Microwave atomic probe and its fabrication method, microwave electric field measurement system

Abstract

This invention relates to the field of microwave electric field measurement technology, and provides a microwave atomic probe and its fabrication method, as well as a microwave electric field measurement system. The microwave atomic probe is constructed by sequentially connecting a probe light transmission fiber, a probe light collimator assembly, an atomic gas cell, a coupling light collimator assembly, and a coupling light transmission fiber. The probe light transmission fiber and the coupling light transmission fiber are photonic crystal fibers. The probe light transmission fiber includes a first pigtail ferrule, which is connected to the probe light collimator assembly to horizontally collimate the emitted laser. The coupling light transmission fiber includes a second pigtail ferrule, which is connected to the coupling light collimator assembly. The atomic gas cell is located between the probe light collimator assembly and the coupling light collimator assembly. This invention ensures stable probe light polarization, achieves higher probe light collection efficiency, and effectively solves the problem of signal abrupt changes caused by unstable laser polarization.

Description

Technical Field

[0001] This application relates to the field of microwave electric field measurement technology, and more specifically, to a microwave atomic probe and its fabrication method, and a microwave electric field measurement system. Background Technology

[0002] Traditional microwave electric field meters are susceptible to interference from metallic components and require calibration with a standard field before measurement. Furthermore, leveraging the large orbital radius and electric dipole moment of Rydberg atoms, which make them highly sensitive to external electric fields, a new approach was developed in 2007. This approach utilized the electromagnetically induced transparency (EIT) phenomenon in a hot atom gas chamber to achieve [the following is a separate, unrelated sentence:] ... 85 Non-destructive detection of Rb atom Rydberg states; In 2012, the Shaffer research group in the United States and the Pfau research group in Germany used the electromagnetically induced transparency (EIT) effect of Rydberg atoms and the Autler-Townes (AT) splitting of microwave interaction to measure microwave electric field intensity; In 2018, the National Institute of Standards and Technology (NIST) of the United States announced a portable fiber-coupled Rydberg atom electric field sensor, making quantum-based microwave electric field measurement no longer limited to optical platforms.

[0003] However, the optical fiber used to transmit the laser in the aforementioned Rydberg atomic electric field sensor is typically a common single-mode fiber. Its operating bandwidth is insufficient to simultaneously cover the wavelength of Rydberg two-photon excitation, and it cannot guarantee the stability of laser polarization. This instability in laser polarization can cause small peaks in the detection signal, thus affecting measurement accuracy. Summary of the Invention

[0004] This application provides a microwave atomic probe and its fabrication method, as well as a microwave electric field measurement system, which can reduce or even eliminate measurement errors caused by laser polarization instability.

[0005] The first aspect of this application provides a microwave atomic probe, which includes: a probe light transmission fiber, a probe light collimator assembly, an atomic gas cell, a coupling light collimator assembly, and a coupling light transmission fiber, wherein the probe light transmission fiber, the probe light collimator assembly, the atomic gas cell, the coupling light collimator assembly, and the coupling light transmission fiber are connected in sequence;

[0006] Wherein, the probe light transmission fiber and the coupling light transmission fiber are photonic crystal fibers; the probe light transmission fiber includes a first pigtail ferrule, and the probe light transmission fiber is connected to the probe light collimator assembly through the first pigtail ferrule, the probe light collimator assembly being used to horizontally collimate the emitted laser; the coupling light transmission fiber includes a second pigtail ferrule, and the coupling light transmission fiber is connected to the coupling light collimator assembly through the second pigtail ferrule, the atomic gas cell being disposed between the probe light collimator assembly and the coupling light collimator assembly.

[0007] A second aspect of this application provides a method for fabricating a microwave atomic probe, the microwave atomic probe comprising: a probe light transmission fiber, a probe light collimator assembly, an atomic gas cell, a coupling light collimator assembly, and a coupling light transmission fiber, wherein the probe light transmission fiber includes a first pigtail ferrule, the coupling light transmission fiber includes a second pigtail ferrule, the probe light collimator assembly includes a probe light graded refractive index lens, a first laser collimating glass sleeve, and a first laser fixing glass sleeve, and the coupling light collimator assembly includes a coupling light graded refractive index lens, a second laser collimating glass sleeve, and a second laser fixing glass sleeve; the method includes:

[0008] The coupling light graded refractive index lens, the second laser collimating glass sleeve, and the second pigtail ferrule in the coupling light collimator assembly are assembled and bonded.

