High-order transverse mode compression state preparation device based on optical parameter resonant cavity mode selection

Abstract

The invention relates to a high-order transverse mode compression state preparation device based on optical parameter resonant cavity mode selection, and belongs to the technical field of quantum state light field generation. Fundamental frequency light and pump light output by the laser source generate a high-order transverse mode light field through the mode conversion module, and then the high-order transverse mode light field enters the optical parametric resonant cavity to be subjected to parametric down-conversion with the nonlinear crystal. The cavity length of the optical parametric resonant cavity is locked at the optimal pumping mode position corresponding to the high-order transverse mode compression state, so that resonance of an impurity mode in the optical parametric resonant cavity can be avoided, and the compression level of a high-order transverse mode light field is improved. Under injection of high-order transverse mode pump light, the pump mode is purified through the optical parametric resonant cavity of the annular structure, the compression level of a high-order transverse mode light field is enhanced, adjustment is easy, practicability is high, productization is easy, and wide application prospects are achieved in the fields of quantum space measurement, biological measurement, atomic force microscope detection and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of quantum state optical field generation, and specifically relates to a device for preparing a high-order transverse mode squeezed state based on mode selection of an optical parametric resonator, which purifies the pump mode through an optical parametric cavity with an annular structure and enhances the high-order transverse mode squeezing level. Background Art

[0002] Squeezed states, as a kind of quantum state optical field, have extensive applications in the fields of quantum precision measurement, quantum sensing, quantum imaging, etc., such as enhancing the sensitivity of quantum sensors, applying squeezed light to gravitational wave detection and biological measurement, etc. The improvement of these measurement performances depends to a large extent on the squeezing level of the squeezed state. The optical parametric process has been proven to be one of the most effective squeezed state generation systems, especially for generating squeezed state optical fields with high squeezing levels. In recent years, many studies have focused on using the optical parametric process to prepare high-order mode squeezed state optical fields. High-order modes, such as high-order Hermite-Gaussian modes and Laguerre-Gaussian modes, contain more spatial degrees of freedom and can provide more information than the fundamental mode in applications. Therefore, the squeezed state optical field of high-order modes can provide more possibilities for the field of quantum measurement.

[0003] However, when using an optical parametric amplifier (OPA) to generate a high-order transverse mode squeezed state, the pump mode needs to be a high-order mode. Usually, a mode converter (such as a spatial light modulator, phase plate) is used to generate a high-order pump mode. However, due to hardware effects such as pixel pitch and fill factor in the mode converter, the generated high-order pump mode has low purity. The pump mode is mixed with other impurity modes. Based on this impurity pump mode, while generating the target squeezed light, entangled light corresponding to the target squeezed light will also be generated, thus affecting the squeezing level of the target squeezed light. For example, when generating an HG 10 mode squeezed state, the corresponding optimal pump mode is HG 20 mode. There will also be an impurity mode HG 20 of the same order as the HG 11 mode in the OPA. According to the spatial overlap relationship between the pump mode and the down-converted mode, the impurity mode HG 11 will generate an entangled state between HG 10 and HG 01 as the pump field. During the actual measurement and application process, it will affect the squeezing level of the HG 10 mode. Therefore, this impurity mode will further introduce thermal noise and affect the squeezing level of the high-order transverse mode. Summary of the Invention

[0004] To solve the technical problem of insufficient compression level of high-order transverse modes in the prior art, the present invention proposes a device for preparing a high-order transverse mode squeezed state based on mode selection in an optical parametric resonator, which filters out impurity modes through an optical parametric resonator with an annular structure to eliminate the influence of thermal noise on the compression level of high-order modes, so as to improve the compression level of high-order transverse modes.

