Enhanced phase sensing platform based on high-order scattering zero point

Abstract

The invention discloses an enhanced phase sensing platform based on a high-order scattering zero point, which comprises a high-order scattering zero point control unit and a sensing unit, and is characterized in that the phase sensing platform does not need to adjust sensor parameters, the high-order scattering zero point is realized by regulating and controlling the high-order scattering zero point control unit, and the change of a transmission spectrum is measured; therefore, the phase change at the sensor is measured. The sensing unit is a plug-in external sensor separated from the high-order scattering zero point control unit, and the sensor can respond to disturbance caused by a sensing target or an external field to change an optical phase; the high-order scattering zero point control unit is a non-Hermite multimode non-reciprocal optical system formed by two mutually coupled echo wall mode optical microcavities and a waveguide, and in the coupled echo wall mode optical microcavity group, bidirectional coupling channels caused by scattering of an isotropic scatterer are respectively introduced. And a non-reciprocal unidirectional coupling channel caused by single-end mirror reflection. The method is suitable for any conventional sensor.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical sensing and quantum sensing, in particular to a high-order scattering zero-point enhanced phase sensing platform. Background Art

[0002] Optical sensors use optical phase to transmit valuable information and play an important role in many fields such as gravitational wave detection, biomedical imaging, and structural health monitoring. Due to the sensitivity limitations of traditional optical sensing technology, the increasing accuracy requirements of optical phase sensing are difficult to meet. Therefore, it is of great significance to seek new technologies to improve sensitivity.

[0003] Existing methods to improve phase sensing include the exceptional point (EP) enhanced phase sensing platform. (Mao W, Fu Z, Li Y, at el. Exceptional–point–enhanced phase sensing[J / OL]. Science Advances, 2024, 10(14): eadl5037. DOI: 10.1126 / sciadv.adl5037 .)The EP enhanced phase sensing platform applies EP enhanced sensing technology to traditional optical sensors. The platform is equipped with a plug-in external sensor separated from the outlier control unit. The improvement in sensitivity is due to the square root behavior of the eigenvalue, and the valley of the transmission spectrum has a corresponding correlation with the real part of the eigenvalue, so that the small disturbances to the system will be converted and amplified into spectral features. By separating the sensing and control functions, the applicability of outlier enhancement technology to various conventional sensors is expanded. A general platform has been built for the application of outlier enhancement technology to different phase-dependent structures, which is expected to achieve ultra-high sensitivity sensing in various applications. However, the EP implementation generates basic noise accompanied by the collapse of eigenvalues, which will reduce the sensing performance, and this method constructs a second-order EP system, and there is also the possibility of improved sensitivity. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned existing EP enhanced phase sensing platform and provide a high-stability, high-performance high-order scattering zero-point enhanced phase sensing platform.

[0005] The technical solution to achieve the purpose of the present invention is: a phase sensing platform based on a high-order scattering zero point enhancement, including a high-order scattering zero point control unit and a sensing unit, the phase sensing platform does not need to adjust the sensor parameters, and realizes the high-order scattering zero point and measures the change of the transmission spectrum by regulating the high-order scattering zero point control unit, thereby realizing the phase change at the sensor; the sensing unit is an inserted external sensor separated from the high-order scattering zero point control unit, and the sensor can change the optical phase in response to the disturbance caused by the sensing target or the external field; the high-order scattering zero point control unit is a non-Hermitian multimode non-reciprocal optical system composed of two mutually coupled whispering gallery mode optical microcavities and waveguides, and in the coupled whispering gallery mode optical microcavity group, a bidirectional coupling channel caused by scattering of an isotropic scatterer and a non-reciprocal unidirectional coupling channel caused by single-ended mirror reflection are respectively introduced.

[0006] Furthermore, the two whispering gallery mode optical microcavities are respectively recorded as microcavity a and microcavity b; the high-order scattering zero point control unit also includes a bus waveguide, an interconnecting waveguide and a phase conversion device, the microcavity a is coupled with the bus waveguide, the detection light is input from the first port of the bus waveguide, and the transmission spectrum is measured by the second port of the bus waveguide; the microcavity b is coupled with the interconnecting waveguide, the left side of the interconnecting waveguide is connected to the phase conversion device and the sensing unit in sequence, and the right side is used as a non-reflection end; the phase conversion device is used to adjust the phase of the coupling coefficient to meet the conditional parameters for realizing the high-order scattering zero point.