[0009] Assemble the probe light graded refractive index lens, the first laser collimating glass sleeve, and the first pigtail ferrule in the probe light collimator assembly;

[0010] The probe light collimator assembly and the coupling light collimator assembly are aligned so that the output light of the probe light collimator assembly coincides with the output light of the coupling light collimator assembly, and the distance between the probe light collimator assembly and the coupling light collimator assembly is sufficient to accommodate the atomic gas cell.

[0011] Adjust the positions of the probe light collimator assembly and the coupling light collimator assembly so that the collection efficiency of the coupling light transmission fiber 205 for the probe light meets the preset conditions;

[0012] The probe light graded refractive index lens, the first laser collimating glass sleeve, and the first pigtail ferrule in the probe light collimator assembly are bonded together.

[0013] An atomic gas cell is positioned between the probe light collimator assembly and the coupling light collimator assembly;

[0014] Adjust the relative distances between the probe collimator assembly and the coupling collimator assembly and the atomic gas cell;

[0015] According to the adjusted distance, the probe collimator assembly is installed into the first laser fixing glass sleeve, and the coupling light collimator assembly is installed into the second laser fixing glass sleeve;

[0016] The probe collimator assembly and the atomic gas cell are bonded together using optical adhesive, as are the coupling collimator assembly and the atomic gas cell.

[0017] A third aspect of this application provides a microwave electric field measurement system. The system includes a microwave atomic probe as described in the first aspect, and further includes a probe light system, a coupling light system, a dichroic mirror, a signal data acquisition system, a photodetector, and a microwave transmitting system. The probe light transmission fiber of the microwave atomic probe is connected to the probe light system, the coupling light transmission fiber of the microwave atomic probe is connected to the coupling light system, the signal data acquisition system acquires signals through the dichroic mirror and the photodetector, and the microwave transmitting system transmits microwave signals.

[0018] Implementing the embodiments of this application has the following beneficial effects:

[0019] The microwave atomic probe is sequentially connected via a probe light transmission fiber, a probe light collimator assembly, an atomic gas cell, a coupling light collimator assembly, and a coupling light transmission fiber. The probe light transmission fiber is a photonic crystal fiber, ensuring stable probe light polarization. The coupling light transmission fiber is also a photonic crystal fiber, offering a wide transmission bandwidth and polarization-maintaining effect. It not only stabilizes the polarization of the coupling light but also collects and transmits more probe light to enhance the detection signal. The probe light transmission fiber includes a first pigtail ferrule, which connects to the probe light collimator assembly, used to horizontally collimate the emitted laser. The coupling light transmission fiber includes a second pigtail ferrule, which connects to the coupling light collimator assembly. The atomic gas cell is positioned between the probe light collimator assembly and the coupling light collimator assembly. This microwave atomic probe, with its two photonic crystal fiber lasers providing stable laser polarization, achieves higher probe light collection efficiency and effectively solves the problem of signal abrupt changes caused by unstable laser polarization. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 The diagram shown is a flowchart illustrating a method for fabricating a microwave atomic probe according to an embodiment of the present invention.

[0022] Figure 2 The figure shown is a schematic diagram of the overall structure of a microwave atomic probe provided in an embodiment of the present invention;

[0023] Figure 3 The diagram shown is a schematic representation of a probe collimator assembly provided in an embodiment of the present invention.

[0024] Figure 4 The figure shown is a schematic diagram of a microwave electric field measurement system provided in an embodiment of the present invention;

[0025] Figure 5 The diagram shown is a schematic diagram of a polarization adjustment tool provided in an embodiment of the present invention for polarization adjustment.

[0026] Explanation of reference numerals in the attached figures:

[0027] 201 Detector light transmission fiber; 202 Detector light collimator assembly; 203 Atomic gas cell; 204 Coupler light collimator assembly; 205 Coupler light transmission fiber; 206 Laser transmission path;

[0028] 301 First pigtail ferrule; 302 Probe light graded refractive index lens; 303 First laser collimating sleeve; 304 First laser fixing sleeve;

[0029] 401 Atomic probe; 402 Probe optical system; 403 Coupled optical system; 404 Dichroic mirror; 405 Signal data recording and acquisition system; 406 Photodetector; 407 Microwave emission system; 408 Laser polarization direction; 409 Microwave polarization direction;

[0030] 501 Polarization rotating component; 502 Fixing component; 503 Probe collimator assembly or coupling collimator assembly; 504 V-type fixing bracket; 505 Polarization beam splitter (PBS); 506 Vertical reflector end of PBS. Detailed Implementation

[0031] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0032] The terms "first," "second," "third," and "fourth," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0033] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0034] like Figures 2-3 As shown, Figure 2 This is a schematic diagram of the overall structure of a microwave atomic probe provided in an embodiment of the present invention. Figure 3 This is a schematic diagram of a probe light collimator assembly provided in an embodiment of the present invention. The microwave atomic probe includes: a probe light transmission fiber 201, a probe light collimator assembly 202, an atomic gas cell 203, a coupling light collimator assembly 204, and a coupling light transmission fiber 205. The probe light transmission fiber 201, the probe light collimator assembly 202, the atomic gas cell 203, the coupling light collimator assembly 204, and the coupling light transmission fiber 205 are connected sequentially.

