Weak measurement assisted echo wall mode microcavity time-varying signal sensing method and system

Abstract

The invention provides a weak measurement assisted echo wall mode microcavity time-varying signal sensing method and system. The method comprises the following steps: constructing a weak measurement assisted echo wall mode microcavity adaptive sensing platform for time-varying signal sensing; a time-varying signal is sensed through the echo wall mode microcavity, and a time-varying phase is introduced into the sensing platform; the light intensity of the echo wall mode microcavity sensing platform assisted by weak measurement is received through a photoelectric detector and a balance detector, the size of a current time-varying phase is calculated, and then the size of a current time-varying signal is solved; according to the size of the current time-varying phase, the bias phase, the first reference phase and the second reference phase are adjusted, so that the system works in a working interval of a preset condition; and estimating the time-varying signal in real time until the measurement is finished. On the basis of ensuring high-sensitivity sensing, the sensing interval of the echo wall mode microcavity is further expanded, and self-adaptive real-time measurement of the time-varying signal which is not limited by the sensitivity of the microcavity is realized.

Description

Technical Field

[0001] The present invention relates to the fields of quantum optics and optoelectronic signal detection, and specifically, to a method and system for sensing time-varying signals in a whispering-gallery mode microcavity assisted by weak measurement. Background Art

[0002] Whispering-gallery mode microcavity sensing has been widely applied in applications such as biochemical sensing, refractive index sensing, temperature sensing, magnetic field sensing, pressure sensing, and ultrasonic sensing due to its high sensitivity. For the measurement of time-varying signals, a single-frequency laser is used to observe the change in intensity at a fixed wavelength. However, the current sensing technology based on whispering-gallery mode microcavities detects the region near the resonance peak, and its dynamic range is limited. When applying microcavities with higher quality factors, although higher sensitivity is provided, it further restricts its dynamic range.

[0003] Weak measurement technology realizes the abnormal amplification of unknown signals by setting pre-selection states and post-selection states that are nearly orthogonal. Since the weak measurement technology was proposed, the weak value amplification technology has been widely applied in the field of quantum precision measurement, achieving precision and sensitivity that cannot be achieved by classical means, and having a good inhibitory effect on technical noise. Based on the reference phase theory of weak measurement, the weak measurement technology can be used to achieve adaptive measurement of the signal to be measured with adjustable sensitivity and dynamic range.

[0004] Patent document CN112113923A discloses a whispering-gallery mode microbubble cavity-coupled CO2 sensor and its manufacturing method. After the optical signal emitted by the amplified spontaneous emission light source is coupled into the microbubble cavity through an optical fiber taper, the optical signal couples with the PHMB solid film on the inner wall of the microbubble cavity to form a coupled optical signal. Then, the coupled optical signal is coupled into a spectrometer through the optical fiber taper. Since the PHMB solid film reacts with CO2 gas, the refractive index of the PHMB solid film changes, so that the position of the spectral absorption peak corresponding to the coupled optical signal received by the spectrometer shifts. Then, the corresponding CO2 gas concentration is matched from a pre-established relational database to obtain the concentration of the CO2 gas to be measured. However, this patent cannot completely solve the existing technical problems and cannot meet the requirements of the present invention. Summary of the Invention

[0005] Aiming at the defects in the prior art, the purpose of the present invention is to provide a method and system for sensing time-varying signals in a whispering-gallery mode microcavity.

[0006] According to the method for sensing time-varying signals in a whispering-gallery mode microcavity assisted by weak measurement provided by the present invention, it includes:

[0007] Step S1: Build an adaptive sensing platform for a whispering-gallery mode microcavity assisted by weak measurement for time-varying signal sensing;

[0008] Step S2: When a time-varying signal is sensed by the whispering gallery mode microcavity, a time-varying phase is introduced into the sensing platform;

[0009] Step S3: The light intensity of the whispering gallery mode microcavity sensing platform assisted by weak measurement is received by a photodetector and a balanced detector, and the magnitude of the current time-varying phase is calculated, and then the magnitude of the current time-varying signal is solved;

[0010] Step S4: According to the magnitude of the current time-varying phase, the bias phase, reference phase 1 and reference phase 2 are adjusted so that the system operates within the working range of the preset conditions;

[0011] Step S5: Steps S3 and S4 are repeatedly executed to perform real-time estimation of the time-varying signal until the measurement ends.

[0012] Preferably, the step S1 includes:

[0013] The light output by a single-frequency light source with a frequency of ω0 is modulated into a preselected state after passing through a preselection process |H> represents horizontally polarized light, i.e., H light; |V> represents vertically polarized light, i.e., V light;

[0014] In the weak coupling process, the preselected light is split into two orthogonally polarized lights by a polarization beam splitter: H light and V light. After the H light enters the coupling device and senses the change caused by the time-varying signal acting on the whispering gallery mode microcavity, it passes through a mirror; after the V light passes through the mirror, it passes through the bias phase used to adjust the phase difference between the two lights; the above two lights converge at the beam splitter and are then split into two lights: the first light and the second light;

[0015] The coupling device includes a tapered fiber, a prism fiber, and a lens fiber;

