Silicon quantum dot enhanced raman optical microcavity laser sensing method and system

Abstract

The application discloses a kind of silicon quantum dot enhanced Raman's optical microcavity laser sensing method and system.The method comprises: reference light and excitation light are coupled to optical microcavity, and the Raman laser of optical microcavity is excited by excitation light;First sharp peak signal and second sharp peak signal are obtained by the interference of two split Raman lasers with reference light respectively, and third sharp peak signal is obtained by the mutual interference between two split Raman lasers;The line width and intensity of third sharp peak signal are observed by adjusting the intensity difference of first sharp peak signal and second sharp peak signal, the line width and intensity of third sharp peak signal are optimized, and the intensity difference of optimized first sharp peak signal and second sharp peak signal is determined;According to the third sharp peak signal after optimization, determine the information of the substance to be measured.The problems of traditional sensing system in signal-to-noise ratio, detection accuracy and detection limit are solved by the embodiment of the application, the detection accuracy is optimized, the signal-to-noise ratio is improved, and the detection limit is reduced.

Description

Technical Field

[0001] This invention relates to the field of sensing technology, and in particular to an optical microcavity laser sensing method and system for silicon quantum dot enhanced Raman spectroscopy. Background Technology

[0002] Optical microcavities possess ultra-high quality factors and low mode volumes, resulting in significant local enhancement of light and thus a marked increase in the interaction between light and matter, making them a highly promising platform for high-sensitivity sensing and detection.

[0003] Traditional microcavity sensing utilizes the optical whispering-gallery mode within the microcavity. When the analyte enters the potential field range of the optical mode, it alters the frequency, linewidth, and intensity of the optical mode. By using this change in the optical mode as the sensing signal, sensors with ultra-low detection limits are achieved. In traditional silicon quantum dot-enhanced Raman spectroscopy (SMP) optical microcavity laser sensing systems, a tunable laser generates a beam that is coupled into the optical mode of the microcavity via a waveguide. Utilizing the Raman gain inherent in the microcavity material, Raman lasing is generated when the laser power exceeds the Raman lasing threshold. Since the surface of the optical microcavity cannot be perfectly smooth, the Raman lasing, due to scattering, forms light fields propagating in clockwise and counterclockwise directions. The interference of two Raman lasing beams propagating in opposite directions creates two split Raman lasing beams, and this interference forms a Raman beat frequency. The correlation sensing system determines the analyte information by monitoring the beat frequency signal.

[0004] In the process of realizing this invention, the inventors discovered that the sensing systems in related technologies have certain experimental noise, which affects the signal-to-noise ratio, detection accuracy, and detection limit of the sensing systems. Summary of the Invention

[0005] This invention provides a silicon quantum dot-enhanced Raman optical microcavity laser sensing method and system, which can improve the signal-to-noise ratio of the sensing system, optimize detection accuracy, and reduce the detection limit.

[0006] According to one aspect of the present invention, a silicon quantum dot enhanced Raman optical microcavity laser sensing method is provided, comprising:

[0007] A reference light and an excitation light are coupled to an optical microcavity, and the excitation light excites a Raman laser in the optical microcavity. The Raman laser comprises two split Raman lasers formed by the interference of two Raman laser beams propagating in clockwise and counterclockwise directions.

[0008] The first and second peak signals are obtained by interfering with the reference light by the two split Raman lasers respectively, and the third peak signal is obtained by interfering with each other by the two split Raman lasers.

[0009] The linewidth and intensity of the third peak signal are optimized by adjusting the intensity difference between the first and second peak signals, and the information of the object to be measured is determined based on the optimized third peak signal.

[0010] According to another aspect of the present invention, a silicon quantum dot enhanced Raman optical microcavity laser sensing system is provided, the device comprising:

[0011] The first optical beam splitter is used to split the laser generated by the tunable laser into two laser beams. One of the laser beams is output to the acousto-optic modulator, and the other laser beam is output as the excitation light to the adjustment module.

[0012] The acousto-optic modulator is used to shift the frequency of one of the laser beams to obtain a reference beam, and output the reference beam to the adjustment module;

[0013] The adjustment module is used to adjust the optical power and polarization state of the reference light and the excitation light, and output the adjusted reference light and excitation light to the optical combiner;

[0014] The optical beam combiner is used to input the adjusted reference light and the excitation light into the same waveguide. When the wavelength of the excitation light matches the optical mode of the optical microcavity, the adjusted reference light and the excitation light are coupled to the optical microcavity through the waveguide.

[0015] The optical microcavity is used to excite a Raman laser in the optical microcavity according to the adjusted excitation light when the power of the excitation light is greater than the Raman laser threshold, and to couple the Raman laser into the waveguide, so that the transmission light in the waveguide includes a reference light, an excitation light and a Raman laser, wherein the Raman laser includes two split Raman lasers formed by the interference of two Raman laser beams propagating in the clockwise and counterclockwise directions;

[0016] The waveguide is used to interfere with the reference light through the two split Raman lasers to obtain a first peak signal and a second peak signal, and to obtain a third peak signal through the mutual interference between the two split Raman lasers.

[0017] A spectrum analyzer is used to monitor interference signals in transmitted light and adjust the intensity difference between the first and second peak signals based on the monitoring results to optimize the linewidth and intensity of the third peak signal.