[0035] The probe light transmission fiber 201 and the coupling light transmission fiber 204 are photonic crystal fibers. The probe light transmission fiber 201 includes a first pigtail ferrule 301, which is connected to the probe light collimator assembly 202. The probe light collimator assembly 202 is used to horizontally collimate the emitted laser. The coupling light transmission fiber 204 includes a second pigtail ferrule, which is connected to the coupling light collimator assembly 205. The atomic gas cell 203 is disposed between the probe light collimator assembly 202 and the coupling light collimator assembly 204.

[0036] The probe light transmission fiber 201 is a photonic crystal fiber, which can ensure the stability of the probe light polarization; the atomic gas cell 203 is a closed glass space filled with alkali metal element; the coupling light transmission fiber 205 is a photonic crystal fiber with a large transmission bandwidth and polarization-maintaining effect on all transmission wavelengths. It can not only be used to stabilize the polarization of the coupling light, but also to collect and transmit more probe light to enhance the probe signal.

[0037] The microwave atomic probe is sequentially connected via a probe light transmission fiber, a probe light collimator assembly, an atomic gas cell, a coupling light collimator assembly, and a coupling light transmission fiber. The probe light transmission fiber is a photonic crystal fiber, ensuring stable probe light polarization. The coupling light transmission fiber is also a photonic crystal fiber, offering a wide transmission bandwidth and polarization-maintaining effect. It not only stabilizes the polarization of the coupling light but also collects and transmits more probe light to enhance the detection signal. The probe light transmission fiber includes a first pigtail ferrule, which connects to the probe light collimator assembly, used to horizontally collimate the emitted laser. The coupling light transmission fiber includes a second pigtail ferrule, which connects to the coupling light collimator assembly. The atomic gas cell is positioned between the probe light collimator assembly and the coupling light collimator assembly. This microwave atomic probe, with its two photonic crystal fiber lasers providing stable laser polarization, achieves higher probe light collection efficiency and effectively solves the problem of signal abrupt changes caused by unstable laser polarization.

[0038] like Figure 3 As shown, the probe collimator assembly 201 includes a probe graduated refractive index lens 302, a first laser collimating glass sleeve 303, and a first laser fixing glass sleeve 304; the first pigtail ferrule 301 extends into the first laser collimating glass sleeve 303, and the first laser collimating glass sleeve 303 at least partially encloses the first pigtail ferrule 301 and the probe graduated refractive index lens 302; the first laser fixing glass sleeve 304 encloses the first laser collimating glass sleeve 303.

[0039] The first laser collimating glass sleeve 303 encloses the first pigtail ferrule 301 and the probe light graded refractive index lens 302, serving to fix and connect the first pigtail ferrule 301 and the probe light graded refractive index lens 302 and to horizontally collimate the emitted laser. The first laser fixing glass sleeve 304 encloses the first laser collimating glass sleeve 303, serving to protect the probe light collimator assembly 203 and connect the laser collimating glass sleeve 303 and the atomic gas cell 203, making the probe light collimator assembly 202 and the atomic gas cell 203 a single unit. The first laser fixing glass sleeve 304 is used to connect the probe light collimator assembly 201 and the atomic gas cell 203, serving to protect and stabilize the probe light collimator assembly 201. The second laser fixing glass sleeve is used to connect the coupling light collimator assembly and the atomic gas cell 203, serving to protect and stabilize the coupling light collimator assembly 204. The entire device system is very small and portable.

[0040] like Figure 3 As shown, the first pigtail ferrule is an 8° angled photonic crystal fiber pigtail, and the probe light graded refractive index lens is a graded refractive index lens with one end at 8° and the other end at 0°. The 8° end is set towards the first pigtail ferrule, and the 8° end of the first pigtail ferrule and the 8° end of the probe light graded refractive index lens are set parallel to each other.

[0041] In the collimator assembly 202, the 8° plane of the first fiber optic ferrule 301 and the 8° plane of the probe light graded refractive index lens 302 are parallel to each other. By changing the distance between the first fiber optic ferrule 301 and the probe light graded refractive index lens 302, the size of the laser spot inside the atomic gas chamber 203 can be adjusted to achieve a better detection signal.

