Raman spectrometer chip based on mach-zehnder interferometer

Abstract

The application provides a Raman spectrometer chip based on Mach-Zehnder interference, which realizes 360-degree turning of the direction of input light and makes the light pass through different lengths of optical paths to realize interference by using the principle of Mach-Zehnder interference and combining twice reflection of first to fourth directional couplers and arrangement modes of the directional couplers, so that the 180-degree bending waveguide is not needed, the chip volume can be effectively reduced, and the cost is reduced; in addition, the spectrometer units based on Mach-Zehnder interference are arranged side by side, so that the image sensor chip can be arranged as a one-dimensional array, the signal-to-noise ratio is improved, and the cost is reduced; furthermore, the compound parabolic concentrator is arranged at the side end surface of the spectrometer chip based on Mach-Zehnder interference, the end surface coupling has no polarization selectivity, and the light spot size is matched with the size of the coupling structure through the condensing effect of the lens, so that the light is focused on the side surface of the chip to enter the spectrometer chip, the light spot enters the chip through the lens, and the light coupling efficiency is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of Raman spectroscopy detection, and in particular to a Raman spectrometer chip based on Mach-Zehnder interferometry. Background Technology

[0002] Raman scattering is an inelastic scattering process. When light shines on a substance, photons are scattered at frequencies different from the excitation light due to the interaction of the vibrations of the molecules. Therefore, different molecules, and even different chemical bonds, have different Raman peak positions. Raman spectroscopy is non-destructive, non-invasive, requires no sample processing, is rich in information, and has high analytical efficiency. As a result, it has been widely used in fields such as biology, chemistry, medicine, food safety, aerospace, and environmental protection.

[0003] However, the emission intensity of Raman scattering itself is very weak; the intensity of a conventional Raman signal is only 10 times that of the incident light intensity. -6 ~10 -12 Detecting Raman signals is extremely difficult; therefore, maximizing the amount of Raman signals received by the instrument has always been a key design consideration for Raman spectroscopy detection instruments. Current mature Raman spectrometer designs are limited by the maximum light throughput allowed by the device structure, making it difficult to receive a sufficient number of signals while maintaining high spectral resolution. This places higher demands on subsequent Raman signal extraction in terms of data processing and fitting algorithms.

[0004] Chip-based Raman spectrometers are very small, enabling miniaturization and portability of spectrometers, and even wearable devices for disease and health management and monitoring. However, there are currently very few, if any, chip-based Raman spectrometer products available, and those that exist suffer from problems such as insufficient size, low light collection efficiency, and low signal-to-noise ratio. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a Raman spectrometer chip based on Mach-Zehnder interferometry to solve the problems of large size, low light collection efficiency and low signal-to-noise ratio of Raman spectrometer chips in the prior art.

[0006] To achieve the above and other related objectives, the present invention provides a Raman spectrometer chip based on Mach-Zehnder interferometry, the Raman spectrometer chip comprising: a package in which the spectrometer chip based on Mach-Zehnder interferometry and an image sensor chip are packaged together, and a composite parabolic condenser lens and a lens mechanically connected to the package;

[0007] The spectrometer chip based on Mach-Zehnder interferometry includes multiple spectrometer units based on Mach-Zehnder interferometry arranged side by side.

[0008] Each of the Mach-Zehnder interferometer-based spectrometer units includes, in sequence, an optical coupling structure, a first 50 / 50 beam splitter, a first directional coupler and a second directional coupler respectively connected to the two output terminals of the first 50 / 50 beam splitter, a third directional coupler and a fourth directional coupler respectively connected to the output terminals of the first directional coupler and the second directional coupler, and a second 50 / 50 beam splitter connected to the output terminals of the third directional coupler and the fourth directional coupler;

[0009] The optical path difference of each of the Mach-Zehnder interferometer-based spectrometer units increases or decreases sequentially along its arrangement direction;

[0010] The first directional coupler, the second directional coupler, the third directional coupler, and the fourth directional coupler are arranged side by side, one above the other; the first directional coupler and the third directional coupler are located above one output end of the first 50 / 50 beam splitter and are staggered left and right, and the second directional coupler and the fourth directional coupler are located below the other output end of the first 50 / 50 beam splitter and are staggered left and right.