[0016] Among them, the magnitude of the bias phase is

[0017] After the first light passes through the polarization beam splitter, it is received by a photodetector to monitor the change in the light intensity of the light output by the coupling device due to the action of an external signal on the whispering gallery mode microcavity; the second light is split into two lights after passing through the beam splitter: the 2-1 light and the 2-2 light, and post-selection is performed respectively;

[0018] In the post-selection process, the 2-1 light is phase-adjusted by reference phase 1 and projected onto a post-selection state 1 that is close to being orthogonal to the preselected state After that, the light intensity is collected by a balanced detector, where the post-selection angle between the post-selection state 1 and the preselection is ε1; after the 2-2 light passes through the mirror, it is phase-adjusted by reference phase 2, and the magnitude of reference phase 2 is And in the subsequent selection process two, it is projected onto a subsequent selection state two that is close to being orthogonal to the previous selection state. After that, the light intensity is collected by a balanced detector, where the subsequent selection angle between the subsequent selection state two and the previous selection is ε2;

[0019] Among them, the magnitude of the reference phase one is The evolution process that occurs is The magnitude of the reference phase two is The evolution process that occurs is Where e is the natural exponential and i is the imaginary unit,

[0020] The reference phase one and the reference phase two are opposite to each other, Denote

[0021] The subsequent selection angle one and the subsequent selection angle two are opposite to each other, ε1 = -ε2, and denote ε = |ε1| = |ε2|;

[0022] The bias phase, the reference phase one, the reference phase two, the photodetector, and the balanced detector are connected to a computer for data processing and regulation.

[0023] Preferably, the step S2 includes:

[0024] When the time-varying signal acts on the whispering gallery mode microcavity, the output optical field of the coupling device changes, and the change relationship is Where, E in Is the input optical field of the coupling device; κ0 is the intrinsic loss of the whispering gallery mode microcavity; κ e Is the coupling loss of the whispering gallery mode microcavity; ω c (t) is the resonant frequency of the whispering gallery mode microcavity. The whispering gallery mode microcavity causes changes in the effective refractive index and perimeter due to the signal action, and thus causes a change in the resonant frequency, that is, ω c (t) = f(x(t)), where x is the signal to be measured and f(·) is the relationship between the resonant frequency and the signal to be measured;

[0025] The above change relationship causes changes introduced in the H light and the V light. On the one hand, it causes a change in the optical field intensity of the H light, and correspondingly causes a change in the output intensity of the first path of light Among them, I0 is the light intensity of the light source; on the other hand, a changing phase is introduced in the H light and the V light Then the changes introduced in the H light and the V light are expressed as

[0026]

[0027] Preferably, the step S3 includes:

[0028] Using the light intensity as the detection index, when the weak measurement condition is satisfied wherein The light intensity of the 2-1 channel light output is expressed as

[0029] The light intensity of the 2-2 channel light output is expressed as

[0030] Select the intensity contrast as the observation index, and perform real-time estimation on to obtain the estimated values at each moment

[0031] Furthermore, according to the response relationship of the whispering gallery mode microcavity to the signal and ω c (t) = f(x(t)), the estimation of x(t) of the signal to be measured is obtained;

[0032] When T(t) ≈ 1, the intensity contrast for the phase change caused by the signal is expressed as When the difference between the value of T(t) and 1 exceeds the preset range, the estimation of the sensing signal is realized according to the change of T(t).

[0033] Preferably, the step S4 includes: at the current moment t j , where j is the moment serial number, compare the estimated value of the current phase with the dynamic range of the current weak measurement system at the current moment. If the phase to be measured is within the dynamic range of the current weak measurement system, perform the next measurement; if it is not within the dynamic range, adjust the reference phase and the bias phase to ensure that the system always satisfies the weak measurement condition

[0034] According to the time-varying signal sensing system of the whispering gallery mode microcavity assisted by weak measurement provided by the present invention, it includes:

[0035] Module M1: Build an adaptive sensing platform of a whispering gallery mode microcavity assisted by weak measurement for time-varying signal sensing;

[0036] Module M2: Sense the time-varying signal through the whispering gallery mode microcavity and introduce a time-varying phase into the sensing platform;

[0037] Module M3: Receive the light intensity passing through the weak measurement assisted whispering gallery mode microcavity sensing platform through a photodetector and a balanced detector, calculate the magnitude of the current time-varying phase, and then solve the magnitude of the current time-varying signal;

[0038] Module M4: Adjust the bias phase, reference phase 1, and reference phase 2 according to the magnitude of the current time-varying phase, so that the system operates within the working range of the preset conditions;

[0039] Module M5: Repeatedly trigger Module M3 and Module M4 to perform real-time estimation on the time-varying signal until the measurement ends.

