Photonic integrated chip, soil and water loss online monitoring device and method

Abstract

The present invention discloses a photonic integrated chip, an online soil and water loss monitoring device, and a method. The photonic integrated chip comprises a substrate, a beam splitter / combiner, a first grating waveguide array, and a second grating waveguide array disposed on the substrate. The beam splitter / combiner splits incident light into a first transmitted light and a first reflected light of equal amplitude. The first grating waveguide array is configured to output light of discrete wavelengths based on the first transmitted light through interference. The beam splitter / combiner is further configured to split the second reflected light into a second transmitted light and a third reflected light of equal amplitude. The second grating waveguide array is configured to output light of discrete wavelengths based on the third reflected light through interference. This invention incorporates integrated photonics into online soil and water loss monitoring, obtaining real-time three-dimensional point cloud images of the ground surface. It has no moving scanning components, is highly reliable, can be mass-produced, and is low-cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of online monitoring of soil and water conservation, and in particular relates to a photon integrated chip, an online soil and water loss monitoring device and a method. Background Art

[0002] The existing traditional soil and water loss monitoring technology mainly relies on manual rod measurement. The manual rod measurement method refers to the regular insertion of several thin rods with scales into the surface of the slope while minimizing surface disturbance as much as possible. The rods are marked to record the original soil layer height. Later, the changes in soil layer height are manually recorded to observe and calculate the amount of soil erosion. The above existing methods are too dependent on manual labor and have defects such as high cost, long monitoring cycle and poor timeliness. They cannot meet the current needs of information and intelligent soil and water conservation monitoring.

[0003] At present, a soil and water loss monitoring technology based on laser radar three-dimensional point cloud imaging has been developed, which can greatly improve the accuracy of soil and water loss monitoring and realize automatic monitoring without manual labor. However, traditional laser radar has a complex optical path, high cost, and contains active scanning components. It has exposed poor reliability problems when used in harsh conditions such as high humidity and low temperature in the field. The large power consumption demand caused by the active components brings difficulties to long-term field applications that require independent power supply. Therefore, there is an urgent need for a fully solid-state soil and water loss measurement device and method with no moving parts and low cost. Summary of the Invention

[0004] The present invention aims to provide a photonic integrated chip, an online soil and water loss monitoring device, and a method to address one or more of the aforementioned technical problems. The technical solution provided by the present invention incorporates integrated photonics into online soil and water loss monitoring, enabling real-time acquisition of three-dimensional point cloud images of the ground surface. The device, which has no moving scanning components, is highly reliable, can be mass-produced, and is low-cost.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a photonic integrated chip, comprising: a substrate, and a beam splitter / combiner, a first grating waveguide array, and a second grating waveguide array provided on the substrate; wherein the beam splitter / combiner is connected to a first waveguide, a second waveguide, and a third waveguide;

[0007] The first waveguide is used to guide the incident light of the broadband light source into the beam splitter / combiner; the beam splitter / combiner splits the introduced incident light into a first transmitted light and a first reflected light of equal amplitude; the second waveguide is used to guide the first transmitted light into the first grating waveguide array; the first grating waveguide array is used to output light of discrete wavelengths through interference based on the first transmitted light guided by the second waveguide;

[0008] The first grating waveguide array is further used to receive second reflected light based on the light of the discrete wavelength; the second waveguide is further used to introduce the second reflected light into the beam splitter / combiner; the beam splitter / combiner is further used to split the introduced second reflected light into a second transmitted light and a third reflected light of equal amplitude; the third waveguide is used to introduce the third reflected light into the second grating waveguide array; the second grating waveguide array is used to output light of discrete wavelengths through interference based on the third reflected light introduced by the third waveguide.

[0009] A further improvement of the present invention is that the substrate is a silicon substrate.

[0010] A further improvement of the present invention is that the first grating waveguide array and the second grating waveguide array are both composed of a series of waveguides of different lengths; wherein the input light can be coupled into all waveguides at the same time, and the phase delay φ of each waveguide is

[0011] Where L is the waveguide length, n is the effective refractive index of the waveguide, and λ is the average wavelength of light.