[0042] In one embodiment, the coupled light collimator assembly includes a coupled light graded refractive index lens, a second laser collimating glass sleeve, and a second laser fixing glass sleeve; the second pigtail extends into the second laser collimating glass sleeve, and the second laser collimating glass sleeve at least partially encloses the second pigtail and the coupled light graded refractive index lens; the second laser fixing glass sleeve encloses the second laser collimating glass sleeve.

[0043] The structure of the coupling light collimator assembly is the same as that of the probe light collimator assembly, and its internal structure can be referenced. Figure 3The structure shown has a second laser collimating glass sleeve that encloses the second pigtail ferrule and the coupling light graded refractive index lens, serving to fix and connect the second pigtail ferrule and the coupling light graded refractive index lens and to horizontally collimate the emitted laser; a second laser fixing glass sleeve that encloses the second laser collimating glass sleeve serves to protect the coupling light collimator assembly and connect the second laser collimating glass sleeve and the atomic gas cell, making the coupling light collimator assembly and the atomic gas cell a whole.

[0044] The second pigtail ferrule is an 8° angled photonic crystal fiber pigtail, and the coupled light graded refractive index lens is a graded refractive index lens with one end at 8° and the other end at 0°. The 8° end faces the second pigtail ferrule, and the 8° end of the second pigtail ferrule is parallel to the 8° end of the coupled light graded refractive index lens.

[0045] In the coupled light collimator assembly, the 8° plane of the second pigtail 30 1 is parallel to the 8° plane of the coupled light graded refractive index lens. By changing the distance between the second pigtail 30 1 and the coupled light graded refractive index lens, the size of the laser spot inside the atomic gas chamber can be adjusted to achieve a better detection signal.

[0046] like Figure 1 As shown, Figure 1 This is a flowchart illustrating a method for fabricating a microwave atomic detector according to an embodiment of the present invention. The method includes the following steps:

[0047] 101. Assemble and bond the coupling light graded refractive index lens and the second laser collimating glass sleeve in the second pigtail ferrule and coupling light collimator assembly;

[0048] 1.02. Assemble the probe light graded refractive index lens, the first laser collimating glass sleeve, and the first pigtail ferrule in the probe light collimator assembly;

[0049] 103. Align the probe light collimator assembly and the coupling light collimator assembly so that the output light of the probe light collimator assembly coincides with the output light of the coupling light collimator assembly, and the distance between the probe light collimator assembly and the coupling light collimator assembly is sufficient to accommodate the atomic gas cell;

[0050] 1.04. Adjust the positions of the probe light collimator assembly and the coupling light collimator assembly so that the collection efficiency of the coupling light transmission fiber 205 for the probe light meets the preset conditions.

[0051] 1.05. Bond the probe light graded refractive index lens, the first laser collimating glass sleeve, and the first pigtail ferrule in the probe light collimator assembly;

[0052] 106. The atomic gas chamber is disposed between the probe collimator assembly and the coupling collimator assembly;

[0053] 107. Adjust the relative distance between the probe collimator assembly and the coupling collimator assembly and the atomic gas cell;

[0054] 108. Install the probe collimator assembly into the first laser fixing glass sleeve according to the adjusted distance, and install the coupling light collimator assembly into the second laser fixing glass sleeve;

[0055] 109. The probe collimator assembly and the atomic gas cell are fixedly connected, and the coupling collimator assembly and the atomic gas cell are fixedly connected.

[0056] First, the glass components used can be cleaned with alcohol, such as the probe light graded refractive index lens, the first laser collimating glass sleeve, the first laser fixing glass sleeve, the first pigtail ferrule, the second pigtail ferrule, the coupling light graded refractive index lens, the second laser collimating glass sleeve, and the second laser fixing glass sleeve. At the same time, the tools and platform holding the components should also be cleaned.

[0057] The probe light collimator assembly and the atomic gas cell are fixedly connected, and the coupling light collimator assembly and the atomic gas cell are also fixedly connected. Specifically, the probe light collimator assembly and the atomic gas cell can be bonded together, and the coupling light collimator assembly and the atomic gas cell can be bonded together.

[0058] In step 1.01, adjust the distance between the first pigtail ferrule and the coupled light graded refractive index lens, fix it with the second laser collimating glass sleeve, and bond it with optical adhesive.

[0059] In step 1.02, the second pigtail ferrule and the probe light graded refractive index lens are fixed in the first laser collimating glass sleeve. The two laser beams are aligned so that as much probe light as possible enters the coupling optical fiber, and the probe light collimator assembly is bonded with optical adhesive.

