Integrated distributed fiber optic sensing system

Abstract

The present invention provides an integrated distributed optical fiber sensing system comprising: an on-chip integrated laser (1), an injection locking unit (3), a distributed feedback laser (2), a semiconductor optical amplifier (5), an optical circulator (6), a sensing optical fiber (7), and a coherent detection unit (4), wherein the on-chip integrated unit (10a) is obtained by on-chip integration of the injection locking unit (3) and the coherent detection unit (4).

Description

Technical Field

[0001] This invention relates to a distributed optical fiber sensing system utilizing distributed optical fiber sensing technology, and more specifically to an integrated distributed optical fiber sensing system obtained by on-chip integration of discrete devices in a distributed optical fiber sensing system. Background Technology

[0002] Distributed fiber optic sensing technology is widely used in energy, power, aerospace, communications, transportation, and security fields due to its characteristics such as resistance to electromagnetic interference, high concealment, corrosion resistance, and insulation. Distributed fiber optic sensors employ unique distributed fiber optic sensing technology to measure or monitor the spatial distribution and time-varying information along the fiber optic transmission path. In distributed fiber optic sensors, the sensing fibers are arranged along the measured area, allowing simultaneous acquisition of both the spatial distribution and time-varying information of the measured area, making it highly attractive for industrial applications.

[0003] Among them, the phase-sensitive optical time domain reflectometer (Φ-OTDR) is a high-sensitivity distributed optical fiber sensing technology based on Rayleigh scattering. It can realize real-time and quantitative measurement of information along the optical fiber (such as vibration, strain, etc.), meeting the application needs of perimeter security, seismic wave detection, structural health monitoring and other fields.

[0004] Specifically, traditional phase-sensitive optical time-domain reflectometers (Φ-OTDRs) primarily employ discrete fiber optic components, such as... Figure 10 As shown, it includes devices such as a narrow linewidth laser (Laser), an acousto-optic modulator (AOM), an erbium-doped fiber amplifier (EDFA), a circulator, a sensing fiber (FURT), and a balanced detector (BPD), where OC indicates coupling.

[0005] Regarding the specific structure of a traditional phase-sensitive optical time-domain reflectometer (Φ-OTDR), such as... Figure 10As shown, firstly, coupling the narrow-linewidth laser (LAS) with the acousto-optic modulator (AOM) provides a good coherent light source for the AOM, enabling the phase-sensitive optical time-domain reflectometer (OTDR) to have a longer detection range as a sensing system. Furthermore, coupling the LAS with the balanced detector (BPD) provides local oscillator light to the BPD. Next, chopping and frequency shifting are performed using the AOM to convert the continuous light from the LAS into short pulses, achieving high-resolution detection of the spatial location of the fiber optic cable. Frequency shifting allows for the detection of scattered light via heterodyne beat frequency, significantly reducing low-frequency noise. Then, an erbium-doped fiber amplifier (EDFA) connected to the acousto-optic modulator (AOM) amplifies the pulsed light, thereby increasing the intensity of the scattered signal input from the sensing fiber FURT via the circulator. Finally, in the balanced detector (BPD), balanced detection is performed on the local oscillator light from the narrow-linewidth laser coupled to the BPD and the scattered light from the circulator coupled to the BPD.

[0006] However, in traditional phase-sensitive optical time-domain reflectometers (Φ-OTDRs), the devices in the system are usually discrete fiber optic devices, which are not only large in size, have high power consumption and cost, but are also not conducive to automated manufacturing and cannot meet the needs of current large-scale applications.

[0007] On the other hand, on-chip integrated optoelectronic technology is developing rapidly, and the performance of various optoelectronic devices has been greatly improved. On-chip integrated lasers can now achieve laser output with narrow linewidth, wide tuning range, and high side-mode rejection ratio. Silicon photonic modulators with high-order coupled micro-ring structures can achieve chopping with a dynamic extinction ratio of 60 dB, and IQ modulators can generate frequency shifts with a side-mode rejection ratio higher than 15 dB. However, the complex control and high loss of on-chip systems limit their further applications. Summary of the Invention The technical problem that the invention aims to solve

[0008] This invention was made to solve the above-mentioned problems. Its purpose is to provide an integrated distributed fiber optic sensing system, which includes an on-chip integrated laser, an injection locking unit, a distributed feedback laser, a semiconductor optical amplifier, an optical circulator, a sensing fiber, and a coherent detection unit. By integrating the injection locking unit and the coherent detection unit on-chip, an on-chip integrated unit is obtained, thereby realizing the integration of the distributed fiber optic sensing system.

[0009] Furthermore, at least one of the following components—an on-chip integrated laser, a distributed feedback laser, and a semiconductor optical amplifier—is also integrated on the on-chip integrated unit, thereby further improving the integration level of the integrated distributed fiber optic sensor system.

[0010] Furthermore, by utilizing injection-locking technology to achieve frequency shifting with the signal light, and the output characteristics of the injection-locking technology itself, the output power can be made unaffected by devices in the locking loop, such as electro-optic modulators and tunable optical attenuators, so as to obtain high-power and stable local oscillator output.

[0011] Furthermore, signal demodulation is performed based on the coherent detection unit, and the local oscillator light and signal light are mixed to obtain the difference frequency component. Then, the signal in the optical path is obtained by detecting the intensity information of the two beams of light, the local oscillator light and the signal light. This not only improves the conversion gain and enhances the detection capability, but also has a higher signal-to-noise ratio.

[0012] Furthermore, by integrating semiconductor optical amplifiers through heterogeneous integration, amplified high extinction ratio light pulses can be generated, thereby completing the chopping of signal light.

[0013] Furthermore, by utilizing the large bandwidth and high modulation efficiency of electro-optic modulators such as silicon photoelectric modulators, high-performance modulation sidebands can be generated.

