CN115164863A - A Fiber Optic Gyroscope Based on Cascade Quantum Weak Measurement - Google Patents

Abstract

The present invention provides an optical fiber gyroscope based on cascaded quantum weak measurement, comprising a front selection module, a first beam splitter, a first electro-optic modulator, a second electro-optic modulator, a weak coupling module, a first plane mirror, a second plane mirror, A post selection module, a third plane mirror, a second beam splitter and a data processing module, wherein the weak coupling module includes a polarization beam splitter, a first collimating lens, a polarization maintaining fiber ring, and a second collimating lens, and the post selection The module contains a second polarizer and a third polarizer. The beneficial effects of the invention are as follows: the measuring beam is divided into two paths, respectively realizing the functions of the optical vernier and the optical master ruler in the Vernier effect. The different periods of the beam correspond to the periods of the vernier and the main ruler, respectively, which can amplify the movement of the vernier and the results of the traditional quantum weak measurement scheme, so as to achieve high sensitivity and high precision measurement of angular velocity.

Description

A Fiber Optic Gyroscope Based on Cascade Quantum Weak Measurement

technical field

The invention relates to the technical field of rotational angular velocity measurement, in particular to an optical fiber gyroscope based on cascaded quantum weak measurement.

Background technique

The development and application of high-precision, high-sensitivity and low-drift gyroscopes have been involved in various scientific fields. The basic principle of gyroscope is that the Sagnac effect was first proposed by French scientist Sagnac in the 1970s. The Sagnac effect indicates that two oppositely propagating beams emitted by the same light source will interfere due to different propagation times after they converge. The Sagnac effect has been widely used in the measurement of angular velocity since it was first proposed. The earliest application was as a marine fiber optic gyroscope. times.

Optical inertial measurement instruments supported by the above principles can be used for precise physical quantity measurement: 1) Measurement of Universal Time (UT1), which is one of the Earth Orientation Parameters (EOP), which describes the spatial orientation of the Earth As well as the rotation motion, it is the link parameter that realizes the transformation of the coordinate system of the celestial body and the earth reference frame, and affects all the application fields of the design of precise space technology. 2) Measurement of seismic waves in rotational seismology: Rotational seismology has become an emerging field of study, which includes rotational ground motions caused by earthquakes, explosions, and environmental vibrations; 3) Ordinary angular velocity fiber optic sensors: missile control, etc. The above application of fiber optic gyroscopes in different fields is mainly determined by the sensitivity and zero drift of its design. The sensitivity of fiber optic gyroscopes for marine-grade and self-aligned strategic missiles is 5×10 ^-7 rad/s, and the zero drift is: 0.00010 /h, but has not reached the precision and zero drift of studying rotational geology and measuring the world. If we want to further meet the requirements of studying rotational geology and measuring world time, if we do not consider the limitation of miniaturization, the Sagnac interferometer composed of super-large ring laser can reach 12×10 ^-12 rad/s/√Hz. At present, fiber optic gyroscopes tend to be developed with high precision and miniaturization. Therefore, the development of high-precision, portable, high-sensitivity and low-drift gyroscopes is still a challenging task.

SUMMARY OF THE INVENTION

In view of this, in order to meet the requirements of high precision and miniaturization when studying rotational geology and measuring the world, embodiments of the present invention provide a fiber optic gyroscope based on cascaded quantum weak measurement.

