阅读说明：本技术 纳米粒子尺寸信息测量装置及方法 (Nano particle size information measuring device and method ) 是由 张靖 杨震宁 张皖哲 关剑卿 霍跃 施炜 于 2020-04-16 设计创作，主要内容包括：本申请涉及一种纳米粒子尺寸信息测量装置及方法。包括激光泵浦源、光学微腔系统、光电探测器以及频谱分析仪。激光泵浦源提供满足驻波条件的光信号。光信号耦合进入光学微腔系统后,调节激光泵浦源出射的光信号频率,以实现光信号与光学微腔系统的极限耦合。光信号经光电探测器转换为电信号。频谱分析仪获取电信号,并对电信号进行分析。当出现倍周期分岔现象时,将纳米粒子贴近光学微腔系统边缘,当电信号再次被频谱分析仪获取后,分析倍周期的峰值信息,进而解读出纳米粒子的尺寸信息。上述测量过程由于引入了较强的非线性现象,在粒子半径较小的时候能够将信息放大较高倍数,从而能够提升信噪比,同时,能够避免噪声淹没信号的问题。(The application relates to a device and a method for measuring nano particle size information. The device comprises a laser pumping source, an optical microcavity system, a photoelectric detector and a spectrum analyzer. The laser pump source provides an optical signal that satisfies the standing wave condition. After the optical signal is coupled into the optical microcavity system, the frequency of the optical signal emitted by the laser pumping source is adjusted to realize the limit coupling of the optical signal and the optical microcavity system. The optical signal is converted into an electrical signal by a photodetector. The spectrum analyzer acquires and analyzes the electrical signal. When the bifurcation phenomenon of the multiple period occurs, the nano particles are attached to the edge of the optical microcavity system, and after the electric signal is acquired by the spectrum analyzer again, the peak value information of the multiple period is analyzed, so that the size information of the nano particles is read. The measurement process introduces stronger nonlinear phenomenon, and can amplify information by higher times when the particle radius is smaller, so that the signal-to-noise ratio can be improved, and meanwhile, the problem that the signal is submerged by noise can be avoided.)

1. A nanoparticle size information measuring apparatus, comprising:

a laser pump source (110) for providing an optical signal satisfying a standing wave condition;

the optical microcavity system (120) is used for adjusting the frequency of an optical signal emitted by the laser pumping source (110) after the optical signal is coupled into the optical microcavity system (120), so that the optical signal is coupled with the optical microcavity system (120) in a limiting mode;

a photodetector (130), wherein the optical signal emitted by the optical microcavity system (120) is converted into an electrical signal by the photodetector (130); and

and the spectrum analyzer (140) acquires the electric signal, analyzes the electric signal, presses the nanoparticles to the edge of the optical microcavity system (120) when a period-doubling bifurcation phenomenon occurs, and analyzes the peak information of the period-doubling after the spectrum analyzer (140) acquires the electric signal again, thereby reading the size information of the nanoparticles.

2. The nanoparticle size information measurement device of claim 1, wherein the laser pump source (110) comprises:

a tunable laser source (111) for emitting an optical signal;

a laser isolator (112) that receives the optical signal and prevents reflected light of the optical signal from breaking down the tunable laser source (111); and

a laser amplifier (113) receiving the optical signal emitted through the laser isolator (112) for adjusting the power of the optical signal to provide the optical signal satisfying a standing wave condition.

3. The nanoparticle size information measurement device of claim 2, wherein the optical microcavity system (120) comprises:

an optical fiber (121) that receives the optical signal emitted from the laser amplifier (113); and

an optical microcavity (122) spaced a predetermined distance from the optical fiber (121) such that the optical signal in the optical fiber (121) is coupled into the optical microcavity (122).

4. The nanoparticle size information measuring device of claim 3, wherein the preset distance is 0.1 μm-0.8 μm.

5. The nanoparticle size information measurement device according to claim 4, wherein the optical microcavity (122) employs a deformed micro-core ring or a deformed spherical cavity.

6. A method for measuring nanoparticle size information, comprising:

s10, providing an optical signal meeting the standing wave condition by using a laser pumping source (110);

s20, adjusting the frequency of the optical signal to realize limit coupling of the optical signal and the optical microcavity system (120);

s30, converting the optical signal emitted by the optical microcavity system (120) into an electrical signal by the photodetector (130);

and S40, acquiring the electric signal by using a spectrum analyzer (140), analyzing the electric signal, attaching the nanoparticles to the edge of the optical microcavity system (120) when a period-doubling bifurcation phenomenon occurs, and analyzing the peak value information of the period-doubling after the spectrum analyzer (140) acquires the electric signal again, thereby reading the size information of the nanoparticles.