[0005] To solve the above technical problem, the technical solution adopted by the present invention is as follows: A device for preparing a high-order transverse mode squeezed state based on mode selection in an optical parametric resonator, comprising: a laser, a mode conversion module, and a high-order mode squeezed state preparation module; the high-order mode squeezed state preparation module includes an optical parametric resonator, a cavity locking detector, and a dichroic mirror; The laser is used to output fundamental frequency light and pump light. After the pump light passes through the mode conversion module, high-order pump light is generated and incident on the optical parametric resonator. After the transmitted light of the high-order pump light is output from the optical parametric resonator, it enters the cavity locking detector through the first output port of the dichroic mirror to extract the reflected signal of the high-order mode pump field, and then a cavity locking signal is generated to lock the cavity length of the optical parametric resonator at the optimal pump mode corresponding to the high-order mode squeezed state; the fundamental frequency light generates high-order fundamental frequency light after passing through the mode conversion module, and the high-order fundamental frequency light enters the optical parametric resonator as seed light. The squeezed light generated by the interaction of the seed light and the high-order pump light in the optical parametric resonator is output from the optical parametric resonator and then output through the second output port of the dichroic mirror.

[0006] The optical parametric resonator is an eight-shaped ring cavity, including a first mirror, a second mirror, a third mirror, a fourth mirror, and a nonlinear crystal. The high-order pump light is incident on the optical parametric resonator through the first mirror, and then returns to the first mirror and is output from the optical parametric resonator after passing through the fourth mirror, the third mirror, and the second mirror. The seed light is incident on the optical parametric resonator through the fourth mirror, and then returns to the fourth mirror after passing through the third mirror, the second mirror, and the first mirror in sequence.

[0007] The nonlinear crystal is a wedge-shaped crystal. The optical parametric resonator is an optical resonator that is double-resonant for squeezed light and pump light, and the optical parametric resonator is locked at the cavity length position of the optimal pump mode by the PDH frequency stabilization method.

[0008] The first mirror and the second mirror are plane mirrors, the third mirror and the fourth mirror are plano-concave mirrors, and a piezoelectric ceramic for adjusting the cavity length is provided on the second mirror.

[0009] The reflectivity of the second mirror, the third mirror, and the fourth mirror for the squeezed light is greater than 99.9%. Both end faces of the nonlinear crystal are coated with dual-band antireflection films for the squeezed light and the pump light. The first mirror is an input / output coupling mirror, and its outer end face is coated with a dual-band antireflection film for the squeezed light and the pump light, and the transmittance of its inner end face for the squeezed light and the pump light is greater than or equal to 5%.

[0010] The transmittance of the inner end face of the first endoscope to the squeezed light is 15%, and the transmittance to the pump light is 5%.

[0011] One side of the dichroic mirror close to the optical parametric resonator has high transmittance to the pump light and high reflectivity to the squeezed light, and the other side far from the optical parametric resonator has high transmittance to the pump light.

[0012] The mode conversion module includes a first mode converter, a first light guiding device, a second mode converter and a second light guiding device. After the pump light passes through the first mode converter, high-order pump light is generated and incident on the optical parametric resonator through the first light guiding device; after the fundamental frequency light generates high-order fundamental frequency light through the second mode converter, it is incident on the optical parametric resonator through the second light guiding device.

[0013] The first mode converter and the second mode converter are phase plates or spatial light modulators.

[0014] The device for preparing a high-order transverse mode squeezed state based on mode selection of an optical parametric resonator further includes a half-wave plate, a polarization beam splitting prism and a balanced homodyne detection module; The squeezed light output from the second output port of the dichroic mirror is incident on the balanced homodyne detection module through the first high-reflection mirror to detect the squeezed state; the high-order fundamental frequency light output from the mode conversion module is divided into two beams after passing through the half-wave plate and the polarization beam splitting prism. One beam is used as the seed light and is incident on the optical parametric resonator through the second high-reflection mirror, and the other beam is used as the local light and is incident on the balanced homodyne detection module as the shot noise reference of the squeezed light after being reflected by the third high-reflection mirror; a piezoelectric ceramic for adjusting the relative phase between the squeezed light and the local field is provided on the third high-reflection mirror.