[0007] Furthermore, each of the whispering gallery mode optical microcavity supports two transmission modes, namely CW and CCW. The eigenfrequencies of the four modes are degenerate but the eigenvectors are mutually orthogonal.

[0008] Furthermore, a bidirectional coupling channel caused by scattering is introduced into the microcavity a, so that the CW mode and the CCW mode in the microcavity a are bidirectionally coupled;

[0009] A non-reciprocal unidirectional coupling channel caused by single-ended mirror reflection is introduced into the microcavity b, so that the CCW mode in the microcavity b returns to the microcavity b through the reflection of the interconnected waveguide and the sensor unit, while the CW mode passes through the non-reflective end on the right side of the interconnected waveguide, introducing unidirectional coupling from the CCW mode to the CW mode.

[0010] Furthermore, the effective Hamiltonian of the high-order scattering zero-point control unit Represented as a 4×4 matrix:

[0011]

[0012] In the formula, is the resonant frequency of microcavity a and microcavity b, are the intrinsic losses of microcavity a and microcavity b respectively, is the gain of microcavity a, is the coupling coefficient between microcavity a and bus waveguide, and between microcavity b and interconnect waveguide; is the bidirectional coupling coefficient between CW and CCW modes caused by scattering in microcavity a, is the unidirectional coupling coefficient of the CCW mode in microcavity b reflected back to microcavity b through the interconnected waveguide and the sensing unit without the action of the optical phase signal, is the bidirectional coupling coefficient between microcavity a and microcavity b, where i represents the imaginary number.

[0013] Furthermore, the high-order scattering zero point control unit realizes a fourth-order quasi-singular point, which is specifically realized by constructing a fourth-order scattering zero point of the transmission spectrum.

[0014] Furthermore, the transmission spectrum is :

[0015]

[0016] In the formula, is the eigenvalue of the effective Hamiltonian H, , is a fourth-order polynomial related to frequency w, for The solution, The solution of is also the eigenvalue of the effective Hamiltonian H, .

[0017] Furthermore, the fourth-order scattering zero point of the transmission spectrum is constructed by controlling the coupling coefficient and the gain-loss ratio of each part of the high-order scattering zero point control unit to make the transmission spectrum The roots of the fourth-order polynomial are all degenerate.

[0018] Furthermore, the phase sensing platform further comprises:

[0019] The noise feedback unit is used to feed back the phase shift to the phase conversion device on the interconnected waveguide according to the influence of environmental noise on the signal-to-noise ratio under different disturbances and the sensitivity under different disturbances before the phase sensing platform measures, so as to adjust the working point of the high-order scattering zero point control unit, i.e., the non-Hermitian multimode non-reciprocal optical system, to a suitable position; the suitable position means that the signal-to-noise ratio is within a preset acceptance range and the sensitivity is greater than a preset standard threshold.

[0020] Furthermore, the noise feedback unit specifically implements:

[0021] Introduce sensitivity to obtain the frequency splitting, sensitivity and phase disturbance response curves of the valley point of the phase sensing platform under ideal conditions;

[0022] Obtaining a response curve of a signal-to-noise ratio and a disturbance under noise in a measurement environment; the signal-to-noise ratio is defined as a ratio of a valley point frequency splitting under an ideal condition to a valley point frequency splitting fluctuation caused by noise;

[0023] Based on the above response curve, the position where the signal-to-noise ratio is within the preset acceptance range and the sensitivity is greater than the preset standard threshold is selected as the working point of the non-Hermitian multimode non-reciprocal optical system. The phase perturbation at this position is recorded as , and feed it back as a phase shift to the phase conversion device on the interconnected waveguide, so that it adds a phase shift that changes the working point on the basis of the phase shift of the scattering zero point.

[0024] Compared with the prior art, the present invention has the following significant advantages:

[0025] (1) The present invention applies high-order scattering zero-point enhancement technology to the design of a sensing platform with a separate control unit and a sensing unit, ensuring its applicability to a wide range of conventional sensors.

[0026] (2) For the first time, we proposed to introduce a coupling channel in two coupled whispering gallery mode microcavities through scattering by isotropic scatterers and single-ended mirror reflection, thus breaking the symmetry of the coupled cavity group and realizing a four-mode non-Hermitian non-reciprocal system.