[0060] In step 104, the collection efficiency meeting the preset condition means that the collection efficiency reaches its maximum or exceeds the preset efficiency threshold. The probe light collimator assembly 202 is then installed and collimated, but not yet bonded. The probe light collimator assembly 202 and the coupling light collimator assembly 204 are aligned, ensuring sufficient distance between the atomic gas chamber 203. The alignment in step 103 ensures that the output light of the probe light collimator assembly 202 coincides with the output light of the coupling light collimator assembly 204. Aligning the two laser beams allows the probe light to enter the coupling light transmission fiber as much as possible. The alignment process follows a fine-tuning process at close range and a coarse-tuning process at distant range. The coarse-tuning refers to adjusting the vertical and horizontal movement of the translation stage on which the coupling light collimator assembly 204 is installed, i.e., adjusting the overall vertical or horizontal movement of the coupling light collimator assembly 204. The fine-tuning refers to adjusting the knobs of the rotating frame on which the coupling light collimator assembly 204 is installed, i.e., adjusting the overall vertical or horizontal movement of the coupling light collimator assembly 204. 4. Tilt the optical fiber 204 vertically and horizontally; repeatedly coarsely and finely adjust until the probe light can be observed at the flange end of the coupling optical transmission fiber 205, and the light alignment is complete; then repeatedly coarsely and finely adjust the position of the coupling optical collimator assembly 204 and the probe light graded refractive index lens to improve the collection efficiency of the coupling optical transmission fiber 205 for the probe light 206 until the collection efficiency reaches the highest level or exceeds the preset efficiency threshold. The above collection efficiency is defined as follows:

[0061]

[0062] P1 is the intensity of the probe light collected at the flange end of the coupled optical transmission fiber 205, and P2 is the intensity of the probe light emitted from the 0° end face of the probe light graded refractive index lens of the probe light collimator assembly 202. After the collection efficiency reaches the highest level or exceeds the preset efficiency threshold, an optical adhesive is injected into the first collimating glass sleeve using a syringe to bond the first pigtail ferrule of the probe light transmission fiber and the probe light graded refractive index lens.

[0063] After aligning the two beams and adjusting the efficiency of the collected probe light, they are placed into the atomic gas chamber 203. The target signal is observed, and the positions of the probe light collimator assembly 202 and the coupling light collimator assembly 204 relative to the atomic gas chamber 203 are adjusted to optimize the target signal. The relative distances between the probe light collimator assembly 202 and the coupling light collimator assembly 204 and the atomic gas chamber 203 are recorded. Based on these two data, the probe light collimator assembly and the first laser fixing glass sleeve are bonded together, and the coupling light collimator assembly and the second laser fixing glass sleeve are bonded together. After applying optical adhesive to the outside of the first laser collimator glass sleeve and the second laser collimator glass sleeve, they are inserted into the first laser fixing glass sleeve and the second laser fixing glass sleeve until the distance between the probe light graded refractive index lens and the end of the first laser collimator glass sleeve meets the recorded distance. Then, optical adhesive is added for bonding.

[0064] After step 105 and before step 108, the probe collimator assembly and the first laser fixing glass sleeve can be rotated to adjust the laser polarization direction as a whole. The coupling collimator assembly and the second laser fixing glass sleeve can also be rotated to adjust the laser polarization direction as a whole. After adjusting the polarization direction of the two laser beams, the first laser fixing glass sleeve, the second laser fixing glass sleeve, and the atomic gas chamber can be recoupled and bonded.

[0065] In step 101, the assembly and bonding of the coupled light graded refractive index lens, the second laser collimating glass sleeve, and the second pigtail ferrule in the coupled light collimator assembly includes:

[0066] 11. The optical fiber for coupling transmission is connected to the optical collimator assembly via the second pigtail ferrule. The second pigtail ferrule extends into the second laser collimating glass sleeve, and the second laser collimating glass sleeve at least partially encloses the second pigtail ferrule and the optical graded refractive index lens for coupling.

[0067] 12. Rotate the base platform on which the second laser collimating glass sleeve is placed to collimate the output light;

[0068] 13. Use a beam quality analyzer to observe the size of the coupled beam spot, and adjust the spot size by adjusting the position of the coupled beam graded refractive index lens;

[0069] 14. Use a syringe to inject optical adhesive into the second laser collimating glass sleeve to bond the second pigtail ferrule and the coupled light graded refractive index lens.

[0070] The output light is collimated by rotating the base platform of the second laser collimating glass sleeve. A clamp is used to hold the planar end of the coupled light graded-index lens, allowing it to move left and right. The collimation process follows the principle of rotating the base platform at a distance and translating it at a closer distance. "Close" and "far" refer to the distance between the observed laser position and the planar end of the coupled light graded-index lens. After the coupled light collimator assembly is installed, a beam quality analyzer can be used to observe the size of the coupled light spot. The spot size is adjusted by changing the position of the coupled light graded-index lens. Finally, optical adhesive is injected into the second laser collimating glass sleeve using a disposable syringe to bond the second pigtail ferrule of the coupled light transmission fiber and the coupled light graded-index lens.