[0014] Furthermore, by integrating mode converters on the on-chip integrated unit or by setting collimating lens groups separately from the on-chip integrated unit, the transmission quality and efficiency of optical signals in optical fiber communication systems can be improved. Technical means for solving technical problems

[0015] This invention provides an integrated distributed optical fiber sensing system, comprising: An on-chip integrated laser, wherein the on-chip integrated laser outputs a narrow linewidth laser; An injection locking unit receives the narrow linewidth laser and outputs a multi-order sideband spectrum and a local oscillator beam; A distributed feedback laser, wherein the distributed feedback laser generates a signal light with a certain frequency shift from the local oscillator light based on the multi-order sideband spectrum received from the injection locking unit, and inputs the signal light to the injection locking unit; A semiconductor optical amplifier receives the signal light from the injection-locking unit and chops the signal light into pulsed light; An optical circulator, having a first port, a second port, and a third port, wherein the first port is connected to the semiconductor optical amplifier and receives the pulsed light; The sensing fiber receives the pulsed light from the second port and inputs the resulting scattered light to the third port; and A coherent detection unit receives the local oscillator light from the injection-locking unit and the scattered light from the third port, and performs coherent demodulation on the local oscillator light and the scattered light to obtain the optical path information of the sensing fiber. An on-chip integrated unit is obtained by on-chip integration of the injection locking unit and the coherent detection unit.

[0016] Furthermore, the integrated distributed optical fiber sensing system involved in this invention, The injection locking unit has: A first optical beam splitter splits the narrow-linewidth laser received from the on-chip integrated laser into a reference beam and the local oscillator signal according to a fixed beam splitting ratio. An optical modulator that modulates the reference light received from the first optical beamsplitter into the multi-order sideband light; A tunable optical attenuator that adjusts the power of the received multi-order sideband light; and The second optical beam splitter inputs the power-adjusted multi-order sideband light to the distributed feedback laser and outputs the signal light input from the distributed feedback laser to the semiconductor optical amplifier.

[0017] Furthermore, the integrated distributed optical fiber sensing system of the present invention is characterized in that, The coherent detection unit has: An optical polarization beam splitter / rotator separates the received scattered light into first TE-polarized light and TM-polarized light, and then rotates the TM-polarized light into second TE-polarized light. The third optical beam splitter receives the local oscillator light and splits it into a first TE local oscillator light and a second TE local oscillator light. The first optical coupler receives the first TE local oscillator light and the first TE polarized light and couples them to obtain the first coupled light. The second optical coupler receives the second TE local oscillator light and the second TE polarized light and couples them to obtain the second coupled light. A first photoelectric balance detector receives the first coupled light and converts it into an electrical signal; The second photoelectric balance detector receives the second coupled light and converts it into an electrical signal.

[0018] Furthermore, in the integrated distributed optical fiber sensing system of the present invention, at least one of the on-chip integrated laser, the distributed feedback laser, and the semiconductor optical amplifier is integrated on the on-chip integrated unit.

[0019] Furthermore, in the integrated distributed optical fiber sensing system of the present invention, the substrate material of the on-chip integrated unit is any one of silicon, lithium niobate, and lithium tantalate.

[0020] Furthermore, in the integrated distributed optical fiber sensing system of the present invention, the cross-sectional structure of the waveguide material of the on-chip integrated unit is strip-shaped or ridge-shaped.

[0021] Furthermore, in the integrated distributed fiber optic sensing system of the present invention, the on-chip integrated laser is an on-chip narrow linewidth laser.

[0022] Furthermore, in the integrated distributed fiber optic sensing system of the present invention, the on-chip integrated laser and the injection locking unit are coupled through a first mode converter integrated on the on-chip integrated unit, or through a first collimating lens group separately disposed from the on-chip integrated unit.

[0023] Furthermore, in the integrated distributed optical fiber sensing system of the present invention, the first mode spot converter is integrated in the injection locking unit.

[0024] Furthermore, in the integrated distributed fiber optic sensing system of the present invention, the distributed feedback laser and the injection locking unit are coupled through a second mode converter integrated on the on-chip integrated unit, or through a second collimating lens group separately disposed from the on-chip integrated unit.

[0025] Furthermore, in the integrated distributed optical fiber sensing system of the present invention, the second mode spot converter is integrated in the injection locking unit.

[0026] Furthermore, in the integrated distributed optical fiber sensing system of the present invention, the injection locking unit and the semiconductor optical amplifier are coupled through a third mode converter integrated on the on-chip integrated unit, or through a third collimating lens group separately disposed from the on-chip integrated unit.

[0027] Furthermore, in the integrated distributed optical fiber sensing system of the present invention, the third mode spot converter is integrated in the injection locking unit.

[0028] Furthermore, in the integrated distributed optical fiber sensing system of the present invention, the coherent detection unit and the optical circulator are coupled through a fourth mode converter integrated on the on-chip integrated unit.

[0029] Furthermore, in the integrated distributed optical fiber sensing system of the present invention, the fourth mode spot converter is integrated in the coherent detection unit.

[0030] Furthermore, in the integrated distributed optical fiber sensing system of the present invention, the semiconductor optical amplifier and the optical circulator are coupled through a fifth mode converter integrated on the on-chip integrated unit, or through a fourth collimating lens group separately disposed from the on-chip integrated unit.

[0031] Furthermore, the integrated distributed fiber optic sensing system of the present invention integrates an isolator inside the on-chip integrated laser.

[0032] Furthermore, the integrated distributed fiber optic sensing system of the present invention does not integrate an isolator inside the distributed feedback laser. Invention Effects

[0033] First, according to the integrated distributed optical fiber sensing system of the present invention, an on-chip integrated unit is obtained by integrating the injection locking unit and the coherent detection unit on a chip, thereby realizing the integration of the distributed optical fiber sensing system.

[0034] Secondly, according to the integrated distributed fiber optic sensing system of the present invention, by further integrating at least one of the on-chip integrated laser, distributed feedback laser, and semiconductor optical amplifier on the on-chip integrated unit, the integration level of the integrated distributed fiber optic sensor system can be further improved.

