CN116576842A - A kind of resonant optical gyroscope and angular velocity measurement method - Google Patents

Abstract

The disclosure provides a resonant optical gyroscope and a method for measuring angular velocity. The gyroscope includes: an optical resonant unit, a tunable laser, a photoelectric detector, and a signal processing and control system. The optical resonant unit includes a bus waveguide and at least two waveguide rings; The signal processing and control system are respectively connected to the photodetector and the tunable laser signal; in the optical resonance unit, the bus waveguide is adjacent to the first waveguide ring, the first waveguide ring is adjacent to the second waveguide ring, and the first waveguide ring is connected to the bus There is optical coupling between the waveguide and the adjacent parts of the second waveguide ring. The signal processing and control system obtains the free spectral range of the double ring according to the resonance spectrum of the double ring. When there is an external angular velocity, the magnitude of the external angular velocity is calculated according to the change in the free spectral range of the double ring. , compared with the prior art, the resonant optical gyroscope of the present disclosure has a simple structure and can greatly improve the angular velocity sensitivity of the gyroscope.

Description

A kind of resonant optical gyroscope and angular velocity measurement method

technical field

The present disclosure relates to the technical field of gyroscopes, in particular to a resonant optical gyroscope and an angular velocity measurement method.

Background technique

Gyroscope is an angular velocity sensor, which is used to sense angular velocity and can be applied to inertial navigation of missiles, aircraft, etc. Resonant optical gyroscopes are usually based on an optical resonant ring, which is a ring-shaped optical device. As shown in Figure 1, the optical resonant ring is composed of a bus waveguide and a waveguide ring.

The general structure of the existing resonant optical gyroscope is shown in Figure 2. The entire gyroscope system is composed of tunable lasers, isolators, electro-optic modulators, photodetectors, resonant rings, signal processing and control systems, etc. The structure is relatively Complex and less sensitive to angular velocity.

Contents of the invention

The purpose of the present disclosure is to provide a resonant optical gyroscope and a method for measuring angular velocity, so as to simplify the resonant optical gyroscope and improve the sensitivity of angular velocity measurement.

The embodiment of the first aspect of the present disclosure provides a resonant optical gyroscope, including:

An optical resonance unit, a tunable laser, a photodetector, and a signal processing and control system, the optical resonance unit includes a bus waveguide and at least two waveguide rings, and the two waveguide rings are respectively a first waveguide ring and a second waveguide ring ;

The tunable laser is set at the input end of the bus waveguide, the photodetector is set at the output end of the bus waveguide, and the signal processing and control system is connected with the photodetector and the tunable laser respectively signal connection;

In the optical resonance unit, the bus waveguide is adjacent to the first waveguide ring, the first waveguide ring is adjacent to the second waveguide ring, and there is optical coupling between the first waveguide ring and the adjacent parts of the bus waveguide and the second waveguide ring;

The signal processing and control system is used to output a frequency sweep signal to the tunable laser, so that the tunable laser can output continuous linear frequency sweep laser;

The laser light emitted by the tunable laser is coupled into the first waveguide ring through the bus waveguide, and then coupled into the second waveguide ring; the frequency of the laser input by the tunable laser satisfies the resonance conditions of the first waveguide ring and the second waveguide ring at the same time ;

The photodetector is used to collect the light intensity of the output light after passing through the first waveguide ring and the second waveguide ring, and obtain the frequency response spectrum of the first waveguide ring and the second waveguide ring, that is, the double-ring resonant spectral line;

The signal processing and control system is also used to obtain the free spectral range of the double ring according to the resonance spectrum of the double ring, and calculate the magnitude of the external angular velocity according to the change of the free spectral range of the double ring when there is an external angular velocity.

According to some embodiments of the present disclosure, the cavity length difference between the first waveguide ring and the second waveguide ring is set such that the double-ring resonant spectral lines are sufficient to scan two complete deep resonances in the frequency sweep range of the tunable laser The maximum value that can be reached in the case of valleys.

According to some embodiments of the present disclosure, the total length of the first waveguide ring is greater than the total length of the second waveguide ring.

According to some embodiments of the present disclosure, a line connecting centers of the first waveguide ring and the second waveguide ring is perpendicular to the bus waveguide.

According to some embodiments of the present disclosure, the first waveguide ring and the second waveguide ring have the same shape.

According to some embodiments of the present disclosure, the shapes of the first waveguide ring and the second waveguide ring are different.