An embodiment of the present invention provides a fiber optic gyroscope based on cascaded quantum weak measurement, comprising a front selection module, a first beam splitter, a first electro-optic modulator, a second electro-optic modulator, a weak coupling module, a first plane mirror, a first Two plane mirrors, a rear selection module, a third plane mirror, a second beam splitter and a data processing module, wherein the weak coupling module includes a polarization beam splitter, a first collimating lens, a polarization maintaining fiber ring, and a second collimating lens. The latter selection module includes a second polarizer and a third polarizer;

The polarized light output by the front selection module is divided into a first beam and a second beam by the first beam splitter;

The first beam passes through the first electro-optic modulator to generate a first Gaussian pulse beam, the polarization beam splitter separates the first Gaussian pulse beam to form a first polarized light V and a second polarized light H, and the first The polarized light V propagates along the first collimating lens, the polarization-maintaining fiber ring, and the second collimating lens in sequence and returns to the polarization beam splitter, and the second polarized light H sequentially travels along the The second collimating lens, the polarization-maintaining fiber ring, and the first collimating lens propagate and return to the polarization beam splitter, and the first polarized light V and the second polarized light H are weakly coupled to form The coupled light beams pass through the first plane mirror, the second polarizer and the second beam splitter in sequence;

The second beam passes through the second electro-optic modulator to generate a second Gaussian pulse beam, and the second Gaussian pulse beam passes through the second plane mirror, the third polarizer, the third plane mirror and the second plane mirror in sequence. a beam splitter, which is combined with the coupled beam on the second beam splitter to form a combined beam;

The data processing module collects the combined beam, calculates the movement of the envelope of the superimposed signal in the combined beam, and obtains the magnitude of the measured rotational angular velocity.

Further, the period of the first Gaussian pulse beam is FSR ₁ , the period of the second Gaussian pulse beam is FSR ₂ , and FSR ₁ and FSR ₂ correspond to the periods of the vernier and the master scale in the optical Vernier effect, respectively. The magnification factor of is equal to Eh=FSR ₂ /|FSR ₁ −FSR ₂ |.

S对应所述保偏光纤环的有效面积，等于所述保偏光纤环的面积乘以所述保偏光纤环的匝数，Ω对应待测角速度的大小，c为光速，α对应第所述二偏振片和所述第三偏振片的光轴与-45°的夹角，第一偏振片的偏振角为45°。Further, the relationship between the movement of the envelope and the magnitude of the angular velocity to be measured:

S corresponds to the effective area of the polarization-maintaining fiber ring, which is equal to the area of the polarization-maintaining fiber ring multiplied by the number of turns of the polarization-maintaining fiber ring, Ω corresponds to the angular velocity to be measured, c is the speed of light, and α corresponds to the first The included angle between the optical axes of the second polarizer and the third polarizer is -45°, and the polarization angle of the first polarizer is 45°.

Further, the polarized light output by the front selection module is

The first Gaussian pulse beam is

The second Gaussian pulsed beam

t ₀ corresponds to the center value of the Gaussian pulse, and τ ² corresponds to the broadening of a single Gaussian pulse;

λ₀为第一光束的中心波长。The phase difference between the first polarized light V and the second polarized light H is

λ ₀ is the center wavelength of the first light beam.

Further, the data processing module includes an avalanche photodiode APD, an analog-to-digital conversion module AD and an FPGA programmable control module, the avalanche photodiode APD is used to receive the combined beam and convert the intensity of the optical signal into an electrical signal, and the The digital conversion module AD converts the pressure signal into a digital signal, and the FPGA programmable control module is used to process the collected digital signal in real time and calculate the position of the envelope, so as to calculate the magnitude of the angular velocity to be measured.

处理，通过算法计算得到信号

的包络线随角速度变化的移动，最终得到包络线的移动随角速度变化的关系，其中Further, the FPGA programmable control module is used for real-time digital signals collected

Processing, the signal is obtained through algorithm calculation

The movement of the envelope with the angular velocity changes, and finally the relationship between the movement of the envelope and the angular velocity is obtained, where

Among them, m is an integer, t is time, t ₀ corresponds to the central value of the Gaussian pulse, τ ² corresponds to the broadening of a single Gaussian pulse, FSR1 and FSR2 correspond to the period of the vernier and the master scale in the optical Vernier effect, respectively, α is the first The included angle between the optical axis of the two polarizers 161 and -45°;

Further, the front selection module includes a laser and a first polarizer, and the laser output from the laser is adjusted by the first polarizer to obtain polarized light of a predetermined polarization state.