[0035] Furthermore, according to the integrated distributed optical fiber sensing system of the present invention, frequency shifting with the signal light is achieved by using injection locking technology, and the output characteristics of the injection locking technology itself can also ensure that the output power is not affected by the devices in the locking loop, such as electro-optic modulators, tunable optical attenuators, etc., thereby obtaining high-power and stable local oscillator output.

[0036] Furthermore, signal demodulation is performed based on the coherent detection unit, and the local oscillator light and signal light are mixed to obtain the difference frequency component. Then, the signal in the optical path is obtained by detecting the intensity information of the two beams of light, the local oscillator light and the signal light. This not only improves the conversion gain and enhances the detection capability, but also has a higher signal-to-noise ratio.

[0037] Then, according to the integrated distributed optical fiber sensing system of the present invention, a semiconductor optical amplifier is integrated in a heterogeneous manner, which can generate amplified high extinction ratio optical pulses, thereby completing the chopping of signal light.

[0038] Furthermore, according to the integrated distributed optical fiber sensing system of the present invention, by integrating semiconductor optical amplifiers in a heterogeneous manner, amplified high extinction ratio optical pulses can be generated, thereby completing the chopping of signal light.

[0039] Furthermore, the integrated distributed optical fiber sensing system according to the present invention can generate high-performance modulation sidebands by utilizing the large bandwidth and high modulation efficiency of electro-optic modulators such as silicon photoelectric modulators.

[0040] Of course, this invention is not limited to silicon photonics integration technology, but can also be optoelectronic integration technology such as lithium niobate photonics integration technology and lithium tantalate photonics integration technology.

[0041] Finally, according to the integrated distributed optical fiber sensing system of the present invention, by integrating a mode converter on the on-chip integrated unit or by separately setting a collimating lens group from the on-chip integrated unit, the transmission quality and efficiency of optical signals in the optical fiber communication system can be improved.

[0042] In summary, the integrated distributed fiber optic sensing system of the present invention utilizes integration technologies such as silicon photonics integration technology and optoelectronic chips such as silicon photonics chips to realize an integrated distributed fiber optic sensing system based on injection locking technology. This integrated distributed fiber optic sensing system has high system integration and low overall power consumption, which can greatly reduce the system size and power consumption. The silicon photonics chips can be mass-produced, further reducing the system's production cost.

[0043] Moreover, because laser light sources based on injection-locking technology have narrow linewidths and high frequency stability, they can also achieve high signal-to-noise ratio signal sensing.

[0044] Silicon photonics chips are a new type of integrated circuit that integrates optoelectronic devices onto a single chip using silicon-based materials and processes, representing the pinnacle of optoelectronic convergence technology. However, this invention is not limited to silicon photonics chips; it can also include other optoelectronic integrated chips such as lithium niobate photonics chips and lithium tantalate photonics chips. Attached Figure Description

[0045] Figure 1 This is a schematic diagram illustrating an example of the overall structure of an integrated distributed optical fiber sensing system according to the first embodiment of the present invention. Figure 2 This is a schematic diagram illustrating a specific structural example of the integrated distributed optical fiber sensing system according to the first embodiment of the present invention. Figure 3 This is a schematic diagram illustrating a specific structural example of an integrated distributed optical fiber sensing system according to a first variation of the first embodiment of the present invention. Figure 4 This is a schematic diagram illustrating a specific structural example of an integrated distributed optical fiber sensing system according to a second variation of the first embodiment of the present invention. Figure 5 This is a schematic diagram illustrating an example of the overall structure of an integrated distributed optical fiber sensing system according to the second embodiment of the present invention. Figure 6 This is a schematic diagram illustrating an example of the overall structure of an integrated distributed optical fiber sensing system according to the third embodiment of the present invention. Figure 7 This is a schematic diagram illustrating an example of the overall structure of an integrated distributed optical fiber sensing system according to the fourth embodiment of the present invention. Figure 8 This is a schematic diagram illustrating an example of the overall structure of an integrated distributed optical fiber sensing system according to the fifth embodiment of the present invention. Figure 9 This is a schematic diagram illustrating an example of the overall structure of an integrated distributed optical fiber sensing system according to the sixth embodiment of the present invention. Figure 10 This is a schematic diagram illustrating an example of the overall structure of a distributed fiber optic sensing system as described in the prior art. Detailed Implementation

[0046] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this application. For those skilled in the art, these drawings can be applied to other similar scenarios without creative effort. Unless obvious from the context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0047] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" are not specifically singular and may include plural forms. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0048] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application. In addition, although the terminology used in this application is selected from commonly known and used terms, some terms mentioned in this application's specification may have been chosen by the applicant according to his or her judgment, and their detailed meanings are explained in the relevant sections of this description. Moreover, this application should be understood not only through the actual terms used, but also through the meaning implied by each term. First Implementation Method <Overall Structure of the 100A Integrated Distributed Fiber Optic Sensing System>

[0049] Figure 1 This is a schematic diagram illustrating an example of the overall structure of an integrated distributed optical fiber sensing system according to the first embodiment of the present invention. Below, refer to Figure 1 The overall structure of the integrated distributed optical fiber sensing system 100A according to the first embodiment of the present invention will be described in detail.

[0050] like Figure 1 As shown, the integrated distributed optical fiber sensing system 100A according to the first embodiment of the present invention includes: an on-chip integrated laser 1, a distributed feedback laser 2, an injection locking unit 3, a semiconductor optical amplifier 5, an optical circulator 6, a sensing optical fiber 7, and a coherent detection unit 4.