[0027] (3) Realize higher-order scattering zeros in a non-reciprocal multimode non-Hermitian system by adjusting system parameters, where the non-reciprocal design can enhance the robustness of the system (for example, the parameters given in the implementation example are The coupling phase does not have to be π / 5. With other phases, the spectrum of this system has the same response characteristics to disturbances. As long as the parameter relationship can meet the requirements of the given algebraic expressions, such as , (other parameters to be determined are reasonable), there will be no collapse of eigenvalues ​​in the implementation of high-order scattering zero points, the eigenvalues ​​of the Hamiltonian can have negative imaginary parts, and the evanescent field in the solution will decay quickly and be more stable.

[0028] (4) The non-reciprocal high-order scattering zeros are used to enhance phase sensing. The fourth root behavior of the zeros of the numerator polynomial of the transmission spectrum expression leads to an enhancement in the sensitivity of phase measurement, which mainly determines the valley characteristics of the transmission spectrum. This makes the small disturbances to the system appear as amplified spectral changes. The valley frequency splitting of the transmission spectrum is proportional to the fourth root of the optical phase change under small disturbances, thereby achieving enhanced measurement of small signals that induce phase changes.

[0029] (5) The response of the sensing platform to phase changes is increased from proportional to the second root to the fourth root, which has higher sensitivity when measuring small disturbances.

[0030] (6) The platform also has a noise feedback system that monitors the noise in the environment and then feeds back the phase shift to move the operating point to the appropriate position, effectively achieving a balance between sensitivity and anti-interference ability.

[0031] The present invention is further described in detail below in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the overall structure of the present invention based on a high-order scattering zero-point enhanced phase sensing platform.

[0033] Figure 2 (a) is a graph showing the transmission spectrum of the present invention as the optical phase changes due to the sensor unit. Figure 2 (b) is a curve of the valley frequency splitting of the transmission spectrum in the presence of noise according to the present invention as the optical phase changes caused by the sensing unit, and the embedded figure is a comparison diagram of the quarter-power function curve and the frequency splitting curve after taking the double logarithm.

[0034] Figure 3 (a) is a curve of the sensitivity of the present invention as the optical phase changes caused by the sensing unit and a negative cubic power function curve, and the embedded figure is a comparison diagram of the frequency splitting curve, the negative cubic power function curve and the negative one-half power function curve after taking double logarithms. Figure 3 (b) is a graph showing the signal-to-noise ratio in the presence of noise according to the present invention as the optical phase changes caused by the sensing unit.

[0035] Reference numerals: 1 bus waveguide, 2 interconnect waveguide, 3 whispering gallery mode optical microcavity a, 4 whispering gallery mode optical microcavity b, 5 phase conversion device, 6 sensing unit, 7 noise feedback unit. 1, 2, 3, 4, 5 together constitute a high-order scattering zero-point control unit. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0037] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0038] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0039] In one embodiment, in combination Figure 1 , provides a phase sensing platform based on high-order scattering zero point enhancement, including a high-order scattering zero point control unit and a sensing unit. The phase sensing platform does not need to adjust the sensor parameters. By adjusting the high-order scattering zero point control unit to achieve the high-order scattering zero point and measure the change of the transmission spectrum, the phase change at the sensor is measured (the change of the transmission spectrum is specifically manifested as the change of the valley point with the change of the disturbance, such as Figure 2 As shown in (a) in the figure); the sensing unit is an inserted external sensor separated from the high-order scattering zero-point control unit, and the sensor can change the optical phase in response to the disturbance caused by the sensing target or the external field; the high-order scattering zero-point control unit is a non-Hermitian multimode non-reciprocal optical system composed of two mutually coupled whispering gallery mode optical microcavities and waveguides, and in the coupled whispering gallery mode optical microcavity group, a bidirectional coupling channel caused by scattering of isotropic scatterers and a non-reciprocal unidirectional coupling channel caused by single-ended mirror reflection are introduced respectively.

[0040] Furthermore, in one of the embodiments, the two whispering gallery mode optical microcavities are respectively recorded as microcavity a and microcavity b; the high-order scattering zero point control unit also includes a bus waveguide, an interconnecting waveguide and a phase conversion device, the microcavity a is coupled with the bus waveguide, the detection light is input from the first port of the bus waveguide, and the transmission spectrum is measured by the second port of the bus waveguide; the microcavity b is coupled with the interconnecting waveguide, the left side of the interconnecting waveguide is connected to the phase conversion device and the sensing unit in sequence, and the right side is used as a reflection-free end; the phase conversion device is used to adjust the phase of the coupling coefficient to meet the conditional parameters for realizing the high-order scattering zero point.