[0011] The composite parabolic condenser lens is disposed on the end face of the spectrometer chip based on Mach-Zehnder interferometry, and the input light is coupled into the light coupling structure by the focusing of the lens;

[0012] The image sensor chip is positioned after the output of the second 50 / 50 beam splitter to receive the interference light output by the second 50 / 50 beam splitter.

[0013] Optionally, the optical path difference of each of the Mach-Zehnder interferometer-based spectrometer units increases or decreases arithmetically along its arrangement direction.

[0014] Optionally, the first 50 / 50 beam splitter is a 1×2MMI optical beam splitter or a 50 / 50 coupler.

[0015] Optionally, the first directional coupler, the second directional coupler, the third directional coupler, and the fourth directional coupler are all 50 / 50 directional couplers.

[0016] Optionally, the first directional coupler, the second directional coupler, the third directional coupler, and the fourth directional coupler are all four-port elements, including an input port, an output port, and two reflecting ports equipped with mirrors, with a coupling waveguide region between the four ports.

[0017] Optionally, a filter is also provided behind the composite parabolic condenser to filter out the excitation light introduced into the pre-processor system.

[0018] Optionally, the optical coupling structure includes a coupling waveguide and a wedge waveguide connected in sequence to achieve chip coupling of input light.

[0019] Optionally, the lens is a cylindrical lens.

[0020] Optionally, the image sensor chip is one of a CCD chip, a CMOS image sensor chip, a PD array, a SPAD array, a PMT array, and a SiPM array; the image sensor chip is a one-dimensional array.

[0021] Optionally, the spectrometer chip based on Mach-Zehnder interferometry is formed on a silicon substrate, a silicon nitride substrate, a lithium niobate substrate, or a glass substrate.

[0022] As described above, the Mach-Zehnder interferometer-based Raman spectrometer chip of the present invention achieves a 360° bend in the direction of the input light by using the Mach-Zehnder interferometer principle and combining the two reflections of the first to fourth directional couplers and their arrangement, thus enabling interference through different optical path lengths. This eliminates the need for a 180° bent waveguide, effectively reducing chip size and cost. Furthermore, arranging the Mach-Zehnder interferometer-based spectrometer units side-by-side allows the image sensor chip to be configured as a one-dimensional array, improving the signal-to-noise ratio and reducing cost. Moreover, by placing the composite parabolic condenser lens on the side face of the Mach-Zehnder interferometer-based spectrometer chip, the end-face coupling lacks polarization selectivity. Through the focusing effect of the lens, the spot size matches the size of the coupling structure, allowing all light to be focused onto the side face of the chip and enter the spectrometer chip. The entire light spot enters the chip through the lens, significantly improving the light coupling efficiency. Attached Figure Description

[0023] Figure 1 The diagram shows the structure of the Raman spectrometer chip based on Mach-Zehnder interferometry of the present invention.

[0024] Figure 2 The diagram shows a schematic of the structure of the spectrometer chip based on Mach-Zehnder interferometry of the present invention.

[0025] Figure 3 and Figure 4 The diagram shown is a schematic representation of the Mach-Zehnder interferometer section in the spectrometer unit based on the Mach-Zehnder interferometer of the present invention.

[0026] Figure 5 The diagram shown is a schematic representation of the structure of a first 50 / 50 beam splitter in an example of a Mach-Zehnder interferometer-based spectrometer unit of the present invention.

[0027] Figure 6The diagram shown is a schematic representation of the first 50 / 50 beam splitter, which is another example of a spectrometer unit based on Mach-Zehnder interferometry according to the present invention.

[0028] Figure 7 The diagram shows the structure of the first directional coupler, the second directional coupler, the third directional coupler, and the fourth directional coupler in the spectrometer unit based on Mach-Zehnder interferometry of the present invention.

