technology, nanometer-scale deformation and refractive index modulation are manufactured on the surface of calcium fluoride to form an axial periodic potential well to confine the light field. Figure 2 As shown in the figure, the light input pulse is from one end, and the pulse is output from the other end. It is coupled into the cavity through the tapered fiber waveguide, rotates around the axis on the outer surface of the calcium fluoride microcavity and transmits slowly along the axial direction, so that the light is localized in the axial direction and forms a resonant mode. The whispering gallery mode in cylindrical coordinates is expressed as m, p correspond to the angular and radial quantum numbers respectively. The propagation of the light pulse in the cavity is described by the non-steady-state one-dimensional Schrodinger equation:

[0040]

[0041] Where, μ = 2ω0n0 2 / c 2 , potential well V(z,t)=-2k 2 Δr eff (z, t) / r0, the cavity propagation constant k = ω0n0 / c. The propagation of light in the microbottle cavity is determined by the potential well V(z, t), which is in turn determined by the radius change Δr and the refractive index change Δn. Therefore, the propagation of light in the microbottle cavity can be manipulated by modifying the effective radius. Compared with the ring resonator, this type of microcavity has a larger equivalent diameter and a very high quality factor Q value, which can enhance the storage time of light in the cavity and increase the delay, such as Figure 5 As shown, when the tuning power is increased at the same time, the delay time of the traditional optical delay line d is 3ns, and the delay time of the optical Kerr effect tuning is 6ns. The delay time of the optical Kerr effect tuning is approximately twice that of the traditional optical delay line, indicating that the Kerr effect tuned delay line has a larger delay.

[0042] The optical delay process includes: absorbing the optical pulse, delaying for a certain period of time, and then releasing the pulse without deformation. The effective radius of the cavity along the axial direction is a whole parabola, the middle of the cavity is the parabola vertex, or other resonant shapes, and the effective radius of the open cavity along the axial direction is half a parabola or other resonant shapes. The delay of the SNAP microbottle cavity is achieved by changing the effective radius of the cavity surface at the nanometer level. The potential energy of the microbottle cavity changes with time during the delay process. The Kerr optical nonlinear method is used. In the process of realizing the delay function, neither the shape of the light pulse nor the shape of the potential well will be changed, ensuring that the parabolic shape or other resonant oscillator potential is always maintained during the conversion process. Establish a quantum mechanical model of light propagation in the microbottle cavity (described by the one-dimensional Schrodinger equation):

[0043]

[0044] Where λ0 and γ0 are the resonant wavelength and the loss factor of the whispering gallery mode, respectively, and β0 = (2πn0 / λ0) is the propagation constant of the cavity with radius r0 along the z-axis. is the refractive index of unstressed silica. The change in the effective cavity radius ERV can be written as:

[0045]

[0046] Includes the geometric change of the outer radius Δr(z) and the change of the effective refractive index Δn eff (z). Figure 6 As shown, the light field distribution in the SANP micro-bottle cavity shows that the micro-bottle cavity mode volume is large, the mode has a long extension in the axial direction, and the light continuously travels back and forth between the two "turning points", which greatly increases the propagation distance of the light in the cavity. This feature is very advantageous in delay line applications. The near-parabolic shape makes the axial modes of the micro-bottle cavity almost evenly distributed, and the micro-bottle cavity of a specific shape can achieve near-zero dispersion. This feature can achieve lower losses compared to traditional delay lines.

[0047] The above examples are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above examples, and there are many similar modifications. All modifications that can be directly derived or associated with the content disclosed by ordinary technicians in this field should be considered as the scope of protection of the present invention.