[0018] A data acquisition device is used to acquire an optimized third peak signal, determine the sensing signal of the object under test based on the spectral information of the third peak signal, and determine the information of the object under test based on the sensing signal.

[0019] The technical solution of this invention monitors the linewidth and intensity of two spike signals generated by the interference between the reference light and two split Raman lasers. By adjusting the excitation power, polarization state, and coupling state, the linewidth and intensity of the spike signals generated by the interference between the two split Raman lasers are optimized. Based on this, the intensity difference of the optimized two spike signals generated by the interference between the reference light and the two split Raman lasers is determined. This solves the problems of signal-to-noise ratio, detection accuracy, and detection limit in traditional sensing systems, optimizes detection accuracy, improves signal-to-noise ratio, and reduces detection limit.

[0020] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A flowchart illustrating a silicon quantum dot-enhanced Raman optical microcavity laser sensing method provided in this embodiment of the invention;

[0023] Figure 2 A flowchart of another silicon quantum dot enhanced Raman optical microcavity laser sensing method provided in an embodiment of the present invention;

[0024] Figure 3 A schematic diagram of the structure of a silicon quantum dot enhanced Raman optical microcavity laser sensing system provided in an embodiment of the present invention;

[0025] Figure 4 This is a schematic diagram of another silicon quantum dot enhanced Raman optical microcavity laser sensing system provided in an embodiment of the present invention. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0028] First, the technical terms that may appear in this invention will be explained.

[0029] Sensitivity: The ratio of the sensing signal to the information of the analyte. For example, when the sensing signal is the frequency shift of an optical mode and the information of the analyte is the refractive index, the sensitivity is the frequency shift of the optical mode caused by each unit change in refractive index, expressed in nanometers per unit of refractive index (nm / RIU); when the information of the analyte is a single nanoparticle, the sensitivity is the frequency shift of the optical mode caused by each particle, expressed in nanometers per particle (nm / particle).

[0030] Detection accuracy: The smallest sensing signal that a sensor can detect. For example, when the sensing signal is a frequency shift of an optical mode, the detection accuracy is the smallest wavelength shift that can be detected.

[0031] Detection limit: The detection limit is the smallest analyte property that can be detected. It is the ratio of detection accuracy to sensitivity. Therefore, when designing a sensor, the smaller the detection accuracy, the higher the sensitivity, and the smaller the detection limit, the smaller the analyte property that can be detected.

[0032] Figure 1 This is a flowchart illustrating a silicon quantum dot-enhanced Raman optical microcavity laser sensing method according to an embodiment of the present invention. This embodiment is applicable to Raman laser detection based on optical microcavities, and the method can be executed by a silicon quantum dot-enhanced Raman optical microcavity laser sensing system. Figure 1 As shown, the method includes:

[0033] S110. Couple the reference light and the excitation light to the optical microcavity, and excite the optical microcavity with the excitation light to generate Raman laser.

[0034] The Raman laser consists of two split Raman laser beams formed by the interference of two Raman laser beams propagating in clockwise and counterclockwise directions.

[0035] By utilizing the Raman gain inherent in the microcavity material, Raman lasers are generated within the optical microcavity when the excitation light power exceeds the Raman laser threshold. Since the surface of the optical microcavity cannot achieve absolute smoothness, the Raman laser beams within the microcavity are scattered, forming light fields propagating in both clockwise and counterclockwise directions. The interference of these two Raman laser beams propagating in opposite directions forms two split Raman laser beams, and the interference of these two split Raman laser beams generates the Raman beat frequency.

[0036] In this invention, the reference light and the excitation light are two laser beams with different frequencies. For example, a tunable laser can generate a laser of a set wavelength, and then the laser output from the tunable laser is split into two laser beams by a first optical beam splitter. One of the laser beams is frequency-shifted by an acousto-optic modulator and serves as the reference light, while the other beam retains its original frequency and serves as the excitation light.

[0037] The reference light and excitation light are input into the same waveguide via an optical beam combiner. When the wavelength of the excitation light matches the optical mode of the microcavity, the reference light and excitation light in the waveguide are coupled into the optical microcavity. The optical microcavity is placed on a three-dimensional nanoscale translation stage, and the coupling state between the two can be adjusted by adjusting the relative position of the microcavity and the waveguide.

[0038] An oscilloscope can be used to monitor whether the wavelength of the excitation light matches the optical mode of the optical microcavity. When the wavelength of the excitation light matches the optical mode, laser energy is coupled into the optical microcavity, and a sharp trough appears in the spectrum displayed on the oscilloscope. As the excitation light power increases, the linewidth of this trough increases due to thermal effects. When the power of the excitation light exceeds the Raman laser threshold, Raman laser light is excited in the optical microcavity. The optical microcavity then couples the Raman laser light into the waveguide, so that the transmitted light in the waveguide includes the reference light, the excitation light, and the Raman laser light.

