A multi-parameter parallel detection method based on a single whispering gallery optical microcavity

Abstract

The invention discloses a multi-parameter parallel detection method based on a single whispering gallery optical microcavity, which belongs to the field of whispering gallery microcavities; the method comprises: the two ends of an optical polarization controller are respectively connected to a laser and a whispering gallery microcavity sensor, the whispering gallery microcavity sensor is connected to multiple target parameter information disturbance devices, and a photodetector; the laser outputs an optical signal, which is adjusted to the maximum coupling efficiency by the optical polarization controller and then output to the whispering gallery microcavity sensor, and the target parameter information disturbance device is adjusted to disturb the optical signal by the target parameter, and the disturbed optical signal is output to an oscilloscope through the photodetector, which is reflected as n resonance mode offsets, and the changes of n target parameters are calculated by a signal processing method combining n offsets with an n-order sensor matrix, thereby realizing the multi-parameter parallel detection of the whispering gallery optical microcavity. The invention can realize high-precision decoupling and parallel detection of multiple parameters.

Description

Technical Field

[0001] The invention belongs to the field of whispering gallery microcavities, and in particular is a multi-parameter parallel detection method based on a single whispering gallery optical microcavity. Background Art

[0002] Whispering gallery microcavities, due to their ultra-high quality factor and small mode volume, can greatly enhance the interaction between light and matter, and have attracted more and more attention in the fields of high-sensitivity sensing. For example, ultra-high quality factor whispering gallery microcavities, by combining technologies or mechanisms such as localized surface plasmon enhancement, laser mode locking, optical spring effect, and heterodyne detection, have reached the level of single-molecule and even single-ion detection; such as reference 1: Yu D, Humar M, Meserve K, et al. Whispering-gallery-mode sensors for biological and physical sensing [J]. Nature Reviews Methods Primers, 2021, 1 (1): 1-22. However, traditional microcavity sensing mechanisms (such as wavelength shift of a single resonant mode) are difficult to achieve independent decoupling and parallel detection of multiple parameters. This is mainly because in actual complex detection environments, the shift of a single resonant wavelength of a microcavity sensor is caused by the combined effect of changes in multiple different parameters.

[0003] To solve the above problems, in recent years, relevant research groups at home and abroad have proposed a multi-parameter parallel detection scheme based on the whispering gallery microcavity array structure. For example, in 2008, Kwon et al. used two whispering gallery microring resonator array structures to realize the parallel detection of glucose solution temperature and concentration. For example, reference 2: Kwon MS, Steier W H. Microring-resonator-based sensor measuring both the concentration and temperature of a solution. Optics express, 2008, 16(13): 9372-9377. In 2018, Mallik et al. realized the parallel detection of ammonia and humidity based on the mode shift mechanism by coupling two microsphere cavity array structures to the same optical fiber cone; for example, reference 3: Mallik AK, Farrell G, Ramakrishnan M, et al. Whispering gallery mode microresonators for multi-parameter sensing applications. Optics express, 2018, 26(24): 31829-31838. In 2019, Kavungal et al. realized the parallel detection of temperature and strain based on three cascaded packaged microcolumn cavity array structures; for example, reference 4: Kavungal V, Farrell G, Wu Q, et al. Packaged inline cascaded optical micro-resonators for multi-parameter sensing. Optical FiberTechnology,2019,50:50-54.

[0004] However, most of the above works are based on the whispering gallery microcavity sensor array structure and combined with wavelength division multiplexing technology to achieve multi-parameter parallel detection. Compared with single-cavity sensing, the array structure is complex, the detection cost is high, and the operation is difficult, which hinders its further development.

[0005] The multiple resonance modes in the whispering gallery mode spectrum have different responses to different targets to be measured, which provides a solution for the parallel measurement of multiple parameters. Summary of the invention

[0006] In view of the above problems, the present invention proposes a multi-parameter parallel detection method based on a single whispering gallery optical microcavity, which utilizes the multiple resonance modes existing in the same spectrum of the whispering gallery microcavity and combines signal processing methods such as sensor matrix to achieve independent decoupling and parallel detection of multiple parameters.