[0051] Specifically, such as Figure 1As shown, the on-chip integrated laser 1 outputs a narrow-linewidth laser to the injection-locked unit 3. After receiving the narrow-linewidth laser, the injection-locked unit 3 splits it into two outputs: one is a multi-order sideband spectrum, and the other is a local oscillator beam. The multi-order sideband spectrum is input to the distributed feedback laser 2, and the local oscillator beam is input to the coherent detection unit 4. The distributed feedback laser 2 generates a signal light with a certain frequency difference from the local oscillator beam based on the multi-order sideband spectrum received from the injection-locked unit 3, and inputs this signal light to the injection-locked unit 3. The semiconductor optical amplifier 5 chops the signal light received from the injection-locked unit 3 into pulsed light and then outputs the pulsed light to the optical circulator 6. The optical circulator 6 has a first port 6a, a second port 6b, and a third port 6c. The first port 6a is connected to the semiconductor optical amplifier 5, and after receiving the pulsed light from the semiconductor optical amplifier 5, it outputs the pulsed light to the sensing fiber 7 through the second port 6b. After receiving the pulsed light from the second port 6a of the optical circulator 6, the sensing fiber 7 inputs the pulsed light into the light transmission path and receives the scattered light from the light transmission path. The scattered light is then input into the second port 6b of the optical circulator 6, which in turn inputs the scattered light into the coherent detection unit 4 via the third port 6c. The coherent detection unit 4 performs coherent demodulation on the local oscillator light received from the injection-locking unit 3 and the scattered light received from the third port 6c of the optical circulator 6, thereby obtaining the optical path information of the sensing fiber 7.

[0052] The following describes in more detail the various structural components of the integrated distributed optical fiber sensing system 100A according to the first embodiment of the present invention, and their associated technical effects.

[0053] First, the injection locking unit 3 uses master-slave injection locking technology to ensure that the signal light generated by the distributed feedback laser 2 based on the multi-order sideband spectrum has a basically consistent linewidth with the local oscillator light generated by the injection locking unit 3 based on the narrow linewidth laser, while also having a certain frequency shift.

[0054] Therefore, by utilizing master-slave injection locking technology, injection locking unit 3 can fully ensure that the characteristics between the signal light and the local oscillator light meet the requirements of coherent detection.

[0055] Secondly, the on-chip integrated laser 1 is generally constructed by coupling an active gain chip with a passive external cavity chip, which can be in the form of external cavity feedback or self-injection locking.

[0056] Furthermore, an isolator needs to be integrated inside the on-chip integrated laser 1 to prevent the influence of reflected light on the on-chip integrated laser 1.

[0057] The linewidth of the on-chip integrated laser 1 is typically in the kHz range or below.

[0058] Furthermore, since the distributed feedback laser 2 does not require an integrated isolator, its structure is relatively more compact.

[0059] Moreover, since the frequency shift function required by the integrated distributed fiber optic sensing system 100A is mainly determined by the center frequency locked by the distributed feedback laser 2, the distributed feedback laser 2 needs to adjust its own temperature control or driving current before injection locking so that its center frequency is near the sideband to be locked.

[0060] Furthermore, compared to the linewidth of the on-chip integrated laser 1, the linewidth of the distributed feedback laser 2 is typically in the hundreds of kHz or MHz range. Therefore, by reducing the linewidth of the distributed feedback laser 2 from 2 MHz to the kHz range, and simultaneously increasing the frequency stability of the distributed feedback laser 2, the signal-to-noise ratio of the sensing signal can also be improved. Moreover, the structure of the distributed feedback laser 2 itself is relatively more compact.

[0061] Next, the scattered light and the local oscillator light are coherently demodulated by the coherent detection unit 4, and the local oscillator light and the signal light are mixed to obtain the difference frequency component. Then, the signal in the optical path is obtained by detecting the intensity information of the two beams of light, the local oscillator light and the signal light.

[0062] Therefore, by using the coherent detection unit 4, not only can the conversion gain be improved and the detection capability enhanced, but it also has a higher signal-to-noise ratio.

[0063] Then, the signal light is chopped based on the semiconductor optical amplifier 5. The semiconductor optical amplifier 5 can form a detection pulse light with a narrow linewidth and a high extinction ratio. The extinction ratio is generally above 50dB. When combined with a high-performance electrical drive, the extinction ratio can reach 70dB.

[0064] Therefore, the semiconductor optical amplifier 5 can generate a detection pulse light with a narrow linewidth and a high extinction ratio.

[0065] Finally, the sensing fiber 7 contains different scattering mechanisms, mainly Rayleigh scattering, Brillouin scattering and Raman scattering.

[0066] Furthermore, in the integrated distributed optical fiber sensing system 100A according to the first embodiment of the present invention, such as Figure 1 As shown, the injection locking unit 3 and the coherent detection unit 4 are integrated on-chip using a silicon photonic integrated chip with silicon as the substrate material, thereby obtaining the on-chip integrated unit 10a.

[0067] However, the substrate material of the on-chip integrated unit 10a involved in the first embodiment of the present invention is not limited to silicon, but can be any one of silicon, lithium niobate, and lithium tantalate.

[0068] In addition, the cross-sectional structure of the waveguide material of the on-chip integrated unit 10a according to the first embodiment of the present invention is strip-shaped or ridge-shaped.

[0069] As described above, the integrated distributed optical fiber sensing system 100A according to the first embodiment of the present invention achieves the integration of the distributed optical fiber sensing system by integrating the injection locking unit 3 and the coherent detection unit 4 on-chip to obtain the on-chip integrated unit 10a.

[0070] Figure 2 This is a schematic diagram illustrating a specific structural example of the integrated distributed optical fiber sensing system according to the first embodiment of the present invention. Below, refer to Figure 2 The specific structure of the integrated distributed optical fiber sensing system 100A according to the first embodiment of the present invention will be described in detail. <Detailed Structure of Injection Locking Unit 3>

[0071] First, regarding the specific structure of the injection locking unit 3 in the integrated distributed optical fiber sensing system 100A according to the first embodiment of the present invention, the injection locking unit 3 further includes: a first optical beam splitter 311, an optical modulator 32, an adjustable optical attenuator 33, and a second optical beam splitter 312.

