Optical resonant cavity enhanced microwave receiving system and method

Abstract

The invention provides an optical resonant cavity enhanced high-sensitivity microwave receiving system and method. The system comprises a first laser, an atomic gas chamber, an optical resonant cavity, a second laser, a photoelectric detector and an upper computer, the atomic gas chamber is arranged in a microwave field to be measured, the optical resonant cavity comprises a first reflecting mirror and a second reflecting mirror which are arranged on the two opposite sides of the atomic gas chamber, probe light generated by the first laser is transmitted in the atomic gas chamber in an oscillation mode under the reflecting action of the first reflecting mirror and the second reflecting mirror, and positive feedback is formed; the probe light excites atoms in the atomic gas chamber from a ground state energy level to a metastable state energy level, and the coupling light generated by the second laser excites the atoms from the metastable state energy level to a Rydberg energy level; the photoelectric detector is used for detecting the detection light output from the optical resonant cavity, and the upper computer is used for calculating field intensity information of the microwave field to be detected based on a detection result. By adopting the microwave receiving system provided by the invention, the number of atoms interacting with probe light can be increased, and the microwave receiving performance is improved.

Description

Technical Field

[0001] The present application relates to the field of microwave receiving technology, and in particular to a high-sensitivity microwave receiving system and method enhanced by an optical resonant cavity. Background Art

[0002] Microwave receiving technology can be used in radar detection, wireless communication, medical diagnosis and geological exploration. The microwave receiving technology based on Rydberg atoms uses the response of atoms in a highly excited state to the external microwave electric field to achieve microwave reception and measurement. It has the advantages of high microwave reception sensitivity and a wide frequency range. Atoms are the core component of this new technology. They are used in sensitive environmental microwave fields. The number of atoms participating in the microwave action in the atomic gas chamber directly affects the microwave reception sensitivity. Therefore, it is very important to increase the number of Rydberg state atoms. Under normal circumstances, increasing the optical length of the atomic vapor cavity along the laser propagation direction can increase the number of Rydberg state atoms, but it will lead to an increase in the system volume and require higher laser power. Therefore, there is an urgent need for a method to increase the number of atoms without increasing the system volume, so as to achieve high-sensitivity microwave reception. Summary of the invention

[0003] In order to solve the above technical problems, the present application proposes an optical resonant cavity enhanced microwave receiving system and method, which can achieve high-sensitivity reception of microwave fields.

[0004] In order to solve the above technical problems, the present application proposes a microwave receiving system enhanced by an optical resonant cavity, the microwave receiving system comprising: a first laser, an atomic gas chamber, an optical resonant cavity, a second laser, a photodetector and a host computer;

[0005] The atomic gas chamber is arranged in the microwave field to be measured, the optical resonant cavity comprises a first reflector and a second reflector arranged on opposite sides of the atomic gas chamber, the detection light generated by the first laser is oscillated and transmitted in the atomic gas chamber under the reflection action of the first reflector and the second reflector, and positive feedback is formed, the detection light excites the atoms in the atomic gas chamber from the ground state energy level to the metastable state energy level, and the coupling light generated by the second laser excites the atoms from the metastable state energy level to the Rydberg energy level;

[0006] The photoelectric detector is used to detect the detection light output from the optical resonant cavity, and the host computer is used to calculate the field intensity information of the microwave field to be measured based on the detection result of the detection light.

[0007] The microwave receiving system further comprises an adjusting mechanism, which is physically connected to the first reflector and / or the second reflector and electrically connected to the host computer, and the host computer controls the adjusting mechanism to adjust the cavity length of the optical resonant cavity.

[0008] Wherein, the adjusting mechanism adjusts the optical resonator such that the fundamental mode of the optical resonator resonates with the detection light mode.

[0009] Wherein, the first mirror is disposed on a side of the atomic gas cell facing the first laser, and the reflectivity of the second mirror for the detection light is less than the reflectivity of the first mirror for the detection light, so that the detection light is output from the side of the second mirror.