[0039] It should be noted that the laser linewidth is limited by the excitation light power, widening as the excitation light power decreases, thus exhibiting a high degree of dependence on the excitation light power. Before coupling the reference light and excitation light into the optical microcavity, the optical power and polarization state of the reference light can be adjusted using a first adjustable attenuator and a first polarization controller, and the optical power and polarization state of the excitation light can be adjusted using a second adjustable attenuator and a second polarization controller. Since exciting the Raman laser mode of the optical microcavity requires a relatively high excitation light power, the attenuation coefficient can be adjusted to ensure that the power of the attenuated excitation light is greater than that of the attenuated reference light. Then, the adjusted reference light and excitation light are input into the same waveguide through an optical beam combiner, and the adjusted reference light and excitation light are coupled into the optical microcavity through the waveguide.

[0040] Optionally, a power amplifier can be added to the silicon quantum dot enhanced Raman optical microcavity laser sensing system. First, the excitation light is amplified by the power amplifier, and then the optical power and polarization state of the excitation light are adjusted by a second adjustable attenuator and a second polarization controller.

[0041] Existing microcavity Raman lasers utilize the Raman gain of the microcavity material itself. However, limited by the material's inherent gain, high excitation power is required to stimulate the microcavity's Raman gain and obtain Raman laser light. The optical microcavity in this invention is a composite structure consisting of a silicon dioxide microcavity surface with a thin layer of silicon quantum dots of a predetermined thickness. This predetermined thickness can be on the nanometer scale. This composite microcavity structure can improve the Raman gain of the microcavity and lower the Raman laser threshold.

[0042] By enhancing Raman gain with silicon quantum dots, Raman lasers from optical microcavities can be excited with lower excitation power. For example, by adding a silicon quantum dot layer of a predetermined thickness to the surface of the silicon dioxide microcavity, the Raman laser threshold is lowered, thereby enabling the excitation of Raman lasers from the optical microcavity with lower excitation power.

[0043] Furthermore, since the refractive index of silicon quantum dot thin layers is greater than that of silicon dioxide, the sensitivity of the sensing device can be improved and the detection limit optimized by adjusting the thickness of the quantum dot thin layers and the light field distribution of the microcavity excitation light mode and Raman laser mode.

[0044] S120. The first peak signal and the second peak signal are obtained by interfering with the reference light by the two split Raman lasers respectively. The third peak signal is obtained by interfering with each other by the two split Raman lasers.

[0045] Two split Raman lasers in the waveguide interfere with the reference light, forming a first and a second spike signal. The mutual interference between these two split Raman lasers forms a third spike signal, which is the sensing signal. Due to experimental noise, the signal-to-noise ratio of the third spike signal is low, failing to effectively reduce the detection limit of the sensing device.

[0046] In this embodiment of the invention, the waveguide and photodetector are connected via optical fiber, and the transmitted light in the waveguide is converted into an electrical signal by the photodetector. A spectrum analyzer monitors the spike signals in the transmitted light. When the transmitted light contains only reference light, excitation light, and Raman laser, the spectrum of the spectrum analyzer contains three spike signals: two split Raman lasers interfere with the reference light respectively, forming a first spike signal and a second spike signal; and the mutual interference between these two split Raman lasers forms a third spike signal.

[0047] When the excitation light excites wavelengths generated by other nonlinear phenomena, interference occurs between other coherent lights, between other coherent lights and Raman lasers, and between other coherent lights and reference light. This results in other peak signals appearing in the spectrum besides the three peak signals mentioned above. These other peak signals not only broaden the spectrum of the sensing device and introduce experimental noise, but also waste the excitation light power and reduce the intensity of the sensing signal because some of the excitation light is used to excite other nonlinear lights.

[0048] S130. The linewidth and intensity of the third peak signal are optimized by adjusting the intensity difference between the first peak signal and the second peak signal, and the information of the object to be measured is determined based on the optimized third peak signal.

[0049] For example, when the spectrum contains peak signals other than the first, second, and third peak signals, at least one of the second adjustable attenuator, the second polarization controller, and the relative positions of the optical microcavity and the waveguide is adjusted to adjust the intensity difference between the first and second peak signals. The linewidth and intensity of the third peak signal are optimized by adjusting this intensity difference. For example, the linewidth of the third peak signal is reduced, and the intensity of the third peak signal is increased.

[0050] The power of the excitation light can be changed by adjusting the second adjustable attenuator; the polarization state of the excitation light can be changed by adjusting the second polarization controller; and the coupling state of the microcavity and waveguide can be changed by adjusting the relative position of the microcavity and waveguide through a three-dimensional nano-translation stage. This achieves the effects of optimizing the sensing signal, optimizing the detection accuracy, improving the signal-to-noise ratio, and thus optimizing the detection limit.

[0051] When the analyte (typically nanometer-sized) adheres to the surface of an optical microcavity, it causes scattering and absorption of the microcavity's optical modes, resulting in a change in the Raman beat frequency signal. This change can be used as a sensing signal. The transmitted light is converted into an electrical signal by a photodetector, and the electrical signal corresponding to the Raman beat frequency signal is acquired by a data acquisition device. The sensing signal of the analyte is determined based on the spectral information of the third peak signal, and the information of the analyte is determined based on the sensing signal. In this invention, the Raman beat frequency signal is the third peak signal.