[0072] Specifically, such as Figure 2 As shown, after the on-chip integrated laser 1 sends a narrow-linewidth laser beam to the injection locking unit 3, the narrow-linewidth laser beam is input to the first optical beam splitter 311. The first optical beam splitter 311 splits the received narrow-linewidth laser beam into a reference beam and a local oscillator beam according to a fixed beam splitting ratio. Then, the reference beam is input to the optical modulator 32 and the local oscillator beam is input to the coherent detection unit 4. In the optical modulator 32, the reference beam received from the first optical beam splitter 311 is modulated into multi-order sideband light, and then the generated multi-order sideband light is output to the tunable optical attenuator 33. In the tunable optical attenuator 33, the power of the multi-order sideband light received from the optical modulator 3 is adjusted, and the power-adjusted multi-order sideband light is output to the second optical beam splitter 312. In the second optical beam splitter 312, the multi-order sideband light after power adjustment is output to the distributed feedback laser 2. Then, the distributed feedback laser 2 generates signal light based on the multi-order sideband light after power adjustment, and then outputs the signal light to the semiconductor optical amplifier 5 through the second optical beam splitter 312.

[0073] Specifically, by changing the frequency of the radio frequency signal loaded onto the optical modulator 32, the spacing of the spectral sidebands of the multi-order sideband light is changed.

[0074] Therefore, in the integrated distributed optical fiber sensing system 100A according to the first embodiment of the present invention, the injection-locking unit 3 is constructed by using a first optical beam splitter 311, an optical modulator 32, an adjustable optical attenuator 33, and a second optical beam splitter 312. Thus, the injection-locking unit 3 uses injection-locking technology to achieve frequency shifting with the signal light, and the output characteristics of the injection-locking technology itself can also ensure that the output power is not affected by the devices in the locking loop, such as the electro-optic modulator and the adjustable optical attenuator, thereby obtaining a high-power and stable local oscillator output.

[0075] Furthermore, in the integrated distributed optical fiber sensing system 100A according to the first embodiment of the present invention, the large bandwidth and high modulation efficiency of a silicon photoelectric modulator such as optical modulator 32 are utilized, thereby enabling the generation of high-performance modulation sidebands.

[0076] This invention is not limited to silicon photonics integration technology, but can also be optoelectronic integration technologies such as lithium niobate photonics integration technology and lithium tantalate photonics integration technology. <Detailed Structure of Coherent Detection Unit 4>

[0077] Secondly, regarding the specific structure of the coherent detection unit 4 in the integrated distributed optical fiber sensing system 100A according to the first embodiment of the present invention, the coherent detection unit 4 further includes: an optical polarization beam splitter rotator 41, a third optical beam splitter 42, a first optical coupler 431, a second optical coupler 432, a first photoelectric balance detector 441, and a second photoelectric balance detector 442.

[0078] Specifically, such as Figure 2As shown, in the coherent detection unit 4, after receiving scattered light from the third port 6c of the optical circulator 6, the scattered light is input to the optical polarization beam splitter rotator 41. The optical polarization beam splitter rotator 41 performs polarization separation on the received scattered light to generate first TE polarized light and TM polarized light, and rotates the TM polarized light into second TE polarized light. The first TE polarized light is then input to the first optical coupler 431, and the second TE polarized light is input to the second optical coupler 432. Moreover, after the local oscillator light is input to the coherent detection unit 4 from the first optical beam splitter 311 in the injection locking unit 3, the local oscillator light is input to the third optical beam splitter 42. The third optical beam splitter 42 separates the received local oscillator light into first TE local oscillator light and second TE local oscillator light. The first TE local oscillator light is then input to the first optical coupler 431, and the second TE local oscillator light is input to the second optical coupler 432. After receiving the first TE local oscillator light and the first TE polarized light, the first optical coupler 431 couples them together to obtain a first coupled light, which is then input to the first photoelectric balance detector 441. After receiving the second TE local oscillator light and the second TE polarized light, the second optical coupler 432 couples them together to obtain a second coupled light, which is then input to the second photoelectric balance detector 442. In the first photoelectric balance detector 441, the first coupled light received from the first optical coupler 431 is converted into an electrical signal for coherent demodulation. In the second photoelectric balance detector 442, the second coupled light received from the second optical coupler 432 is converted into an electrical signal for coherent demodulation.

[0079] Therefore, in the integrated distributed optical fiber sensing system 100A according to the first embodiment of the present invention, a coherent detection unit 4 is constructed using an optical polarization beam splitter rotator 41, a third optical beam splitter 42, a first optical coupler 431, a second optical coupler 432, a first photoelectric balance detector 441, and a second photoelectric balance detector 442. Based on the coherent detection unit 4, signal demodulation is performed, and the difference frequency component is obtained by mixing the local oscillator light and the signal light. Then, the signal in the optical path is obtained by detecting the intensity information of the two beams of light, the local oscillator light and the signal light. This not only improves the conversion gain and enhances the detection capability, but also has a higher signal-to-noise ratio.

[0080] Figure 3 This is a schematic diagram illustrating a specific structural example of an integrated distributed optical fiber sensing system according to a first variation of the first embodiment of the present invention. Below, refer to Figure 3 This section provides a detailed structural example of the integrated distributed optical fiber sensing system 100A' according to a first modification of the first embodiment of the present invention. Only the differences between the integrated distributed optical fiber sensor 100A' and the integrated distributed optical fiber sensor 100A will be explained.

[0081] like Figure 3 As shown, compared to the integrated distributed fiber optic sensor 100A, the integrated distributed fiber optic sensing system 100A' according to the first variation of the first embodiment of the present invention further integrates a first mode-spot converter 81, a second mode-spot converter 82, a third mode-spot converter 83, and a fourth mode-spot converter 84. Thus, the on-chip integrated laser 1 and the injection locking unit 3 can be coupled through the first mode-spot converter 81 integrated on the on-chip integrated unit 10a', the distributed feedback laser 2 and the injection locking unit 3 can be coupled through the second mode-spot converter 82 integrated on the on-chip integrated unit 10a', the injection locking unit 3 and the semiconductor optical amplifier 5 can be coupled through the third mode-spot converter 83 integrated on the on-chip integrated unit 10a', and the coherent detection unit 4 and the optical circulator 6 can be coupled through the fourth mode-spot converter 84 integrated on the on-chip integrated unit 10a'.