The embodiment of the second aspect of the present disclosure provides a method for measuring angular velocity, based on the resonant optical gyroscope described in the first aspect, the method includes:

The signal processing and control system outputs the frequency sweep signal to the tunable laser;

The tunable laser outputs continuous linear frequency-sweeping laser to the bus waveguide, the laser is coupled into the first waveguide ring through the bus waveguide, and then coupled into the second waveguide ring; the frequency of the tunable laser input laser meets the requirements of the first waveguide The resonance conditions of the ring and the second waveguide ring;

The photodetector collects the light intensity of the output light after passing through the first waveguide ring and the second waveguide ring, and obtains the frequency response spectrum of the first waveguide ring and the second waveguide ring, that is, the double-ring resonant spectral line;

The signal processing and control system obtains the free spectral range of the double ring according to the double ring resonant spectral line;

When there is an external angular velocity, the signal processing and control system calculates the magnitude of the external angular velocity according to the variation of the free spectral range of the double rings.

The advantages of the present disclosure over the prior art are:

The resonant optical gyroscope provided by the present disclosure includes: an optical resonant unit, a tunable laser, a photodetector, and a signal processing and control system, the optical resonant unit includes a bus waveguide and at least two waveguide rings, and the two waveguides The rings are respectively the first waveguide ring and the second waveguide ring; the tunable laser is set at the input end of the bus waveguide, the photodetector is set at the output end of the bus waveguide, and the signal processing and control system respectively connected to the photodetector and the tunable laser signal; in the optical resonance unit, the bus waveguide is adjacent to the first waveguide ring, the first waveguide ring is adjacent to the second waveguide ring, and the first waveguide ring is adjacent to the second waveguide ring. There is optical coupling between the bus waveguide and the adjacent parts of the second waveguide ring, and the signal processing and control system obtains the free spectral range of the double ring according to the resonance spectrum of the double ring, and when there is an external angular velocity, calculates the external Regarding the size of the angular velocity, compared with the prior art, the resonant optical gyroscope of the present disclosure has a simple structure, and the double-ring structure based on the resonant spectral line vernier effect can greatly improve the angular velocity sensitivity of the gyroscope.

Description of drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiment. The drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present disclosure. Also throughout the drawings, the same reference numerals are used to designate the same components. In the attached picture:

FIG. 1 shows a schematic structural view of an existing optical resonant ring;

FIG. 2 shows a schematic structural view of an existing resonant optical gyroscope;

Fig. 3 shows a schematic diagram of the resonant spectral lines of the optical resonant ring shown in Fig. 1;

FIG. 4 shows a schematic structural diagram of a resonant optical gyroscope provided by the present disclosure;

FIG. 5 shows a schematic diagram of the double-ring resonance spectrum provided by the present disclosure.

Detailed ways

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. It should be understood, however, that these descriptions are exemplary only, and are not intended to limit the scope of the present disclosure. Also, in the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concepts of the present disclosure.

Various structural schematic diagrams according to embodiments of the present disclosure are shown in the accompanying drawings. The figures are not drawn to scale, with certain details exaggerated and possibly omitted for clarity of presentation. The shapes of the various regions and layers shown in the figure, as well as their relative sizes and positional relationships are only exemplary, and may deviate due to manufacturing tolerances or technical limitations in practice, and those skilled in the art will Regions/layers with different shapes, sizes, and relative positions can be additionally designed as needed.

In the context of the present disclosure, when a layer/element is referred to as being "on" another layer/element, the layer/element may be directly on the other layer/element, or there may be intervening layers/elements in between. element. Additionally, if a layer/element is "on" another layer/element in one orientation, the layer/element can be located "below" the other layer/element when the orientation is reversed.

The optical resonant ring shown in Figure 1 is composed of a bus waveguide and a waveguide ring. The waveguide here can be an optical fiber, or an on-chip optical waveguide made of SOI, Si3N4 and other materials. In Figure 1, the waveguide ring is a circular example, and the actual It can also be various shapes such as racetrack shape and rectangle. There is optical coupling between the bus waveguide and the adjacent position of the waveguide ring, and the light entering the bus waveguide through the input end can be coupled into the waveguide ring when passing through the coupling part.

The waveguide ring is actually a ring resonant cavity, and the optical frequency coupled into the waveguide ring can resonate in the cavity when the following conditions are met:

In the formula, f is the optical frequency, L is the total length of the waveguide ring, c is the speed of light, and n _eff is the effective refractive index of the waveguide ring waveguide. When the input light resonates in the waveguide ring, it will be partially confined in the cavity and cannot be transmitted from The output at the output end of the bus waveguide can be seen from formula (1) that the optical frequency that can resonate in the cavity is periodically distributed, and the interval between two adjacent resonant frequencies, that is, the free spectral range is:

At this time, the tunable laser is used to input a continuous linear frequency sweep laser at the input end, and the output optical power after passing through the resonant ring is collected at the output end, and the frequency response spectrum of the resonant ring can be obtained, that is, its resonant spectral line, the schematic diagram of the resonant spectral line As shown in Figure 3. Figure 3 shows the two resonance valleys of the waveguide ring, f ₁ and f ₂ are the two resonance frequencies of the waveguide ring, and the frequency difference between them is the free spectral range f _FSR .