Further, the first light beam is a horizontal light beam, and the second light beam is a vertical light beam.

Further, the beam splitting ratio of the first beam splitter is 50:50.

Further, the first collimating lens and the second collimating lens are used to realize the connection between the free optical path and the polarization-maintaining fiber ring.

The beneficial effects brought by the technical solutions provided by the embodiments of the present invention are as follows: a fiber optic gyroscope based on cascaded quantum weak measurement of the present invention divides the measurement beam into two paths, respectively realizing the optical vernier and the optical vernier in the Vernier effect. The function of the main scale, the two beams pass through the optical modulator to generate continuous Gaussian pulse beams of different periods, and the different periods of the Gaussian pulse beam correspond to the vernier in the optical Vernier effect and the periods of the main scale FSR ₁ and FSR ₂ respectively, and the vernier can be enlarged. , and amplify the results of traditional quantum weak measurement schemes, so as to achieve high sensitivity and high precision measurement of angular velocity.

Description of drawings

Fig. 1 is the optical path diagram of a kind of optical fiber gyroscope based on cascade quantum weak measurement of the present invention;

FIG. 2 is a structural diagram of the data processing module in FIG. 1 .

In the figure: 11-front selection module, 111-laser, 112-first polarizer, 12-first beam splitter, 20-first electro-optical modulator, 13-second electro-optical modulator, 21-weak coupling module, 211 -Polarization beam splitter, 212-first collimating lens, 213-polarization maintaining fiber ring, 214-second collimating lens, 15-first plane mirror, 14-second plane mirror, 16-rear selection module, 161-th Two polarizers, 162-third polarizer, 17-third plane mirror, 18-first beam splitter, 19-data processing module.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be further described below with reference to the accompanying drawings. The following description is a preferred one among the multiple possible embodiments of the present invention, which is intended to provide a basic understanding of the present invention, but is not intended to identify key or decisive elements of the present invention or limit the scope of protection to be protected.

In the description of the present invention, it should be noted that, unless otherwise expressly specified and limited, the terms "installation" and "connection" should be understood in a broad sense, for example, it may be a fixed connection, a detachable connection, or an integral connection. It can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal communication between the two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

Referring to FIG. 1 , an embodiment of the present invention provides a fiber optic gyroscope based on cascaded quantum weak measurement, including a front selection module 11 , a first beam splitter 12 , a first electro-optic modulator 20 , and a second electro-optic modulator 13 , a weak coupling module 21 , a first plane mirror 15 , a second plane mirror 14 , a rear selection module 16 , a third plane mirror 17 , a second beam splitter 18 and a data processing module 19 .

The front selection module 11 includes a laser 111 and a first polarizer 112 , and the laser output from the laser 111 is adjusted by the first polarizer 112 to obtain polarized light of a predetermined polarization state. As described in this embodiment, the angle between the polarization direction of the first polarizer 112 and the vertical direction is π/4, and the expression of the polarized light after the laser is adjusted and selected is:

Subsequently, the polarized light is divided into two beams of light after passing through the first beam splitter 12 to achieve cascaded quantum weak measurement. beam and second beam. As shown in FIG. 1 , the first light beam is a horizontal light beam, and its optical path is used to measure the angular velocity by using the weak value amplification technology of quantum weak measurement, which corresponds to the optical travel in the Vernier effect. The second light beam is a vertical light beam, and its optical path is used to realize the traditional quantum weak measurement without weak coupling, which corresponds to the optical master ruler in the Vernier effect.

Specifically, the first beam passes through the first electro-optic modulator 20 to generate a first Gaussian pulse beam,

The first Gaussian pulse beam is

Among them, m is an integer, t is time, t ₀ is the center value of the corresponding Gaussian pulse, and τ ² is the broadening of a single Gaussian pulse.

At the same time, the second beam passes through the second electro-optic modulator 13 to generate a second Gaussian pulse beam.