[0010] Wherein, the microwave receiving system further includes a dichroic mirror disposed between the second mirror and the photodetector. The detection light output from the side of the second mirror is incident on the photodetector after passing through the dichroic mirror. The coupling light generated by the second laser is incident on the second mirror after being reflected by the dichroic mirror, and is incident on the atomic gas cell after passing through the second mirror.

[0011] Wherein, the first mirror is further configured to reflect the detection light.

[0012] Wherein, the first laser, the atomic gas cell, the optical resonator, the dichroic mirror and the photodetector are disposed on the same axis.

[0013] Wherein, the microwave receiving system further includes a microwave system configured to apply a continuous local oscillator microwave field to the atomic gas cell. The continuous local oscillator microwave field and the microwave field to be measured jointly cause a periodic change in the energy level of the atom, and further produce a periodic modulation on the intensity of the detection light.

[0014] To solve the above technical problems, the present application further proposes an optical resonator enhanced microwave receiving method, and the method includes:

[0015] Using the detection light to excite the atoms in the atomic gas cell from the ground state energy level to the metastable energy level, and using the coupling light to excite the atoms from the metastable energy level to the Rydberg energy level;

[0016] Adjusting the first mirror and the second mirror on opposite sides of the atomic gas cell, so that the cavity length of the optical resonator formed by the first mirror and the second mirror allows the detection light to oscillate and propagate in the atomic gas cell and form positive feedback;

[0017] Applying a continuous local oscillator microwave field to the atomic gas cell, so that the continuous local oscillator microwave field and the microwave field to be measured jointly cause a periodic change in the energy level of the atom, and further produce a periodic modulation on the intensity of the detection light;

[0018] Detect the probe light output from the optical resonator, and calculate the field strength information of the microwave field to be measured based on the detection result of the probe light.

[0019] Compared with the prior art, the beneficial effects of the present application are as follows: The microwave receiving system provided by the present application includes: a first laser, an atomic gas cell, an optical resonator, a second laser, a photodetector, and a host computer; wherein the atomic gas cell is disposed in the microwave field to be measured, the optical resonator includes a first mirror and a second mirror disposed on opposite sides of the atomic gas cell, the probe light generated by the first laser oscillates and propagates in the atomic gas cell under the reflection of the first mirror and the second mirror, and forms positive feedback, the probe light excites the atoms in the atomic gas cell from the ground state energy level to the metastable energy level, and the coupling light generated by the second laser excites the atoms from the metastable energy level to the Rydberg energy level; the photodetector is used to detect the probe light output from the optical resonator, and the host computer is used to calculate the field strength information of the microwave field to be measured based on the detection result of the probe light. By using the microwave receiving system of the present application, the number of atoms interacting with the probe light can be increased, and the microwave receiving performance can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0021] Wherein:

[0022] Figure 1 is a schematic structural diagram of an embodiment of the microwave receiving system with enhanced optical resonator provided by the present application;

[0023] Figure 2 is a schematic structural diagram of another embodiment of the microwave receiving system with enhanced optical resonator provided by the present application;

[0024] Figure 3 is a schematic flowchart of an embodiment of the method for enhancing microwave reception with an optical resonator provided by the present application;

[0025] Figure 4 is a schematic overall flowchart of the method for enhancing microwave reception with an optical resonator provided by the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0027] The terms "first", "second", "third", "fourth", etc. (if any) in the specification, claims and above-mentioned drawings of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application described here, for example, can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0028] The present application provides a microwave receiving system enhanced by an optical resonator. For details, please refer to Figure 1 , Figure 1 which is a schematic structural diagram of an embodiment of the microwave receiving system enhanced by the optical resonator provided by the present application.

[0029] As Figure 1 shown, the microwave receiving system 100 provided by the present application includes: a first laser 11, an atomic gas cell 12, an optical resonator 13, a second laser 14, a photodetector 15, and a host computer 16.

[0030] Among them, the atomic gas cell 12 is encapsulated with gaseous alkali metal atoms and can achieve omnidirectional microwave reception.

