阅读说明：本技术 原子磁力计及其碱金属原子气室压强的原位检测方法 (Atomic magnetometer and in-situ detection method for pressure intensity of alkali metal atomic gas chamber thereof ) 是由 蔡宾 于 2020-06-01 设计创作，主要内容包括：本发明公开了原子磁力计及其碱金属原子气室压强的原位检测方法,其中原子磁力计包括光源、起偏器、四分之一波片、碱金属原子气室、无磁电加热膜、光学微腔、微纳光纤、分光棱镜、光谱仪和信号处理电路。光学微腔与微纳光纤相接触并且集成在所述碱金属原子气室内。通过测量光学微腔的谐振波长及波长变化量,计算出碱金属原子气室中的压强。该方法可以在碱金属原子气室的输出信号中同时提取原子磁力计的信号及碱金属原子气室的压强信号。能够在原子磁力计正常工作的同时进行碱金属原子气室压强的检测,并且具有较高的测量精度。同时,光学微腔不引入任何磁场噪声。该方法也可以用在其他利用碱金属原子气室的量子精密测量系统中。(The invention discloses an atomic magnetometer and an in-situ detection method for the pressure of an alkali metal atomic gas chamber thereof, wherein the atomic magnetometer comprises a light source, a polarizer, a quarter-wave plate, the alkali metal atomic gas chamber, a non-magnetic electric heating film, an optical microcavity, a micro-nano optical fiber, a beam splitter prism, a spectrometer and a signal processing circuit. The optical microcavity is in contact with the micro-nano optical fiber and integrated in the alkali metal atom gas chamber. And calculating the pressure intensity in the alkali metal atom gas chamber by measuring the resonance wavelength and the wavelength variation of the optical microcavity. The method can simultaneously extract the signal of the atomic magnetometer and the pressure signal of the alkali metal atom gas chamber from the output signal of the alkali metal atom gas chamber. The pressure intensity of the alkali metal atomic gas chamber can be detected while the atomic magnetometer works normally, and the method has high measurement precision. At the same time, the optical microcavity does not introduce any magnetic field noise. The method can also be used in other quantum precision measurement systems using alkali metal atom gas cells.)

1. The atomic magnetometer is characterized by comprising a light source, a polarizer, a quarter-wave plate, an alkali metal atomic gas chamber, a non-magnetic electric heating film, an optical microcavity, a micro-nano optical fiber, a beam splitter prism, a spectrometer, a photoelectric detector and a signal processing circuit; the non-magnetic electric heating film is arranged on the outer surface of the alkali metal atom air chamber and is used for heating the alkali metal atom air chamber; the optical microcavity is in contact with the micro-nano optical fiber and is integrated in the alkali metal atomic gas chamber; light emitted by the light source sequentially passes through the polarizer and the quarter-wave plate and then is incident into the heated alkali metal atom gas chamber, and simultaneously is incident into one end of the micro-nano optical fiber, light transmitted in the micro-nano optical fiber is coupled to the optical microcavity, and then is incident into the beam splitter prism after being emitted from the other end of the micro-nano optical fiber; the light emitted from the alkali metal atom gas chamber is also incident to the beam splitter prism; the beam splitting prism splits the received light into two beams, and one beam is incident to a spectrometer to detect the resonance wavelength and wavelength variation of the optical microcavity, so that the pressure in the alkali metal atom gas chamber is calculated; and the other beam of light enters a photoelectric detector and is processed by the photoelectric detector and a signal processing circuit to obtain an external magnetic field of the atomic magnetometer.

2. The atomic magnetometer of claim 1, wherein the alkali metal atomic gas cell is heated to 120-200 ℃ using a magnetoelectric heating film.

3. The atomic magnetometer of claim 1, wherein the optical microcavity and the micro-nano fiber are made of fused silica, and the optical microcavity and the micro-nano fiber are encapsulated by a polymer with a low refractive index.