[0015] The present invention has the following beneficial effects compared with the prior art: 1. The present invention proposes a device for preparing a high-order transverse mode squeezed state based on mode selection of an optical parametric resonator. The optical parametric resonator is locked by the transmitted light of the high-order pump mode, realizing the selection of the high-order pump mode and the filtering of the impurity modes in the pump field. Only the optimal pump mode corresponding to the high-order transverse mode squeezed light enters the optical parametric resonator system. The impurity modes are filtered by the annular optical parametric resonator. Under the condition of mode selection of the optical parametric resonator, the impurity modes are prevented from resonating in the optical parametric resonator; the influence of thermal noise on the high-order mode squeezing level is eliminated. Experiments confirm that when the fundamental mode pump light generates a 30 mW high-order pump light field through a customized HG 20 mode phase plate, the squeezed state preparation device of the present invention can obtain 8 dB of HG 10 mode vacuum squeezed light; 2. In the present invention, a wedge-shaped crystal is used instead of an ordinary crystal in the optical parametric resonator, achieving simultaneous resonance of the pump mode and the compression mode. Sufficient pump mode power provides a basis for preparing higher-order mode squeezed states. The device has a compact structure, is easy to adjust, has strong practicability, is easy to be productized and mass-produced, and can be applied to frontier fields such as quantum precision measurement, biological measurement, and quantum imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 FIG. is a schematic block diagram of a device for realizing the preparation of higher-order transverse mode squeezed states by mode selection in an optical parametric resonator according to an embodiment of the present invention; Figure 2 FIG. is a schematic optical path diagram of a device for realizing the preparation of higher-order transverse mode squeezed states by mode selection in an optical parametric resonator according to an embodiment of the present invention; Figure 3 FIG. is a measurement result diagram of higher-order transverse mode squeezed light generated by the present invention in the analysis frequency range of 0 - 15 MHz; Figure 4 FIG. is a measurement result diagram of squeezed light of higher-order transverse mode squeezed light generated by an embodiment of the present invention at an analysis frequency of 3 MHz; In the figures, 1 - laser source, 2 - mode conversion module, 3 - higher-order mode squeezed state preparation module, 4 - balanced homodyne detection module, 5 - platform, 6 - first mode converter, 7 - second mode converter, 8 - optical parametric resonator, 9 - cavity locking detector, 10 - dichroic mirror, 11 - first cavity mirror, 12 - second cavity mirror, 13 - third cavity mirror, 14 - fourth cavity mirror, 15 - nonlinear crystal, 16 - half-wave plate, 17 - polarization beam splitter prism, 18 / 19 - first high reflection mirror, 19 - second high reflection mirror, 20 - third high reflection mirror, 21 - 50 / 50 beam splitter. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0018] Embodiment An embodiment of the present invention provides a device for preparing higher-order transverse mode squeezed states based on mode selection in an optical parametric resonator. The optical parametric resonator is used to select the pump mode, and only the optimal pump mode corresponding to the target squeezed light is retained to resonate in the OPA. The higher-order transverse mode compression level is enhanced by purifying the pump mode. As Figure 1As shown in the figure, a high-order transverse mode squeezed state preparation device based on optical parametric resonator mode selection provided in this embodiment includes: a laser source 1, a mode conversion module 2, and a high-order mode squeezed state preparation module 3. The laser source 1 is used to output fundamental frequency light and pump light; the mode conversion module 2 is used to generate fundamental frequency light and pump light of high-order modes; the high-order mode squeezed state preparation module 3 is used to select pump light of high-order modes and generate high-order squeezed states. In addition, a balanced homodyne detection module 4 is also shown in the figure, where the balanced homodyne detection module 4 is used to detect high-order mode squeezed states. In order to enable the device to stably output squeezed light and be applicable to a variety of application scenarios, the above-mentioned component elements are fixed on a small vibration isolation platform 5 that is convenient to move.