The resonant optical gyroscope is a gyroscope designed based on the Sagnac effect. The Sagnac effect is based on the theory of relativity, that is, the length of a moving object will change, so the external rotational angular velocity will change the cavity length of the waveguide ring. When When the direction of external angular velocity is the same as the direction of light propagation, the cavity length of the waveguide ring will become longer. When the direction of external angular velocity is opposite to the direction of light propagation, the cavity length of the waveguide ring will be shortened. At this time, the waveguide ring can be known from formula (1) The resonant frequency of the clockwise and counterclockwise two paths of light will shift, and a small frequency difference Δf will be generated between the two. Within a certain range, this frequency difference is proportional to the angular velocity:

In the formula, Ω is the angular velocity, n is the refractive index, _λ0 is the wavelength of the light wave in vacuum, and D is the diameter of the waveguide ring. In practical applications, photodetectors can be used to detect the two paths of clockwise and counterclockwise light in the waveguide ring. Light intensities P ₁ and P ₂ are modulated and demodulated on the gyroscope signal by phase modulation spectrum technology to obtain the frequency difference Δf, and the external rotational angular velocity is calculated according to the relationship in (3).

The general structure of a resonant optical gyroscope is shown in Figure 2. The entire gyroscope system is composed of tunable lasers, isolators, electro-optical modulators, photodetectors, resonant rings, signal processing and control systems and other components. The solid line chain in the figure The path represents the optical path, and the dotted link represents the electrical path, in which the optical path is provided by a tunable laser with a narrow line width light source, and after passing through the isolator I, it is divided into two paths of light with equal light intensity by a 1-2 beam splitter C ₀ , where One path is modulated by the phase modulator P ₁ and coupled to the resonant ring for transmission in the counterclockwise direction, and then coupled into the photodetector D ₁ through the coupler C 1 , and the other path is modulated by the phase modulator P _{2 and} clockwise along the silicon-based resonant ring direction transmission, and then coupled into the photodetector D ₂ via the coupler C ₂ , the signal modulation and control system will demodulate the light intensity signals of the two paths of light detected by the photodetectors D ₁ and D ₂ and judge whether they are forward or reverse The frequency offset of the two beams of light relative to the resonance center frequency of the silicon-based resonant ring, and then the signal modulation and control system sends the frequency tracking signal to the tunable laser, so that the frequency of the light source and the resonance of one of the clockwise and counterclockwise light The frequency is always consistent. At this time, the difference between the resonant frequency of the forward and reverse beams can be judged according to the output optical power value of the other beam, and then the external angular velocity value can be calculated.

The application provides a resonant optical gyroscope with two ring resonators. It can be known from the above-mentioned related technologies that when the ring resonator (resonant ring for short) rotates, its length will change. According to (2) formula, The change of the cavity length will change the free spectral range f _FSR of the resonant light in the ring. This application is based on this principle, and is sensitive to the angular velocity by collecting the f _FSR change of the resonant ring caused by the external angular velocity.

Because the change of f _FSR of the single resonant ring caused by the external angular velocity is too small, its change is difficult to be detected. In order to increase the sensitivity of the gyroscope, this application designs a double resonant ring structure. FIG. 4 shows a schematic diagram of a resonant optical gyroscope provided by the present disclosure. As shown in FIG. 4 , the resonant optical gyroscope provided by the present disclosure includes:

Optical resonance unit, tunable laser 100, photodetector 200 and signal processing and control system 300, the optical resonance ring includes a bus waveguide 410 and at least two waveguide rings, the two waveguide rings are respectively the first waveguide ring 420 and the second waveguide ring 430 . Optionally, the shape of the above-mentioned waveguide ring can be set to a shape such as a circle, a racetrack, or a rectangle.

According to some embodiments of the present application, the total length of the first waveguide ring 420 can be set to be longer than the total length of the second waveguide ring 430 , and the connecting line between the centers of the first waveguide ring 420 and the second waveguide ring 430 is perpendicular to the bus waveguide 410 .

According to some embodiments of the present disclosure, the first waveguide ring 420 and the second waveguide ring 430 have the same shape, for example, both are circular. The shapes of the first waveguide ring 420 and the second waveguide ring 430 may also be different, for example, one is circular and the other is racetrack-shaped.