[0071] In step 102, the assembly of the probe light graded refractive index lens, the first laser collimating glass sleeve, and the first pigtail ferrule in the probe light collimator assembly includes:

[0072] 21. The probe light transmission fiber is connected to the probe light collimator assembly through the first pigtail ferrule. The first pigtail ferrule extends into the first laser collimating glass sleeve, and the first laser collimating glass sleeve at least partially encloses the first pigtail ferrule and the probe light graded refractive index lens.

[0073] 22. The base platform on which the first laser collimating glass sleeve is placed is rotated to collimate the output light;

[0074] 23. Use a beam quality analyzer to observe the size of the probe light spot, and adjust the spot size by adjusting the position of the probe light's graded refractive index lens.

[0075] The base platform on which the first laser collimating glass sleeve 303 is placed is rotated to collimate the output light. The planar end of the probe light graded refractive index lens 302 is held by a clamp so that it can move left and right. The collimation process follows the principle of rotating the base platform at a distance and translating it at a closer distance. The distances refer to the distance between the observed laser position and the planar end of the probe light graded refractive index lens 302. The size of the probe light spot can be observed using a beam quality analyzer, and the spot size can be adjusted by adjusting the position of the probe light graded refractive index lens 302.

[0076] In step 105, the bonding of the probe light graded refractive index lens, the first laser collimating glass sleeve, and the first pigtail ferrule in the probe light collimator assembly includes:

[0077] Optical adhesive is injected into the first laser collimating glass sleeve using a syringe to bond the first pigtail ferrule and the probe light graded refractive index lens.

[0078] Specifically, optical adhesive can be injected into the first laser collimating glass sleeve using a disposable syringe to bond the first pigtail ferrule 301 and the probe light graded refractive index lens 302.

[0079] In step 106, the method further includes:

[0080] Press the probe collimator assembly and the coupling collimator assembly into the grooves of the V-shaped bracket respectively;

[0081] A rotating polarization rotator drives the probe light transmission fiber or the coupling light transmission fiber to rotate, thereby adjusting the laser polarization direction.

[0082] like Figure 5 As shown, Figure 5This is a schematic diagram of a polarization adjustment tool provided in an embodiment of the present invention. The polarization adjustment tool includes a polarization rotator 501; a fixing component 502; a V-shaped fixing frame 504; a polarization beam splitter PBS 505; and a PBS reflection vertical end 506. 503 can be a coupling light collimator assembly 204 or a probe light collimator assembly 202.

[0083] After the coupling light collimator assembly 204 and the probe light collimator assembly 202 are bonded together, the polarization directions of the two laser beams are adjusted. Photonic crystal fibers maintain polarization for all transmission wavelengths, but the polarization direction of the input laser must first be aligned with the polarization-maintaining axis of the fiber. The probe light collimator assembly 202 and the coupling light collimator assembly 204 are pressed into the grooves of the V-shaped fixing frame 504. The polarization rotating component 501 rotates either the probe light transmission fiber or the coupling light transmission fiber, thus adjusting the laser polarization direction within the atomic gas chamber. The adjustment of the polarization direction requires the use of other tools to visually observe the effect. Based on the characteristic that the transmission end of the polarization beam splitter is horizontally polarized and the reflection end is vertically polarized, the laser polarization direction can be roughly determined. The polarization state of the probe light can be directly observed using a polarization analyzer. The polarization rotating component 501 is then adjusted. 1. Ensure the polarization state observed by the polarization analyzer is vertical, meaning the polarization of the coupled light emitted from the collimator assembly is vertical; Re-couple the two laser beams as in step 103; determine the polarization state of the coupled light by the beam splitter's splitting effect, monitor the light intensity at the reflector end of the polarization beam splitter, and adjust the polarization rotation element 50 1 to maximize the light intensity at the reflector end 50 6, meaning the polarization of the coupled light emitted from the collimator assembly is vertical; after adjusting the polarization, directly couple the light to reduce error, and probe the polarization directions of the light and coupled light as follows. Figure 4 As shown, an atomic gas cell 203 is placed between the probe collimator assembly and the coupling collimator assembly. The signal is observed and optimized until a signal with a large amplitude and a narrow linewidth is obtained. Finally, optical adhesive is used to bond the probe collimator assembly 202 and the atomic gas cell 203, and to bond the coupling collimator assembly 204 and the atomic gas cell 203.