The second Gaussian pulsed beam is

In addition, the period of the first Gaussian pulse beam is FSR ₁ , the period of the second Gaussian pulse beam is FSR ₂ , and FSR ₁ and FSR ₂ correspond to the periods of the vernier and the master scale in the optical Vernier effect, respectively. The magnification is equal to Eh=FSR ₂ /|FSR ₁ −FSR ₂ |.

Then the first Gaussian pulse beam enters the weak coupling module 21 to realize weak coupling of quantum weak measurement. The weak coupling module 21 includes a polarization beam splitter 211, a first collimating lens 212, a polarization maintaining fiber ring 213, The second collimating lens 214 .

First, the polarization beam splitter 211 splits the first Gaussian pulse beam to form a first polarized light V and a second polarized light H, wherein the first polarized light V is polarized along the vertical direction, and the second polarized light H is polarized along the vertical direction. polarized in the horizontal direction. Then, the first polarized light V propagates clockwise through the first collimating lens 212 , the polarization-maintaining fiber ring 213 , and the second collimating lens 214 in sequence, and returns to the polarization beam splitter. At the same time, the second polarized light H propagates counterclockwise through the second collimating lens 214, the polarization-maintaining fiber ring 213, the first collimating lens 212, and returns to the polarization beam splitter 211. A coupled light beam formed by weak coupling of the first polarized light V and the second polarized light H. The first collimating lens 212 and the second collimating lens 214 are used to realize the connection between the free optical path and the polarization-maintaining fiber ring 213 .

其中s对应所述保偏光纤环213的有效面积，等于所述保偏光纤环213的面积乘以所述保偏光纤环213的匝数，Ω对应待测角速度的大小，c为光速，λ₀为第一光束的中心波长。Since the Sagnac effect will generate a phase difference between the first polarized light H and the second polarized light V, the phase difference between the first polarized light V and the second polarized light H is

where s corresponds to the effective area of the PM fiber ring 213, which is equal to the area of the PM fiber ring 213 multiplied by the number of turns of the PM fiber ring 213, Ω corresponds to the size of the angular velocity to be measured, c is the speed of light, λ ₀ is the center wavelength of the first beam.

As shown in FIG. 1 , after weak coupling, the coupled beam passes through the first plane mirror 15 , the second polarizer 161 and the second beam splitter 18 in sequence. The coupled beam passes through the first plane mirror 15 and the second polarizer 161 to achieve conventional post-selection of quantum weak measurement. The angle between the optical axis of the second polarizer 161 and -45° is α, then at this time The post-selection state of is:

The corresponding observable operator in this embodiment is: A=|H><H|-|V><V|.

According to the definition of weak value in quantum weak measurement:

The movement of the Gaussian pulse of the outgoing light can be obtained as:

Due to the post-selection of quantum weak measurements, the number of photons is reduced by a factor of

|<Φ _f |Φ _i >| ² =sin ² α.

The optical path of the second beam realizes conventional quantum weak measurements without weak coupling. Specifically, the second beam passes through the second electro-optic modulator 13 to generate a second Gaussian pulse beam, and passes through the second plane mirror 14 , the third polarizer 162 , the third plane mirror 17 and the The second beam splitter 18 is combined with the coupled beam on the second beam splitter 18 to form a combined beam. In this embodiment, the angle between the optical axis of the third polarizer 162 and -45° is α. At this time, due to the post-selection of the quantum weak measurement, the number of photons will also decrease, and finally reach the two beams of the second beam splitter 18 . The expression for the beam of light is

程对应Vernier效应中的光学游标，

程对应Vernier效应中的光学主尺。根据Vernier光学游标在时间上的移动δt₀可以被进一步放大，放大的倍数等于Eh＝FSR₂/|FSR₁-FSR₂|。最后两个光信号

和

由第二分光镜18合成所述汇合光束最后传到所述数据处理模块19。in

The process corresponds to the optical cursor in the Vernier effect,

The distance corresponds to the optical master ruler in the Vernier effect. According to the movement δt ₀ of the Vernier optical vernier in time, it can be further magnified, and the magnification factor is equal to Eh=FSR ₂ /|FSR ₁ −FSR ₂ |. The last two optical signals

and

The combined beam is synthesized by the second beam splitter 18 and finally transmitted to the data processing module 19 .