[0019] Specifically, as Figure 2 shown, in this embodiment, the high-order mode squeezed state preparation module 3 includes an optical parametric resonator 8, a cavity locking detector 9, and a dichroic mirror 10; the laser source 1 is used to output fundamental frequency light of 1064 nm and pump light of 532 nm. After the pump light passes through the mode conversion module 2, high-order pump light is generated and incident on the optical parametric resonator 8. After the transmitted light of the high-order pump light is output from the optical parametric resonator 8, it enters the cavity locking detector 9 through the first output port of the dichroic mirror 10, and then a cavity locking signal is generated to lock the cavity length of the optical parametric resonator 8 and lock it at the optimal transverse mode pump mode corresponding to the high-order mode squeezed state; the fundamental frequency light generates high-order fundamental frequency light after passing through the mode conversion module 2, and the high-order fundamental frequency light enters the optical parametric resonator 8 as a seed light. The squeezed light generated by the interaction of the seed light and the high-order pump light in the optical parametric resonator 8 is output from the optical parametric resonator 8 and then output through the second output port of the dichroic mirror 10.

[0020] Furthermore, as Figure 2 shown, in this embodiment, the optical parametric resonator 8 is an eight-shaped ring cavity, including a first cavity mirror 11, a second cavity mirror 12, a third cavity mirror 13, a fourth cavity mirror 14, and a nonlinear crystal 15. The high-order pump light is incident on the optical parametric resonator 8 through the first cavity mirror 11, and then returns to the first cavity mirror 11 and is output from the optical parametric resonator 8 after passing through the fourth cavity mirror 14, the third cavity mirror 13, and the second cavity mirror 12. The seed light is incident on the optical parametric resonator 8 through the fourth cavity mirror 14, and then returns to the fourth cavity mirror 14 after passing through the third cavity mirror 13, the second cavity mirror 12, and the first cavity mirror 11 in sequence.

[0021] Specifically, in this embodiment, the nonlinear crystal 15 is a wedge-shaped crystal, the optical parametric resonator 8 is an optical resonator with double resonance of squeezed light and pump light, and the optical parametric resonator 8 is locked at the cavity length position of the optimal pump mode by the PDH frequency stabilization method. Specifically, the nonlinear crystal 15 has a size of PPKTP wedge crystal. Both sides of the crystal are coated with antireflection films for both the squeezed light and the pump light. The temperature of the PPKTP crystal is controlled at the phase-matching point by a commercial temperature controller.

[0022] Specifically, in this embodiment, the first mirror 11 and the second mirror 12 are plane mirrors, and the third mirror 13 and the fourth mirror 14 are plano-concave mirrors.

[0023] Specifically, in this embodiment, the optical parametric resonator 8 is an optical resonator that is double-resonant for the fundamental light and the pump light. After the transmitted light of the higher-order pump light exits from the optical parametric resonator 8 and enters the cavity locking detector 9 through the first output port of the dichroic mirror 10, the reflected signal of the higher-order mode pump field can be extracted by the cavity locking detector 9, and then the cavity length of the optical parametric resonator 8 can be locked at the cavity length position corresponding to the higher-order pump light, so as to realize the selection of the optimal pump light for the higher-order mode. The cavity locking detector 9 is used for locking the optical parametric resonator.

[0024] Specifically, in this embodiment, the optical parametric resonator 8 is locked at the cavity length position of the optimal pump mode by the PDH frequency stabilization method. Specifically, a piezoelectric ceramic can be set on one of the mirrors of the optical parametric resonator 8 to actively control the cavity length of the optical parametric resonator 8, that is, to lock the cavity length of the optical parametric resonator 8. By adjusting the voltage of the piezoelectric ceramic through the PDH frequency stabilization method, the cavity length of the optical parametric resonator 8 is locked at the cavity length position of the optimal pump mode.

[0025] Specifically, in this embodiment, the piezoelectric ceramic for adjusting and locking the cavity length is set on the second mirror 12, that is, the second mirror 12 is fixed by the piezoelectric ceramic. The optical parametric resonator 8 adjusts the voltage of the piezoelectric ceramic set on the second mirror 12 through the PDH frequency stabilization method, and then locks the cavity length of the optical parametric resonator 8 at the cavity length position of the optimal pump mode.