[0041] Here, preferably, the phase conversion device is a phase shifter.

[0042] Furthermore, in one of the embodiments, each of the whispering gallery mode optical microcavity supports two transmission modes, namely CW and CCW, and the eigenfrequencies of the four modes are degenerate but the eigenvectors are mutually orthogonal.

[0043] Furthermore, in one of the embodiments, a bidirectional coupling channel caused by scattering is introduced into the microcavity a, so that the CW mode and the CCW mode in the microcavity a are bidirectionally coupled;

[0044] A non-reciprocal unidirectional coupling channel caused by single-ended mirror reflection is introduced into the microcavity b, so that the CCW mode in the microcavity b returns to the microcavity b through the reflection of the interconnected waveguide and the sensor unit, while the CW mode passes through the non-reflective end on the right side of the interconnected waveguide, introducing unidirectional coupling from the CCW mode to the CW mode.

[0045] Further, in one embodiment, without considering the input and noise, using , , , The effective Hamiltonian of the control unit of the high-order scattering zero point is Represented as a 4×4 matrix:

[0046]

[0047] In the formula, is the resonant frequency of microcavity a and microcavity b, are the intrinsic losses of microcavity a and microcavity b respectively, is the gain of microcavity a, is the coupling coefficient between microcavity a and bus waveguide, and between microcavity b and interconnect waveguide; is the bidirectional coupling coefficient between CW and CCW modes caused by scattering in microcavity a, is the unidirectional coupling coefficient of the CCW mode in microcavity b reflected back to microcavity b through the interconnected waveguide and the sensing unit without the action of the optical phase signal, is the bidirectional coupling coefficient between microcavity a and microcavity b, where i represents the imaginary number.

[0048] Furthermore, in one of the embodiments, the high-order scattering zero point control unit realizes a fourth-order quasi-singular point, specifically by constructing a fourth-order scattering zero point of the transmission spectrum.

[0049] The transmission spectrum is :

[0050]

[0051] In the formula, is the eigenvalue of the effective Hamiltonian H, , is a fourth-order polynomial related to frequency w, for The solution, The solution of is also the eigenvalue of the effective Hamiltonian H, .

[0052] Specifically here:

[0053] use , , , To represent the amplitudes of the four modes, the system only has the probe light coupled with the CW mode in cavity a from the first port input, and its amplitude is expressed as The output is measured at the second port and its amplitude is expressed as express.

[0054] The equation of motion is:

[0055]

[0056] in:

[0057]

[0058] To determine the cavity mode amplitude , we can perform a Fourier transform on the equations of motion and then use Cramer's law.

[0059]

[0060] is the eigenvalue of the Hamiltonian H, is a fourth-order polynomial, for The solution.

[0061] Then the expression of the transmission spectrum is:

[0062]

[0063] Preferably, in some embodiments, the fourth-order scattering zero point of the transmission spectrum is constructed by controlling the coupling coefficient and the gain-loss ratio of each part of the high-order scattering zero point control unit to make the transmission spectrum The roots of the fourth-order polynomial are all degenerate.

[0064] Here, the coupling coefficient and gain-loss ratio between the various parts of the control unit can be set according to the normalized parameter relationship. The system normalized parameter relationship satisfies and of The coefficient of the term should be The coefficients of the same-order terms of correspond one to one, is an auxiliary real number that obtains the fourth-order scattering zeros.

[0065] Exemplarily, a set of parameters is set according to the normalized parameter relationship as follows: , , .

[0066] Furthermore, in one embodiment, the phase sensing platform further includes:

[0067] The noise feedback unit is used to feed back the phase shift to the phase conversion device on the interconnected waveguide according to the influence of environmental noise on the signal-to-noise ratio under different disturbances and the sensitivity under different disturbances before the phase sensing platform measures, so as to adjust the working point of the high-order scattering zero point control unit, i.e., the non-Hermitian multimode non-reciprocal optical system, to a suitable position; the suitable position means that the signal-to-noise ratio is within a preset acceptance range and the sensitivity is greater than a preset standard threshold.