7. The method for measuring information on the size of nanoparticles according to claim 6, wherein the step of providing an optical signal satisfying a standing wave condition by using a laser pumping source (110) at S10 is preceded by:

adjusting a spacing between an optical fiber (121) and an optical microcavity (122) in the optical microcavity system (120) such that the optical microcavity system (120) satisfies a limit coupling condition.

8. The method of measuring nanoparticle size information of claim 7, wherein the step of adjusting the spacing between the optical fiber (121) and the optical microcavity (122) in the optical microcavity system (120) such that the optical microcavity system (120) satisfies the limit coupling condition comprises:

and adjusting the distance between the optical fiber (121) and the optical microcavity (122) in the optical microcavity system (120) to be 0.5 mu m.

9. The method of claim 8, wherein the step of providing an optical signal satisfying a standing wave condition using a laser pumping source (110) at S10 comprises:

the frequency of an optical signal emitted by a tunable laser source (111) is adjusted within a preset frequency by a laser amplifier (113) to provide the optical signal satisfying a standing wave condition.

10. The method for measuring nanoparticle size information of claim 9, wherein the step of adjusting the frequency of the optical signal to achieve limit coupling of the optical signal with the optical microcavity system (120) comprises, at S20:

and adjusting the frequency of an optical signal emitted by the tunable laser source (111) to be resonant with the frequency of the optical microcavity (122) by using the laser amplifier (113).

11. The method for measuring nanoparticle size information according to claim 10, wherein the step S40 of acquiring the electrical signal by a spectrum analyzer (140), analyzing the electrical signal, approaching the nanoparticles to the edge of the optical microcavity system (120) when the bifurcation of the period occurs, and analyzing the peak information of the period after the spectrum analyzer (140) acquires the electrical signal again, thereby interpreting the size information of the nanoparticles comprises:

when a multiple period bifurcation phenomenon occurs, acquiring peak value information of a first multiple period at the moment;

after the nano particles are close to the edge of the optical microcavity system (120), acquiring peak value information of a second doubling period;

and obtaining the variation value of the peak value of the time period by utilizing the peak value information of the first time period and the peak value information of the second time period, and further reading the size information of the nano particles.

Technical Field

The present disclosure relates to the field of optical measurement technologies, and in particular, to a device and a method for measuring information on size of nanoparticles.

Background

The optical microcavity has potential application value in the fields of micro-nano particle detection and size measurement due to high Q value and small size. When light leaks into the optical microcavity through the optical fiber, the light meeting a certain frequency condition is easier to stay in the optical microcavity and is transmitted along the cavity wall; when external signals affect the cavity wall, the light is greatly affected, and when the external signals leak back to the optical fiber from the optical microcavity, the affected information can be presented in the form of light intensity.

The detection of micro-nano particles using optical microcavities has been proposed in the early years: due to the fact that the micro-nano particles can cause coupling of a degenerate cavity mode, an output optical field of the micro-nano particles has two frequencies, namely one higher supermode and one lower supermode, and effective nano particle size can be obtained through measurement of line width and frequency difference of the two split supermodes. The method can accurately measure the size of particles with the particle size of more than 50 nm. However, when the particle is small, the two cleaved supermodes are close to each other, and the frequency difference signal and the line width signal of the supermode are submerged by noise or the line width of the pump laser itself, so that the method cannot detect particles below 50 nm.

Disclosure of Invention

Based on the above, the present application provides a device and a method for measuring nanoparticle size information, so as to detect particles below 50 nm.

A nanoparticle size information measuring apparatus comprising:

the laser pumping source is used for providing an optical signal meeting the standing wave condition;

the optical microcavity system is used for adjusting the frequency of an optical signal emitted by the laser pumping source after the optical signal is coupled into the optical microcavity system so as to realize limit coupling of the optical signal and the optical microcavity system;

the optical signal emitted by the optical microcavity system is converted into an electrical signal by the photodetector; and

and the spectrum analyzer acquires the electric signal and analyzes the electric signal, when a period bifurcation phenomenon occurs, the nano particles are attached to the edge of the optical microcavity system, and after the electric signal is acquired by the spectrum analyzer again, the peak information of the period is analyzed, so that the size information of the nano particles is read.