[0052] This invention provides a silicon quantum dot-enhanced Raman optical microcavity laser sensing method. By monitoring the linewidth and intensity of the two spike signals generated by the interference between the reference light and two split Raman lasers, and by adjusting the excitation power, polarization state, and coupling state, the linewidth and intensity of the spike signals generated by the interference between the two split Raman lasers are optimized. This optimizes the intensity difference between the two spike signals generated by the interference between the reference light and the two split Raman lasers. This method solves the problems of signal-to-noise ratio, detection accuracy, and detection limit in traditional sensing systems, optimizes detection accuracy, improves signal-to-noise ratio, and reduces detection limit.

[0053] In some embodiments, coupling a reference light and an excitation light to an optical microcavity, and exciting a Raman laser in the optical microcavity by the excitation light, includes: inputting the reference light and the excitation light into the same waveguide via an optical combiner; coupling the reference light and the excitation light to the optical microcavity via the waveguide when the wavelength of the excitation light matches the optical mode of the optical microcavity, wherein the optical microcavity is a composite structure with a silicon quantum dot thin layer of a predetermined thickness added to the surface of a silicon dioxide microcavity. When the power of the excitation light is greater than the Raman laser threshold, the Raman laser in the optical microcavity is excited by the excitation light, and the Raman laser is coupled into the waveguide.

[0054] Optionally, during the tuning of the tunable laser, an oscilloscope displays the spectrum based on the electrical signal corresponding to the transmitted light, and the wavelength of the excitation light is monitored to see if it matches the optical mode of the optical microcavity. When the wavelength of the excitation light matches the optical mode, the excitation energy is coupled into the optical microcavity. Then, the wavelength of the excitation light at this point is used as the wavelength of the laser generated by the tunable laser in the actual measurement scenario.

[0055] In traditional microcavity Raman laser sensing devices, Raman laser light is generated when the excitation power reaches the Raman laser threshold, utilizing the gain of the silicon dioxide material itself. The excitation light power needs to be higher than the Raman laser threshold, which is limited by the material's inherent gain. This invention employs a composite microcavity structure, adding a silicon quantum thin layer of a predetermined thickness to the surface of the silicon dioxide microcavity. This composite microcavity structure can improve the Raman gain of the microcavity, lower the Raman laser threshold, thereby reducing the excitation power and saving energy.

[0056] Furthermore, since an important performance characteristic of a sensing device is the detection limit, which is the smallest analyte that can be detected, the detection limit depends on sensitivity and detection accuracy. A composite microcavity structure with a thin layer of silicon quantum dots can improve the sensitivity of the sensing device and optimize the detection limit by adjusting the thickness of the quantum dot layer and the light field distribution of the microcavity excitation light mode and Raman laser mode.

[0057] Figure 2 This is a flowchart of another silicon quantum dot-enhanced Raman optical microcavity laser sensing method provided by an embodiment of the present invention. This embodiment adds the monitoring of the excitation state of the Raman laser using a spectrometer to the above embodiment. Figure 2 As shown, the method includes:

[0058] S201. The laser generated by the tunable laser is split into two laser beams by the first optical beam splitter.

[0059] For example, the wavelength of the laser generated by the tunable laser in the actual measurement scenario is determined by tuning the tunable laser, and laser of the corresponding wavelength is generated by the tunable laser. The laser is then split into two beams by a first optical beam splitter. The first optical beam splitter is connected to an acousto-optic modulator and a second adjustable attenuator via optical fibers, and outputs one laser beam to the acousto-optic modulator and the other laser beam to the second adjustable attenuator.

[0060] S202. The reference light is obtained by frequency shifting one of the laser beams using an acousto-optic modulator, and the optical power and polarization state of the reference light are adjusted by a first adjustable attenuator and a first polarization controller.

[0061] S203. Use another laser beam as the excitation light, and adjust the optical power and polarization state of the excitation light through a second adjustable attenuator and a second polarization controller.

[0062] S204. The adjusted reference light and excitation light are input into the same waveguide through an optical beam combiner.

[0063] S205. When the wavelength of the excitation light matches the optical mode of the optical microcavity, the reference light and the excitation light are coupled to the optical microcavity through the waveguide.

[0064] The optical microcavity is a composite structure in which a thin layer of silicon quantum dots of a predetermined thickness is added to the surface of a silicon dioxide microcavity.

[0065] S206. When the power of the excitation light is greater than the Raman laser threshold, the nonlinear light of the optical microcavity is excited according to the excitation light, and the excited nonlinear light is coupled to the waveguide.

[0066] The nonlinear light includes Raman lasers, and may also include other nonlinear lights besides Raman lasers. The Raman lasers consist of two split Raman laser beams formed by the interference of two Raman laser beams propagating in clockwise and counterclockwise directions.

[0067] S207. The transmitted light in the waveguide is split into two beams by the second optical beam splitter. One beam is input into the spectrometer and the other beam is input into the photodetector.

[0068] S208. A transmission spectrum is generated by a spectrometer, the wavelength of the Raman laser is monitored based on the transmission spectrum, and it is determined whether the transmission spectrum contains nonlinear light other than the Raman laser based on the wavelength of the Raman laser.