[0068] Here, preferably, the preset standard threshold is the maximum sensitivity value. .

[0069] Preferably, in some embodiments, the noise feedback unit specifically implements:

[0070] Introduce sensitivity to obtain the frequency splitting, sensitivity and phase disturbance response curves of the valley point of the phase sensing platform under ideal conditions;

[0071] Obtaining a response curve of a signal-to-noise ratio and a disturbance under noise in a measurement environment; the signal-to-noise ratio is defined as a ratio of a valley point frequency splitting under an ideal condition to a valley point frequency splitting fluctuation caused by noise;

[0072] Based on the above response curve, the position where the signal-to-noise ratio is within the preset acceptance range and the sensitivity is greater than the preset standard threshold is selected as the working point of the non-Hermitian multimode non-reciprocal optical system. The phase perturbation at this position is recorded as , and feed it back to the phase shift device on the interconnect waveguide as a phase shift, so that it adds a phase shift to change the working point on the basis of the phase shift of the scattering zero point (by satisfying the phase shift of the high-order scattering zero point in the phase shifter). On the basis of increase , to achieve the offset of the working point).

[0073] Here, the phase brought by the sensing unit Acting on the unidirectional coupling process, changing the coupling coefficient for , As a perturbation input to the control unit, after the coupling process, it is converted into quantifiable spectral characteristics. Specifically, the transmission spectrum is When the center frequency is 0, the transmittance is 0. When it is not 0, the transmittance at the center frequency is 1, and there will be a valley at each end. The absolute value of the difference between the frequencies of the two valleys is defined as the valley frequency splitting. Increase and increase, in Directly proportional.

[0074] For example, to simulate a measurement, we need to consider how the system interacts with its environment and how noise affects the output signal. We introduce input noise to the system, including an incoherent input vector of a radiated noise source. , the incoherent input vector of the dissipative noise source .

[0075] The noise function contained in the noise vector satisfies the following conditions and obeys the noise function of Gaussian distribution It has the following properties:

[0076]

[0077]

[0078] in, are the noise functions associated with the radiation and amplification / dissipation channels, respectively, with autocorrelation, i=1,2.

[0079] Based on standard coupled mode theory, the evolution of an open, noisy system with 4 resonances and 4 ports can be written as:

[0080]

[0081]

[0082] in, is the input matrix, is the incoherent input vector of the radiated noise source input from the waveguide, is the incoherent input vector of the dissipative noise source. N is a 4 × 4 diagonal matrix that describes how the dissipative noise couples with the mode. For the radiated noise source, the noise input of the port with only unidirectional output can be suppressed by the optical isolator, so we consider that the second port of the BWG and the non-reflective end of the IWG have no radiated noise. and amplification / dissipation channels The correlated noise has autocorrelation and is assumed to be low frequency thermal noise.

[0083] Cramer's rule is used to Fourier transform the noisy motion equation. According to the standard input-output relationship, , ,in , The noise ,noise and the dissipative noise input vector The influence of the CW mode amplitude in cavity a. Therefore, the noisy transmission spectrum can be written as:

[0084]

[0085] because , thus approximating to ,in is the transmission spectrum under theoretical conditions.

[0086] In the presence of noise, the relationship between the frequency splitting of the valley point and the phase disturbance of the sensor unit is as follows: Figure 2 As shown in (b) in the figure. Under the interference of Gaussian noise, the curve shows some fluctuations, but it does not prevent us from identifying its trend and line shape. This is due to the fact that the realization of high-order scattering zeros does not bring about noise amplification with the collapse of eigenvalues. The eigenvalues ​​of the Hamiltonian can have negative imaginary parts, and the evanescent field in the solution will decay quickly and become more stable. It can be found that for smaller phase perturbations, the frequency splitting of the valley point is similar to It shows an almost perfect fourth root relationship and exhibits fourth-order EP-like splitting behavior, that is, ∆W ∝ However, as the disturbance increases, the fourth root correlation diverges and the slope of the curve in the logarithmic coordinate axis increases, such as Figure 2 In addition, the minimum detection limit is defined as the frequency fluctuation caused by the maximum noise, and the minimum detection limit is measured to be 0.12-0.18 MHz, that is, at least 0.001 rad (the noise is randomly generated in each measurement, so it is a range. In the absence of noise, a perturbation of 0.001 rad corresponds to a frequency split of 0.2 MHz).