4. The atomic magnetometer of claim 1 wherein said optical microcavity has a diameter not exceeding 500 microns.

5. The atomic magnetometer of claim 1, wherein the optical microcavity has a resonant wavelength that is different from the absorption wavelength of the alkali metal atoms in the alkali metal atom gas cell, such that the resonant wavelength of the optical microcavity does not coincide with the absorption wavelength of the alkali metal atoms when measuring the pressure in the alkali metal atom gas cell.

6. The atomic magnetometer of claim 1, wherein the micro-nanofiber has a waist region diameter of 1-10 microns.

7. The atomic magnetometer of claim 1, wherein the pressure in the alkali metal atomic gas cell is calculated by the formula:

wherein: λ is the resonance wavelength of the optical microcavity, Δ λ is the variation of the wavelength, P is the pressure in the alkali metal atom gas chamber, G and ν are the shear modulus and poisson's ratio of the material of the optical microcavity, n is the refractive index of the material of the optical microcavity, C₁And C₂The elastic-optical coefficient of the material of the optical microcavity.

8. The in-situ detection method of the pressure of the alkali metal atom gas chamber of the atomic magnetometer is characterized by comprising the following steps of:

step S1, the light emitted by the light source is changed into linearly polarized light after passing through the polarizer;

step S2, making the linearly polarized light enter the quarter-wave plate and become circularly polarized light;

step S3, circularly polarized light is incident into the heated alkali metal atom gas chamber, is transmitted and coupled into the optical microcavity along the micro-nano optical fiber in the alkali metal atom gas chamber, and light emitted from the other end of the micro-nano optical fiber and light emitted from the alkali metal atom gas chamber are incident into the beam splitter prism;

and step S4, the beam splitter prism divides the received light into two beams, one beam is incident to the spectrometer to detect the resonance wavelength and wavelength variation of the optical microcavity, the other beam is incident to the photoelectric detector, and the magnetic field of the external environment where the atomic magnetometer is located is obtained after photoelectric conversion and signal processing.

And step S5, calculating the pressure in the alkali metal atom gas chamber according to the resonance wavelength and the wavelength variation of the optical microcavity.

9. The method for in-situ measurement of the pressure in an alkali metal atom gas chamber of an atomic magnetometer according to claim 8, wherein the calculation formula of the pressure in the alkali metal atom gas chamber in step S5 is:

wherein: λ is the resonant wavelength of the optical microcavity, Δ λ is the variation of the wavelength, and P is alkali goldBelongs to the pressure intensity in an atomic gas chamber, G and v are the shear modulus and Poisson's ratio of the material of the optical microcavity, n is the refractive index of the material of the optical microcavity, C₁And C₂The elastic-optical coefficient of the material of the optical microcavity.

Technical Field

The invention relates to the technical field of quantum precision measurement, in particular to an atomic magnetometer and an in-situ detection method of the pressure of an alkali metal atom air chamber thereof.

Background

In a high sensitivity atomic magnetometer, in order to reduce the relaxation of alkali metal atoms, it is generally necessary to flush a certain amount of buffer gas into the gas chamber of the alkali metal atoms, in order to reduce the electron spin destruction relaxation. Meanwhile, in order to avoid the influence of the fluorescence effect on the electron pumping, quenching gas is filled in the alkali metal atom gas chamber and is used for capturing photons radiated in the depolarization process of the outermost layer electrons of the alkali metal atoms so as to avoid the influence of the fluorescence effect on the electron pumping. The gas pressures of the buffer gas and the quenching gas influence the relaxation rate and the polarizability of the alkali metal atoms, and further influence the sensitivity of the atomic magnetometer. Therefore, the pressure of the alkali metal atom gas cell needs to be detected as an important parameter of the gas cell. At present, the pressure broadening of an alkali metal atom absorption spectral line is measured by a spectral absorption method commonly used, so that the pressure of an alkali metal atom gas chamber is obtained through fitting, but the method has large error and is difficult to accurately measure the pressure of the alkali metal atom gas chamber. Meanwhile, the method needs to tune the light source and measure in a pressure broadening range, so that the measurement cannot be carried out while the atomic magnetometer works, and the measurement efficiency is reduced.