[0029] Figures 8 to 10 The diagram shows the principle of optical coupling of input light by the first, second, third, and fourth directional couplers in the spectrometer unit based on Mach-Zehnder interferometry of the present invention.

[0030] Component designation explanation

[0031] 10. Spectrometer Chip Based on Mach-Zehnder Interferometry

[0032] 101 Spectrometer Unit Based on Mach-Zehnder Interferometry

[0033] 11 Image sensor chip

[0034] 12. Compound parabolic condenser lens

[0035] 13 Filters

[0036] 14 Lenses

[0037] 15 Optical Coupler Structure

[0038] 151 Coupled Waveguide

[0039] 152 Wedge Waveguide

[0040] 16 First 50 / 50 beam splitter

[0041] 161 50 / 50 Coupler

[0042] 162 1×2MMI optical beam splitter

[0043] 163 Input Terminal

[0044] 164 Output Terminal

[0045] 17 First Directional Coupler

[0046] 18 Second directional coupler

[0047] 19 Third directional coupler

[0048] 20 Fourth directional coupler

[0049] 21 Second 50 / 50 beam splitter

[0050] 22 First Direct Waveguide

[0051] 23 Second Straight Waveguide

[0052] 241 Input Terminal

[0053] 242 Output Terminal

[0054] 243 Reflector end

[0055] 244 Reflector

[0056] 245 Coupled waveguide region Detailed Implementation

[0057] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0058] Please see Figures 1 to 10 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be changed according to actual needs, and the layout of the components may also be more complex.

[0059] like Figures 1 to 7 As shown, this embodiment provides a Raman spectrometer chip based on Mach-Zehnder interferometry, the Raman spectrometer chip comprising:

[0060] like Figure 1 As shown, a package containing a spectrometer chip 10 based on Mach-Zehnder interferometry and an image sensor chip 11, and a composite parabolic condenser lens 12 and a lens 14 mechanically connected to the package;

[0061] like Figure 1 and Figure 2 As shown, the spectrometer chip 10 based on Mach-Zehnder interferometry includes multiple spectrometer units 101 arranged side by side in a vertical arrangement based on Mach-Zehnder interferometry.

[0062] like Figure 2 and Figure 4As shown, each of the Mach-Zehnder interferometer-based spectrometer units 101 includes, in sequence, an optical coupling structure 15, a first 50 / 50 beam splitter 16, a first directional coupler 17 and a second directional coupler 18 connected to the two output terminals of the first 50 / 50 beam splitter 16 respectively, a third directional coupler 19 and a fourth directional coupler 20 connected to the output terminals of the first directional coupler 17 and the second directional coupler 18 respectively, and a second 50 / 50 beam splitter 21 connected to the output terminals of the third directional coupler 19 and the fourth directional coupler 20.

[0063] like Figure 2 As shown, the optical path difference of each of the Mach-Zehnder interferometer-based spectrometer units 101 increases or decreases sequentially along its arrangement direction;

[0064] like Figure 4 As shown, the first directional coupler 17, the second directional coupler 18, the third directional coupler 19, and the fourth directional coupler 20 are arranged side by side, one above the other; the first directional coupler 17 and the third directional coupler 19 are located above one output end of the first 50 / 50 beam splitter 16 and are staggered left and right, while the second directional coupler 18 and the fourth directional coupler 20 are located below the other output end of the first 50 / 50 beam splitter 16 and are staggered left and right.

[0065] like Figure 1 As shown, the composite parabolic condenser lens 12 is disposed on the end face of the spectrometer chip 10 based on Mach-Zehnder interferometry, and the input light is coupled into the light coupling structure 15 by the focusing of the lens 14.

[0066] The image sensor chip 11 is disposed after the output end of the second 50 / 50 beam splitter 16 to receive the interference light output by the second 50 / 50 beam splitter 21.