In one embodiment, the laser pumping source comprises:

a tunable laser source for emitting an optical signal;

a laser isolator that receives the optical signal and prevents reflected light of the optical signal from breaking down the tunable laser source; and

and the laser amplifier receives the optical signal emitted by the laser isolator and is used for adjusting the power of the optical signal so as to provide the optical signal meeting the standing wave condition.

In one embodiment, the optical microcavity system comprises:

an optical fiber for receiving the optical signal emitted from the laser amplifier; and

an optical microcavity spaced a predetermined distance from the optical fiber such that the optical signal in the optical fiber is coupled into the optical microcavity.

In one embodiment, the predetermined distance is 0.1 μm to 0.8 μm.

In one embodiment, the optical microcavity employs an anamorphic minicore ring or an anamorphic spherical cavity.

A method of measuring nanoparticle size information, comprising:

s10, providing an optical signal meeting the standing wave condition by using a laser pumping source;

s20, adjusting the frequency of the optical signal to realize limit coupling of the optical signal and the optical microcavity system;

s30, converting the optical signal emitted by the optical microcavity system into an electrical signal by a photodetector;

and S40, acquiring the electric signal by using a spectrum analyzer, analyzing the electric signal, attaching the nanoparticles to the edge of the optical microcavity system when a bifurcation phenomenon of the period of the times occurs, and analyzing peak information of the period of the times after the spectrum analyzer acquires the electric signal again so as to read the size information of the nanoparticles.

In one embodiment, the step of providing the optical signal satisfying the standing wave condition by using the laser pump source at S10 includes:

and adjusting the distance between the optical fiber in the optical microcavity system and the optical microcavity so that the optical microcavity system meets the limit coupling condition.

In one embodiment, the step of adjusting the spacing between the optical fiber and the optical microcavity in the optical microcavity system such that the optical microcavity system satisfies the limit coupling condition comprises:

and adjusting the distance between the optical fiber in the optical microcavity system and the optical microcavity to be 0.5 μm.

In one embodiment, the step of providing an optical signal satisfying a standing wave condition by using a laser pump source S10 includes:

and adjusting the frequency of the optical signal emitted by the tunable laser source within a preset frequency by using the laser amplifier to provide the optical signal meeting the standing wave condition.

In one embodiment, the step of adjusting the frequency of the optical signal to achieve limit coupling of the optical signal with the optical microcavity system at S20 includes:

and adjusting the frequency of an optical signal emitted by the tunable laser source to be in resonance with the frequency of the optical microcavity by using the laser amplifier.

In one embodiment, in S40, the step of acquiring the electrical signal by a spectrum analyzer, analyzing the electrical signal, approaching the nanoparticles to the edge of the optical microcavity system when the period bifurcation occurs, and analyzing the peak information of the period after the spectrum analyzer acquires the electrical signal again, so as to interpret the size information of the nanoparticles includes:

when a multiple period bifurcation phenomenon occurs, acquiring peak value information of a first multiple period at the moment;

after the nano particles are close to the edge of the optical microcavity system, peak value information of a second doubling period is obtained;

and obtaining the variation value of the peak value of the time period by utilizing the peak value information of the first time period and the peak value information of the second time period, and further reading the size information of the nano particles.

The nano particle size information measuring device comprises a laser pumping source, an optical microcavity system, a photoelectric detector and a spectrum analyzer. The laser pumping source is used for providing an optical signal meeting a standing wave condition. And after the optical signal is coupled and enters the optical microcavity system, the frequency of the optical signal emitted by the laser pumping source is adjusted so as to realize the limit coupling of the optical signal and the optical microcavity system. And the optical signal emitted by the optical microcavity system is converted into an electrical signal by the photodetector. The spectrum analyzer acquires the electrical signal and analyzes the electrical signal. And when the bifurcation phenomenon of the multiple period occurs, the nano particles are attached to the edge of the optical microcavity system, and after the electric signal is acquired by the spectrum analyzer again, the peak value information of the multiple period is analyzed, so that the size information of the nano particles is read. The device measures the change of a nonlinear phenomenon of mechanical multiple period bifurcation generated by a photomechanical effect so as to obtain the size of the radius of the particle. In the process, due to the introduction of a strong nonlinear phenomenon, information can be amplified by a high factor when the radius of the particle is small, so that the signal-to-noise ratio can be improved. Meanwhile, the measurement is realized under a high-power optical field, and the problem that signals are submerged by noise can be avoided.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings used in the descriptions of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following descriptions are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a block diagram of a device for measuring information on size of nanoparticles according to an embodiment of the present application;

FIG. 2 is a block diagram of a device for measuring information on size of nanoparticles according to an embodiment of the present application;

FIG. 3 is a block diagram of an optical microcavity system according to one embodiment of the present application;

fig. 4 is a flowchart of a method for measuring information on size of nanoparticles according to an embodiment of the present disclosure.