[0007] The multi-parameter parallel detection method of a single whispering gallery optical microcavity is specifically described as follows:

[0008] First, a multi-parameter parallel detection device for a single whispering gallery optical microcavity was built, including a laser, a light polarization controller, a whispering gallery microcavity sensor, n target parameter information perturbation devices (n≥2, consistent with the target parameter to be measured), a photodetector, an oscilloscope, and a data acquisition card;

[0009] The whispering gallery microcavity sensor is a sensing platform formed by coupling a whispering gallery microcavity and a tapered optical fiber;

[0010] The two ends of the optical polarization controller are respectively connected to the laser and the whispering gallery microcavity sensor, the whispering gallery microcavity sensor is connected to n target parameter information disturbance devices and a photodetector, and the output of the photodetector is simultaneously connected to an oscilloscope and a data acquisition card;

[0011] Then, the laser outputs a continuous light signal, which is adjusted to the maximum coupling efficiency by the optical polarization controller and then output to the whispering gallery microcavity sensor. The n target parameter information disturbance devices are adjusted to disturb the target parameters of the light signal output to the whispering gallery microcavity sensor. The disturbed light signal is received by the photodetector and output to the oscilloscope, where it is reflected as n resonance mode shifts. The transmission spectrum is collected in real time using a data acquisition card.

[0012] By calculating the offset of n resonance modes in the collected data and combining the signal processing method of the n-order sensor matrix, the changes of n target parameters are calculated, thereby realizing the parallel detection of multi-parameters of the whispering gallery optical microcavity.

[0013] The specific calculation process is:

[0014] Firstly, the whispering gallery microcavity and the tapered optical fiber are coupled in the whispering gallery microcavity sensor, and there are multiple resonance modes in the excited spectrum. Select n resonance modes with different responses to perform n target parameter sensing.

[0015] By using the control variable method, n-1 target parameters are fixed and unchanged, and the corresponding target parameter information perturbation device is used to control a single target parameter. The change of the refractive index of the whispering gallery microcavity causes the resonance mode to shift. According to the shift of n different modes, the n mode sensitivities of a single target parameter are obtained respectively [S 11 S 21 …S n1 ] -1 ;

[0016] Repeat the above process to obtain n mode sensitivities of n target parameters in turn, forming an n×n order sensitivity matrix;

[0017]

[0018] Then, the n target parameters are changed by the n target parameter information disturbance devices, so that the n target parameters act on the sensing platform together, and the n resonance mode offsets [Δλ1Δλ2…Δλ] are obtained according to the changes in the starting positions of the n resonance modes in the spectrum. n ] -1 .

[0019] Using the n-order sensitivity matrix, combined with the n resonant mode offsets, the relationship between the n target parameter changes is calculated; the relationship is as follows:

[0020]

[0021] M n×n is a reversible matrix, and finally solves the n target parameter changes [ΔV1ΔV2…ΔV n ] -1 , thus realizing multi-parameter parallel sensing.

[0022] The advantages of the present invention are:

[0023] (1) A multi-parameter parallel detection method based on a single whispering gallery optical microcavity, which uses a single cavity for multi-mode sensing. The preparation method is simple, low cost, and easy to control. It can avoid complex cascade operations, simplify the sensor structure, and simultaneously achieve the acquisition of multi-parameter sensing information.

[0024] (2) A multi-parameter parallel detection method based on a single whispering gallery optical microcavity. A single whispering gallery microcavity has multiple resonance modes. Combined with an n-order sensor matrix signal processing method, high-precision decoupling and parallel detection of n parameters can be achieved.

[0025] (3) A multi-parameter parallel detection method based on a single whispering gallery optical microcavity. In actual detection, it is only necessary to ensure a certain mode spacing, that is, different modes will not interfere with each other when the external environment changes. Multiple resonant modes can be selected for multi-parameter parallel detection and independent decoupling. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 (a) and (b) are respectively an experimental device diagram and a principle schematic diagram of the temperature and pressure dual-parameter sensor based on a single whispering gallery microcavity of the present invention;

[0027] Figure 2 (a) and (b) are schematic diagrams of the transmission spectrum and quality factor of the whispering gallery microcavity of the present invention, respectively;

[0028] Figure 3 (a) and (b) are schematic diagrams of the temperature and pressure sensing sensitivities achieved by the whispering gallery microcavity of the present invention, respectively;

[0029] Figure 4 This is a temperature and pressure-wavelength shift data diagram based on the whispering gallery microcavity achieved by the present invention. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0031] A multi-parameter parallel detection method based on a single whispering gallery optical microcavity, the specific steps are as follows:

[0032] First, a multi-parameter parallel detection device for a single whispering gallery optical microcavity was constructed. Figure 1 As shown in (a), it includes a laser, a light polarization controller, a whispering gallery microcavity sensor, a barometer and a pressurizing device, a heating stage, a photodetector, an oscilloscope and a data acquisition card;

[0033] The laser is a tunable laser;