[0067] The working principle of the Mach-Zehnder interferometer-based Raman spectrometer chip in this embodiment is as follows: A monochromatic pump laser irradiates the sample. After inelastic scattering by the sample, the scattered Raman signal light or fluorescence signal is collected by the composite parabolic condenser lens 12 (CPC condenser lens). The composite parabolic condenser lens 12 converts the light into a collimated beam. The collimated beam is focused by the lens 14 and received by the optical coupling structure 15. The optical coupling structure 15 transmits and performs mode conversion on the Raman signal light or fluorescence signal, allowing the Raman signal light or fluorescence signal to enter the structure of the Mach-Zehnder interferometer in a suitable mode. Figure 3 and Figure 4As shown, the light entering the Mach-Zehnder interferometer is split into two beams of equal intensity by the first 50 / 50 beam splitter 16. These two beams then undergo two reflections by the first directional coupler 17 and the third directional coupler 19, and two reflections by the second directional coupler 18 and the fourth directional coupler 20, respectively, achieving a 360° bend and passing through different optical path lengths. Finally, they merge and interfere in the second 50 / 50 beam splitter 21 and are detected by the image sensor chip 11. After detecting a set of interference intensities, the image sensor chip 11 performs a Fourier transform on it to obtain the spectrum of the measured Raman signal light or fluorescence signal.

[0068] As described above, the Mach-Zehnder interferometer-based Raman spectrometer chip of this embodiment achieves a 360° bend in the direction of the input light by using the Mach-Zehnder interferometer principle and combining the two reflections of the first to fourth directional couplers and their arrangement, thus enabling interference through different optical path lengths. This eliminates the need for a 180° bent waveguide, effectively reducing chip size and cost. Furthermore, arranging the Mach-Zehnder interferometer-based spectrometer units side-by-side allows the image sensor chip to be configured as a one-dimensional array, improving the signal-to-noise ratio and reducing cost. Moreover, by placing the composite parabolic condenser lens on the side face of the Mach-Zehnder interferometer-based spectrometer chip, the end-face coupling lacks polarization selectivity. Through the focusing effect of the lens, the spot size matches the size of the coupling structure, allowing all light to be focused onto the side face of the chip and enter the spectrometer chip. The entire light spot enters the chip through the lens, significantly improving the light coupling efficiency.

[0069] like Figure 7 As shown, the first directional coupler 17, the second directional coupler 18, the third directional coupler 19, and the fourth directional coupler 20 are all four-port elements, including an input port 241, an output port 242, and two reflecting ports 243 equipped with a reflector 244. A coupling waveguide region 245 connects the four ports, allowing the input light to achieve a 180° optical path deflection after passing through its respective directional coupler. Figures 8 to 10 The diagram illustrates the optical coupling process of the first directional coupler 17, the second directional coupler 18, the third directional coupler 19, and the fourth directional coupler 20 to the input light. Specifically: as shown... Figure 8 As shown, input light A enters the directional coupler, and optical coupling is achieved in the coupling waveguide region 245, resulting in beam C and beam B, with a phase difference of 90° between beam C and beam B; Figure 9 As shown, beams C and B become beams D and E respectively after passing through their respective reflectors 244, and the phase difference between beams D and E is 90°. Assume the phase of beam D is 90° and the phase of beam E is 0°. Figure 10As shown, beam D splits into beams D1 and D2 after passing through coupling waveguide region 245. The phase of beam D1 remains unchanged at 90°, while the phase of beam D2 changes to 180°. Beam E splits into beams E1 and E2 after passing through coupling waveguide region 245. The phase of beam E1 remains unchanged at 0°, while the phase of beam E2 changes to 90°. Therefore, beams E1 and D2 have a phase difference of 180° and are coherently destructive, while beams D1 and E2 have a phase difference of 0° and are coherently constructive. Thus, the light achieves a 180° redirection from input to output. Therefore, after passing through two directional couplers, a 360° redirection of the input light can be achieved. As a preferred example, the first directional coupler 17, the second directional coupler 18, the third directional coupler 19, and the fourth directional coupler 20 are all 50 / 50 directional couplers to achieve maximum efficiency output of the input light.