In order to realize high-precision detection of the pressure of the alkali metal atomic gas chamber without influencing the normal work of the high-sensitivity atomic magnetometer, the atomic magnetometer in the prior art needs to be improved.

Disclosure of Invention

The invention aims to provide an atomic magnetometer and an in-situ detection method of the pressure of an alkali metal atomic gas chamber thereof, which can perform high-precision detection of the pressure of the alkali metal atomic gas chamber while the atomic magnetometer works normally.

The purpose of the invention is realized by the following technical scheme:

in a first aspect, the invention discloses an atomic magnetometer, which comprises a light source, a polarizer, a quarter wave plate, an alkali metal atomic gas chamber, a nonmagnetic electric heating film, an optical microcavity, a micro-nano optical fiber, a beam splitter prism, a spectrometer, a photoelectric detector and a signal processing circuit, wherein the optical microcavity is arranged on the light source; the non-magnetic electric heating film is arranged on the outer surface of the alkali metal atom air chamber and is used for heating the alkali metal atom air chamber; the optical microcavity is in contact with the micro-nano optical fiber and is integrated in the alkali metal atomic gas chamber; light emitted by the light source sequentially passes through the polarizer and the quarter-wave plate and then is incident into the heated alkali metal atom gas chamber, and simultaneously is incident into one end of the micro-nano optical fiber, light transmitted in the micro-nano optical fiber is coupled to the optical microcavity, and then is incident into the beam splitter prism after being emitted from the other end of the micro-nano optical fiber; the light emitted from the alkali metal atom gas chamber is also incident to the beam splitter prism; the beam splitting prism splits the received light into two beams, and one beam is incident to a spectrometer to detect the resonance wavelength and wavelength variation of the optical microcavity, so that the pressure in the alkali metal atom gas chamber is calculated; and the other beam of light enters a photoelectric detector and is processed by the photoelectric detector and a signal processing circuit to obtain an external magnetic field of the atomic magnetometer.

Further, the alkali metal atom gas chamber is heated to 120-200 ℃ by using a non-magnetoelectric heating film.

Furthermore, the optical microcavity and the micro-nano optical fiber are made of fused quartz, and are packaged by a polymer with low refractive index.

Further, the diameter of the optical microcavity is not more than 500 microns.

Further, the resonant wavelength of the optical microcavity is different from the absorption wavelength of the alkali metal atoms in the alkali metal atom gas chamber, so that when the pressure of the alkali metal atom gas chamber is measured, the resonant wavelength of the optical microcavity does not coincide with the absorption wavelength of the alkali metal atoms.

Furthermore, the diameter of the waist region of the micro-nano optical fiber is 1-10 micrometers.

Further, the calculation formula of the pressure in the alkali metal atom gas chamber is as follows:

wherein: λ is the resonance wavelength of the optical microcavity, Δ λ is the variation of the wavelength, P is the pressure in the alkali metal atom gas chamber, G and ν are the shear modulus and poisson's ratio of the material of the optical microcavity, n is the refractive index of the material of the optical microcavity, C₁And C₂The elastic-optical coefficient of the material of the optical microcavity.

In a second aspect, the invention discloses an in-situ detection method for the pressure of an alkali metal atom gas chamber of an atomic magnetometer, which comprises the following steps:

step S1, the light emitted by the light source is changed into linearly polarized light after passing through the polarizer;

step S2, making the linearly polarized light enter the quarter-wave plate and become circularly polarized light;

step S3, circularly polarized light is incident into the heated alkali metal atom gas chamber, is transmitted and coupled into the optical microcavity along the micro-nano optical fiber in the alkali metal atom gas chamber, and light emitted from the other end of the micro-nano optical fiber and light emitted from the alkali metal atom gas chamber are incident into the beam splitter prism;

and step S4, the beam splitter prism divides the received light into two beams, one beam is incident to the spectrometer to detect the resonance wavelength and wavelength variation of the optical microcavity, the other beam is incident to the photoelectric detector, and the magnetic field of the external environment where the atomic magnetometer is located is obtained after photoelectric conversion and signal processing.