[0082] In addition, Figure 3 Although the illustration shows a case where the first mode spot converter 81, the second mode spot converter 82, the third mode spot converter 83, and the fourth mode spot converter 84 are simultaneously integrated on the on-chip integrated unit 10a', the present invention is not limited to this. It is sufficient to provide at least one of the first mode spot converter 81, the second mode spot converter 82, the third mode spot converter 83, and the fourth mode spot converter 84.

[0083] Furthermore, the first mode-spot converter 81 can be integrated into the on-chip integrated unit 10a', or even directly integrated into the injection locking unit 3. Similarly, the second mode-spot converter 82 can be integrated into the on-chip integrated unit 10a', or even directly integrated into the injection locking unit 3; the third mode-spot converter 83 can be integrated into the on-chip integrated unit 10a', or even directly integrated into the injection locking unit 3; and the fourth mode-spot converter 84 can be integrated into the on-chip integrated unit 10a', or even directly integrated into the coherent detection unit 4.

[0084] As mentioned above, in optical fiber communication systems, mode converters can be used to improve the quality and efficiency of optical signal transmission, and can adjust and optimize the beam pattern to better adapt to the transmission conditions in the optical fiber, thereby improving the performance and stability of the communication system.

[0085] Therefore, in the integrated distributed optical fiber sensing system 100A' of the first modified example according to the first embodiment of the present invention, by providing at least one of the first mode converter 81, the second mode converter 82, the third mode converter 83, and the fourth mode converter 84, the transmission quality and efficiency of optical signals in the optical fiber communication system can be improved.

[0086] Figure 4 This is a schematic diagram illustrating a specific structural example of an integrated distributed optical fiber sensing system according to a second variation of the first embodiment of the present invention. Below, refer to Figure 4 This section provides a detailed structural example of the integrated distributed optical fiber sensing system 100A according to the second variation of the first embodiment of the present invention. Only the differences between the integrated distributed optical fiber sensor 100A and the integrated distributed optical fiber sensor 100A will be explained.

[0087] like Figure 4 As shown, compared to the integrated distributed fiber optic sensor 100A, in the integrated distributed fiber optic sensing system 100A” according to the second variation of the first embodiment of the present invention, a third collimating lens group 9 is separately provided between the injection locking unit 3 and the semiconductor optical amplifier 5, and the third collimating lens group 9 includes a first collimating lens 91 and a second collimating lens 92. Thus, the injection locking unit 3 and the semiconductor optical amplifier 5 are coupled through the third collimating lens group 9, which is separately provided with the on-chip integrated unit 10a”.

[0088] In addition, Figure 4 Although only the third collimating lens group 9 is shown between the injection locking unit 3 and the semiconductor optical amplifier 5, the present invention is not limited to this. The on-chip integrated laser 1 and the injection locking unit 3 can also be coupled through a first collimating lens group (not shown) separately from the on-chip integrated unit 10a”. Alternatively, the distributed feedback laser 2 and the injection locking unit 3 can be coupled through a second collimating lens group (not shown) separately from the on-chip integrated unit 10a”. Or, the semiconductor optical amplifier 5 and the optical circulator 6 can be coupled through a fourth collimating lens group (not shown) separately from the on-chip integrated unit 10a”.

[0089] As mentioned above, in optical fiber communication systems, collimating lens groups can also be used to improve the quality and efficiency of optical signal transmission, and can adjust and optimize the beam pattern to better adapt to the transmission conditions in the optical fiber, thereby improving the performance and stability of the communication system.

[0090] Therefore, in the integrated distributed optical fiber sensing system 100A” according to the second variation of the first embodiment of the present invention, by providing at least one of the first collimating lens group (not shown), the second collimating lens group (not shown), the third collimating lens group 9 and the fourth collimating lens group (not shown), the transmission quality and efficiency of optical signals in the optical fiber communication system can also be improved. Second Implementation Method <Overall Structure of the Integrated Distributed Fiber Optic Sensing System 100B>

[0091] Figure 5 This is a schematic diagram illustrating an example of the overall structure of an integrated distributed optical fiber sensing system according to the second embodiment of the present invention. Below, refer to Figure 5 This section provides a detailed structural example of the integrated distributed optical fiber sensing system 100B according to the second embodiment of the present invention. Only the differences between the integrated distributed optical fiber sensor 100B and the integrated distributed optical fiber sensor 100A are described.

[0092] and Figure 1 In comparison, such as Figure 5 As shown, the on-chip integrated laser 1 is further integrated on the on-chip integrated unit 10b, thereby obtaining the integrated distributed fiber optic sensing system 100B.

[0093] As described above, the integrated distributed fiber optic sensing system 100B according to the second embodiment of the present invention can further improve the integration level of the integrated distributed fiber optic sensor system 100B by further integrating the on-chip integrated laser 1 on the on-chip integrated unit 10b. Third Implementation Method <Overall Structure of the Integrated Distributed Fiber Optic Sensing System 100C>

[0094] Figure 6 This is a schematic diagram illustrating an example of the overall structure of an integrated distributed optical fiber sensing system according to the third embodiment of the present invention. Below, refer to Figure 6 This section provides a detailed structural example of the integrated distributed optical fiber sensing system 100C according to the third embodiment of the present invention. Only the differences between the integrated distributed optical fiber sensor 100C and the integrated distributed optical fiber sensor 100A are described.

[0095] and Figure 1 In comparison, such as Figure 6 As shown, the distributed feedback laser 2 is further integrated on the on-chip integrated unit 10c, thereby obtaining the integrated distributed fiber optic sensing system 100C.