[0087] In order to further quantify the efficiency of the sensing platform of the present invention, the sensitivity χ = ∂ / ∂ ,like Figure 3 (a) in the figure shows that near the scattering zero point For a sensor device with N-order EP, the frequency splitting response of its spectrum is proportional to the Nth root of the disturbance, that is, its sensitivity should show a disturbance near EP. The divergence of the power further proves the EP-like characteristics of the fourth-order higher-order scattering zero point. In fact, near a specific state, the sensitivity of the fourth-order scattering zero point sensing system is significantly higher than that of the second-order EP sensor.

[0088] Although it is possible from Figure 2As can be seen in (b), noise does not cause huge fluctuations in the response curve. However, the nonlinearity of sensitivity to disturbances causes noise to interfere with the measurement of different disturbances to different degrees.

[0089] In order to more comprehensively demonstrate the performance of the sensing scheme proposed in the present invention, the influence of noise on the measurement is further revealed. The signal-to-noise ratio is defined as the ratio of the ideal valley frequency splitting to the valley frequency splitting fluctuation caused by noise. The signal-to-noise ratio changes with disturbance as shown in Figure 3 As shown in (b), when the initial disturbance is small, the system sensitivity is very large, and the noise has a greater impact on the measurement, which is reflected in the low signal-to-noise ratio. As the disturbance increases, although the sensitivity decreases, the impact of noise on the measurement decreases, which is reflected in the signal-to-noise ratio gradually increasing and stabilizing.

[0090] From the above, it can be seen that the balance between sensitivity and anti-interference ability can be achieved by changing the initial working point. The specific implementation method is to adjust the phase shifter so that it adds a phase shift of changing the working point on the basis of the phase shift of the scattering zero point.

[0091] In summary, the phase sensing platform based on high-order scattering zero-point enhancement proposed in the present invention does not need to adjust the sensor parameters. It can accurately measure the phase change at the sensor only by adjusting the control unit to realize the high-order scattering zero point and measuring the change in the transmission spectrum. Here, the enhancement of the phase measurement sensitivity originates from the zero-point fourth root behavior of the numerator polynomial of the transmission spectrum expression, which is the main factor determining the valley characteristics of the transmission spectrum. In addition, small disturbances to the system will appear as amplified spectral changes, and the valley frequency splitting of the transmission spectrum is proportional to the fourth root of the optical phase change under smaller disturbances, thereby achieving enhanced measurement of small signals that induce phase changes. Therefore, the present invention can expand the applicability of high-order scattering zero-point enhancement technology to conventional optical sensors. In addition, the platform of the present invention also has a noise feedback unit, which moves the working point to a signal-to-noise ratio within an acceptable range and a sensitivity at least greater than the maximum value by feedback of the phase offset after monitoring the noise in the environment. to achieve a balance between sensitivity and anti-interference ability.

[0092] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-order scattering zero-point enhanced phase sensing platform, characterized in that: The invention comprises a high-order scattering zero point control unit and a sensing unit. The phase sensing platform does not need to adjust the sensor parameters. The high-order scattering zero point is realized by regulating the high-order scattering zero point control unit and measuring the change of the transmission spectrum, thereby realizing the phase change at the measuring sensor. The sensing unit is an inserted external sensor separated from the high-order scattering zero point control unit, and the sensor can change the optical phase in response to the disturbance caused by the sensing target or the external field. The high-order scattering zero point control unit is a non-Hermitian multimode non-reciprocal optical system composed of two mutually coupled whispering gallery mode optical microcavities and a waveguide, and in the coupled whispering gallery mode optical microcavity group, a bidirectional coupling channel caused by scattering of an isotropic scatterer and a non-reciprocal unidirectional coupling channel caused by single-ended mirror reflection are respectively introduced.

2. The high-order scattering zero-point enhanced phase sensing platform according to claim 1 is characterized in that: The two whispering gallery mode optical microcavities are respectively recorded as microcavity a and microcavity b; the high-order scattering zero point control unit also includes a bus waveguide, an interconnecting waveguide and a phase conversion device, the microcavity a is coupled with the bus waveguide, the detection light is input from port 1 of the bus waveguide, and the transmission spectrum is measured from port 2 of the bus waveguide; the microcavity b is coupled with the interconnecting waveguide, the left side of the interconnecting waveguide is connected to the phase conversion device and the sensing unit in sequence, and the right side is used as a non-reflection end; the phase conversion device is used to adjust the phase of the coupling coefficient to meet the conditional parameters for realizing the high-order scattering zero point.