And step S5, calculating the pressure in the alkali metal atom gas chamber according to the resonance wavelength and the wavelength variation of the optical microcavity.

Further, the calculation formula of the pressure in the alkali metal atom gas chamber in the step S5 is as follows:

wherein: λ is the resonance wavelength of the optical microcavity, Δ λ is the variation of the wavelength, P is the pressure in the alkali metal atom gas chamber, G and ν are the shear modulus and poisson's ratio of the material of the optical microcavity, n is the refractive index of the material of the optical microcavity, C₁And C₂The elastic-optical coefficient of the material of the optical microcavity.

According to the atomic magnetometer, the micro-nano optical fiber and the optical microcavity are integrated into the alkali metal atom gas chamber, and the pressure of the alkali metal atom gas chamber is calculated by measuring the harmonic wavelength and the wavelength variation of the optical microcavity. When the atomic magnetometer works, the in-situ detection of the pressure of the alkali metal atomic gas chamber can be realized without any external magnetic field.

The micro-nano optical fiber and the optical microcavity are made of fused quartz, no magnetic field noise is introduced, the measurement precision is high, and the sensitivity of the atomic magnetometer is improved.

The optical microcavity and the atomic magnetometer utilize the same light beam to realize the measurement of the pressure of the alkali metal atomic gas chamber and the external magnetic field without introducing an external device.

Drawings

FIG. 1 is a schematic diagram of the structure of an atomic magnetometer of the present invention.

The reference numerals are explained below:

1: light source, 2: polarizer, 3: quarter-wave plate, 4: alkali metal atom gas cell, 5: non-magnetic electric heating film, 6: optical microcavity, 7: micro-nano fiber, 8: beam splitter prism, 9: spectrometer, 10: photodetector, 11: preamplifier, 12: lock-in amplifier, 13: and a signal acquisition processing circuit.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

The embodiments of the present disclosure are described below with specific examples, and other advantages and effects of the present disclosure will be readily apparent to those skilled in the art from the disclosure in the specification. It is to be understood that the described embodiments are merely illustrative of some, and not restrictive, of the embodiments of the disclosure. The disclosure may be embodied or carried out in various other specific embodiments, and various modifications and changes may be made in the details within the description without departing from the spirit of the disclosure. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict. All other embodiments, which can be derived by a person skilled in the art from the embodiments disclosed herein without making any creative effort, shall fall within the protection scope of the present disclosure.

The schematic diagram of the structure of the atomic magnetometer of the invention is shown in fig. 1. The device comprises a light source 1, a polarizer 2, a quarter wave plate 3, an alkali metal atom gas chamber 4, a non-magnetic electric heating film 5, an optical microcavity 6, a micro-nano optical fiber 7, a beam splitter prism 8, a spectrometer 9, a photoelectric detector 10, a preamplifier 11, a phase-locked amplifier 12 and a signal acquisition processing circuit 13. The nonmagnetic electric heating film 5 is arranged on the outer surface of the alkali metal atom gas chamber 4 and used for heating the alkali metal atom gas chamber 4, preferably to 120-200 ℃. The optical microcavity 6 and the micro-nano optical fiber 7 are integrated in the alkali metal atom gas chamber 4. Light emitted by the light source 1 sequentially passes through the polarizer 2 and the quarter-wave plate 3 and then is incident to the heated alkali metal atom gas chamber 4, and simultaneously is incident to one end of the micro-nano optical fiber 7, light transmitted in the micro-nano optical fiber 7 is coupled to the optical microcavity 6, and then is emitted through the other end of the micro-nano optical fiber 7 and then is incident to the beam splitter prism 8. The light emitted from the alkali metal atom gas cell 4 is also incident on the beam splitter prism 8. The beam splitter prism 8 splits the received light into two beams, and one beam is incident into the spectrometer 9 to detect the resonance wavelength and wavelength conversion amount of the optical microcavity 6, so that the pressure in the alkali metal atom gas chamber 4 is calculated according to the resonance wavelength and wavelength conversion amount of the optical microcavity 6. And the other beam sequentially passes through the photoelectric detector 10, the preamplifier 11, the lock-in amplifier 12 and the signal acquisition processing circuit 13, and then the magnetic field is measured.