[0096] As described above, the integrated distributed fiber optic sensing system 100C according to the third embodiment of the present invention can further improve the integration level of the integrated distributed fiber optic sensor system 100C by further integrating the distributed feedback laser 2 on the on-chip integration unit 10c. Fourth Implementation Method <Overall Structure of the 100D Integrated Distributed Fiber Optic Sensing System>

[0097] Figure 7 This is a schematic diagram illustrating an example of the overall structure of an integrated distributed optical fiber sensing system according to the fourth embodiment of the present invention. Below, refer to Figure 7 This section provides a detailed structural example of the integrated distributed optical fiber sensing system 100D according to the fourth embodiment of the present invention. Only the differences between the integrated distributed optical fiber sensor 100D and the integrated distributed optical fiber sensor 100A are described.

[0098] and Figure 1 In comparison, such as Figure 7 As shown, on the on-chip integrated unit 10d, the semiconductor optical amplifier 5 is further integrated on-chip, thereby obtaining the integrated distributed optical fiber sensing system 100D.

[0099] As described above, the integrated distributed optical fiber sensing system 100D according to the fourth embodiment of the present invention can further improve the integration level of the integrated distributed optical fiber sensor system 100D by further integrating the semiconductor optical amplifier 5 on the on-chip integration unit 10d. Fifth Implementation Method <Overall Structure of the 100E Integrated Distributed Fiber Optic Sensing System>

[0100] Figure 8 This is a schematic diagram illustrating an example of the overall structure of an integrated distributed optical fiber sensing system according to the fifth embodiment of the present invention. Below, refer to Figure 8 This document provides a detailed structural example of the integrated distributed optical fiber sensing system 100E according to the fifth embodiment of the present invention. Only the differences between the integrated distributed optical fiber sensor 100E and the integrated distributed optical fiber sensor 100A are described.

[0101] and Figure 1 In comparison, such as Figure 8 As shown, on the on-chip integrated unit 10e, the on-chip integrated laser 1 and the distributed feedback laser 2 are further integrated on-chip, thereby obtaining the integrated distributed fiber optic sensing system 100E.

[0102] As described above, the integrated distributed fiber optic sensing system 100E according to the fifth embodiment of the present invention can further improve the integration level of the integrated distributed fiber optic sensor system 100E by further integrating the on-chip integrated laser 1 and the distributed feedback laser 2 on the on-chip integrated unit 10e. Sixth Implementation Method <Overall Structure of the 100F Integrated Distributed Fiber Optic Sensing System>

[0103] Figure 9 This is a schematic diagram illustrating an example of the overall structure of an integrated distributed optical fiber sensing system according to the sixth embodiment of the present invention. Below, refer to Figure 9 This document provides a detailed structural example of the integrated distributed optical fiber sensing system 100F according to the sixth embodiment of the present invention. Only the differences between the integrated distributed optical fiber sensor 100F and the integrated distributed optical fiber sensor 100A are described.

[0104] and Figure 1 In comparison, such as Figure 9 As shown, on the on-chip integrated unit 10f, the on-chip integrated laser 1, the distributed feedback laser 2 and the semiconductor optical amplifier 5 are further integrated on the chip, thereby obtaining the integrated distributed fiber optic sensing system 100E.

[0105] As described above, the integrated distributed fiber optic sensing system 100F according to the sixth embodiment of the present invention can further improve the integration level of the integrated distributed fiber optic sensor system 100F by further integrating the on-chip integrated laser 1, the distributed feedback laser 2 and the semiconductor optical amplifier on the on-chip integrated unit 10f.

[0106] As described above, several integration methods of the present invention have been explained based on the second to sixth embodiments, but the present invention is not limited thereto. It is possible to integrate at least one of the on-chip laser 1, the distributed feedback laser 2, and the semiconductor optical amplifier 5 on a chip-to-chip integration unit using heterogeneous integration or monolithic integration methods.

[0107] Furthermore, in the integrated distributed optical fiber sensing systems 100B to 100F according to the second to sixth embodiments of the present invention, the substrate material of the on-chip integrated unit 10b to on-chip integrated unit 10f is not limited to silicon, but can be any one of silicon, lithium niobate, and lithium tantalate.

[0108] Furthermore, in the integrated distributed optical fiber sensing systems 100B to 100F according to the second to sixth embodiments of the present invention, coupling can also be achieved on the on-chip integrated units 10b to 10f by providing at least one of the first mode-spot converter 81, the second mode-spot converter 82, the third mode-spot converter 83, and the fourth mode-spot converter 84. This allows for adjustment and optimization of the beam mode to better adapt to the transmission conditions in the optical fiber, thereby improving the performance and stability of the communication system.

[0109] In summary, the integrated distributed fiber optic sensing system of the present invention utilizes integration technologies such as silicon photonics integration technology and optoelectronic chips such as silicon photonics chips to realize an integrated distributed fiber optic sensing system based on injection-locking technology. This integrated distributed fiber optic sensing system has high system integration and low overall power consumption, which can significantly reduce the system size and power consumption. Silicon photonics chips can be mass-produced, further reducing the system's production cost. Moreover, due to the narrow linewidth and high frequency stability of the laser source based on injection-locking technology, high signal-to-noise ratio signal sensing can also be achieved. Industrial practicality

[0110] This invention is particularly applicable to integrated distributed fiber optic sensing systems based on injection locking, obtained by on-chip integration of discrete devices in distributed fiber optic sensing systems. Label Explanation

[0111] 1. On-chip integrated laser; 2. Distributed feedback laser; 3. Injection-locked unit; 311. First optical beamsplitter; 312. Second optical beamsplitter; 32. Optical modulator; 33. Adjustable optical attenuator; 4. Coherent detection unit; 41. Optical polarization beam rotator; 42. Third optical beamsplitter; 431. First optical coupler; 432. Second optical coupler; 441. First photoelectric balanced detector; 442. Second photoelectric balanced detector; 5. Semiconductor optical amplifier; 6. Optical circulator; 6a. First port; 6b. Second port; 6c. Third port; 7. Sensing fiber; 81. First mode converter; 82. Second mode converter; 83. Third mode converter; 84. Fourth mode converter; 9. Third collimating lens group; 91. First collimating lens. 92 Second collimating lens, 10a, 10a', 10a”, 10b, 10c, 10d, 10e, 10f on-chip integrated units, 100A, 100A', 100A”, 100B, 100C, 100D, 100E, 100F Integrated Distributed Fiber Optic Sensing System.