[0070] like Figure 2 As shown, as an example, the optical path difference of each of the Mach-Zehnder interferometer-based spectrometer units 101 can be achieved by setting straight waveguides between the two directional couplers and between the directional couplers and the second 50 / 50 beam splitter. For example, a first straight waveguide 22 is set between the first directional coupler 17 and the third directional coupler 19 and between the third directional coupler 19 and the second 50 / 50 beam splitter 21, and a second straight waveguide 23 is set between the second directional coupler 18 and the fourth directional coupler 20 and between the fourth directional coupler 20 and the second 50 / 50 beam splitter 21, with the distance between the first straight waveguide 22 and the second straight waveguide 23 differing by D, to achieve the optical path difference of each of the Mach-Zehnder interferometer-based spectrometer units 101. As a preferred example, the optical path difference of each of the Mach-Zehnder interferometer-based spectrometer units 101 increases or decreases arithmetically along its arrangement direction, so that multiple sets of interference fringes with uniformly varying fringe spacing and peak intensities can be finally acquired, thereby further improving the accuracy of the resolved spectrum.

[0071] As an example, the first 50 / 50 beam splitter 16 can adopt a commonly available beam splitter structure, as long as it can achieve 1:1 intensity splitting of the incident light. Figure 5 As shown, the first 50 / 50 beam splitter 16 is selected as a 50 / 50 coupler, as... Figure 6 As shown, the first 50 / 50 beam splitter is selected as a 1×2MMI optical beam splitter.

[0072] like Figure 2 As shown, as an example, the spectrometer chip 10 based on Mach-Zehnder interferometry can be fabricated using existing conventional substrates, such as silicon substrates, silicon nitride substrates, lithium niobate substrates, or glass substrates, etc., without limitation.

[0073] like Figure 1As shown, as an example, the image sensor chip 11 can be any suitable existing image sensor, such as an array of PMTs, SPADs, CMOS, CCDs, SiPMs, PDs, or linear PMTs, SPADs, CMOS, CCDs, SiPMs, PDs, or a single PMT, SPAD, CCD, SiPM, or photodiode. If it is a single PMT, SPAD, CMOS, CCD, SiPM, or photodiode, this chip architecture can be used to detect the fluorescence signal intensity of a single molecule. In this embodiment, a CCD chip is preferred to improve the signal-to-noise ratio. The image sensor chip 11 is preferably configured as a one-dimensional array to improve the signal-to-noise ratio and reduce costs.

[0074] like Figure 1 As shown, as an example, a filter 13 is also provided behind the composite parabolic condenser lens 12. The filter 13 can filter out the wavelength portion of the excitation light that may be introduced from the pre-amplifier system, so that the light entering the chip is pure Raman signal light.

[0075] like Figure 1 As shown, as an example, lens 14 is a cylindrical lens.

[0076] like Figure 2 As shown, as an example, the optical coupling structure 15 includes a coupling waveguide 151 and a wedge waveguide 152 connected in sequence to realize chip coupling of input light.

[0077] In summary, the Mach-Zehnder interferometer-based Raman spectrometer chip of this invention achieves a 360° deflection of the input light direction and interference through different optical path lengths by utilizing the Mach-Zehnder interferometry principle and combining the two reflections of the first to fourth directional couplers with their arrangement. This eliminates the need for a 180° bent waveguide, effectively reducing chip size and cost. Furthermore, arranging the Mach-Zehnder interferometer-based spectrometer units side-by-side allows the image sensor chip to be configured as a one-dimensional array, improving the signal-to-noise ratio and reducing cost. Moreover, by placing the composite parabolic condenser lens on the side face of the Mach-Zehnder interferometer-based spectrometer chip, end-face coupling eliminates polarization selectivity. The focusing effect of the lens matches the size of the light spot with the size of the coupling structure, ensuring all light is focused onto the side face of the chip before entering the spectrometer chip. The entire light spot then enters the chip through the lens, significantly improving the light coupling efficiency. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and possesses high industrial applicability.