As shown in FIG. 2 , the data processing module 19 includes an avalanche photodiode APD, an analog-to-digital conversion module AD, an FPGA programmable control module, a dynamic random access memory RAM, and a liquid crystal display LED that are electrically connected in sequence. The avalanche photodiode The APD is used to receive the combined beam and convert the intensity of the optical signal into an electrical signal. The analog-to-digital conversion module AD converts the pressure signal into a digital signal. The FPGA programmable control module is used to process and calculate the collected digital signal in real time. The position of the envelope, thereby calculating the magnitude of the angular velocity. The dynamic random access memory RAM can record the measured data, and the liquid crystal display LCD can display the measured results in real time.

处理，通过算法计算得到信号

的包络线随角速度变化的移动，最终得到包络线的移动随角速度变化的关系：The specific method for calculating the angular velocity by the FPGA programmable control module is:

Processing, the signal is obtained through algorithm calculation

The movement of the envelope with the angular velocity changes, and finally the relationship between the movement of the envelope and the angular velocity is obtained:

This embodiment also tests the measurement accuracy of the above-mentioned fiber optic gyroscope based on cascaded quantum weak measurement. As described in this embodiment, the effective area of the polarization-maintaining fiber ring 213 is S=100 m ² , and the first electro-optic modulator 20 The period of generating continuous Gaussian pulses is FSR ₁ =1.98ms, the second electro-optical modulator 13 generates Gaussian pulses with the period of continuous Gaussian pulses being FSR ₂ =2.00ms, and the minimum time resolution corresponding to the sampling rate of the analog-to-digital conversion module AD is 0.002ms, and the angle between the optical axis of the second polarizer 161 and the third polarizer 162 and -45° is α=0.001rad, then the corresponding cascading quantum weak measurement fiber optic gyroscope measures the angular velocity The resolution is 5×10 ^-13 rad/s, which can theoretically meet the requirements of studying rotational geology and measuring world time.

In this document, the related terms such as front, rear, upper and lower are defined by the positions of the components in the drawings and the positions between the components, which are only for the clarity and convenience of expressing the technical solution. It should be understood that they are relative concepts, which may be changed accordingly according to different ways of use and placement, and the use of the locative words should not limit the scope of protection claimed in this application.

The above-described embodiments and features of the embodiments herein may be combined with each other without conflict.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within the range.

Claims (10)