[0069] For example, the spectrometer is connected to the second optical beamsplitter via optical fiber to acquire the transmitted light output from the second optical beamsplitter and generate the corresponding transmission spectrum. The wavelength of the Raman laser is monitored based on the transmission spectrum, and the presence of wavelengths generated by other nonlinear effects is observed. If the transmission spectrum contains wavelengths different from the Raman laser wavelength, it is considered that the transmission spectrum contains nonlinear light other than the Raman laser wavelength.

[0070] S209. If the transmission spectrum contains nonlinear light other than the Raman laser, adjust at least one of the second adjustable attenuator, the second polarization controller, and the relative position of the optical microcavity and the waveguide until the transmission spectrum contains only the Raman laser.

[0071] For example, in the presence of other nonlinear light in the transmission spectrum, the power of the excitation light can be changed by adjusting the second adjustable attenuator; the polarization state of the excitation light can be changed by adjusting the second polarization controller; and the coupling state of the microcavity and waveguide can be changed by adjusting the relative position of the microcavity and waveguide by adjusting the three-dimensional nano-translation stage, so as to ensure that only Raman laser is excited in the nonlinear process.

[0072] S210. When only the Raman laser is present in the transmission spectrum, the first peak signal and the second peak signal are obtained by interfering with the reference light by the two split Raman lasers respectively, and the third peak signal is obtained by interfering with each other by the two split Raman lasers.

[0073] S211. Monitor the spike signals in the transmitted light using a spectrum analyzer.

[0074] For example, the spectrum analyzer and the photodetector are connected by a cable. The spectrum analyzer acquires the electrical signal output by the photodetector, generates and displays the spectrum of the transmitted light based on the electrical signal, and monitors the interference between coherent lights in the transmitted light through the spectrum analyzer.

[0075] S212. When the spectrum contains other peak signals besides the first peak signal, the second peak signal, and the third peak signal, at least one of the second adjustable attenuator, the second polarization controller, and the relative position of the optical microcavity and the waveguide is adjusted to adjust the intensity difference between the first peak signal and the second peak signal, and the linewidth and intensity of the third peak signal are optimized by adjusting the intensity difference.

[0076] S213. Obtain the optimized third peak signal through the data acquisition device.

[0077] For example, the data acquisition device and the photodetector are connected by a cable. After optimizing the third peak signal, the data acquisition device acquires the electrical signal of the optimized third peak signal output by the photodetector.

[0078] This embodiment ensures that only Raman lasers are excited during the nonlinear process. By observing the linewidth and intensity of the two spike signals generated by the interference between the reference light and the two split Raman lasers, the intensity difference between the two spike signals is optimized, thereby optimizing the linewidth and intensity of the sensing signal. This suppresses the generation of other nonlinear light besides Raman lasers, improves the signal-to-noise ratio, reduces energy loss, and optimizes the detection limit.

[0079] Figure 3 This is a schematic diagram of a silicon quantum dot-enhanced Raman optical microcavity laser sensing system provided in an embodiment of the present invention. Figure 3 As shown, the system includes:

[0080] The first optical beam splitter 310 is used to split the laser generated by the tunable laser 3130 into two laser beams, output one of the laser beams to the acousto-optic modulator 320, and output the other laser beam as the excitation light to the adjustment module 330.

[0081] The acousto-optic modulator 320 is used to shift the frequency of one of the laser beams to obtain a reference light, and output the reference light to the adjustment module 330.

[0082] The adjustment module 330 is used to adjust the optical power and polarization state of the reference light and the excitation light, and output the adjusted reference light and excitation light to the optical combiner 340.

[0083] The optical beam combiner 340 is used to input the adjusted reference light and excitation light into the same waveguide 360, and couple the adjusted reference light and excitation light to the optical microcavity 350 through the waveguide 360.

[0084] The optical microcavity 350 is used to excite the Raman laser of the optical microcavity 350 according to the adjusted excitation light when the power of the excitation light is greater than the Raman laser threshold, and to couple the Raman laser into the waveguide 360, so that the transmission light in the waveguide 360 ​​includes the reference light, the excitation light and the Raman laser, wherein the Raman laser includes two split Raman lasers formed by the interference of two Raman laser beams propagating in the clockwise and counterclockwise directions;

[0085] The waveguide 360 ​​is used to obtain a first peak signal and a second peak signal by interfering with the reference light through the two split Raman lasers respectively, and to obtain a third peak signal by interfering with each other through the two split Raman lasers.

[0086] The spectrum analyzer 370 is used to acquire the transmission spectrum corresponding to the transmitted light in the waveguide 360, monitor the interference signal generated by interference in the transmitted light, and adjust the intensity difference between the first peak signal and the second peak signal according to the monitoring results to optimize the linewidth and intensity of the third peak signal.

[0087] The data acquisition device 380 is used to acquire the optimized third peak signal, determine the sensing signal of the object under test based on the spectral information of the third peak signal, and determine the information of the object under test based on the sensing signal.

[0088] Optionally, the adjustment module 330 includes:

[0089] The first adjustable attenuator 331 is connected to the first polarization controller 332 and is used to adjust the optical power of the reference light and input the adjusted reference light into the first polarization controller 332.

[0090] The second adjustable attenuator 333 is connected to the second polarization controller 334 to adjust the optical power of the excitation light and input the adjusted excitation light into the second polarization controller 334.