[0034] The optical polarization controller is connected to the laser and is used to adjust the continuous laser input by the laser to the maximum coupling efficiency to meet the excitation of the whispering gallery microcavity mode; at the same time, the other end of the optical polarization controller is connected to the whispering gallery microcavity sensor, which is placed on the heating table and connected to the barometer, the pressurizing device and the photodetector; the output of the photodetector is connected to the oscilloscope and the data acquisition card at the same time;

[0035] The whispering gallery microcavity sensor uses low-refractive index optical glue to encapsulate the whispering gallery microcavity and tapered optical fiber, and is used as a sensing platform. Specifically, a CO2 laser melts the capillary wall and increases the internal pressure of the capillary. The heated area gradually expands to form a hollow microbubble cavity. At the same time, the tapered optical fiber is coupled. By optimizing the preparation parameters and adjusting the coupling position, the microbubble cavity and the tapered optical fiber are encapsulated with low-refractive index optical glue to form a whispering gallery microcavity sensor. While ensuring a high Q value, the mode is excited to meet the application requirements of dual-parameter sensors. The transmission spectrum of the whispering gallery microcavity sensor module is shown in Figure 2. Figure 2 (a), where the quality factor of the whispering gallery microcavity can be obtained by fitting the Lorentz curve, as shown in Figure 2 (b) as shown.

[0036] By adjusting the pressurizing device and the heating platform respectively, the pressure and temperature of the optical signal output to the whispering gallery microcavity sensor are disturbed. The heating platform regulates the temperature by heating up / cooling down, and the pressurizing device controls the air pressure in the microbubble cavity by inputting / releasing air. The barometer is used to display the air pressure in the microbubble cavity.

[0037] The disturbed optical signal is received by a photodetector and output to an oscilloscope, where it is reflected as a resonant mode shift. The transmission spectrum is collected in real time using a data acquisition card.

[0038] The photodetector is used to convert photoelectric signals and output electrical signals to the oscilloscope;

[0039] The oscilloscope is used to record the transmission spectrum of the whispering gallery mode;

[0040] The data acquisition card is used for real-time collection of sensor information.

[0041] By calculating the offset of the two resonant modes in the collected data, the pressure change and temperature change are calculated, thereby realizing the parallel detection of dual parameters of the whispering gallery optical microcavity.

[0042] The specific calculation process is:

[0043] First, the whispering gallery microcavity and tapered optical fiber are coupled in the whispering gallery microcavity sensor, and there are multiple resonance modes in the excited spectrum. Two resonance modes 1 and 2 with different responses are selected for sensing. There needs to be a certain interval between the two modes, that is, to ensure that the two modes will not interfere with each other when disturbed by the external environment.

[0044] The specific method is as follows: the relative air pressure is fixed at 0 kPa, and the temperature is regulated by a heating stage, including the rise and fall of the temperature. The change of the refractive index of the microbubble cavity causes the resonance mode to shift, and two temperature sensitivities are obtained according to the shift of two different modes.

[0045] The temperature starts from 30℃ and steps up to 35℃ with 1℃. The two resonant wavelength responses are blue-shifted. The two temperature sensitivities can be obtained based on the offset of the two modes. It can be further seen that the two sensitivities show a good linear relationship, such as Figure 3 (a), where S T1 =-26.12pm / ℃,S T2 =-19.09pm / ℃;

[0046] One end of the microbubble cavity is sealed with UV glue, and the other end is connected to a three-way pipe to form a closed space inside the microbubble cavity. The three-way pipe is connected to a barometer and a pressurizing device respectively. The barometer is used to display the air pressure in the microbubble cavity, and the pressurizing device controls the air pressure in the microbubble cavity.

[0047] Then, the relative temperature (30°C) is fixed and air is injected into the hollow microbubble cavity to pressurize it starting from 0 kPa. The barometer can monitor the pressure inside the microbubble cavity. The microbubble cavity deforms and changes its refractive index due to the increase in pressure, which causes the resonance mode to shift. Both resonance wavelength responses are red-shifted. The pressure sensitivity of the two resonance modes is obtained again based on the shift; it is also an approximately linear change, such as Figure 3 (b), where S P1 =0.27pm / kPa, S P2 =0.31pm / kPa.

[0048] The temperature sensitivity and pressure sensitivity of the two resonance modes are used to form a second-order sensitivity matrix;

[0049]

[0050] S T1 is the temperature sensitivity of resonance mode 1; S T2 is the temperature sensitivity of resonance mode 2; S P1 is the pressure sensitivity of resonance mode 1; S P2 is the pressure sensitivity of resonance mode 2;

[0051] Using the second-order sensitivity matrix, combined with the two resonant mode offsets, the relationship between the temperature change and the pressure change is calculated; the relationship is as follows:

[0052]

[0053] ΔT represents the temperature change, ΔP represents the pressure change; Δλ1 is the offset of resonance mode 1 under the combined effect of pressure and temperature, and Δλ2 represents the offset of resonance mode 2 under the combined effect of pressure and temperature, wherein Δλ1 and Δλ2 are respectively obtained based on the changes in the starting positions of resonance mode 1 and resonance mode 2 in the spectrum.