Description of the main element reference numerals

10. A nanoparticle size information measuring device; 110. a laser pump source; 120. an optical microcavity system; 130. a photodetector; 140. a spectrum analyzer; 111. a tunable laser source; 112. a laser isolator; 113. a laser amplifier; 121. an optical fiber; 122. an optical microcavity.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying the present application are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is capable of embodiments in many different forms than those described herein and those skilled in the art will be able to make similar modifications without departing from the spirit of the application and it is therefore not intended to be limited to the embodiments disclosed below.

It will be understood that, as used herein, the terms "first," "second," and the like may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, a first acquisition module may be referred to as a second acquisition module, and similarly, a second acquisition module may be referred to as a first acquisition module, without departing from the scope of the present application. The first acquisition module and the second acquisition module are both acquisition modules, but are not the same acquisition module.

It will be understood that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Referring to fig. 1, an embodiment of the present application provides a nanoparticle size information measuring device 10. The nanoparticle size information measuring device 10 includes a laser pumping source 110, an optical microcavity system 120, a photodetector 130, and a spectrum analyzer 140.

The laser pump source 110 is used to provide an optical signal satisfying a standing wave condition. After the optical signal of the optical microcavity system 120 is coupled into the optical microcavity system 120, the frequency of the optical signal emitted from the laser pumping source 110 is adjusted to realize the limit coupling between the optical signal and the optical microcavity system 120. The optical signal emitted from the optical microcavity system 120 is converted into an electrical signal by the photodetector 130. The spectrum analyzer 140 acquires the electrical signal and analyzes the electrical signal. When the bifurcation phenomenon of the multiple period occurs, the nanoparticles are close to the edge of the optical microcavity system 120, and after the electrical signal is acquired by the spectrum analyzer 140 again, the peak information of the multiple period is analyzed, so as to interpret the size information of the nanoparticles.

It is understood that the structure of the laser pump source 110 is not particularly limited as long as the laser pump source 110 can provide an optical signal satisfying a standing wave condition. The optical signal may be a laser signal. The standing wave condition is a frequency satisfying a specific range. When the optical signal emitted by the laser pumping source 110 satisfies the standing wave condition, the optical signal can be coupled with the optical microcavity system 120, so that the optical signal with a certain energy enters the optical microcavity system 120.

The structure of the optical microcavity system 120 is not particularly limited. In an alternative embodiment, the optical microcavity system 120 employs an anamorphic micro-core annular cavity or an anamorphic spherical cavity. The type and structure of the spectrum analyzer 140 are not particularly limited as long as the spectrum analyzer 140 can observe the electrical signal and can observe the mechanical vibration frequency.

The optical signal satisfying the standing wave condition can stably exist in the optical microcavity system 120, so that the optical signal with certain energy enters the optical microcavity system 120. When the energy entering the optical microcavity system 120 is large enough, a certain pressure is generated on the cavity wall of the optical microcavity system 120, which causes a certain deformation of the cavity wall, and thus changes the standing wave condition, so that the laser energy entering the optical microcavity system 120 can be changed. This interaction is a non-linear process. When the laser energy is not high, the optical signal in the cavity carries information related to the cavity wall deformation frequency, and the signal appears near the cavity wall vibration frequency (about 20MHz for a cavity with a radius of 30um and an edge thickness of about 8 um). When the energy of the input optical signal reaches the mW magnitude or so, due to the more important position occupied by the nonlinear phenomenon, the vibration frequency of the cavity wall is no longer a single frequency, a new frequency appears at a half of the frequency, the phase diagram of the optical field in the cavity is changed from one limit cycle to two, and the process is called a mechanical multiple cycle bifurcation phenomenon. To a certain extent, as the energy in the optical microcavity system 120 increases, this phenomenon becomes more and more pronounced, and the peak corresponding to the new frequency at its frequency spectrum becomes higher and higher.