[0091] The first polarization controller 332 is used to adjust the polarization state of the adjusted reference light and output the adjusted reference light to the optical beam combiner 340.

[0092] The second polarization controller 334 is used to adjust the polarization state of the adjusted excitation light and output the adjusted excitation light to the optical combiner 340.

[0093] Optionally, the system also includes: a second optical beam splitter 390, a photodetector 3100, and a spectrometer 3110;

[0094] The second optical beam splitter 390 is used to split the transmitted light in the waveguide 360 ​​into two transmitted light beams, inputting one of the transmitted light beams into the spectrometer 3110 and the other transmitted light beam into the photodetector 3100.

[0095] The spectrometer 3110 is used to generate a transmission spectrum, monitor the wavelength of the Raman laser based on the transmission spectrum, and determine whether the transmission spectrum contains nonlinear light other than the Raman laser based on the wavelength of the Raman laser.

[0096] If the transmission spectrum contains nonlinear light other than the Raman laser, at least one of the second adjustable attenuator 333, the second polarization controller 334, and the relative positions of the optical microcavity 350 and the waveguide 360 ​​is adjusted until the transmission spectrum contains only the Raman laser.

[0097] The photodetector 3100 is used to convert the optical signal in the waveguide 360 ​​into an electrical signal, and output the electrical signal to the data acquisition device 380 and the spectrum analyzer 370.

[0098] Optionally, the spectrum analyzer 370 is connected to the photodetector 3100;

[0099] The spectrum analyzer 370 is specifically used to acquire the electrical signal output by the photodetector 3100, generate the spectrum corresponding to the transmitted light based on the electrical signal, and adjust the intensity difference between the first peak signal and the second peak signal by adjusting at least one of the second adjustable attenuator 333, the second polarization controller 334, and the relative positions of the optical microcavity 350 and the waveguide 360, when the spectrum contains other peak signals besides the first peak signal, the second peak signal, and the third peak signal, and optimize the linewidth and intensity of the third peak signal by adjusting the intensity difference.

[0100] Optionally, during the tuning process of the tunable laser 3130, an oscilloscope 3120 displays the spectrum based on the electrical signal corresponding to the transmitted light, and monitors whether the wavelength of the excitation light matches the optical mode of the optical microcavity 350. When the wavelength of the excitation light matches the optical mode, excitation energy is coupled into the optical microcavity 350. Then, the wavelength of the excitation light at this time is used as the wavelength of the laser generated by the tunable laser 3130 in the sensing scene.

[0101] Figure 4 This is a schematic diagram of another silicon quantum dot-enhanced Raman optical microcavity laser sensing system provided by an embodiment of the present invention. In the silicon quantum dot-enhanced Raman optical microcavity laser sensing system provided by the present invention, a reference beam is introduced to monitor two split Raman lasers, optimizing the sensing signal, reducing experimental noise, and thus lowering the detection limit. Figure 4As shown, the laser generated by the tunable laser 4130 is split into two beams by the first optical beam splitter 410. One beam is frequency-shifted by the acousto-optic modulator 420 and serves as a reference beam. The optical power and polarization state of the reference beam are controlled by the first adjustable attenuator 431 and the first polarization controller 432. The other beam maintains its original frequency and serves as the excitation beam. The optical power and polarization state of the excitation beam are controlled by the second adjustable attenuator 433 and the second polarization controller 434. The reference beam output from the first polarization controller 432 and the excitation beam output from the second polarization controller 434 are input into the same waveguide 460 via the optical beam combiner 440. The reference beam and the excitation beam are coupled into the optical microcavity 450 through the waveguide 460. The excitation beam excites the Raman laser in the microcavity 450. The transmitted light after passing through the waveguide 460 includes the reference beam, the excitation beam, and the Raman laser.

[0102] Among them, the optical microcavity 450 is a composite structure in which a silicon quantum dot thin layer of a set thickness is added to the surface of the silicon dioxide microcavity, and the optical microcavity 450 is placed on a three-dimensional nano-translation stage. The coupling state between the microcavity 450 and the waveguide 460 can be adjusted by adjusting the relative position of the microcavity 450 and the waveguide 460.

[0103] By forming a composite microcavity structure using silicon quantum dot thin films, the Raman gain of the microcavity material is enhanced, resulting in low-threshold microcavity Raman lasers and reduced energy loss.

[0104] The transmitted light is split into two beams by the second beam splitter 490. One beam is collected by the spectrometer 4110, which monitors the wavelength and order of the generated Raman laser. The other beam is converted into an electrical signal by the photodetector 4100, which is collected by the oscilloscope 4120, the data acquisition device, and the spectrum analyzer.

[0105] The spectrometer collects a portion of the transmitted light, generates a transmission spectrum, monitors the wavelength of the generated Raman laser based on the transmission spectrum, and observes whether wavelengths generated due to other nonlinear effects are produced. When nonlinear light other than Raman light is generated, the coupling state of microcavity 450 and waveguide 460 is adjusted by adjusting the second adjustable attenuator, the second polarization controller, and the relative position of microcavity 450 and waveguide 460 through a three-dimensional nano-translation stage, ensuring that only Raman light is excited during the nonlinear process.