The tunable laser 100 is set at the input end of the bus waveguide 410 , the photodetector 200 is set at the output end of the bus waveguide 410 , and the signal processing and control system 300 is connected with the photodetector 200 and the tunable laser 100 respectively.

In the optical resonance unit, the bus waveguide 410 is adjacent to the first waveguide ring 420, the first waveguide ring 420 is adjacent to the second waveguide ring 430, and the first waveguide ring 420 is adjacent to the bus waveguide 410 and the second waveguide ring 430. Both are optically coupled.

The signal processing and control system 300 is used to output frequency sweeping signals to the tunable laser 100, so that the tunable laser 100 outputs continuous linear frequency sweeping laser.

The laser light emitted by the tunable laser 100 is coupled into the first waveguide ring 420 through the bus waveguide 410, and then coupled into the second waveguide ring 430; the frequency of the laser input from the tunable laser 100 can meet the requirements of the first waveguide ring 420 and the second waveguide ring at the same time. 430 resonance conditions. When the input laser frequency satisfies the resonance condition of any waveguide ring, the laser can be partially confined in the waveguide ring, and when the input laser frequency satisfies the resonance conditions of the first waveguide ring 420 and the second waveguide ring 430 at the same time, the laser will be more confined within the two waveguide rings.

The photodetector 200 is used to collect the light intensity of the output light passing through the first waveguide ring 420 and the second waveguide ring 430 to obtain the frequency response spectrum of the first waveguide ring 420 and the second waveguide ring 430 , that is, double-ring resonant spectral lines.

The signal processing and control system 300 is also used to obtain the free spectral range of the double ring according to the resonance spectrum of the double ring, and calculate the magnitude of the external angular velocity according to the variation of the free spectral range of the double ring when there is an external angular velocity.

As shown in Figure 5, if the resonance curves of the first waveguide ring 420 and the second waveguide ring 430 are curve 1 and curve 2 respectively, it can be seen that the double-ring resonance spectrum is the superposition of the two, that is, as shown in curve 3 in Figure 5, it can be seen that The frequency at which the deep resonance valley of curve 3 appears is the difference between the frequencies at which the resonance valley of the resonance curve of the first waveguide ring 420 and the second waveguide ring 430 appears. If the difference in cavity length is very small, the frequency difference between the resonance valleys in the two resonance curves is very small, that is, the frequency of the double-ring deep resonance valleys is very small, that is, the free spectral range f _FSR is very large. At this time, when When there is an external angular velocity, the cavity lengths of the first waveguide ring 420 and the second waveguide ring 430 will change at the same time, and because the direction of light propagation in the two is opposite, the change trend of the two cavity lengths caused by the same external angular velocity It is also the opposite, and will eventually cause a significant change in the double-ring deep resonance valley f _FSR , and the magnitude of the change is proportional to the magnitude of the external angular velocity. At this time, the magnitude of the external angular velocity can be calculated from the detected double-ring resonance spectral line f _FSR .

According to some embodiments of the present application, the cavity length difference between the first waveguide ring 420 and the second waveguide ring 430 is set so that the double-ring resonant spectral line is sufficient to scan two complete deep resonances in the frequency sweep range of the tunable laser The maximum value that can be reached in the case of valleys.

That is to say, in practical applications, the length difference of the double-ring cavity can be reasonably set to make the f _FSR of the double-ring as large as possible when the frequency sweep range of the tunable laser is sufficient to scan two complete deep resonance valleys, so as to obtain the maximum angular velocity sensitivity .

The advantages of the present disclosure over the prior art are:

The resonant optical gyroscope proposed in this disclosure has a simple structure, and uses the Sagnac effect of two ring resonators and the vernier effect to change the free spectral range of the double-ring resonant spectral lines to be sensitive to the external angular velocity. Compared with the traditional resonant optical gyroscope, There is no need to track the resonant frequency, so the requirements for the signal control system are relatively low, no complex signal modulation and demodulation technology is required, so no phase modulator is needed, and the double-ring structure based on the vernier effect of the resonant spectral line can greatly improve the angular velocity of the gyroscope sensitivity.