When the nanoparticles approach the cavity wall, due to rayleigh scattering, the forward and reverse modes of the optical field in the cavity are coupled, so that the standing wave condition of the optical microcavity 122 is changed, the laser energy entering the optical microcavity system 120 is changed, and the period division phenomenon is changed. The rayleigh scattering power of the particle, and hence its size, can be known from the change in height of the peak at the new frequency.

In this embodiment, the apparatus 10 for measuring information on size of nanoparticles includes a laser pump source 110, an optical microcavity system 120, a photodetector 130, and a spectrum analyzer 140. The laser pump source 110 is used to provide an optical signal satisfying a standing wave condition. After the optical signal is coupled into the optical microcavity system 120, the frequency of the optical signal emitted from the laser pump source 110 is adjusted to realize the limit coupling between the optical signal and the optical microcavity system 120. The optical signal emitted from the optical microcavity system 120 is converted into an electrical signal by the photodetector 130. The spectrum analyzer 140 acquires the electrical signal and analyzes the electrical signal. When the bifurcation phenomenon of the multiple period occurs, the nanoparticles are attached to the edge of the optical microcavity system 120, and after the electrical signal is obtained by the spectrum analyzer 140 again, the peak information of the multiple period is analyzed, so that the size information of the nanoparticles is read. The device measures the change of a nonlinear phenomenon of mechanical multiple period bifurcation generated by a photomechanical effect so as to obtain the size of the radius of the particle. In the process, due to the introduction of a strong nonlinear phenomenon, information can be amplified by a high factor when the radius of the particle is small, so that the signal-to-noise ratio can be improved. Meanwhile, the measurement is realized under a high-power optical field, and the problem that signals are submerged by noise can be avoided.

Referring to fig. 2, in an alternative embodiment, the laser pump source 110 includes a tunable laser source 111, a laser isolator 112 and a laser amplifier 113.

The tunable laser source 111 is used to emit an optical signal. The laser isolator 112 receives the optical signal and prevents reflected light of the optical signal from breaking down the tunable laser source 111. The laser amplifier 113 receives the optical signal emitted through the laser isolator 112 for adjusting the power of the optical signal to provide the optical signal satisfying a standing wave condition. The laser isolator 112 is provided to prevent reverse breakdown of the tunable laser source 111. The devices can be used together to provide an optical signal meeting standing wave conditions for the measurement process.

Referring to FIG. 3, in one embodiment, the optical microcavity system 120 includes an optical fiber 121 and an optical microcavity 122.

The optical fiber 121 receives the optical signal emitted from the laser amplifier 113. The optical microcavity 122 is spaced a predetermined distance from the optical fiber 121, so that the optical signal in the optical fiber 121 is coupled into the optical microcavity 122. In one alternative embodiment, the predetermined distance is 0.1 μm to 0.8 μm. For example, the preset distance is 0.5 μm. When the distance between the optical microcavity 122 and the optical fiber 121 is adjusted to about 0.5um, the rate of the optical signal leaking into the optical microcavity 122 from the optical fiber 121 is similar to the rate of the optical signal leaking into the external environment from the optical microcavity 122, that is, the limit coupling condition is reached. In this case, when the optical signal is tuned to a resonant frequency with the optical microcavity 122, the laser light can be coupled to the optical microcavity 122 through the optical fiber 121 to a limit (i.e., the energy into the optical microcavity 122 is maximized). By observing the spectrum analyzer 140, when the period-doubling phenomenon occurs, the nanoparticles are attached to the edge of the optical microcavity 122 and the peak-to-peak value of the period-doubling phenomenon is changed, so as to detect and obtain the size of the nanoparticles.

Referring to fig. 4, an embodiment of the present application provides a method for measuring information on a size of a nanoparticle. The method for measuring the size information of the nano particles comprises the following steps:

s10, providing an optical signal satisfying the standing wave condition by using the laser pump source 110. In step S10, the structure of the laser pump source 110 is not particularly limited as long as the laser pump source 110 can provide an optical signal satisfying the standing wave condition. The optical signal may be a laser signal. The standing wave condition is a frequency satisfying a specific range. In an alternative embodiment, the step of providing the optical signal satisfying the standing wave condition by using the laser pump source 110, S10, may be adjusting the frequency of the optical signal emitted by the tunable laser source 111 within a preset frequency by using the laser amplifier 113 to provide the optical signal satisfying the standing wave condition. When the optical signal emitted by the laser pumping source 110 satisfies the standing wave condition, the optical signal can be coupled with the optical microcavity system 120, so that the optical signal with a certain energy enters the optical microcavity system 120.