[0054] If the second-order sensitivity matrix is ​​a full-rank matrix, that is, a reversible matrix, the above formula can be converted to the following form:

[0055]

[0056] Finally, ΔT and ΔP are solved to realize dual parameter sensing of temperature and pressure.

[0057] The reversibility of the second-order sensitivity matrix is ​​the premise of using the whispering gallery sensing matrix. On this basis, the whispering gallery sensing matrix and other related formulas are solved to decouple the temperature and pressure information, thereby realizing dual-parameter sensing of temperature and pressure, such as Figure 1 (b) as shown.

[0058] The premise of using the second-order sensitivity matrix is ​​that it is full rank. For example, when the temperature and pressure sensitivities of the two modes are substituted into the above formula (1), the result is 3.08, which means that there is a unique solution. The whispering gallery sensor matrix can be used to achieve the decoupling of the pressure and temperature parameters. Figure 4 As shown, the temperature and pressure change simultaneously, the temperature increases from 30°C to 35°C, the pressure increases from 0 kPa to 110 kPa, Δλ1 and Δλ2 are -101.95 pm and -60.94 pm respectively. Substituting into the above formula (3), ΔP and ΔT are obtained to be 115.01 kPa and 5.07°C respectively.

[0059] The above data are all obtained by collecting data from a data acquisition card. Therefore, the pressure change and temperature change can be calculated by calculating the offset of the two resonance modes, thereby achieving the purpose of parallel detection of multi-parameters of the whispering gallery optical microcavity.

Claims

1. A multi-parameter parallel detection method based on a single whispering gallery optical microcavity, characterized in that: Specifically include: First, a multi-parameter parallel detection device for a single whispering gallery optical microcavity is built, including a laser, a light polarization controller, a whispering gallery microcavity sensor, and n target parameter information disturbance devices; n ≥ 2, which is consistent with the target parameter to be measured; Photodetectors, oscilloscopes and data acquisition cards; The two ends of the optical polarization controller are respectively connected to a laser and a whispering gallery microcavity sensor, the whispering gallery microcavity sensor is connected to n target parameter information disturbance devices and a photoelectric detector, and the output of the photoelectric detector is simultaneously connected to an oscilloscope and a data acquisition card; Then, the laser outputs a continuous optical signal, which is adjusted to the maximum coupling efficiency by the optical polarization controller and then output to the whispering gallery microcavity sensor. The n target parameter information disturbance devices are adjusted to disturb the target parameters of the optical signal output to the whispering gallery microcavity sensor. The disturbed optical signal is received by the photodetector and output to the oscilloscope, which is reflected as n resonance mode shifts on the oscilloscope. The transmission spectrum is collected in real time using a data acquisition card. By calculating the offset of n resonance modes in the collected data and combining the signal processing method of n-order sensor matrix, n target parameters to be measured are calculated, thus realizing the parallel detection of multi-parameters of whispering gallery optical microcavity. The specific calculation process is: Firstly, the whispering gallery microcavity and the tapered optical fiber are coupled in the whispering gallery microcavity sensor, and there are multiple resonance modes in the excited spectrum. Select n resonance modes with different responses to perform n target parameter sensing. By using the control variable method, n-1 target parameters are fixed and unchanged, and the corresponding target parameter information perturbation device is used to control a single target parameter. The change in the refractive index of the whispering gallery microcavity causes the resonance mode to shift. According to the shift of n different modes, the n mode sensitivities of a single target parameter are obtained. ; Repeat the above process to obtain n mode sensitivities of n target parameters in turn, forming an n×n order sensitivity matrix; Then, n target parameters are changed through n target parameter information disturbance devices, so that n target parameters act on the sensing platform together, and n resonance mode offsets are obtained according to the changes in the starting positions of n resonance modes in the spectrum. ; Using the n-order sensitivity matrix, combined with the n resonant mode offsets, the relationship between the n target parameter changes is calculated; the relationship is as follows: is a reversible matrix, and finally solves the n target parameter changes , thus realizing multi-parameter parallel sensing.

2. A multi-parameter parallel detection method based on a single whispering gallery optical microcavity as claimed in claim 1, characterized in that: The whispering gallery microcavity sensor is a sensing platform formed by coupling a whispering gallery microcavity and a tapered optical fiber.

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