[0031] Among them, the atomic gas cell 12 is arranged in the microwave field to be measured. The optical resonator 13 includes a first mirror 131 and a second mirror 132 arranged on opposite sides of the atomic gas cell 12. The probe light generated by the first laser 11 oscillates and transmits in the atomic gas cell 12 under the reflection of the first mirror 131 and the second mirror 132, and forms positive feedback. The probe light excites the atoms in the atomic gas cell 12 from the ground state energy level to the metastable energy level, and the coupling light generated by the second laser 14 excites the atoms from the metastable energy level to the Rydberg energy level.

[0032] In the embodiments of the present application, the probe light and the coupling light are linearly polarized light and have the same polarization direction.

[0033] The photodetector 15 is used to detect the probe light output from the optical resonator 13, and the host computer 16 is used to calculate the field strength information of the microwave field to be measured based on the detection result of the probe light.

[0034] Specifically, the probe light generated by the first laser 11 is incident into the atomic gas cell 12 and resonates with the atomic ground state and metastable state energy level transitions; the coupling light generated by the second laser 14 resonates with the atomic excited state and Rydberg state energy level transitions. The probe light and the coupling light are transmitted in opposite directions and coincide within the atomic gas cell 12, exciting the atoms to the Rydberg state.

[0035] In a specific embodiment, the probe light resonates with the rubidium atomic ground state 5S 1 / 2 , F = 2 fine energy level and the metastable state 5P 3 / 2 , F` = 3 fine energy level transitions, and the coupling light resonates with the metastable state 5P 3 / 2 , F` = 3 fine energy level and the Rydberg state 50D 5 / 2 transitions.

[0036] The fundamental mode of the optical resonator 13 resonates with the probe light mode, generating positive feedback on the probe light, causing the probe light to oscillate within the optical resonator 13 and increasing the number of atoms interacting with the probe light.

[0037] The signal source, i.e., the microwave system, generates the local oscillator microwave field, which together with the microwave field to be measured causes periodic changes in the atomic energy levels, thereby generating periodic modulation in the intensity of the probe light. The power of the modulation signal is proportional to the power of the microwave field to be measured, thus realizing the measurement of the microwave field to be received.

[0038] Finally, the photodetector 15 measures the light intensity of the probe light exiting the atomic gas cell 12, converts it into an electrical signal, and provides it to the host computer 16. The power of the probe light modulation signal is proportional to the power of the microwave field to be measured, thus realizing the measurement of the microwave field to be received.

[0039] Please continue to refer to Figure 2 , Figure 2 which is a schematic structural diagram of another embodiment of the optical resonator enhanced microwave receiving system provided by this application.

[0040] In Figure 1 Based on the optical resonator enhanced microwave receiving system 100 shown, the microwave receiving system 100 protected by this application further includes an adjustment mechanism 17. The adjustment mechanism 17 is physically connected to the first mirror 131 and / or the second mirror 132 and is electrically connected to the host computer 16. The host computer 16 controls the adjustment mechanism 17 to adjust the cavity length of the optical resonator 13. The adjustment mechanism 17 adjusts the optical resonator 13 such that the fundamental mode of the optical resonator 13 resonates with the probe light mode.

[0041] In Figure 2In the shown microwave receiving system 100, it is shown that the adjusting mechanism 17 is physically connected to the second mirror 132, and the adjusting mechanism 17 is electrically connected to the host computer 16. The adjusting mechanism 17 is used to adjust the second mirror 132 according to the control instruction of the host computer 16, so as to adjust the cavity length of the optical resonator 13. The host computer 16 controls the cavity length of the optical resonator 13 through the adjusting mechanism 17, so that the fundamental mode of the optical resonator 13 resonates with the detection light mode.

[0042] In other embodiments, it is also possible to achieve that the adjusting mechanism 17 is physically connected to the first mirror 131, or physically connected to both the first mirror 131 and the second mirror 132 at the same time.

[0043] Specifically, the host computer 16 controls the cavity length of the optical resonator 13, so that the fundamental mode of the optical resonator 13 resonates with the detection light mode. The signal source, that is, the microwave system 18 generates a continuous local oscillator microwave field, which together with the microwave field to be measured causes a periodic change in the atomic energy level, thereby generating a periodic modulation in the detection light intensity. The power of the modulation signal is proportional to the power of the microwave to be measured, thereby realizing the measurement of the microwave to be received. In a specific embodiment, the microwave generated by the signal source, that is, the microwave system 18, resonates with the 50D 5 / 2 and 49P 3 / 2 transitions. The antenna uses a standard horn antenna.