Claims

1. A dynamic optical microcavity delay line based on optical Kerr tuning, characterized in that: The invention comprises an A laser, an erbium-doped fiber amplifier, an attenuator, an A bandpass filter, a first fiber beam splitter, a B laser, an A polarization controller, a B polarization controller, a second fiber beam splitter, an A photodetector, a B photodetector, a B bandpass filter and an oscilloscope, wherein the coupling system is composed of a tapered fiber waveguide and a calcium fluoride SNAP microbottle cavity, the A polarization controller and the B polarization controller have the same structure; the A photodetector and the B photodetector have the same structure; the A bandpass filter and the B bandpass filter have the same structure; the A laser and the B laser are used to generate optical signals of different powers and frequencies; the A laser is connected to the erbium-doped fiber amplifier, the erbium-doped fiber amplifier is connected to the attenuator, the attenuator is connected to the A bandpass filter, and the two input ends of the first fiber beam splitter are respectively connected to the A bandpass filter and the B laser The output end of the first optical fiber beam splitter is connected to the A polarization controller, and the light output by the A polarization controller enters the coupling system composed of the tapered optical fiber waveguide and the calcium fluoride SNAP microbottle cavity. The output end of the coupling system composed of the optical fiber waveguide and the calcium fluoride SNAP microbottle cavity is connected to the B polarization controller, and the B polarization controller is connected to the input end of the second optical fiber beam splitter. The two outputs of the second optical fiber beam splitter are respectively connected to the A photodetector and the B photodetector, the A photodetector is connected to the oscilloscope, the B photodetector is connected to the B bandpass filter, and the B bandpass filter is connected to the oscilloscope. The calcium fluoride SNAP microbottle cavity is an axially symmetrical device, which is high in the middle and low at both ends, and is shaped like a microbottle. The calcium fluoride SNAP microbottle cavity supports a variety of tuning methods to control the equivalent radius of the cavity, thereby performing real-time tuning of the delay line.

2. The dynamic optical microcavity delay line based on optical Kerr tuning according to claim 1, characterized in that: The preparation process of the calcium fluoride SNAP micro-bottle cavity is as follows: step a-1, using a program-controlled diamond tool to perform initial cutting at a specific distance from the top of the calcium fluoride crystal sample, and the cutting depth is the bottle handle distance of the calcium fluoride SNAP micro-bottle cavity; step a-2, rough grinding the cut sample until its surface reaches a flat state; step a-3, using the diamond tool again to perform secondary cutting on the sample, and accurately cutting two wedge angles at both ends; step a-4, performing rough grinding to initially shape the sample; then entering the ultra-smooth surface preparation stage, step b-1 first uses diamond grinding paste to rough polish the sample, step b-2, fine polishing the sample with a suspension, each step is completed, the ethanol solution needs to be placed in the water circulation system, the particles generated by grinding are thoroughly cleaned, and large particles are prevented from affecting subsequent processing; after each level of polishing, real-time observation is performed using a microscope or interference fringes are observed using a white light interferometer, and the next step is performed after reaching the standard, and finally a high-quality calcium fluoride crystal micro-cavity is obtained.

3. The dynamic optical microcavity delay line based on optical Kerr tuning according to claim 1, characterized in that: The axial length and radial diameter of the calcium fluoride SNAP micro-bottle cavity are in the order of 200 micrometers to 2 millimeters, the effective radius variation size is between 50 nanometers and 400 nanometers, and the effective radius variation is parabolic along the axial direction.

4. The dynamic optical microcavity delay line based on optical Kerr tuning according to claim 1, characterized in that: The tuning system of the dynamic optical microcavity delay line based on optical Kerr tuning adopts optical Kerr nonlinear effect tuning, uses strong pump light to generate polarization in a weak detection light field, causes the cavity refractive index to change based on the pump light intensity, and achieves tuning by changing the effective radius of the calcium fluoride SNAP microbottle cavity surface at the nanometer level.

5. The dynamic optical microcavity delay line based on optical Kerr tuning according to claim 1, characterized in that: The mode volume of the calcium fluoride SNAP micro-bottle cavity is large, the mode of the calcium fluoride SNAP micro-bottle cavity has a long extension in the axial direction, and the near-parabolic shape makes the axial modes of the calcium fluoride SNAP micro-bottle cavity equally spaced, achieving near-zero dispersion.

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