Claims

1. An integrated distributed optical fiber sensing system, characterized in that, have: An on-chip integrated laser, wherein the on-chip integrated laser outputs a narrow linewidth laser; An injection locking unit receives the narrow linewidth laser and outputs a multi-order sideband spectrum and a local oscillator beam; A distributed feedback laser, wherein the distributed feedback laser generates a signal light with a certain frequency shift from the local oscillator light based on the multi-order sideband spectrum received from the injection locking unit, and inputs the signal light to the injection locking unit; A semiconductor optical amplifier receives the signal light from the injection-locking unit and chops the signal light into pulsed light; An optical circulator, having a first port, a second port, and a third port, wherein the first port is connected to the semiconductor optical amplifier and receives the pulsed light; A sensing fiber receives the pulsed light from the second port and inputs the resulting scattered light to the third port; as well as A coherent detection unit receives the local oscillator light from the injection-locking unit and the scattered light from the third port, and performs coherent demodulation on the local oscillator light and the scattered light to obtain the optical path information of the sensing fiber. An on-chip integrated unit is obtained by on-chip integration of the injection locking unit and the coherent detection unit.

2. The integrated distributed optical fiber sensing system as described in claim 1, characterized in that, The injection locking unit has: A first optical beam splitter splits the narrow-linewidth laser received from the on-chip integrated laser into a reference beam and the local oscillator signal according to a fixed beam splitting ratio. An optical modulator that modulates the reference light received from the first optical beamsplitter into the multi-order sideband light; A tunable optical attenuator that adjusts the power of the received multi-order sideband light; as well as The second optical beam splitter inputs the power-adjusted multi-order sideband light to the distributed feedback laser and outputs the signal light input from the distributed feedback laser to the semiconductor optical amplifier.

3. The integrated distributed optical fiber sensing system as described in claim 1, characterized in that, The coherent detection unit has: An optical polarization beam splitter / rotator separates the received scattered light into first TE-polarized light and TM-polarized light, and then rotates the TM-polarized light into second TE-polarized light. The third optical beam splitter receives the local oscillator light and splits it into a first TE local oscillator light and a second TE local oscillator light. The first optical coupler receives the first TE local oscillator light and the first TE polarized light and couples them to obtain the first coupled light. The second optical coupler receives the second TE local oscillator light and the second TE polarized light and couples them to obtain the second coupled light. A first photoelectric balance detector receives the first coupled light and converts it into an electrical signal; The second photoelectric balance detector receives the second coupled light and converts it into an electrical signal.

4. The integrated distributed fiber optic sensing system as described in any one of claims 1 to 3, characterized in that, On the on-chip integrated unit, at least one of the on-chip integrated laser, the distributed feedback laser, and the semiconductor optical amplifier is integrated on-chip.

5. The integrated distributed fiber optic sensing system as described in any one of claims 1 to 3, characterized in that, The substrate material of the on-chip integrated unit is any one of silicon, lithium niobate, and lithium tantalate.

6. The integrated distributed fiber optic sensing system as described in any one of claims 1 to 3, characterized in that, The cross-sectional structure of the waveguide material of the on-chip integrated unit is strip-shaped or ridge-shaped.

7. The integrated distributed fiber optic sensing system as described in any one of claims 1 to 3, characterized in that, The on-chip integrated laser is an on-chip integrated narrow linewidth laser.

8. The integrated distributed fiber optic sensing system as described in any one of claims 1 to 3, characterized in that, The on-chip integrated laser and the injection locking unit are coupled through a first mode converter integrated on the on-chip integrated unit, or through a first collimating lens group separately disposed from the on-chip integrated unit.

9. The integrated distributed optical fiber sensing system as described in claim 8, characterized in that, The first pattern converter is integrated into the injection locking unit.

10. The integrated distributed fiber optic sensing system as described in any one of claims 1 to 3, characterized in that, The distributed feedback laser and the injection locking unit are coupled through a second mode converter integrated on the on-chip integrated unit, or through a second collimating lens group separately disposed from the on-chip integrated unit.

11. The integrated distributed optical fiber sensing system as described in claim 10, characterized in that, The second pattern converter is integrated into the injection locking unit.

12. The integrated distributed fiber optic sensing system as described in any one of claims 1 to 3, characterized in that, The injection locking unit and the semiconductor optical amplifier are coupled through a third mode converter integrated on the on-chip integrated unit, or through a third collimating lens group separately disposed from the on-chip integrated unit.

13. The integrated distributed optical fiber sensing system as described in claim 12, characterized in that, The third pattern converter is integrated into the injection locking unit.

14. The integrated distributed fiber optic sensing system as described in any one of claims 1 to 3, characterized in that, The coherent detection unit and the optical circulator are coupled through a fourth mode converter integrated on the on-chip integrated unit.

15. The integrated distributed optical fiber sensing system as described in claim 14, characterized in that, The fourth mode spot converter is integrated into the coherent detection unit.

16. The integrated distributed fiber optic sensing system as described in any one of claims 1 to 3, characterized in that, The semiconductor optical amplifier and the optical circulator are coupled through a fifth mode converter integrated on the on-chip integrated unit, or through a fourth collimating lens group separately disposed from the on-chip integrated unit.

17. The integrated distributed fiber optic sensing system as described in any one of claims 1 to 3, characterized in that, An internal isolator is integrated into the on-chip laser.

18. The integrated distributed fiber optic sensing system as described in any one of claims 1 to 3, characterized in that, An isolator is not integrated inside the distributed feedback laser.

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