[0040] Preferably, the said Module M1 includes:

[0041] The light output by the single-frequency light source with frequency ω0 is modulated into a preselected state after passing through the preselection process |H> represents horizontally polarized light, i.e., H light; |V> represents vertically polarized light, i.e., V light;

[0042] In the weak coupling process, the preselected light is split into two orthogonally polarized lights by a polarization beam splitter: H light and V light. After the H light enters the coupling device to sense the changes occurring in the whispering gallery mode microcavity due to the action of the time-varying signal, it passes through a mirror; after the V light passes through the mirror, it passes through the bias phase used to adjust the phase difference between the two paths of light; the above two paths of light converge at the beam splitter and are then split into two paths of light: the first path of light and the second path of light;

[0043] The said coupling device includes a tapered fiber, a prism fiber, and a lens fiber;

[0044] Among them, the magnitude of the bias phase is

[0045] After the first path of light passes through the polarization beam splitter, it is received by a photodetector to monitor the change in the light intensity of the light output by the coupling device due to the action of an external signal on the whispering gallery mode microcavity; the second path of light is split into two paths of light after passing through the beam splitter: the 2-1 path of light and the 2-2 path of light, and post-selections are respectively performed on them;

[0046] In the post-selection process, the 2-1 path of light is phase-adjusted by reference phase 1 and projected onto a post-selection state 1 that is close to being orthogonal to the preselected state After that, the light intensity is collected by a balanced detector, where the post-selection angle between the post-selection state 1 and the preselection is ε1; after the 2-2 path of light passes through the mirror, it is phase-adjusted via reference phase 2, and the magnitude of reference phase 2 is And it is projected onto a post-selection state 2 that is close to being orthogonal to the preselected state in the second post-selection process After that, the light intensity is collected by a balanced detector, where the post-selection angle between the post-selection state 2 and the preselection is ε2;

[0047] Among them, the magnitude of reference phase 1 is The occurring evolution process is The magnitude of the reference phase two is The evolution process that occurs is where e is the natural exponent and i is the imaginary unit,

[0048] The reference phase one and the reference phase two are opposite numbers to each other, Denote

[0049] The post-selection angle one and the post-selection angle two are opposite numbers to each other, ε1 = -ε2, and denote ε = |ε1| = |ε2|;

[0050] The bias phase, the reference phase one, the reference phase two, the photodetector, and the balanced detector are connected to a computer for data processing and regulation.

[0051] Preferably, the module M2 includes:

[0052] When the time-varying signal acts on the whispering gallery mode microcavity, the output optical field of the coupling device changes, and the change relationship is where, E in is the input optical field of the coupling device; κ0 is the intrinsic loss of the whispering gallery mode microcavity; κ e is the coupling loss of the whispering gallery mode microcavity; ω c (t) is the resonant frequency of the whispering gallery mode microcavity. The whispering gallery mode microcavity causes changes in the effective refractive index and the perimeter due to the signal action, and further causes changes in the resonant frequency, that is, ω c (t) = f(x(t)), where x is the signal to be measured and f(·) is the relationship between the resonant frequency and the signal to be measured;

[0053] The above change relationship leads to changes introduced in the H light and the V light. On the one hand, it causes changes in the optical field intensity of the H light, and correspondingly causes changes in the output intensity of the first path of light where, I0 is the optical intensity of the light source; on the other hand, a changing phase is introduced in the H light and the V light Then the changes introduced in the H light and the V light are expressed as

[0054] Preferably, the module M3 includes:

[0055] Using the optical intensity as the detection index, under the condition of satisfying the weak measurement where The optical intensity output by the 2-1 path of light is expressed as

[0056] The optical intensity output by the 2-2 path of light is expressed as

[0057] Select the intensity contrast As the observation index, for Perform real-time estimation to obtain the estimated values at each moment

[0058] Furthermore, according to the response relationship of the whispering gallery mode microcavity to the signal And ω c (t) = f(x(t)) to obtain the estimation of x(t) of the signal to be measured;

[0059] When T(t) ≈ 1, the intensity contrast for the phase change caused by the signal is expressed as When the difference between the value of T(t) and 1 exceeds the preset range, the estimation of the sensing signal is realized according to the change of T(t).

[0060] Preferably, the module M4 includes: at the current moment t j , where j is the moment serial number, compare the estimated value of the current phase With the dynamic range of the current weak measurement system at the current moment. If the phase to be measured is within the dynamic range of the current weak measurement system, perform the next measurement; if it is not within the dynamic range, adjust the reference phase And the bias phase To ensure that the system always meets the weak measurement condition

[0061] Compared with the prior art, the present invention has the following beneficial effects:

[0062] (1) From the perspective of the overall technology, the structure of the present invention is simple and easy to use, making up for the deficiency of the small dynamic range in the existing time-varying parameter sensing based on the whispering gallery mode microcavity, and expanding the application range of microcavity sensing;

[0063] (2) From the perspective of the application range, the present invention has a wide range of functions and can be used for time-varying signals such as sound and vibration sensing, refractive index sensing, temperature sensing, pressure sensing, magnetic field sensing, biological sensing, chemical gas sensing, etc. that can cause microcavity deformation and the photoelastic coefficient of materials;

[0064] (3) From the perspective of technology improvement, the present invention expands the application scenarios of many measurement systems based on the theory of weak measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] By reading the detailed description of the non-limiting embodiments with reference to the following drawings, other features, objects, and advantages of the present invention will become more obvious:

[0066] Figure 1 It is a schematic diagram of the principle of the present invention.