[0106] The photodetector 4100 converts a portion of the transmitted light into electrical signals, which are received by the oscilloscope 4120, the spectrum analyzer 470, and the data acquisition device 480, respectively. Exemplarily, the oscilloscope 4120 is used to monitor whether the wavelength of the excitation light matches the optical mode of the microcavity 450 during the tuning process of the tunable laser 4130. When the wavelength of the excitation light matches the optical mode, laser energy is coupled into the microcavity 450, and a sharp trough appears in the spectrum displayed by the oscilloscope 4120. As the excitation light power increases, the linewidth of this trough increases due to thermal effects. When it reaches the Raman laser threshold, Raman laser is excited.

[0107] The spectrum analyzer 470 is used to monitor interference between coherent beams in the transmitted light. When the transmitted light contains only a reference beam, an excitation beam, and a Raman laser, the spectrum of the spectrum analyzer 470 contains three spike signals. Two of these spike signals are formed by the interference between the two split Raman lasers and the reference laser, respectively, and the third spike signal is formed by the interference between the two Raman laser beams. This signal is the sensing signal. When the excitation beam excites wavelengths generated by other nonlinear phenomena, interference occurs between other coherent beams, between other coherent beams and Raman beams, and between other coherent beams and the reference beam. This results in additional spike signals in the spectrum besides the three mentioned above. These spike signals not only affect the sensing signal... The broadening of the spectrum introduces experimental noise, and because some of the excitation light is used to excite other nonlinear lights, it results in wasted excitation light power and reduced intensity of the sensing signal. By adjusting the second adjustable attenuator, the second polarization controller, and adjusting the relative positions of the microcavity 450 and the waveguide 460 through a three-dimensional nano-translation stage, the coupling state of the microcavity 450 and the waveguide 460 is adjusted to achieve the following: First, ensuring that only Raman light is excited during the nonlinear process; Second, observing the interference between the reference light and the two split Raman lights, optimizing their intensity, and thus optimizing the linewidth and intensity of the sensing signal. Ultimately, the generation of other nonlinear phenomena besides Raman light is suppressed, the signal-to-noise ratio is improved, energy loss is reduced, and the detection limit is optimized.

[0108] The data acquisition device 480 is used to: acquire the electrical signal generated by the photodetector 4100, analyze the spectral information of the electrical signal, and obtain the sensing signal in the transmission spectrum.

[0109] In traditional microcavity Raman laser sensing applications, Raman lasers are excited by excitation light, and the information of the analyte is detected by monitoring the beat frequency signal in the transmission spectrum. However, the sensing system lacks a monitoring device for the generated Raman laser, making it impossible to effectively adjust and optimize the beat frequency signal. Therefore, there is a lack of effective methods for optimizing the signal-to-noise ratio and detection limit. The sensing system proposed in this invention monitors the generated Raman laser using a reference light. A reference light beam is generated through the frequency shifting effect of an acousto-optic modulator. By monitoring the beat frequency generated by the interference between the reference light and the Raman laser, the excitation power, polarization state, and coupling state are adjusted to optimize the sensing beat frequency signal, improve detection accuracy, and increase the signal-to-noise ratio, thereby achieving the goal of optimizing the detection limit.

[0110] The silicon quantum dot enhanced Raman optical microcavity laser sensing system provided in this embodiment of the invention can execute the silicon quantum dot enhanced Raman optical microcavity laser sensing method provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects of the method.

[0111] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and no limitation is imposed herein.

[0112] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A silicon quantum dot enhanced Raman optical microcavity laser sensing method, characterized in that, include: A reference light and an excitation light are coupled to an optical microcavity, and the excitation light excites a Raman laser in the optical microcavity. The Raman laser comprises two split Raman lasers formed by the interference of two Raman laser beams propagating in a clockwise and counterclockwise direction. The first and second peak signals are obtained by interfering with the reference light by the two split Raman lasers respectively, and the third peak signal is obtained by interfering with each other by the two split Raman lasers. The linewidth and intensity of the third peak signal are optimized by adjusting the intensity difference between the first and second peak signals, and the information of the object to be measured is determined based on the optimized third peak signal.

2. The method of claim 1, wherein, The process of coupling a reference light and an excitation light to an optical microcavity, and exciting the optical microcavity with the excitation light, includes: The reference light and the excitation light are input into the same waveguide via an optical beam combiner; When the wavelength of the excitation light matches the optical mode of the optical microcavity, the reference light and the excitation light are coupled to the optical microcavity through the waveguide, wherein the optical microcavity is a composite structure in which a thin layer of silicon quantum dots of a predetermined thickness is added to the surface of a silicon dioxide microcavity. When the power of the excitation light is greater than the Raman laser threshold, the Raman laser of the optical microcavity is excited by the excitation light, and the Raman laser is coupled into the waveguide.

3. The method of claim 2, wherein, Before the reference light and excitation light are input into the same waveguide via an optical beam combiner, the following steps are also included: The laser generated by the tunable laser is split into two laser beams by the first optical beam splitter. The reference light is obtained by frequency shifting one of the laser beams using an acousto-optic modulator, and the optical power and polarization state of the reference light are adjusted by a first adjustable attenuator and a first polarization controller. Another laser beam is used as the excitation light, and the optical power and polarization state of the excitation light are adjusted by a second adjustable attenuator and a second polarization controller.