[0012] A further improvement of the present invention is that the first waveguide, the second waveguide, the third waveguide and the waveguides in the first grating waveguide array and the second grating waveguide array are all single-mode waveguides made of silicon nitride or doped silicon dioxide.

[0013] A further improvement of the present invention is that it also includes:

[0014] A broad-spectrum light source is used to emit the incident light.

[0015] A further improvement of the present invention is that the broadband light source is a superluminescent diode or a spontaneous amplification radiation light source.

[0016] The present invention provides an online monitoring device for soil and water loss, comprising: a broadband light source, a first lens, a second lens, a linear array CCD, and the above-mentioned photon integrated chip of the present invention;

[0017] The broadband light source is used to emit incident light;

[0018] The photonic integrated chip is used to introduce the incident light emitted by the broadband light source and output light of a first discrete wavelength;

[0019] The first lens is used to converge the light of the first discrete wavelength and direct it into the ground to be measured; the first lens is also used to receive ground-reflected light based on the light of the first discrete wavelength, converge it, and direct it into the photonic integrated chip; the photonic integrated chip is also used to direct the ground-reflected light and output light of a second discrete wavelength;

[0020] The second lens is used to converge the light of the second discrete wavelength and make it incident on different sensitive array elements of the linear array CCD.

[0021] A further improvement of the present invention is that both the first lens and the second lens are cylindrical lenses.

[0022] The present invention provides an online soil and water loss monitoring method, comprising the following steps:

[0023] Using a broadband light source to interface and couple with the above-mentioned photonic integrated chip of the present invention;

[0024] After light is coupled into the first waveguide, it is split into two beams by the beam splitter / combiner, and the transmitted light is introduced into the first grating waveguide array;

[0025] Based on the first grating waveguide array, the broad spectrum light is decomposed into narrow spectrum components, and the components of different wavelengths are emitted from different spatial positions; the emitted light is collimated by a lens and then incident on different positions on the surface of the earth in the form of parallel light;

[0026] The light reflected from the ground is collimated by a lens and returns to the first grating waveguide array. The different wavelength components are then reflected by the beam splitter and combiner and enter the grating of the second grating waveguide array. The wavelength components are spatially separated and collimated by a lens before being incident on different sensitive elements of the linear array CCD. The light responses at different positions on the linear array CCD represent the responses of light of different wavelengths.

[0027] The broadband light source is driven in a pulse mode, the response time of different CCD elements is recorded, and the transit time of light of different wavelengths in space is calculated;

[0028] Different wavelengths represent different locations on the earth's surface in space. The distance s between different locations on the earth's surface and the output port of the first grating waveguide array in the photonic integrated chip is calculated as follows:

[0029] s=vt / 2;

[0030] Where v is the speed of light, t is the transit time;

[0031] Based on the obtained distance s, the surface undulations at different locations are obtained to obtain the monitoring results.

[0032] A further improvement of the present invention is that the surface undulations at different locations are represented by three-dimensional laser point clouds.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] To address the poor reliability and high power consumption of traditional LiDAR scanning components, which hinder long-term field use, this invention integrates a complex optical path onto a photonic chip. This utilizes wavelength division to achieve spatial separation of laser detection and records the flight times of different laser components of the same wavelength, enabling long-term, automatic monitoring of surface undulations. This invention eliminates the need for active scanning components, enabling online soil and water loss monitoring in a fully solid-state, low-cost manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art; obviously, the drawings described below are some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 Schematic diagram of a multi-wavelength multiplexing photonic integrated chip for soil and water loss monitoring provided by an embodiment of the present invention;

[0037] Figure 2 1 is a typical spectrum diagram in an embodiment of the present invention;

[0038] Figure 3 1 is a schematic diagram of the response time sequence of different elements of a CCD (charge coupled device) in an embodiment of the present invention;

[0039] In the figure, 1. Broad-spectrum light source; 2. Beam splitter / combiner; 3. First grating waveguide array; 4. First lens; 5. Second grating waveguide array; 6. Second lens; 7. Linear array CCD. DETAILED DESCRIPTION

[0040] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0041] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0042] The present invention is described in further detail below with reference to the accompanying drawings:

[0043] See also Figure 1 The embodiment of the present invention provides a multi-wavelength multiplexing photonic integrated chip for soil and water loss monitoring. The integrated photonic chip can be used for online soil and water loss monitoring. The integrated photonic chip includes a substrate, which can be a silicon substrate; a beam splitter / combiner 2, a first grating waveguide array 3, and a second grating waveguide array 5 are provided on the substrate;

[0044] The beam splitter / combiner 2 is provided with an input waveguide, a first output waveguide and a second output waveguide; the input waveguide is used to introduce the incident light of the external broadband light source 1 into the beam splitter / combiner 2, and divide the light into two beams of equal amplitude; the transmitted light is introduced into the first grating waveguide array 3 through the first output waveguide, and light of discrete wavelengths is output based on interference; when in use, the light of discrete wavelengths is converged by the first lens 4 and then incident on the ground; the ground reflected light of the discrete wavelength light is sequentially reflected by the first lens 4, the first grating waveguide array 3, the beam splitter / combiner 2, and the second grating waveguide array 5, and then incident on the linear array CCD 7 through the second lens 6.

[0045] In the embodiment of the present invention, the first grating waveguide array 3 and the second grating waveguide array 5 are both composed of a series of waveguides of different lengths; wherein the input light is coupled into all waveguides simultaneously, and the phase delay φ of each waveguide is,

[0046]

[0047] Where L is the waveguide length, n is the effective refractive index of the waveguide, and λ is the average wavelength of the incident light;

[0048] As can be seen from the phase delay expression, the phase delay of each waveguide varies due to its length. In the embodiment of the present invention, at the output port of the first grating waveguide array 3 or the second grating waveguide array 5, the waveguide output lights interfere with each other. Due to the different phase delays, the spatial positions where the coherence of light of different wavelengths is extremely strong are different, thereby achieving the effect of spatially separating the broadband light according to its wavelength components.

[0049] In an embodiment of the present invention, the waveguide is made of silicon nitride or doped silicon dioxide, and the waveguide and various devices are covered with a silicon dioxide protective layer. A single-mode waveguide is used, and the refractive index and waveguide width of the waveguide layer are controlled to control the mode of the waveguide so that it satisfies single-mode transmission. A mode converter is designed in the coupling part with the light source to match the mode of the waveguide with the mode of the light source, thereby reducing coupling loss.

[0050] The monitoring principle of the embodiment of the present invention is to use a photonic integrated chip to wavelength-division multiplex a wide-spectrum light source, operate light of different wavelengths to be incident on different positions on the ground plane and reflected back to the optical chip, and control the reflected light of different wavelengths to be incident on different photosensitive units of the linear array CCD. Due to the ups and downs of the ground, the time it takes for the reflected light at different positions on the ground (corresponding to different wavelengths of light) to reach the linear array CCD is different, so that a three-dimensional point cloud reflecting the ups and downs of the ground can be drawn, realizing real-time monitoring of soil and water loss.

[0051] The application scheme of the multi-wavelength multiplexing photonic integrated chip for soil and water loss monitoring provided in the embodiment of the present invention is used in an online soil and water loss monitoring device, including:

[0052] A broadband light source 1 is directly coupled to the photonic integrated chip. The spectrum width of the light source should cover all working wavelengths. The typical spectrum is as follows: Figure 2 As shown, it should generally be greater than 20nm;

[0053] After light is coupled into the waveguide, it is split into two beams by the beam splitter. The forward light enters the first grating waveguide array 3. After passing through the first grating waveguide array 3, the broad spectrum light is decomposed into narrow spectrum components, such as λ1, λ2, λ3, etc., and components of different wavelengths are emitted from different spatial positions.

[0054] The outgoing light is collimated by the cylindrical lens and incident on different positions of the ground surface in the form of parallel light; it is reflected by the ground surface and collimated by the cylindrical lens back to the first grating waveguide array 3;

[0055] The different wavelength components are then reflected by the beam splitter / combiner 2 and enter the grating of the second grating waveguide array 5. The wavelength components are spatially separated and, after being collimated by the second lens 6 (which can be a cylindrical lens), are incident on different sensitive array elements of the linear array CCD 7. The light responses at different positions of the linear array CCD 7 represent the responses of light of different wavelengths. Since the light delay of each channel of the all-solid-state chip is constant, the time it takes for light to travel through the chip can be calibrated to eliminate inconsistencies between channels.