[0067] Reference numerals:

[0068] Single-frequency light source - 1, Bias phase - 8, Mirror - 15

[0069] Pre-selection process - 2, Beam splitter - 9, Reference phase two - 16

[0070] Polarizing beam splitter - 3, Polarizing beam splitter - 10, Post-selection process two - 17

[0071] Coupling device - 4, Photoelectric detector - 11, Balanced detector - 18

[0072] Whispering gallery mode microcavity - 5, Beam splitter - 12, Computer - 19

[0073] Mirror - 6, Reference phase one - 13

[0074] Mirror - 7, Post-selection process one - 14 Detailed implementation manners

[0075] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several changes and improvements can still be made. These all belong to the protection scope of the present invention.

[0076] Embodiment 1

[0077] The present invention provides a method for sensing time-varying signals adaptively in a whispering gallery mode microcavity assisted by weak measurement, as Figure 1 shown, including: single-frequency light source 1; pre-selection process 2 (composed of a half-wave plate, a polarizer, and a quarter-wave plate); polarizing beam splitter 3; coupling device 4; whispering gallery mode microcavity 5; mirror 6; mirror 7; bias phase 8; beam splitter 9; polarizing beam splitter 10; photoelectric detector 11; beam splitter 12; reference phase one 13; post-selection process one 14 (composed of a half-wave plate, a polarizer, and a quarter-wave plate); mirror 15; reference phase two 16; post-selection process two 17 (composed of a half-wave plate, a polarizer, and a quarter-wave plate); balanced detector 18; computer 19.

[0078] The method includes the following steps:

[0079] Step S1: Build a weak measurement-assisted adaptive sensing platform for a whispering gallery mode microcavity for time-varying signal sensing;

[0080] Step S2: The whispering gallery mode microcavity 5 senses the time-varying signal and introduces a time-varying phase into the sensing platform;

[0081] Step S3: Receive the light intensity of the whispering gallery mode microcavity sensing platform assisted by weak measurement through the photodetector 12 and the balanced detector 18, calculate the magnitude of the current time-varying phase, and then solve the magnitude of the current time-varying signal.

[0082] Step S4: Adjust the bias phase 9, the reference phase one 14, and the reference phase two 17 according to the magnitude of the current time-varying phase, so that the system operates in a better working range.

[0083] Step S5: Repeat Step S3 and Step S4 to perform real-time estimation of the time-varying signal until the measurement ends.

[0084] The implementation process of the above-mentioned Step S1 is as follows:

[0085] The light output by the single-frequency light source 1 with a frequency of ω0 is modulated into a preselected state after passing through the preselection process 2 |H> represents horizontally polarized light, that is, H light, and |V> represents vertically polarized light, that is, V light;

[0086] In the weak coupling process, the preselected light is split into two orthogonally polarized lights after passing through the polarization beam splitter 3: H light and V light. After the H light enters the coupling device 4 to sense the changes occurring in the whispering gallery mode microcavity 5 due to the action of the time-varying signal, it passes through the mirror 6; after the V light passes through the mirror 7, it passes through the bias phase 8 used to adjust the phase difference between the two beams of light; the above two beams of light converge at the beam splitter 10 and are then split into two beams of light: the first beam of light and the second beam of light.

[0087] Optionally, the coupling device 4 can be a tapered fiber, a prism fiber, a lens fiber, etc.

[0088] Among them, the magnitude of the bias phase is

[0089] After the first beam of light passes through the polarization beam splitter 10, it is received by the photodetector 11 to monitor the change in the light intensity of the light output by the coupling device due to the action of the external signal on the whispering gallery mode microcavity. The second beam of light is split into two beams of light after passing through the beam splitter 12: the 2-1 beam of light and the 2-2 beam of light, and post-selection is performed respectively.

[0090] In the post-selection process, the 2-1 beam of light is phase-adjusted through the reference phase one 13 and projected onto the post-selection state one that is close to being orthogonal to the preselected state After that, the light intensity is collected by the balanced detector 18. Among them, the post-selection angle between the post-selection state one and the preselection is ε1. After the 2-2 beam of light passes through the mirror, it is phase-adjusted through the reference phase two 16, and the magnitude of the reference phase two is And it is projected onto the post-selection state two that is close to being orthogonal to the preselected state in the post-selection process two 17 After that, the light intensity is collected by the balanced detector 18. The post-selection angle between the post-selection state two and the pre-selection is ε2.

[0091] Among them, the magnitude of the reference phase one is The evolution process that occurs is The magnitude of the reference phase two is The evolution process that occurs is where e is the natural exponent and i is the imaginary unit,

[0092] The reference phase one and the reference phase two are opposite to each other, Denote

[0093] The post-selection angle one and the post-selection angle two are opposite to each other, ε1 = -ε2, and denote ε = |ε1| = |ε2|.

[0094] The bias phase, the reference phase one, the reference phase two, the photodetector, and the balanced detector two are connected to the computer 19 for data processing and regulation.