4. The method of claim 3, wherein, After exciting the Raman laser of the optical microcavity with the excitation light, the process further includes: A transmission spectrum is generated by a spectrometer, the wavelength of the Raman laser is monitored based on the transmission spectrum, and it is determined whether the transmission spectrum contains nonlinear light other than the Raman laser based on the wavelength of the Raman laser. If the transmission spectrum contains nonlinear light other than the Raman laser, at least one of the second adjustable attenuator, the second polarization controller, and the relative position of the optical microcavity and the waveguide is adjusted until the transmission spectrum contains only the Raman laser.

5. The method according to any one of claims 1-4, characterized in that, The step of optimizing the linewidth and intensity of the third peak signal by adjusting the intensity difference between the first and second peak signals includes: Monitor the spike signals in the transmitted light using a spectrum analyzer; When the spectrum contains other peak signals besides the first peak signal, the second peak signal, and the third peak signal, at least one of the second adjustable attenuator, the second polarization controller, and the relative position of the optical microcavity and the waveguide is adjusted to adjust the intensity difference between the first peak signal and the second peak signal, and the linewidth and intensity of the third peak signal are optimized by adjusting the intensity difference.

6. The method of claim 1, wherein, The step of determining the analyte information based on the optimized third peak signal includes: The optimized third peak signal is acquired through a data acquisition device; The sensing signal of the object under test is determined based on the spectral information of the third peak signal, and the information of the object under test is determined based on the sensing signal.

7. A silicon quantum dot enhanced Raman optical microcavity laser sensing system, characterized in that, include: The first optical beam splitter is used to split the laser generated by the tunable laser into two laser beams. One of the laser beams is output to the acousto-optic modulator, and the other laser beam is output as the excitation light to the adjustment module. The acousto-optic modulator is used to shift the frequency of one of the laser beams to obtain a reference beam, and output the reference beam to the adjustment module; The adjustment module is used to adjust the optical power and polarization state of the reference light and the excitation light, and output the adjusted reference light and excitation light to the optical combiner; The optical beam combiner is used to input the adjusted reference light and the excitation light into the same waveguide. When the wavelength of the excitation light matches the optical mode of the optical microcavity, the adjusted reference light and the excitation light are coupled to the optical microcavity through the waveguide. The optical microcavity is used to excite a Raman laser in the optical microcavity according to the adjusted excitation light when the power of the excitation light is greater than the Raman laser threshold, and to couple the Raman laser into the waveguide, so that the transmission light in the waveguide includes a reference light, an excitation light and a Raman laser, wherein the Raman laser includes two split Raman lasers formed by the interference of two Raman laser beams propagating in the clockwise and counterclockwise directions; The waveguide is used to obtain a first peak signal and a second peak signal by interfering with the reference light through the two split Raman lasers respectively, and to obtain a third peak signal by interfering with each other through the two split Raman lasers. A spectrum analyzer is used to monitor interference signals in transmitted light and adjust the intensity difference between the first and second peak signals based on the monitoring results to optimize the linewidth and intensity of the third peak signal. A data acquisition device is used to acquire an optimized third peak signal, determine the sensing signal of the object under test based on the spectral information of the third peak signal, and determine the information of the object under test based on the sensing signal.

8. The system of claim 7, wherein, The adjustment module includes: The first adjustable attenuator is connected to the first polarization controller and is used to adjust the optical power of the reference light and input the adjusted reference light into the first polarization controller. The second adjustable attenuator is connected to the second polarization controller and is used to adjust the optical power of the excitation light, and input the adjusted excitation light into the second polarization controller. The first polarization controller is used to adjust the polarization state of the adjusted reference light and output the adjusted reference light to the optical beam combiner. The second polarization controller is used to adjust the polarization state of the adjusted excitation light and output the adjusted excitation light to the optical beam combiner.

9. The system of claim 8, wherein, Also includes: Second optical beam splitter, photodetector, and spectrometer; The second optical beam splitter is used to split the transmitted light in the waveguide into two transmitted light beams, one of which is input into the spectrometer and the other is input into the photodetector. The spectrometer is configured to generate a transmission spectrum, monitor a wavelength of the Raman laser based on the transmission spectrum, and determine whether the transmission spectrum contains nonlinear light other than the Raman laser according to the wavelength of the Raman laser. In the case where the transmission spectrum contains nonlinear light other than the Raman laser, at least one of the second adjustable attenuator, the second polarization controller, and the relative position of the optical microcavity and the waveguide is adjusted until only the Raman laser is contained in the transmission spectrum. The photodetector is configured to convert the optical signal in the waveguide into an electrical signal and output the electrical signal to the data acquisition device and the spectrum analyzer.

10. The system of claim 9, wherein, The spectrum analyzer is specifically configured to: acquire the electrical signal output by the photodetector, generate a spectrum corresponding to the transmission light according to the electrical signal, and in the case where the spectrum contains other peak signals other than the first peak signal, the second peak signal, and the third peak signal, adjust at least one of the second adjustable attenuator, the second polarization controller, and the relative position of the optical microcavity and the waveguide to adjust an intensity difference between the first peak signal and the second peak signal, and optimize the line width and intensity of the third peak signal by adjusting the intensity difference.

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