[0084] like Figure 4 As shown, Figure 4 This is a schematic diagram of a microwave electric field measurement system provided in an embodiment of the present invention. The system includes, as shown in the diagram. Figures 2-3The microwave atomic probe shown also includes a probe light system, a coupling light system, a dichroic mirror, a signal data acquisition system, a photodetector, and a microwave transmitting system. The probe light transmission fiber of the microwave atomic probe is connected to the probe light system, and the coupling light transmission fiber of the microwave atomic probe is connected to the coupling light system. The signal data acquisition system acquires signals through the dichroic mirror and the photodetector. The microwave transmitting system is used to transmit microwave signals. In the figure, 40 8 indicates that the polarization directions of the probe light and the coupling light are perpendicular to the plane of the paper. 9 represents a microwave polarization direction perpendicular to the paper. When a coherent light field with a weak probe field couples with a pair of transition energy levels in an atomic medium, and a resonant transition occurs, the probe field is strongly absorbed by the atomic medium. At this point, another strongly coherent light beam is introduced to couple one of the two energy levels to another atomic energy level (Rydberg state). Under certain conditions, the atomic medium, which initially absorbed the probe field, begins to stop absorbing the probe light or its absorption decreases in the presence of the strongly coupled light field, making the atomic medium transparent to the probe light (electromagnetically induced transparency). When a microwave electric field is introduced to resonate with the two Rydberg states, the electromagnetically induced transparency window changes from a single peak to two peaks. The frequency spacing Δf between these two peaks is related to the field strength E of the microwave electric field.

[0085]

[0086] Where, μ MW It corresponds to the electric dipole moment of the Rydberg transition. It is the reduced Planck constant, and E is the microwave electric field intensity to be measured.

[0087] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0088] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0089] In the several embodiments provided in this application, it should be understood that the disclosed apparatus can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of the units described above is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical or other forms.

[0090] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0091] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for fabricating a microwave atomic detector, characterized in that, The microwave atomic probe includes: a probe light transmission fiber, a probe light collimator assembly, an atomic gas cell, a coupling light collimator assembly, and a coupling light transmission fiber. The probe light transmission fiber includes a first pigtail ferrule, and the coupling light transmission fiber includes a second pigtail ferrule. The probe light collimator assembly includes a probe light graded refractive index lens, a first laser collimating glass sleeve, and a first laser fixing glass sleeve. The coupling light collimator assembly includes a coupling light graded refractive index lens, a second laser collimating glass sleeve, and a second laser fixing glass sleeve. The method includes: The assembly and bonding of the second pigtail ferrule and the second laser collimating glass sleeve in the coupling light graded refractive index lens and the coupling light collimator assembly are carried out. Assemble the probe light graded refractive index lens, the first laser collimating glass sleeve, and the first pigtail ferrule in the probe light collimator assembly; The probe light collimator assembly and the coupling light collimator assembly are aligned so that the output light of the probe light collimator assembly coincides with the output light of the coupling light collimator assembly, and the distance between the probe light collimator assembly and the coupling light collimator assembly is sufficient to accommodate the atomic gas cell. Adjust the positions of the probe collimator assembly and the coupling collimator assembly so that the collection efficiency of the coupling optical transmission fiber for the probe light meets the preset conditions; The probe light graded refractive index lens, the first laser collimating glass sleeve, and the first pigtail ferrule in the probe light collimator assembly are bonded together. An atomic gas cell is positioned between the probe light collimator assembly and the coupling light collimator assembly; Adjust the relative distances between the probe collimator assembly and the coupling collimator assembly and the atomic gas cell; According to the adjusted distance, the probe collimator assembly is installed into the first laser fixing glass sleeve, and the coupling light collimator assembly is installed into the second laser fixing glass sleeve; The probe collimator assembly and the atomic gas cell are fixedly connected, as are the coupling collimator assembly and the atomic gas cell.

2. The method for fabricating a microwave atomic probe as described in claim 1, characterized in that, The assembly and bonding of the coupled light graded refractive index lens, the second laser collimating glass sleeve, and the second pigtail ferrule in the coupled light collimator assembly includes: The optical fiber for coupling light transmission is connected to the optical collimator assembly via the second pigtail ferrule. The second pigtail ferrule extends into the second laser collimating glass sleeve, and the second laser collimating glass sleeve at least partially encloses the second pigtail ferrule and the optical graded refractive index lens for coupling light. The base platform on which the second laser collimating glass sleeve is placed is rotated to collimate the output light; The size of the coupled beam spot was observed using a beam quality analyzer, and the spot size was adjusted by adjusting the position of the coupled beam graded refractive index lens. Optical adhesive is injected into the second laser collimating glass sleeve using a syringe to bond the second pigtail ferrule and the coupled light graded refractive index lens.