[0095] In the step S2, when the time-varying signal acts on the whispering gallery mode microcavity, the output optical field of the coupling device will change, and the change relationship is where, E in is the input optical field of the coupling device; κ0 is the intrinsic loss of the whispering gallery mode microcavity; κ e is the coupling loss of the whispering gallery mode microcavity; ω c (t) is the resonant frequency of the whispering gallery mode microcavity. The whispering gallery mode microcavity will cause changes in the effective refractive index and the perimeter due to the signal action, and further cause changes in the resonant frequency, that is, ω c (t) = f(x(t)), where x is the signal to be measured and f(·) is the relationship between the resonant frequency and the signal to be measured.

[0096] The above change relationship will cause changes introduced in the H light and the V light. That is, on the one hand, it causes changes in the optical field intensity of the H light, and correspondingly, it will cause changes in the output intensity of the first path of light where, I0 is the light intensity of the light source. On the other hand, it also introduces a changing phase in the H light and the V light Then the changes introduced in the H light and the V light can be expressed as

[0097] In the step S3, using the light intensity as the detection index, when the weak measurement condition is satisfied, where The light intensity output by the 2-1 path of light can be expressed as The optical intensity of the 2-2 optical output can be expressed as

[0098] Select the intensity contrast as the observation index, for perform real-time estimation to obtain the estimated values at each moment

[0099] Furthermore, according to the response relationship of the whispering gallery mode microcavity to the signal, and ω c (t) = f(x(t)), the estimation of x(t) of the signal to be measured can be obtained.

[0100] When T(t) ≈ 1, the intensity contrast of the phase change caused by the signal for the method can be written as, It can also achieve high-sensitivity estimation. When the value of T(t) is quite different from 1, that is, when ImAw(t) cannot guarantee amplification, the estimation of the sensing signal can be achieved according to the change of T(t).

[0101] In the step S4, at the current moment t j , where j is the moment serial number, compare the estimated value of the current phase with the dynamic range of the current weak measurement system at the current moment. If the phase to be measured is within the dynamic range of the current weak measurement system, perform the next measurement; if it is not within the dynamic range, adjust the reference phase and the bias phase to ensure that the system always meets the weak measurement condition

[0102] Embodiment 2

[0103] The present invention also provides a whispering gallery mode microcavity adaptive time-varying signal sensing system assisted by weak measurement. The whispering gallery mode microcavity adaptive time-varying signal sensing system assisted by weak measurement can be realized by executing the process steps of the whispering gallery mode microcavity adaptive time-varying signal sensing method assisted by weak measurement. That is, those skilled in the art can understand the whispering gallery mode microcavity adaptive time-varying signal sensing method as the preferred embodiment of the whispering gallery mode microcavity adaptive time-varying signal sensing system.

[0104] The present invention provides a whispering gallery mode microcavity adaptive time-varying signal sensing system assisted by weak measurement, as Figure 1As shown in the figure, it includes: a single-frequency light source 1; a pre-selection process 2 (composed of a half-wave plate, a polarizer, and a quarter-wave plate); a polarization beam splitter 3; a coupling device 4; a whispering gallery mode microcavity 5; a mirror 6; a mirror 7; a bias phase 8; a beam splitter 9; a polarization beam splitter 10; a photodetector 11; a beam splitter 12; a reference phase one 13; a post-selection process one 14 (composed of a half-wave plate, a polarizer, and a quarter-wave plate); a mirror 15; a reference phase two 16; a post-selection process two 17 (composed of a half-wave plate, a polarizer, and a quarter-wave plate); a balanced detector 18; a computer 19.

[0105] The system includes the following modules:

[0106] Module M1: Build a whispering gallery mode microcavity adaptive sensing platform assisted by weak measurement for time-varying signal sensing;

[0107] Module M2: The whispering gallery mode microcavity 5 senses the time-varying signal and introduces a time-varying phase into the sensing platform;

[0108] Module M3: Receive the light intensity of the whispering gallery mode microcavity sensing platform assisted by weak measurement through the photodetector 11 and the balanced detector 18, calculate the magnitude of the current time-varying phase, and then solve the magnitude of the current time-varying signal.

[0109] Module M4: Adjust the bias phase 8, the reference phase one 13, and the reference phase two 16 according to the magnitude of the current time-varying phase to make the system work in a better working range.

[0110] Module M5: Repeatedly trigger Module M3 and Module M4 to perform real-time estimation of the time-varying signal until the measurement is completed.

[0111] The said Module M1 is that the light output by the single-frequency light source 1 with a frequency of ω0 is modulated into a pre-selection state after passing through the pre-selection process 2 |H> represents horizontally polarized light, that is, H light, and |V> represents vertically polarized light, that is, V light;

[0112] In the weak coupling process, the pre-selected light is split into two orthogonally polarized lights: H light and V light after passing through the polarization beam splitter 3. After the H light enters the coupling device 4 and senses the changes occurring in the whispering gallery mode microcavity 5 due to the time-varying signal, it passes through the mirror 6; after the V light passes through the mirror 7, it passes through the bias phase 8 used to adjust the phase difference between the two paths of light; the above two paths of light converge at the beam splitter 9 and are then split into two paths of light: the first path of light and the second path of light.

[0113] Optionally, the said coupling device 4 can be a tapered fiber, a prism fiber, a lens fiber, etc.