[0026] In this embodiment, the reflectivities of the second mirror 12, the third mirror 13 and the fourth mirror 14 for the squeezed light and the pump light are greater than 99.9%. Both end faces of the nonlinear crystal 15 are coated with antireflection films for both the squeezed light and the pump light. The first mirror 11 is an input / output coupling mirror, and its outer end face is coated with an antireflection film for both the squeezed light and the pump light, and the transmittance of the inner end face for the squeezed light and the pump light is greater than or equal to 5%.

[0027] Specifically, in this embodiment, the transmittance of the inner end face of the first mirror 11 for the squeezed light and the pump light can be set as needed. For example, the transmittance of the inner end face of the first mirror 11 for the squeezed light is 15%, and the transmittance for the pump light is 5%. In addition, the transmittance of the inner end face of the first mirror for the squeezed light can also be 10%, and the transmittance for the pump light can also be 20%.

[0028] In this embodiment, one side of the dichroic mirror 10 close to the optical parametric resonator 8 has high transmittance for the pump light and high reflectivity for the squeezed light, and the other side of the dichroic mirror 10 far from the optical parametric resonator 8 has high transmittance for the pump light. Specifically, the transmittance of the pump light on the side of the dichroic mirror 10 close to the optical parametric resonator 8 is greater than 97%, the reflectivity of the squeezed light is greater than 99.9%, and the reflectivity of the pump light on the other side is less than 0.5%.

[0029] Specifically, in this embodiment, the mode conversion module 2 includes a first mode converter 6, a first light guiding device, a second mode converter 7 and a second light guiding device. After the pump light passes through the first mode converter 6, high-order pump light is generated and incident on the optical parametric resonator 8 through the first light guiding device; after the fundamental frequency light generates high-order fundamental frequency light through the second mode converter 7, it is incident on the optical parametric resonator 8 through the second light guiding device.

[0030] Specifically, in this embodiment, the first mode converter 6 and the second mode converter 7 are phase plates or spatial light modulators.

[0031] Furthermore, a high-order transverse mode squeezed state preparation device based on mode selection of an optical parametric resonator in this embodiment further includes a half-wave plate 16, a polarization beam splitting prism 17 and a balanced homodyne detection module 4. The squeezed light output from the second output port of the dichroic mirror 10 is incident on the balanced homodyne detection module 4 through the first high-reflection mirror 18 to measure the high-order transverse mode squeezing level; the high-order fundamental frequency light output from the mode conversion module 2 is divided into two beams after passing through the half-wave plate 16 and the polarization beam splitting prism 17. One beam is used as the seed light and incident on the optical parametric resonator 8 through the second high-reflection mirror 19, and the other beam is used as the local light and incident on the balanced homodyne detection module 4 as the shot noise reference of the squeezed light after being reflected by the third high-reflection mirror 20; a piezoelectric ceramic for adjusting the relative phase between the squeezed light and the local field is arranged on the third high-reflection mirror 20.

[0032] Specifically, the balanced homodyne detection module 4 includes a 50 / 50 beam splitter 21 and two detectors. The signal incident on the 50 / 50 beam splitter 21 is divided into two parts and detected by one of the two detectors respectively. The two detection signals are subtracted to obtain the balanced homodyne detection signal.

[0033] The working principle of the present invention is as follows: The laser output by the laser source 1 includes fundamental frequency light and pump light. After passing through the phase plate in the mode conversion module 2, high-order pump modes and high-order seed light are generated. The high-order pump modes and high-order seed light are incident on the optical parametric resonator 8 and undergo parametric down-conversion. The optical parametric resonator 8 adopts a ring cavity structure. Since the plano-concave mirror reflects at a non-zero angle in the ring cavity, the ordinary fundamental mode (circular spot) will experience two different effective curvature radii in the meridional plane and the sagittal plane of the OPA, resulting in the Gouy phases experienced by the fundamental mode when it travels around the optical parametric resonator 8 being and ( ). The impurity modes HG of the same order 11 and the optimal mode HG 20 experience different Gouy phases when going around once in the OPA, which are and respectively. Thus, the total phases experienced by the HG 11 mode and the HG 20 mode are different when going around once in the OPA. Therefore, the two modes cannot resonate simultaneously in the OPA, and the corresponding cavity length positions are different. The present invention uses the PDH frequency stabilization technology to lock the optical parametric resonator at the cavity length position of the optimal pump mode. Moreover, the squeezed light (seed light) and the pump light are double-resonant in the optical parametric resonator. The optimal pump mode in the high-order pump modes resonates in the optical parametric resonator 8 and undergoes parametric down-conversion with the nonlinear crystal to generate the corresponding high-order transverse mode squeezed light. The impurity mode is reflected at the input mirror (the first cavity mirror 11) of the optical parametric resonator, realizing the filtering of the impurity mode. Therefore, the present invention can realize the preparation of the high-order transverse mode squeezed state and improve the squeezing level.