S20, adjusting the frequency of the optical signal to achieve limit coupling of the optical signal with the optical microcavity system 120. In step S20, the structure of the optical microcavity system 120 is not particularly limited. In an alternative embodiment, the optical microcavity system 120 employs an anamorphic micro-core ring or an anamorphic spherical cavity. The optical signal carries information related to the cavity wall deformation frequency.

S30, the optical signal emitted from the optical microcavity system 120 is converted into an electrical signal by the photodetector 130. In step S30, the photodetector 130 converts the optical signal carrying the information related to the cavity wall deformation frequency into a signal carrying the information related to the cavity wall deformation frequency.

And S40, acquiring the electric signal by using the spectrum analyzer 140, analyzing the electric signal, attaching the nanoparticles to the edge of the optical microcavity system 120 when the bifurcation phenomenon of the multiple period occurs, and analyzing the peak information of the multiple period after the spectrum analyzer 140 acquires the electric signal again, thereby reading the size information of the nanoparticles. In step S40, the type and structure of the spectrum analyzer 140 are not particularly limited as long as the spectrum analyzer 140 can observe the electrical signal and can observe the mechanical vibration frequency.

In this embodiment, the change of the nonlinear phenomenon of mechanical multiple period bifurcation generated by the optomechanical effect is measured, so as to obtain the size of the radius of the particle. In the process, due to the introduction of a strong nonlinear phenomenon, information can be amplified by a high factor when the radius of the particle is small, so that the signal-to-noise ratio can be improved. Meanwhile, the measurement is realized under a high-power optical field, and the problem that signals are submerged by noise can be avoided.

In one embodiment, the step of providing the optical signal satisfying the standing wave condition by using the laser pump source 110 at S10 includes:

the spacing between the optical fiber 121 and the optical microcavity 122 in the optical microcavity system 120 is adjusted so that the optical microcavity system 120 satisfies the limit coupling condition. At this time, the rate of the optical signal leaking from the optical fiber 121 into the optical microcavity 122 is similar to the rate of the optical signal leaking from the optical microcavity 122 into the external environment, that is, the limit coupling condition is reached. In one optional embodiment, the step of adjusting the spacing between the optical fiber 121 and the optical microcavity 122 in the optical microcavity system 120 to make the optical microcavity system 120 satisfy the limit coupling condition may be to adjust the spacing between the optical fiber 121 and the optical microcavity 122 in the optical microcavity system 120 to be 0.5 μm.

In one embodiment, the S20, adjusting the frequency of the optical signal to achieve limit coupling of the optical signal with the optical microcavity system 120 includes:

the frequency of the optical signal emitted by the tunable laser source 111 is tuned to resonate with the frequency of the optical microcavity 122 by the laser amplifier 113. When the optical signal is tuned to a resonant frequency with the optical microcavity 122, the laser light can be coupled to the optical microcavity 122 through the optical fiber 121 to achieve limit coupling (i.e., the energy into the optical microcavity 122 is maximized).

In one embodiment, the step S40 of acquiring the electrical signal by the spectrum analyzer 140, analyzing the electrical signal, when the period bifurcation occurs, approaching the nanoparticles to the edge of the optical microcavity system 120, and after the spectrum analyzer 140 acquires the electrical signal again, analyzing the peak information of the period bifurcation, and then interpreting the size information of the nanoparticles includes:

when the multiple period bifurcation phenomenon occurs, the peak information of the first multiple period at this time is acquired. After the nanoparticles are close to the edge of the optical microcavity system 120, peak information of the second doubling period is obtained. And obtaining the variation value of the peak value of the time period by utilizing the peak value information of the first time period and the peak value information of the second time period, and further reading the size information of the nano particles.

In this embodiment, when the leakage rate of the optical signal from the optical fiber 121 into the optical microcavity 122 is similar to the leakage rate of the optical signal from the optical microcavity 122 into the external environment, that is, the limit coupling condition is reached, and the optical signal is tuned to the resonant frequency of the optical microcavity 122, the laser can be limit-coupled with the optical microcavity 122 through the optical fiber 121 (that is, the energy entering the optical microcavity 122 reaches the maximum). By observing the spectrum analyzer 140, when the period-doubling phenomenon occurs, the nanoparticles are attached to the edge of the optical microcavity 122 and the peak-to-peak value of the period-doubling phenomenon is changed, so as to detect and obtain the size of the nanoparticles.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.