[0114] Among them, the magnitude of the bias phase is

[0115] After the first path of light passes through the polarization beam splitter 10, it is received by the photodetector 11 to monitor the change in the light intensity of the output light of the coupling device caused by the external signal acting on the whispering gallery mode microcavity. The second path of light is split into two paths of light after passing through the beam splitter 12: the 2-1 path of light and the 2-2 path of light, and post-selection is performed separately.

[0116] During the post-selection process, the 2-1 path of light is phase-adjusted by the reference phase one 13 and projected onto the post-selection state one that is close to being orthogonal to the pre-selection state during the post-selection process one 14 After that, the light intensity is collected by the balanced detector 18. The post-selection angle between the post-selection state one and the pre-selection is ε1. After the 2-2 path of light passes through the mirror, it is phase-adjusted by the reference phase two 16, and the magnitude of the reference phase two is and projected onto the post-selection state two that is close to being orthogonal to the pre-selection state during the post-selection process two 17 After that, the light intensity is collected by the balanced detector 18. The post-selection angle between the post-selection state two and the pre-selection is ε2.

[0117] Among them, the magnitude of the reference phase one is The evolution process that occurs is The magnitude of the reference phase two is The evolution process that occurs is where e is the natural exponential and i is the imaginary unit,

[0118] The reference phase one and the reference phase two are opposite to each other, Denote

[0119] The post-selection angle one and the post-selection angle two are opposite to each other, ε1 = -ε2, and denote ε = |ε1| = |ε2|.

[0120] The bias phase, the reference phase one, the reference phase two, the photodetector, and the balanced detector two are connected to the computer 19 for data processing and regulation.

[0121] Preferably, in the module M2, when the time-varying signal acts on the whispering gallery mode microcavity, the output optical field of the coupling device will change, and the change relationship is Among them, E in is the input optical field of the coupling device; κ0 is the intrinsic loss of the whispering gallery mode microcavity; κ e is the coupling loss of the whispering gallery mode microcavity; ω c (t) is the resonant frequency of the whispering gallery mode microcavity. The whispering gallery mode microcavity will cause changes in the effective refractive index and perimeter due to the signal action, and further cause changes in the resonant frequency, that is, ω cI(t) = f(x(t)), where x is the signal to be measured and f(·) is the relationship between the resonant frequency and the signal to be measured.

[0122] The above variation relationship will cause changes introduced in the H light and V light. Specifically, on the one hand, it causes a change in the optical field intensity of the H light. Correspondingly, it will cause a change in the output intensity of the first path of light. Among them, I0 is the optical intensity of the light source. On the other hand, it also introduces a changed phase in the H light and V light. Then the changes introduced in the H light and V light can be expressed as

[0123] In the module M3, the optical intensity is used as the detection index. When the weak measurement condition is satisfied At this time, where The optical intensity output by the 2-1 path of light can be expressed as

[0124] The optical intensity output by the 2-2 path of light can be expressed as

[0125] Select the intensity contrast As the observation index, for Perform real-time estimation to obtain the estimated values at each moment

[0126] Furthermore, according to the response relationship of the whispering gallery mode microcavity to the signal, And ω c I(t) = f(x(t)) can be used to obtain the estimation of x(t) of the signal to be measured.

[0127] When T(t) ≈ 1, the intensity contrast for the phase change caused by the signal of the method can be written as It can also achieve high-sensitivity estimation. When the value of T(t) is quite different from 1, that is, when ImAw(t) cannot guarantee amplification, the estimation of the sensing signal can be realized according to the change of T(t).

[0128] In the module M4, at the current moment t j , where j is the moment serial number, compare the estimated value of the current phase With the dynamic range of the current weak measurement system at the current moment. If the phase to be measured is within the dynamic range of the current weak measurement system, perform the next measurement; if it is not within the dynamic range, adjust the reference phase And the bias phase To ensure that the system always satisfies the weak measurement condition

[0129] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0130] Those skilled in the art know that in addition to implementing the systems, devices and their respective modules provided by the present invention in the form of pure computer-readable program codes, the method steps can be logically programmed to enable the systems, devices and their respective modules provided by the present invention to be implemented in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, embedded microcontrollers, etc. to achieve the same program. Therefore, the systems, devices and their respective modules provided by the present invention can be regarded as a kind of hardware component, and the modules included therein for implementing various programs can also be regarded as the structures within the hardware component; the modules for implementing various functions can also be regarded as either software programs for implementing the methods or the structures within the hardware component.

[0131] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A method for sensing time-varying signals in a whispering gallery mode microcavity assisted by weak measurement, characterized in that Including: Step S1: Build a whispering gallery mode microcavity adaptive sensing platform assisted by weak measurement for time-varying signal sensing; Step S2: Sense the time-varying signal through the whispering gallery mode microcavity and introduce a time-varying phase in the sensing platform; Step S3: Receive the light intensity of the whispering gallery mode microcavity sensing platform assisted by weak measurement through a photodetector and a balanced detector, calculate the magnitude of the current time-varying phase, and then solve the magnitude of the current time-varying signal; Step S4: Adjust the bias phase, reference phase one, and reference phase two according to the magnitude of the current time-varying phase to make the system operate within the working range of the preset conditions; Step S5: Repeat Steps S3 and S4 to perform real-time estimation of the time-varying signal until the measurement ends.