[0044] Furthermore, the first mirror 131 of the embodiment of the present application is arranged on the side of the atomic gas cell 12 facing the first laser 11, and the reflectivity of the second mirror 132 to the detection light is less than the reflectivity of the first mirror 131 to the detection light, so that the detection light is output from the side of the second mirror 132.

[0045] Among them, the first mirror 131 is further arranged to reflect the detection light.

[0046] The microwave receiving system 100 further includes a dichroic mirror 19, that is, a dichroic mirror, arranged between the second mirror 132 and the photodetector 15. The detection light output from the side of the second mirror 132 is incident on the photodetector 15 after being transmitted through the dichroic mirror 19. The coupling light generated by the second laser 14 is incident on the second mirror 132 after being reflected by the dichroic mirror 19, and is incident on the atomic gas cell 12 after being transmitted through the second mirror 132.

[0047] Specifically, the dichroic mirror 19 transmits the detection light and reflects the coupling light. The first laser 11, the atomic gas cell 12, the optical resonator 13, the dichroic mirror 19 and the photodetector 15 are on the same axis.

[0048] Furthermore, the microwave receiving system 100 further includes a microwave system 18 which is configured to apply a continuous local oscillator microwave field to the atomic gas cell 12. The continuous local oscillator microwave field and the microwave field to be measured jointly cause a periodic change in the energy levels of the atoms, and further generate a periodic modulation on the intensity of the probe light.

[0049] The local oscillator microwave field generated by the microwave system 18 and the microwave field to be measured jointly cause a periodic change in the atomic energy levels, thereby generating a periodic modulation on the intensity of the probe light.

[0050] The microwave receiving system provided by the present application includes: a first laser, an atomic gas cell, an optical resonator, a second laser, a photodetector, and a host computer; wherein the atomic gas cell is disposed in the microwave field to be measured, the optical resonator includes a first mirror and a second mirror disposed on opposite sides of the atomic gas cell, the probe light generated by the first laser oscillates and propagates in the atomic gas cell under the reflection of the first mirror and the second mirror, and forms positive feedback. The probe light excites the atoms in the atomic gas cell from the ground state energy level to the metastable energy level, and the coupling light generated by the second laser excites the atoms from the metastable energy level to the Rydberg energy level; the photodetector is configured to detect the probe light output from the optical resonator, and the host computer is configured to calculate the field strength information of the microwave field to be measured based on the detection result of the probe light. By using the microwave receiving system of the present application, the number of atoms interacting with the probe light can be increased, and the microwave receiving performance can be improved.

[0051] The advantages of the present application compared with the existing methods are as follows:

[0052] (1) The fundamental mode of the optical resonator of the present application resonates with the probe light mode, generates positive feedback on the probe light, enables the probe light to oscillate in the optical resonator, and effectively reduces the probe light power.

[0053] (2) Without increasing the system volume, the present application increases the number of atoms participating in microwave reception, thereby realizing high-sensitivity microwave reception.

[0054] Based on Figure 1 and Figure 2 the microwave receiving system enhanced by the optical resonator shown, the present application further proposes a related microwave receiving method. For details, please continue to refer to Figure 3 and Figure 4 , Figure 3 is a schematic flowchart of an embodiment of the microwave receiving method enhanced by the optical resonator provided by the present application, Figure 4 is a schematic overall flowchart of the microwave receiving method enhanced by the optical resonator provided by the present application.

[0055] As Figure 3 shown, the microwave receiving method of the present application includes the following steps:

[0056] Step S31: Use the probe light to excite the atoms in the atomic gas cell from the ground energy level to the metastable energy level, and use the coupling light to excite the atoms from the metastable energy level to the Rydberg energy level.

[0057] Step S32: Adjust the first mirror and the second mirror on the opposite sides of the atomic gas cell so that the cavity length of the optical resonator formed by the first mirror and the second mirror allows the probe light to oscillate and propagate in the atomic gas cell and form positive feedback.