Further, in a preferred embodiment provided herein, the optical microcavity 6 is in contact with the coupling micro-nanofiber 7 and is encapsulated by a low refractive index (the invention refers to a low refractive index with a refractive index of less than 1.4) polymer. The micro-nano optical fiber 7 mainly plays a role in coupling light propagating in the micro-nano optical fiber to the optical microcavity 6. The optical microcavity 6 and the micro-nano optical fiber 7 are made of fused silica and do not have any magnetism, so that an extremely low magnetic field environment is formed in the alkali metal atom gas chamber 4.

Further, in a preferred embodiment provided herein, the optical microcavity 6 is a micro-bottle or microsphere resonator having a diameter of no more than 500 microns, too large to occupy too much of the space of the gas chamber of alkali metal atoms.

Further, in a preferred embodiment provided herein, the resonant wavelength of the optical microcavity 6 is different from the absorption wavelength of the alkali metal atoms in the alkali metal atom gas cell 4, so that the resonant wavelength of the optical microcavity 6 does not coincide with the absorption wavelength of the alkali metal atoms when the pressure of the alkali metal atom gas cell is measured. If the resonance wavelength coincides with the absorption wavelength of the alkali metal atom, the two wavelengths are difficult to distinguish, and detection of the resonance wavelength is affected.

Further, in a preferred embodiment provided by the present application, the diameter of the waist region of the micro-nano optical fiber 7 is 1 to 10 micrometers. The light in the micro-nano optical fiber can be coupled into the optical microcavity at the diameter and can be kept stable.

The pressure of the alkali metal atom gas chamber 4 is calculated by the following formula:

wherein lambda is the resonance wavelength of the optical microcavity 6, delta lambda is the variation of the wavelength, P is the pressure in the alkali metal atom air chamber 4, G and v are the shear modulus and Poisson's ratio of the material of the optical microcavity 6, n is the refractive index of the material of the optical microcavity 6, C₁And C₂The elasto-optic coefficient of the material of the optical microcavity 6. Wherein G, v, n, C₁、C₂For the known data, λ and Δ λ can be measured by the spectrometer 9, and the pressure P of the gas cell 4 of alkali metal atoms can be calculated by substituting the known data and the measured data into the formula (1).

The preamplifier 11, the lock-in amplifier 12 and the signal acquisition and processing circuit 13 form a signal processing circuit, the signal processing circuit and the photodetector 10 are common prior art for measuring magnetic field of atomic magnetometer, and are not the key point of the present invention, and the detailed circuit structure and the working principle of the four parts are not described in detail here. It is only for the purpose of explaining that the atomic magnetometer of the present invention can measure the pressure of the gas chamber of the alkali metal atoms while working normally. The focus of the present invention is on the structure of the alkali metal atom gas chamber 4 and the pressure measurement method therein, the method of measuring the magnitude of the magnetic field by the atomic magnetometer and the circuit structure thereof should not be construed as limiting the present invention.