2. The time-varying signal sensing method for whispering gallery mode microcavity assisted by weak measurement according to claim 1, characterized in that, The said Step S1 includes: The light output from a single-frequency light source with a frequency of ω0 is modulated into a preselected state after a preselection process. |H> represents horizontally polarized light, i.e., H light; |V> represents vertically polarized light, i.e., V light. During the weak coupling process, the pre-selected light is split into two orthogonally polarized lights by a polarization beam splitter: H light and V light. After the H light enters the coupling device to sense the changes occurring in the whispering gallery mode microcavity due to the action of the time-varying signal, it passes through a mirror; after the V light passes through the mirror, it passes through the bias phase used to adjust the phase difference between the two lights; the above two lights converge at the beam splitter and are then split into two lights: the first light and the second light; The said coupling device includes a tapered fiber, a prism fiber, and a lens fiber; Among them, the magnitude of the offset phase is After the first light passes through the polarization beam splitter, it is received by the photodetector to monitor the change in the light intensity of the light output by the coupling device due to the action of the external signal on the whispering gallery mode microcavity; the second light is split into two lights after passing through the beam splitter: the 2-1 light and the 2-2 light, and post-selection is performed respectively; In the post-selection process, the 2-1 path light is phase-modulated through the reference phase one and projected onto the post-selection state one that is nearly orthogonal to the pre-selection state in the first post-selection process. After that, the light intensity is collected by the balanced detector, where the post-selection angle between the post-selection state one and the pre-selection is ε1; after the 2-2 path light passes through the mirror, it is phase-modulated through the reference phase two, and the magnitude of the reference phase two is and projected onto the post-selection state two that is nearly orthogonal to the pre-selection state in the second post-selection process. After that, the light intensity is collected by the balanced detector, where the post-selection angle between the post-selection state two and the pre-selection is ε2; Among them, the magnitude of reference phase one is The evolution process that occurs is The magnitude of reference phase two is The evolution process that occurs is where e is the natural exponent and i is the imaginary unit, The reference phase one and the reference phase two are opposite to each other. Denote The post-selection angle one and the post-selection angle two are opposite to each other, ε1 = -ε2, and let ε = |ε1| = |ε2|; The said bias phase, reference phase one, reference phase two, photodetector, and balanced detector are connected to a computer for data processing and regulation.

3. The time-varying signal sensing method for a whispering gallery mode microcavity assisted by weak measurement according to claim 2, wherein The said Step S2 includes: When a time-varying signal acts on a whispering gallery mode microcavity, the output optical field of the coupling device changes, and the variation relationship is where E in is the input optical field of the coupling device; κ0 is the intrinsic loss of the whispering gallery mode microcavity; κ e is the coupling loss of the whispering gallery mode microcavity; ω c (t) is the resonant frequency of the whispering gallery mode microcavity. The whispering gallery mode microcavity causes changes in the effective refractive index and perimeter due to the signal action, and further causes changes in the resonant frequency, that is, ω c (t) = f(x(t)), where x is the signal to be measured, and f(·) is the relationship between the resonant frequency and the signal to be measured; The above change relationship leads to changes introduced in the H light and the V light. On the one hand, it causes the optical field intensity of the H light to change, and correspondingly causes the output intensity of the first path of light to change. Among them, I0 is the optical intensity of the light source; on the other hand, a changing phase is introduced in the H light and the V light. Then the changes introduced in the H light and the V light are expressed as 4. The time-varying signal sensing method for whispering gallery mode microcavity assisted by weak measurement according to claim 3, wherein, The said Step S3 includes: Using the light intensity as the detection index, when the weak measurement conditions are satisfied where the light intensity of the 2-1 optical output is expressed as The light intensities of the 2-2 optical outputs are expressed as Select the intensity contrast as the observation index, and perform real-time estimation on to obtain the estimated values at each moment Furthermore, according to the response relationship of the whispering gallery mode microcavity to the signal and ω c (t) = f(x(t)), an estimate of x(t) of the signal to be measured is obtained; When T(t) ≈ 1, the intensity contrast for the phase change caused by the signal is expressed as When the difference between the value of T(t) and 1 exceeds a preset range, the estimation of the sensing signal is achieved according to the change of T(t).

5. The method for sensing time-varying signals in a whispering gallery mode microcavity assisted by weak measurement according to claim 4, wherein The said step S4 includes: at the current moment t j , where j is the moment serial number, compare the estimated value of the current phase with the dynamic range of the current weak measurement system at the current moment. If the phase to be measured is within the dynamic range of the current weak measurement system, conduct the next measurement; if it is not within the dynamic range, adjust the reference phase and the bias phase to ensure that the system always meets the weak measurement condition 6. A whispering gallery mode microcavity time-varying signal sensing system assisted by weak measurement, characterized in that Including: Module M1: Build a whispering gallery mode microcavity adaptive sensing platform assisted by weak measurement for time-varying signal sensing; Module M2: Sense the time-varying signal through the whispering gallery mode microcavity and introduce a time-varying phase in the sensing platform; Module M3: Receive the light intensity of the whispering gallery mode microcavity sensing platform assisted by weak measurement through a photodetector and a balanced detector, calculate the magnitude of the current time-varying phase, and then solve the magnitude of the current time-varying signal; Module M4: Adjust the bias phase, reference phase one, and reference phase two according to the magnitude of the current time-varying phase to make the system operate within the working range of the preset conditions; Module M5: Repeat triggering Module M3 and Module M4 to perform real-time estimation of the time-varying signal until the measurement ends.