1. a kind of fiber optic gyroscope based on cascade quantum weak measurement, it is characterized in that: comprise front selection module, the first spectroscope, the first electro-optical modulator, the second electro-optical modulator, the weak coupling module, the first plane mirror, the first Two plane mirrors, a rear selection module, a third plane mirror, a second beam splitter and a data processing module, wherein the weak coupling module includes a polarization beam splitter, a first collimating lens, a polarization maintaining fiber ring, and a second collimating lens. The latter selection module includes a second polarizer and a third polarizer; The polarized light output by the front selection module is divided into a first beam and a second beam by the first beam splitter; The first beam passes through the first electro-optic modulator to generate a first Gaussian pulse beam, the polarization beam splitter separates the first Gaussian pulse beam to form a first polarized light V and a second polarized light H, and the first The polarized light V propagates along the first collimating lens, the polarization-maintaining fiber ring, and the second collimating lens in sequence and returns to the polarization beam splitter, and the second polarized light H sequentially travels along the The second collimating lens, the polarization-maintaining fiber ring, and the first collimating lens propagate and return to the polarization beam splitter, and the first polarized light V and the second polarized light H are weakly coupled to form The coupled light beams pass through the first plane mirror, the second polarizer and the second beam splitter in sequence; The second beam passes through the second electro-optic modulator to generate a second Gaussian pulse beam, and the second Gaussian pulse beam passes through the second plane mirror, the third polarizer, the third plane mirror and the second plane mirror in sequence. a beam splitter, which is combined with the coupled beam on the second beam splitter to form a combined beam; The data processing module collects the combined beam, calculates the movement of the envelope of the superimposed signal in the combined beam, and obtains the magnitude of the measured rotational angular velocity. 2. A fiber optic gyroscope based on cascaded quantum weak measurement as claimed in claim 1, characterized in that: the period of the first Gaussian pulsed beam is FSR ₁ , and the period of the second Gaussian pulsed beam is FSR ₂ , FSR ₁ and FSR ₂ correspond to the period of the vernier and the master scale in the optical Vernier effect, respectively, and the magnification of the Vernier effect is equal to Eh=FSR ₂ /|FSR ₁ -FSR ₂ |. 3. a kind of fiber optic gyroscope based on cascade quantum weak measurement as claimed in claim 2, is characterized in that: the relation between the movement of envelope and angular velocity to be measured size:

s corresponds to the effective area of the polarization-maintaining fiber ring, which is equal to the area of the polarization-maintaining fiber ring multiplied by the number of turns of the polarization-maintaining fiber ring, Ω corresponds to the size of the angular velocity to be measured, c is the speed of light, and α corresponds to the The included angle between the optical axes of the second polarizer and the third polarizer is -45°, and the polarization angle of the first polarizer is 45°. 4. a kind of fiber optic gyroscope based on cascade quantum weak measurement as claimed in claim 3, is characterized in that: The polarized light output by the front selection module is

The first Gaussian pulse beam is

The second Gaussian pulsed beam is

m is an integer, t is time, t ₀ corresponds to the center value of the Gaussian pulse, and τ ² corresponds to the broadening of a single Gaussian pulse; The phase difference between the first polarized light V and the second polarized light H is

λ ₀ is the center wavelength of the first light beam. 5. a kind of fiber optic gyroscope based on cascade quantum weak measurement as claimed in claim 4, is characterized in that: described data processing module comprises avalanche photodiode APD, analog-to-digital conversion module AD and FPGA programmable control module, so The avalanche photodiode APD is used to receive the combined beam and convert the intensity of the optical signal into an electrical signal, the analog-to-digital conversion module AD converts the pressure signal into a digital signal, and the FPGA programmable control module is used for real-time acquisition of digital signals. The position of the envelope is processed and calculated to calculate the magnitude of the angular velocity to be measured. 6. a kind of fiber optic gyroscope based on cascaded quantum weak measurement as claimed in claim 5, is characterized in that: described FPGA programmable control module is used for real-time digital signal collected

Processing, the signal is obtained through algorithm calculation

The movement of the envelope with the angular velocity changes, and finally the relationship between the movement of the envelope and the angular velocity is obtained,

and

for the two beams forming the combined beam, where,

7. A kind of fiber optic gyroscope based on cascaded quantum weak measurement as claimed in claim 1, it is characterized in that: described front selection module comprises laser and first polarizer, and the laser light outputted by described laser passes through the first polarizer is adjusted to obtain polarized light with a predetermined polarization state. 8 . The fiber optic gyroscope based on cascaded quantum weak measurement according to claim 1 , wherein the first light beam is a horizontal light beam, and the second light beam is a vertical light beam. 9 . 9 . The fiber optic gyroscope based on cascaded quantum weak measurement according to claim 1 , wherein the splitting ratio of the first beam splitter is 50:50. 10 . 10. A fiber optic gyroscope based on cascaded quantum weak measurement as claimed in claim 1, characterized in that: the first collimating lens and the second collimating lens are used to realize a free optical path and the polarization maintaining fiber Ring connection.

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