[0056] The light source is driven in pulse mode and the response time of different CCD elements is recorded, such as Figure 3 As shown in the figure, the transit time (t) of light of different wavelengths in space is calculated. Different wavelengths represent different positions on the earth's surface in space. The distance (s) from different positions on the earth's surface to the chip's output port can be calculated as follows:

[0057] s=vt / 2;

[0058] Where V is the speed of light.

[0059] This allows the measurement of surface undulations at different locations, which are generally represented by three-dimensional laser point clouds. When this distance (undulation) changes, it means that soil erosion has occurred, and the amount of soil erosion in the measurement area can be quantified based on the specific change value.

[0060] In a specific embodiment of the present invention, the light source may be a broad-spectrum light source such as SLED or ASE, and may operate at multiple wavelengths such as 850 nm, 1060 nm, 1310 nm, and 1550 nm.

[0061] An embodiment of the present invention provides a photonic integrated chip for online monitoring of soil erosion. The chip integrates optical devices such as a mode converter, a beam splitter, and a waveguide array grating on a silicon substrate to form an integrated photonic chip. A broadband light source such as an SLD is directly coupled to the chip. A waveguide array grating is used to separate the different wavelength components of the broadband light source. A lens system is designed to project the separated monochromatic light onto different locations on the surface plane. The reflected light of the different wavelength components is incident on different photosensitive units of a linear array CCD through a waveguide array, thereby measuring the light transmission time at different locations on the surface and calculating the amount of surface soil erosion.

[0062] In this embodiment of the present invention, a photonic chip specifically designed for soil erosion monitoring is coupled and co-sealed with a light source, lens, linear array CCD, and other components to form a complete and unified photonic device specifically designed for online soil erosion monitoring. This technical solution, provided by this embodiment of the present invention, utilizes wavelength division multiplexing (WDM) to achieve multi-point simultaneous detection and acquisition of a three-dimensional point cloud using a single light source without mechanical scanning components, significantly improving system reliability. This photonic integrated chip utilizes a multi-layer photolithography process for large-scale mass production, significantly improving product consistency and reducing product costs.

[0063] In summary, embodiments of the present invention provide a photonic integrated chip for online soil and water loss monitoring. Based on the soil and water loss measurement function, an integrated optical solution is used to integrate photonic devices such as a spectrometer and a grating waveguide array on a silicon substrate. A broadband light source, a linear array CCD, and a lens system are coupled and co-encapsulated with the photonic chip to form a complete photonic integrated device. This device can separate the laser light emitted by the broadband light source according to wavelength and incident it on the ground surface at different diffraction angles, forming multiple reflection points. The laser light reflected back to the chip is incident on different photosensitive cells of the linear array CCD according to its wavelength component, thereby obtaining the reflection time at different locations on the ground surface and thus the surface elevation changes at different locations. Through point cloud mapping and analysis, the amount of soil and water loss on the ground can be calculated. This invention proposes an all-solid-state, chip-based, multi-beam synchronous measurement solution with no scanning moving parts, high reliability, and high integration. This is the first application of integrated optical technology to online soil and water loss monitoring. Through mature photolithography processes, it can achieve large-scale mass production of soil and water loss monitoring chips, thereby significantly reducing the cost of online soil and water conservation monitoring.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A photonic integrated chip, characterized in that: include: A substrate and a beam splitter / combiner (2), a first grating waveguide array (3), and a second grating waveguide array (5) arranged on the substrate; wherein the beam splitter / combiner (2) is connected to a first waveguide, a second waveguide, and a third waveguide; The first waveguide is used to guide the incident light of the broadband light source (1) into the beam splitter / combiner (2); the beam splitter / combiner (2) divides the introduced incident light into a first transmitted light and a first reflected light of equal amplitude; the second waveguide is used to guide the first transmitted light into the first grating waveguide array (3); the first grating waveguide array (3) is used to output light of discrete wavelengths through interference based on the first transmitted light introduced by the second waveguide; The first grating waveguide array (3) is further used to receive second reflected light based on the light of the discrete wavelength; the second waveguide is further used to introduce the second reflected light into the beam splitter / combiner (2); the beam splitter / combiner (2) is further used to split the introduced second reflected light into a second transmitted light and a third reflected light of equal amplitude; the third waveguide is used to introduce the third reflected light into the second grating waveguide array (5); and the second grating waveguide array (5) is used to output light of discrete wavelengths through interference based on the third reflected light introduced by the third waveguide.