[0034] As Figure 3 shown, it is the noise measurement result of the high-order transverse mode squeezed light generated in the embodiment of the present invention at a scanning frequency of 0 - 15 MHz. At this time, the pump power in front of the cavity of the optical parametric resonator 8 is 30 mW. Among them, (1) the shot noise reference; (2) the noise power curve of the squeezed light varying with the local light phase, and the result shows that high-order mode squeezed light is prepared within the range of 0 - 15 MHz; (3) the electronic noise.

[0035] As Figure 4 shown, it is the noise measurement result of the high-order transverse mode squeezed light generated in the embodiment of the present invention at an analysis frequency of 3 MHz. At this time, the injection power of the optical parametric resonator is 30 mW. Among them, (1) the shot noise reference, (2) the noise power curve of the squeezed light varying with the local light phase, and the result shows that the squeezing degree of the HG 10 mode squeezed light is 8 dB. It shows that the high-order transverse mode squeezed state preparation device of the present invention obtains a stable output of high-order transverse mode squeezed light under the condition of low injection power of the optical parametric resonator.

[0036] In summary, the present invention provides a high-order transverse mode squeezed state preparation device based on mode selection of an optical parametric resonator. By selecting the high-order pump mode through the optical parametric resonator, it not only purifies the pump mode purity but also enhances the pump power in the cavity. This device realizes high-quality high-order transverse mode squeezed light, which helps to widely apply the high-order transverse mode squeezed light to all aspects of real life.

[0037] It should be noted that the present invention can be implemented by using a laser with a fundamental wavelength of 1550 nm (pumping wavelength 775 nm), 1080 nm (pumping wavelength 540 nm), or 850 nm (pumping wavelength 425 nm) as the laser source on the basis of the above embodiments.

[0038] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An apparatus for preparing a high-order transverse mode squeezed state based on mode selection of an optical parametric resonator, characterized in that, Including: A laser source (1), a mode conversion module (2), and a high-order mode squeezed state preparation module (3); The high-order mode squeezed state preparation module (3) includes an optical parametric resonator (8), a cavity locking detector (9), and a dichroic mirror (10); The laser source (1) is used to output fundamental frequency light and pump light. After the pump light passes through the mode conversion module (2), high-order pump light is generated and incident on the optical parametric resonator (8). After the transmitted light of the high-order pump light is output from the optical parametric resonator (8), it enters the cavity locking detector (9) through the first output port of the dichroic mirror (10) to extract the reflected signal of the high-order mode pump field, and then a cavity locking signal is generated to lock the cavity length of the optical parametric resonator (8) at the optimal pump mode corresponding to the high-order mode squeezed state; the fundamental frequency light generates high-order fundamental frequency light after passing through the mode conversion module (2), and the high-order fundamental frequency light is incident on the optical parametric resonator (8) as seed light. The squeezed light generated by the interaction of the seed light and the high-order pump light in the optical parametric resonator (8) is output from the optical parametric resonator (8) and then output through the second output port of the dichroic mirror (10).