7. The weak measurement-assisted whispering gallery mode microcavity time-varying signal sensing system according to claim 6, wherein The said Module M1 includes: The light output by a single-frequency light source with a frequency of ω0 is modulated into a preselected state after a preselection process |H> represents horizontally polarized light, i.e., H light; |V> represents vertically polarized light, i.e., V light; During the weak coupling process, the pre-selected light is split into two orthogonally polarized lights by a polarization beam splitter: H light and V light. After the H light enters the coupling device to sense the changes occurring in the whispering gallery mode microcavity due to the action of the time-varying signal, it passes through a mirror; after the V light passes through the mirror, it passes through the bias phase used to adjust the phase difference between the two lights; the above two lights converge at the beam splitter and are then split into two lights: the first light and the second light; The coupling device includes a tapered optical fiber, a prism optical fiber, and a lens optical fiber; Among them, the magnitude of the offset phase is After the first path of light passes through the polarization beam splitter, it is received by the photodetector to monitor the change in the light intensity of the output light of the coupling device caused by the external signal acting on the whispering gallery mode microcavity. The second path of light is split into two paths of light after passing through the beam splitter: the 2-1 path of light and the 2-2 path of light, and post-selection is performed respectively; In the post-selection process, the 2-1 path light is phase-adjusted through the reference phase one and projected onto the post-selection state one that is nearly orthogonal to the pre-selection state in the post-selection process one. After that, the light intensity is collected by the balanced detector, where the post-selection angle between the post-selection state one and the pre-selection is ε1; after the 2-2 path light passes through the mirror, it is phase-adjusted through the reference phase two, and the magnitude of the reference phase two is and projected onto the post-selection state two that is nearly orthogonal to the pre-selection state in the post-selection process two. After that, the light intensity is collected by the balanced detector, where the post-selection angle between the post-selection state two and the pre-selection is ε2; Among them, the magnitude of reference phase one is The evolution process that occurs is The magnitude of reference phase two is The evolution process that occurs is where e is the natural exponential and i is the imaginary unit, The reference phase one and the reference phase two are opposite to each other. Denote The post-selection angle one and the post-selection angle two are opposite to each other, ε1 = -ε2, and ε = |ε1| = |ε2| is denoted; The bias phase, the reference phase one, the reference phase two, the photodetector, and the balanced detector are connected to a computer for data processing and regulation.

8. The weak measurement-assisted whispering gallery mode microcavity time-varying signal sensing system according to claim 7, characterized in that The module M2 includes: When a time-varying signal acts on the whispering-gallery mode microcavity, the output optical field of the coupling device changes, and the variation relationship is where E in is the input optical field of the coupling device; κ0 is the intrinsic loss of the whispering-gallery mode microcavity; κ e is the coupling loss of the whispering-gallery mode microcavity; ω c (t) is the resonant frequency of the whispering-gallery mode microcavity. The effective refractive index and perimeter of the whispering-gallery mode microcavity change due to the signal action, and thus the resonant frequency changes, that is, ω c (t) = f(x(t)), where x is the signal to be measured, and f(·) is the relationship between the resonant frequency and the signal to be measured; The above change relationship leads to changes introduced in the H light and V light. On the one hand, it causes the optical field intensity of the H light to change, and correspondingly causes the output intensity of the first path of light to change. Among them, I0 is the light intensity of the light source; on the other hand, a changing phase is introduced in the H light and V light. Then the changes introduced in the H light and V light are expressed as 9. The weak measurement-assisted whispering gallery mode microcavity time-varying signal sensing system according to claim 8, wherein The module M3 includes: Using the light intensity as the detection index, when the weak measurement condition is satisfied where the light intensity of the 2-1 optical output is expressed as The light intensity of the 2-2 channel optical output is expressed as Select the intensity contrast as the observation index, and perform real-time estimation on to obtain the estimated values at each moment Furthermore, according to the response relationship of the whispering gallery mode microcavity to the signal and ω c (t) = f(x(t)), an estimate of x(t) of the signal to be measured is obtained; When T(t) ≈ 1, the intensity contrast for the phase change caused by the signal is expressed as When the difference between the value of T(t) and 1 exceeds the preset range, the sensing signal is estimated according to the change of T(t).

10. The time-varying signal sensing system of a whispering gallery mode microcavity assisted by weak measurement according to claim 9, characterized in that, The module M4 includes: at the current moment t j , where j is the moment sequence number, and compares the estimated value of the current phase with the dynamic range of the current weak measurement system at the current moment. If the phase to be measured is within the dynamic range of the current weak measurement system, the next measurement is performed; if it is not within the dynamic range, the reference phase and the bias phase are adjusted to ensure that the system always meets the weak measurement condition

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