2. The photonic integrated chip according to claim 1, characterized in that: The substrate is a silicon substrate.

3. The photonic integrated chip according to claim 1, characterized in that: The first grating waveguide array (3) and the second grating waveguide array (5) are both composed of a series of waveguides of different lengths; wherein the input light can be coupled into all waveguides at the same time, and the phase delay φ of each waveguide is Where L is the waveguide length, n is the effective refractive index of the waveguide, and λ is the average wavelength of light.

4. The photonic integrated chip according to claim 3, characterized in that: The first waveguide, the second waveguide, the third waveguide, and the waveguides in the first grating waveguide array (3) and the second grating waveguide array (5) are all single-mode waveguides made of silicon nitride or doped silicon dioxide.

5. The photonic integrated chip according to claim 1, characterized in that: Also includes: A broadband light source (1) is used for emitting the incident light.

6. The photonic integrated chip according to claim 5, characterized in that: The broadband light source (1) is a superluminescent diode or a spontaneously amplified radiation light source.

7. An online monitoring device for soil and water loss, characterized in that: include: A broadband light source (1), a first lens (4), a second lens (6), a linear array CCD (7), and the photonic integrated chip according to claim 1; The broadband light source (1) is used to emit incident light; The photonic integrated chip is used to introduce the incident light emitted by the broadband light source (1) and output light of a first discrete wavelength; The first lens (4) is used to converge the light of the first discrete wavelength and inject it into the ground to be measured; the first lens (4) is also used to receive the ground reflected light based on the light of the first discrete wavelength, and then introduce it into the photonic integrated chip after convergence; the photonic integrated chip is also used to introduce the ground reflected light and output light of a second discrete wavelength; The second lens (6) is used to converge the light of the second discrete wavelength and make it incident on different sensitive array elements of the linear array CCD (7).

8. The online soil and water loss monitoring device according to claim 7, characterized in that: The first lens (4) and the second lens (6) are both cylindrical lenses.

9. A method for online monitoring of soil and water loss, characterized in that: The following steps are involved: Using a broadband light source (1) to couple with the photonic integrated chip according to claim 1; After light is coupled into the first waveguide, it is split into two beams by a beam splitter / combiner (2), and the transmitted light is introduced into the first grating waveguide array (3); Based on the first grating waveguide array (3), the broad spectrum light is decomposed into narrow spectrum components, and the components of different wavelengths are emitted from different spatial positions; the emitted light is collimated by a lens and incident on different positions on the ground in the form of parallel light; The light reflected from the ground surface is collimated by a lens and returns to the first grating waveguide array (3), and the different wavelength components are then reflected by the beam splitter / combiner (2) and enter the grating of the second grating waveguide array (5); the wavelength components are spatially separated, collimated by a lens, and then incident on different sensitive elements of the linear array CCD (7); wherein the light responses at different positions of the linear array CCD (7) represent the responses of light of different wavelengths; The broadband light source (1) is driven in a pulse mode, the response time of different CCD elements is recorded, and the transit time of light of different wavelengths in space is calculated; Different wavelengths represent different positions on the earth's surface in space. The calculation expression for the distance s between different positions on the earth's surface and the output port of the first grating waveguide array (3) in the photonic integrated chip is: s=vt / 2; Where v is the speed of light, t is the transit time; Based on the obtained distance s, the surface undulations at different locations are obtained to obtain the monitoring results.

10. The method for online monitoring of soil and water loss according to claim 9, characterized in that: The surface relief at different locations is represented by a three-dimensional laser point cloud.

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