2. The high-order transverse mode squeezed state preparation device based on optical parametric resonator mode selection according to claim 1, wherein The optical parametric resonator (8) is an eight-shaped ring cavity, including a first mirror (11), a second mirror (12), a third mirror (13), a fourth mirror (14), and a nonlinear crystal (15). The high-order pump light is incident on the optical parametric resonator (8) through the first mirror (11), and then returns to the first mirror (11) and is output from the optical parametric resonator (8) after passing through the fourth mirror (14), the third mirror (13), and the second mirror (12). The seed light is incident on the optical parametric resonator (8) through the fourth mirror (14), and then returns to the fourth mirror (14) after passing through the third mirror (13), the second mirror (12), and the first mirror (11) in sequence.

3. The apparatus for preparing a high-order transverse mode squeezed state based on mode selection of an optical parametric resonator according to claim 2, wherein The nonlinear crystal (15) is a wedge-shaped crystal. The optical parametric resonator (8) is an optical resonator that is double-resonant for squeezed light and pump light, and the optical parametric resonator (8) is locked at the cavity length position of the optimal pump mode by the PDH frequency stabilization method.

4. A high-order transverse mode squeezed state preparation device based on mode selection of an optical parametric resonator according to claim 2, characterized in that, The first mirror (11) and the second mirror (12) are plane mirrors, the third mirror (13) and the fourth mirror (14) are plano-concave mirrors, and a piezoelectric ceramic for adjusting the cavity length is provided on the second mirror (12).

5. A high-order transverse mode squeezed state preparation device based on mode selection of an optical parametric resonator according to claim 2, characterized in that The reflectivity of the second mirror (12), the third mirror (13), and the fourth mirror (14) for the squeezed light is greater than 99.9%. Both end faces of the nonlinear crystal (15) are coated with antireflection films for both the squeezed light and the pump light. The first mirror (11) is an input / output coupling mirror, and its outer end face is coated with an antireflection film for both the squeezed light and the pump light, and the transmittance of the inner end face for the squeezed light and the pump light is greater than or equal to 5%.

6. The high-order transverse mode squeezed state preparation device based on optical parametric resonator mode selection according to claim 5, characterized in that The transmittance of the inner end face of the first mirror (11) for the squeezed light is 15%, and the transmittance for the pump light is 5%.

7. A device for preparing a high-order transverse mode squeezed state based on mode selection of an optical parametric resonator according to claim 1, characterized in that, One side of the dichroic mirror (10) close to the optical parametric resonator (8) has high transmittance for the pump light and high reflectivity for the squeezed light, and the other side away from the optical parametric resonator (8) has high transmittance for the pump light.

8. An apparatus for preparing a high-order transverse mode squeezed state based on mode selection of an optical parametric resonator according to claim 1, characterized in that The mode conversion module (2) includes a first mode converter (6), a first light guiding device, a second mode converter (7), and a second light guiding device. After the pump light passes through the first mode converter (6), high-order pump light is generated and enters the optical parametric resonator (8) through the first light guiding device; after the fundamental frequency light generates high-order fundamental frequency light through the second mode converter (7), it enters the optical parametric resonator (8) through the second light guiding device.

9. The high-order transverse mode squeezed state preparation device based on optical parametric resonator mode selection according to claim 8, characterized in that, The first mode converter (6) and the second mode converter (7) are phase plates or spatial light modulators.

10. A high-order transverse mode squeezed state preparation device based on mode selection of an optical parametric resonator according to claim 1, characterized in that, It further includes a half-wave plate (16), a polarization beam splitting prism (17), and a balanced homodyne detection module (4); The squeezed light output from the second output port of the dichroic mirror (10) enters the balanced homodyne detection module (4) through the first high reflector (18) to detect the squeezed state; the high-order fundamental frequency light output from the mode conversion module (2) is divided into two beams after passing through the half-wave plate (16) and the polarization beam splitting prism (17). One beam is used as the seed light and enters the optical parametric resonator (8) through the second high reflector (19), and the other beam is used as the local light and is reflected by the third high reflector (20) and then enters the balanced homodyne detection module (4) as the shot noise reference of the squeezed light; a piezoelectric ceramic for adjusting the relative phase between the squeezed light and the local field is provided on the third high reflector (20).

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