[0058] Step S33: Apply a continuous local oscillator microwave field to the atomic gas cell so that the continuous local oscillator microwave field and the microwave field to be measured jointly cause a periodic change in the energy level of the atoms, thereby generating a periodic modulation of the intensity of the probe light.

[0059] Step S34: Detect the probe light output from the optical resonator, and calculate the field strength information of the microwave field to be measured based on the detection result of the probe light.

[0060] Those skilled in the art can understand that in the above method of the specific implementation manner, the writing order of each step does not mean a strict execution order and does not constitute any limitation to the implementation process. The specific execution order of each step should be determined by its function and possible internal logic.

[0061] The above is only the implementation manner of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. An optically resonant cavity enhanced microwave receiving system, characterized in that, The microwave receiving system includes: a first laser, an atomic gas cell, an optical resonator, a second laser, a photodetector, and a host computer; Wherein the atomic gas cell is arranged in the microwave field to be measured, the optical resonator includes a first mirror and a second mirror arranged on opposite sides of the atomic gas cell, the probe light generated by the first laser oscillates and transmits in the atomic gas cell under the reflection of the first mirror and the second mirror, and forms positive feedback, the probe light excites the atoms in the atomic gas cell from the ground state energy level to the metastable energy level, and the coupling light generated by the second laser excites the atoms from the metastable energy level to the Rydberg energy level; The photodetector is used to detect the probe light output from the optical resonator, and the host computer is used to calculate the field strength information of the microwave field to be measured based on the detection result of the probe light.

2. The microwave receiving system according to claim 1, wherein: The microwave receiving system further includes an adjustment mechanism, the adjustment mechanism is physically connected to the first mirror and / or the second mirror, and is electrically connected to the host computer, and the host computer controls the adjustment mechanism to adjust the cavity length of the optical resonator.

3. The microwave receiving system according to claim 2, wherein: The adjustment mechanism adjusts the optical resonator so that the fundamental mode of the optical resonator resonates with the probe light mode.

4. The microwave receiving system according to claim 1, characterized in that: The first mirror is arranged on one side of the atomic gas cell facing the first laser, and the reflectivity of the second mirror to the probe light is less than the reflectivity of the first mirror to the probe light, so that the probe light is output from the side of the second mirror.

5. The microwave receiving system according to claim 4, wherein: The microwave receiving system further includes a dichroic mirror arranged between the second mirror and the photodetector, the probe light output from the side of the second mirror is transmitted through the dichroic mirror and then incident on the photodetector, and the coupling light generated by the second laser is reflected by the dichroic mirror and then incident on the second mirror, and is transmitted through the second mirror and then incident on the atomic gas cell.

6. The microwave receiving system according to claim 5, characterized in that: The first mirror is further arranged to reflect the probe light.

7. The microwave receiving system according to claim 5, characterized in that: The first laser, the atomic gas cell, the optical resonator, the dichroic mirror, and the photodetector are arranged on the same axis.

8. The microwave receiving system according to claim 1, characterized in that: The microwave receiving system further includes a microwave system, the microwave system is arranged to apply a continuous local oscillator microwave field to the atomic gas cell, and the continuous local oscillator microwave field and the microwave field to be measured jointly cause a periodic change in the energy level of the atoms, thereby generating a periodic modulation of the intensity of the probe light.

9. An optical resonator enhanced microwave receiving method, characterized in that, The method includes: Using the probe light to excite the atoms in the atomic gas cell from the ground state energy level to the metastable energy level, and using the coupling light to excite the atoms from the metastable energy level to the Rydberg energy level; Adjusting the first mirror and the second mirror on opposite sides of the atomic gas cell so that the cavity length of the optical resonator formed by the first mirror and the second mirror allows the probe light to oscillate and transmit in the atomic gas cell and form positive feedback; Applying a continuous local oscillator microwave field to the atomic gas cell so that the continuous local oscillator microwave field and the microwave field to be measured jointly cause a periodic change in the energy level of the atoms, thereby generating a periodic modulation of the intensity of the probe light; Detect the probe light output from the optical resonator, and calculate the field strength information of the microwave field to be measured based on the detection result of the probe light.

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