3. The high-order scattering zero-point enhanced phase sensing platform according to claim 2 is characterized in that: Each of the whispering gallery mode optical microcavity supports two transmission modes, CW and CCW. The eigenfrequencies of the four modes are degenerate but the eigenvectors are mutually orthogonal.

4. The high-order scattering zero-point enhanced phase sensing platform according to claim 3 is characterized in that: Introducing a bidirectional coupling channel caused by scattering in the microcavity a, so that the CW mode and the CCW mode in the microcavity a are bidirectionally coupled; A non-reciprocal unidirectional coupling channel caused by single-ended mirror reflection is introduced into the microcavity b, so that the CCW mode in the microcavity b returns to the microcavity b through the reflection of the interconnected waveguide and the sensing unit, while the CW mode passes through the non-reflective end on the right side of the interconnected waveguide, introducing unidirectional coupling from the CCW mode to the CW mode.

5. The high-order scattering zero-point enhanced phase sensing platform according to claim 4 is characterized in that: The effective Hamiltonian of the high-order scattering zero control unit Represented as a 4×4 matrix: ； In the formula, is the resonant frequency of microcavity a and microcavity b, are the intrinsic losses of microcavity a and microcavity b respectively, is the gain of microcavity a, is the coupling coefficient between microcavity a and bus waveguide, and between microcavity b and interconnect waveguide; is the bidirectional coupling coefficient between CW and CCW modes caused by scattering in microcavity a, is the unidirectional coupling coefficient of the CCW mode in microcavity b reflected back to microcavity b through the interconnected waveguide and the sensing unit without the action of the optical phase signal, is the bidirectional coupling coefficient between microcavity a and microcavity b, where i represents the imaginary number.

6. The high-order scattering zero-point enhanced phase sensing platform according to claim 1 is characterized in that: The high-order scattering zero point control unit realizes a fourth-order quasi-singular point, which is specifically realized by constructing a fourth-order scattering zero point of a transmission spectrum.

7. The high-order scattering zero-point enhanced phase sensing platform according to claim 5 or 6, characterized in that: The transmission spectrum is : ； In the formula, is the eigenvalue of the effective Hamiltonian H, , is a fourth-order polynomial related to frequency w, for The solution, The solution of is also the eigenvalue of the effective Hamiltonian H, .

8. The high-order scattering zero-point enhanced phase sensing platform according to claim 7 is characterized in that: The fourth-order scattering zero point of the transmission spectrum is constructed by controlling the coupling coefficient and gain-loss ratio of each part of the high-order scattering zero point control unit to make the transmission spectrum The roots of the fourth-order polynomial are all degenerate.

9. The high-order scattering zero-point enhanced phase sensing platform according to claim 2 is characterized in that: The phase sensing platform further comprises: The noise feedback unit is used to feed back the phase shift to the phase conversion device on the interconnected waveguide according to the influence of environmental noise on the signal-to-noise ratio under different disturbances and the sensitivity under different disturbances before the phase sensing platform measures, so as to adjust the working point of the high-order scattering zero point control unit, i.e., the non-Hermitian multimode non-reciprocal optical system, to a suitable position; the suitable position means that the signal-to-noise ratio is within a preset acceptance range and the sensitivity is greater than a preset standard threshold.

10. The high-order scattering zero-point enhanced phase sensing platform according to claim 9, characterized in that: The noise feedback unit is specifically implemented as follows: Introduce sensitivity to obtain the frequency splitting, sensitivity and phase disturbance response curves of the valley point of the phase sensing platform under ideal conditions; Obtaining a response curve of a signal-to-noise ratio and a disturbance under noise in a measurement environment; the signal-to-noise ratio is defined as a ratio of a valley point frequency splitting under an ideal condition to a valley point frequency splitting fluctuation caused by noise; Based on the above response curve, the position where the signal-to-noise ratio is within the preset acceptance range and the sensitivity is greater than the preset standard threshold is selected as the working point of the non-Hermitian multimode non-reciprocal optical system. The phase perturbation at this position is recorded as , and feed it back as a phase shift to the phase conversion device on the interconnected waveguide, so that it adds a phase shift that changes the working point on the basis of the phase shift of the scattering zero point.

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