The present disclosure also provides a method for measuring angular velocity, the method is based on the resonant optical gyroscope in the above embodiment, and the method includes the following steps:

The signal processing and control system outputs the frequency sweep signal to the tunable laser;

The tunable laser outputs continuous linear frequency-sweeping laser to the bus waveguide, the laser is coupled into the first waveguide ring through the bus waveguide, and then coupled into the second waveguide ring; the frequency of the tunable laser input laser meets the requirements of the first waveguide The resonance conditions of the ring and the second waveguide ring;

The photodetector collects the light intensity of the output light after passing through the first waveguide ring and the second waveguide ring, and obtains the frequency response spectrum of the first waveguide ring and the second waveguide ring, that is, the double-ring resonant spectral line;

The signal processing and control system obtains the free spectral range of the double ring according to the double ring resonant spectral line;

When there is an external angular velocity, the signal processing and control system calculates the magnitude of the external angular velocity according to the variation of the free spectral range of the double rings.

The advantages of the present disclosure over the prior art are:

The angular velocity measurement method proposed in this disclosure uses the Sagnac effect of the two ring resonators and the change in the free spectral range of the double-ring resonant spectral lines caused by the vernier effect to be sensitive to the external angular velocity. Compared with the traditional resonant optical gyroscope, it does not need to track the resonance Frequency, so the requirements for the signal control system are low, no complex signal modulation and demodulation technology is required, so no phase modulator is required, and the sensitivity of angular velocity measurement is high.

In order to form the same structure, those skilled in the art can also devise methods that are not exactly the same as those described above. In addition, although the various embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be advantageously used in combination.

The embodiments of the present disclosure have been described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. The scope of the present disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of the present disclosure, and these substitutions and modifications should all fall within the scope of the present disclosure.

Claims (7)

1. A resonant optical gyroscope, comprising: the optical resonance unit comprises a bus waveguide and at least two waveguide rings, wherein the two waveguide rings are respectively a first waveguide ring and a second waveguide ring;

the tunable laser is arranged at the input end of the bus waveguide, the photoelectric detector is arranged at the output end of the bus waveguide, and the signal processing and control system is respectively connected with the photoelectric detector and the tunable laser in a signal manner;

in the optical resonance unit, a bus waveguide is adjacent to a first waveguide ring, the first waveguide ring is adjacent to a second waveguide ring, and optical coupling exists between adjacent parts of the first waveguide ring, the bus waveguide and the second waveguide ring;

the signal processing and controlling system is used for outputting a sweep frequency signal to the tunable laser so that the tunable laser outputs continuous linear sweep frequency laser;

the laser emitted by the tunable laser is coupled into the first waveguide ring through the bus waveguide and then is coupled into the second waveguide ring; the frequency of the input laser of the tunable laser meets the resonance conditions of the first waveguide ring and the second waveguide ring at the same time;

the photoelectric detector is used for collecting the light intensity of the output light after passing through the first waveguide ring and the second waveguide ring, and obtaining frequency response spectrums of the first waveguide ring and the second waveguide ring, namely double-ring resonance spectrum lines;

the signal processing and controlling system is also used for obtaining the free spectrum range of the double ring according to the double ring resonance spectrum line, and calculating the external angular velocity according to the variable quantity of the free spectrum range of the double ring when the external angular velocity exists.

2. The resonant optical gyroscope of claim 1, wherein a difference in cavity lengths of the first waveguide ring and the second waveguide ring is set to: the dual-ring resonant spectrum is made to reach a maximum value in the case where the tunable laser sweep is sufficient to sweep out two complete deep resonant valleys.

3. The resonant optical gyroscope of claim 2, wherein the total length of the first waveguide ring is greater than the total length of the second waveguide ring.

4. A resonant optical gyroscope according to any of claims 1 to 3, wherein the line between the centres of the first and second waveguide rings is perpendicular to the bus waveguide.

5. The resonant optical gyroscope of claim 1, wherein the first waveguide ring and the second waveguide ring are identical in shape.

6. The resonant optical gyroscope of claim 1, wherein the first waveguide ring and the second waveguide ring are different in shape.

7. A method of angular velocity measurement based on the resonant optical gyroscope of any of claims 1-6, the method comprising:

the signal processing and controlling system outputs a sweep frequency signal to the tunable laser;

the tunable laser outputs continuous linear sweep laser to the bus waveguide, and the laser is coupled into the first waveguide ring through the bus waveguide and then is coupled into the second waveguide ring; the frequency of the input laser of the tunable laser meets the resonance conditions of the first waveguide ring and the second waveguide ring at the same time;

the photoelectric detector acquires the light intensity of the output light after passing through the first waveguide ring and the second waveguide ring, and obtains frequency response spectrums of the first waveguide ring and the second waveguide ring, namely double-ring resonance spectrum lines;

the signal processing and control system obtains a free spectrum range of the double rings according to the double ring resonance spectrum line;

when the external angular velocity exists, the signal processing and control system calculates the external angular velocity according to the variable quantity of the free spectrum range of the double ring.