[0078] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A Raman spectrometer chip based on Mach-Zehnder interferometry, characterized in that, The Raman spectrometer chip includes: a package containing a spectrometer chip based on Mach-Zehnder interferometry and an image sensor chip, and a composite parabolic condenser lens and lens mechanically connected to the package; The spectrometer chip based on Mach-Zehnder interferometry includes multiple spectrometer units based on Mach-Zehnder interferometry arranged side by side. Each of the Mach-Zehnder interferometer-based spectrometer units includes, in sequence, an optical coupling structure, a first 50 / 50 beam splitter, a first directional coupler and a second directional coupler respectively connected to the two output terminals of the first 50 / 50 beam splitter, a third directional coupler and a fourth directional coupler respectively connected to the output terminals of the first directional coupler and the second directional coupler, and a second 50 / 50 beam splitter connected to the output terminals of the third directional coupler and the fourth directional coupler; The optical path difference of each of the Mach-Zehnder interferometer-based spectrometer units increases or decreases sequentially along its arrangement direction; The first directional coupler, the second directional coupler, the third directional coupler, and the fourth directional coupler are arranged side by side, one above the other; the first directional coupler and the third directional coupler are located above one output end of the first 50 / 50 beam splitter and are staggered left and right, and the second directional coupler and the fourth directional coupler are located below the other output end of the first 50 / 50 beam splitter and are staggered left and right. The composite parabolic condenser lens is disposed on the end face of the spectrometer chip based on Mach-Zehnder interferometry, and the input light is coupled into the light coupling structure by the focusing of the lens; The image sensor chip is positioned after the output of the second 50 / 50 beam splitter to receive the interference light output by the second 50 / 50 beam splitter.

2. The Raman spectrometer chip based on Mach-Zehnder interferometry according to claim 1, characterized in that: The optical path difference of each of the Mach-Zehnder interferometer-based spectrometer units increases or decreases arithmetically along its arrangement direction.

3. The Raman spectrometer chip based on Mach-Zehnder interferometry according to claim 1, characterized in that: The first 50 / 50 beam splitter is a 1×2 MMI optical beam splitter or a 50 / 50 coupler.

4. The Raman spectrometer chip based on Mach-Zehnder interferometry according to claim 1, characterized in that: The first directional coupler, the second directional coupler, the third directional coupler, and the fourth directional coupler are all 50 / 50 directional couplers.

5. The Raman spectrometer chip based on Mach-Zehnder interferometry according to claim 1 or 4, characterized in that: The first directional coupler, the second directional coupler, the third directional coupler, and the fourth directional coupler are all four-port elements, including one input port, one output port, and two reflecting ports equipped with mirrors. The four ports are connected by a coupling waveguide region.

6. The Raman spectrometer chip based on Mach-Zehnder interferometry according to claim 1, characterized in that: A filter is also provided behind the composite parabolic condenser to filter out the excitation light introduced into the pre-processor system.

7. The Raman spectrometer chip based on Mach-Zehnder interferometry according to claim 1, characterized in that: The optical coupling structure includes a coupling waveguide and a wedge waveguide connected in sequence to achieve chip coupling of input light.

8. The Raman spectrometer chip based on Mach-Zehnder interferometry according to claim 1, characterized in that: The lens is a cylindrical lens.

9. The Raman spectrometer chip based on Mach-Zehnder interferometry according to claim 1, characterized in that: The image sensor chip is one of a CCD chip, a CMOS image sensor chip, a PD array, a SPAD array, a PMT array, and a SiPM array; the image sensor chip is a one-dimensional array.

10. The Raman spectrometer chip based on Mach-Zehnder interferometry according to claim 1, characterized in that: The spectrometer chip based on Mach-Zehnder interferometry is formed on a silicon substrate, a silicon nitride substrate, a lithium niobate substrate, or a glass substrate.

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