The working principle of the atomic magnetometer of the invention is as follows:

the light emitted by the light source 1 is changed into linearly polarized light after passing through the polarizer 2, and the linearly polarized light is changed into circularly polarized light after entering the quarter-wave plate 3. The alkali metal gas chamber is heated to 120-200 ℃ by the non-magnetic electric heating film 5 and is in an extremely low magnetic field environment. The circularly polarized light is incident into the alkali metal atom gas chamber 4 which is heated to a high temperature and is in an extremely low magnetic field environment, so that the alkali metal atoms in the alkali metal atom gas chamber 4 are in a Spin-Exchange Relaxation (SERF) Free state. Meanwhile, light enters the micro-nano optical fiber 7 integrated in the alkali metal atom gas chamber 4, and light transmitted in the micro-nano optical fiber 7 is coupled to the optical microcavity 6. The resonant wavelength of the optical microcavity 6 will vary with the pressure in the alkali metal atom gas cell 4. If the resonant wavelength and the wavelength variation of the optical microcavity 6 can be measured, the pressure of the alkali metal atom gas chamber 4 can be further calculated by the relational expression between the resonant wavelength of the optical microcavity 6 and the pressure of the alkali metal atom gas chamber 4. Light emitted by the micro-nano optical fiber 7 is incident on a beam splitter prism 8, light emitted from the alkali metal atom gas chamber is also incident on the beam splitter prism, the received light is divided into two beams by the beam splitter prism 8, and one beam is incident on a spectrometer 9 to detect the resonance wavelength of the optical microcavity 6, so that the pressure in the alkali metal atom gas chamber 4 is calculated. The other beam of light is incident on the photoelectric detector 10 and converted into an electric signal, the preamplifier 11 is used for amplifying the electric signal output by the photoelectric detector 10, then the change of the output light intensity is tracked in real time through the lock-in amplifier 12, and the signal acquisition processing circuit 13 converts the electric signal output by the lock-in amplifier 12 into the size of the magnetic field measured by the atomic magnetometer based on the light intensity-magnetic field conversion coefficient calibrated in advance.

The in-situ detection method of the pressure of the alkali metal atom gas chamber of the atomic magnetometer comprises the following steps:

in step S1, the light emitted from the light source is changed into linearly polarized light after passing through the polarizer.

In step S2, the linearly polarized light enters the quarter-wave plate and becomes circularly polarized light.

And step S3, enabling the circularly polarized light to be incident into the heated alkali metal atom gas chamber, propagating and coupling the circularly polarized light into the optical microcavity along the micro-nano optical fiber in the alkali metal atom gas chamber, and enabling the light emitted from the other end of the micro-nano optical fiber and the light emitted from the alkali metal atom gas chamber to be incident into the beam splitter prism.

Preferably, the alkali metal atom gas cell is heated to 120 ℃ to 200 ℃ using a non-magnetoelectric heating film in order to bring the alkali metal atoms in the alkali metal atom gas cell into a non-spin-exchange relaxation state.

Changes in the pressure of the alkali metal atom gas cell can result in changes in the resonant wavelength of the optical microcavity. Therefore, if the resonant wavelength of the optical microcavity can be measured, the pressure of the alkali metal atom gas chamber can be calculated according to the relation between the resonant wavelength and the pressure of the alkali metal atom gas chamber.

And step S4, the beam splitter prism divides the received light into two beams, one beam is incident to a spectrometer to detect the resonance wavelength and wavelength variation of the optical microcavity, the other beam is incident to a photoelectric detector of the atomic magnetometer, and the magnetic field of the environment where the atomic magnetometer is located is measured after photoelectric conversion and signal processing.

And step S5, calculating the pressure in the alkali metal atom gas chamber according to the resonance wavelength and the wavelength variation of the optical microcavity.

The calculation formula is the above formula (1).

The above description is for the purpose of illustrating embodiments of the invention and is not intended to limit the invention, and it will be apparent to those skilled in the art that any modification, equivalent replacement, or improvement made without departing from the spirit and principle of the invention shall fall within the protection scope of the invention.