3. The method for fabricating a microwave atomic probe as described in claim 2, characterized in that, The assembly of the probe light graded refractive index lens, the first laser collimating glass sleeve, and the first pigtail ferrule in the probe light collimator assembly includes: The probe light transmission fiber is connected to the probe light collimator assembly via the first pigtail ferrule. The first pigtail ferrule extends into the first laser collimating glass sleeve, which at least partially encloses the first pigtail ferrule and the probe light graded refractive index lens. The base platform on which the first laser collimating glass sleeve is placed is rotated to collimate the output light. The size of the probe light spot is observed using a beam quality analyzer, and the spot size is adjusted by adjusting the position of the probe light graded refractive index lens. The bonding of the probe light graded refractive index lens, the first laser collimating glass sleeve, and the first pigtail ferrule in the probe light collimator assembly includes: Optical adhesive is injected into the first laser collimating glass sleeve using a syringe to bond the first pigtail ferrule and the probe light graded refractive index lens.

4. The method for fabricating a microwave atomic probe as described in claim 3, characterized in that, The method further includes: Press the probe collimator assembly and the coupling collimator assembly into the grooves of the V-shaped bracket respectively; A rotating polarization rotator drives the probe light transmission fiber or the coupling light transmission fiber to rotate, thereby adjusting the laser polarization direction.

5. A microwave atomic probe manufactured using the method described in any one of claims 1-4, characterized in that, include: The system comprises a probe light transmission fiber, a probe light collimator assembly, an atomic gas cell, a coupling light collimator assembly, and a coupling light transmission fiber, wherein the probe light transmission fiber, the probe light collimator assembly, the atomic gas cell, the coupling light collimator assembly, and the coupling light transmission fiber are connected in sequence. Wherein, the probe light transmission fiber and the coupling light transmission fiber are photonic crystal fibers; the probe light transmission fiber includes a first pigtail ferrule, and the probe light transmission fiber is connected to the probe light collimator assembly through the first pigtail ferrule, the probe light collimator assembly being used to horizontally collimate the emitted laser; the coupling light transmission fiber includes a second pigtail ferrule, and the coupling light transmission fiber is connected to the coupling light collimator assembly through the second pigtail ferrule, the atomic gas cell being disposed between the probe light collimator assembly and the coupling light collimator assembly.

6. A microwave atomic probe as described in claim 5, characterized in that, The probe collimator assembly includes a probe light graded refractive index lens, a first laser collimating glass sleeve, and a first laser fixing glass sleeve; the first pigtail insert extends into the first laser collimating glass sleeve, and the first laser collimating glass sleeve at least partially encloses the first pigtail insert and the probe light graded refractive index lens; the first laser fixing glass sleeve encloses the first laser collimating glass sleeve.

7. A microwave atomic probe as described in claim 6, characterized in that, The first pigtail ferrule is an 8° angled photonic crystal fiber pigtail, and the probe light graded refractive index lens is a graded refractive index lens with one end at 8° and the other end at 0°. The 8° end is set towards the first pigtail ferrule, and the 8° end of the first pigtail ferrule and the 8° end of the probe light graded refractive index lens are set parallel to each other.

8. A microwave atomic probe as described in any one of claims 5-7, characterized in that, The coupled light collimator assembly includes a coupled light graded refractive index lens, a second laser collimating glass sleeve, and a second laser fixing glass sleeve; the second pigtail insert extends into the second laser collimating glass sleeve, and the second laser collimating glass sleeve at least partially encloses the second pigtail insert and the coupled light graded refractive index lens; the second laser fixing glass sleeve encloses the second laser collimating glass sleeve.

9. A microwave atomic probe as described in claim 8, characterized in that, The second pigtail ferrule is an 8° angled photonic crystal fiber pigtail, and the coupled light graded refractive index lens is a graded refractive index lens with one end at 8° and the other end at 0°. The 8° end is set towards the second pigtail ferrule, and the 8° end of the second pigtail ferrule and the 8° end of the coupled light graded refractive index lens are set parallel to each other.

10. A microwave electric field measurement system, characterized in that, The system includes a microwave atomic probe as described in any one of claims 5-9, and further includes a probe light system, a coupling light system, a dichroic mirror, a signal data acquisition system, a photodetector, and a microwave transmitting system; the probe light transmission fiber of the microwave atomic probe is connected to the probe light system, the coupling light transmission fiber of the microwave atomic probe is connected to the coupling light system, the signal data acquisition system acquires signals through the dichroic mirror and the photodetector, and the microwave transmitting system is used to transmit microwave signals.

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