A micro-ring-assisted integrated spectrum reconstruction spectrometer structure

Abstract

The present invention provides a microring-assisted integrated spectral reconstruction spectrometer structure, comprising an input waveguide, a microring resonant cavity, an output waveguide, a loading waveguide, a download waveguide, a microheating electrode, a contact electrode, and a spectral reconstruction and analysis module. The microring resonant cavity comprises a first waveguide, a second waveguide, and a ring waveguide. The first waveguide is provided with an input port and a through port, and the second waveguide is provided with a drop port and an add port. The input waveguide is connected to the input port, and the output waveguide is connected to the through port; the loading waveguide is connected to the add port, and the download waveguide is connected to the drop port; the download waveguide output port is connected to the input port of the spectral reconstruction and analysis module; a microheating electrode is provided above the microring resonant cavity, and the microheating electrode is connected to the contact electrode. The present invention simultaneously achieves high-resolution spectral analysis over a wide spectral range, which has great application value in wearable medical devices and optical sensing.

Description

Technical Field

[0001] The present invention relates to the field of spectrometers, and in particular to a micro-ring assisted integrated spectrum reconstruction spectrometer structure. Background Art

[0002] Spectrometers offer opportunities in a wide range of fields, including biochemical sensing, materials analysis, hyperspectral imaging, and light source characterization. The development of high-performance chip-based spectrometers promises to unlock numerous new applications, from consumer to industrial technologies, including on-site component analysis, instant health monitoring, and even large-scale crop monitoring. Traditional integrated spectrometers utilize dispersive optics or narrowband filters to separate the spectral content of the incident signal into a photodetector array. The spectral resolution of dispersive optical spectrometers is limited by the optical path length, which is inversely proportional to the optical path length. Narrowband filters that select for specific wavelengths of light enable more compact spectrometers. High spectral resolution can be achieved by incorporating multiple filters with narrow channel spacing. However, spectral bandwidth is fundamentally limited by the free spectral range (FSR). For silicon ring resonators with acceptable bending losses, the bending radius should be greater than 5 microns, implying an FSR of no more than 19 nm around 1550 nm. Another challenge lies in the inevitable fabrication imperfections of large-scale filter arrays, which are critical for small channel spacing. Compared to traditional integrated spectrometers, Fourier transform spectrometers (FTS) can provide a higher signal-to-noise ratio (SNR) due to their higher received optical power, or Fellgett advantage. However, FTS has several drawbacks, including high power consumption, large drive voltages, long measurement times, and a relatively large footprint. Over the past decade, reconstructive spectrometers have gained popularity. These use scattering media to provide a unique speckle fingerprint for each incident light wavelength, and then use computational techniques to reconstruct the incident spectrum. While sparse spectra can significantly reduce the number of physical channels and equipment usage, their applicability for analyzing complex spectra requires higher computational power, and algorithm robustness decreases with increasing spectral complexity. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention proposes a microring-assisted integrated spectral reconstruction spectrometer architecture. This spectrometer utilizes a microring resonator to decompose any complex spectrum into a series of simple comb spectra, thereby implementing compressed sensing in hardware. Due to the pre-sparse operation of the microring resonator resonance, calibration is required to construct a sparse comb spectrum with a known line shape, requiring only the amplitude of each resonant peak. Subsequent conventional spectral reconstruction spectrometers only need to measure the comb spectrum and reconstruct it using a convex optimization algorithm, resulting in highly robust performance.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] A micro-ring assisted integrated spectrum reconstruction spectrometer structure includes an incident waveguide, a micro-ring resonant cavity, an output waveguide, a loading waveguide, a downloading waveguide, a micro-heating electrode, a contact electrode, and a spectrum reconstruction and analysis module, wherein:

[0006] The micro-ring resonator is an upload / download type micro-ring resonator, which includes a first waveguide, a second waveguide and a ring waveguide. The first waveguide is provided with an input port and a through port, and the second waveguide is provided with a drop port and an add port.

[0007] The incident waveguide is connected to the input port on the first waveguide, and the output waveguide is connected to the through port on the first waveguide;

[0008] The loading waveguide is connected to the Add port on the second waveguide, and the downloading waveguide is connected to the Drop port on the second waveguide;

[0009] The download waveguide output port is connected to the spectrum reconstruction and analysis module input port;

[0010] A micro heating electrode is provided above the micro ring resonant cavity, and the micro heating electrode is connected to the contact electrode.

[0011] Furthermore, the incident waveguide, the microring resonant cavity, the output waveguide, the loading waveguide and the unloading waveguide are all single-mode waveguides.

[0012] Furthermore, the first waveguide and the second waveguide of the microring resonator are respectively located on two sides of the ring waveguide; the coupling distance between the ring waveguide and the first waveguide is equal to the coupling distance between the ring waveguide and the second waveguide.

[0013] Furthermore, the micro-ring resonant cavity may be an upload-download Fabry-Perot resonant cavity supporting multiple resonant modes.

[0014] Furthermore, the free spectral range of the micro-ring resonator is greater than the spectral resolution of the spectral reconstruction and analysis module.

[0015] Furthermore, by applying driving power to the contact electrode to heat the microring resonant cavity, the resonant wavelength of the microring resonant cavity can be changed.

[0016] Furthermore, by applying driving power to the contact electrode, inputting light from the loading waveguide, and receiving light at the output waveguide, the response spectrum of the microring resonant cavity at different driving powers can be obtained, thereby obtaining the driving power and the central wavelength and bandwidth information of the resonance peak of the microring resonant cavity.

[0017] Furthermore, by inputting light from the loading waveguide and receiving light at the output port of the spectrum reconstruction and analysis module, the response matrix 1 of the spectrum reconstruction and analysis module can be obtained. However, the response matrix carries the direct spectrum information of the microring resonant cavity, which needs to be removed. By applying a suitable driving power to the contact electrode, the response matrix 2 of the spectrum reconstruction and analysis module can be obtained. By comparing the response matrix 1 and the response matrix 2, the direct spectrum information of the microring resonant cavity can be removed to obtain the true response matrix 3 of the spectrum reconstruction and analysis module. Finally, unknown light is input into the incident waveguide and the optical power is received at the output port of the spectrum reconstruction and analysis module. According to the received optical power and the response matrix 3 of the spectrum reconstruction and analysis module, the corresponding download spectrum of the microring resonant cavity under each driving power can be restored. By combining the download spectra of all the microring resonant cavities, the input unknown spectrum can be reconstructed.

[0018] The beneficial effects of the present invention are as follows:

[0019] The microring-assisted integrated spectrum reconstruction spectrometer structure of the present invention can simultaneously achieve high-resolution (<1nm) and large-spectrum (>100nm) spectrum analysis, which has great application value in wearable medical and optical sensing. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the structure of the micro-ring-assisted integrated spectrum reconstruction spectrometer of the present invention;

[0021] Figure 2 Schematic diagram of the spectrum recovery principle of the micro-ring-assisted integrated spectrum reconstruction spectrometer structure of the present invention;

[0022] Figure 3 is the resonance peak of the microring resonator and the corresponding Lorentz fitting;

[0023] Figure 4 is the comb spectrum of the microring resonator and the reconstructed weight factor;

[0024] Figure 5 is the input spectrum and the reconstructed broad spectrum;

[0025] Figure 6 This is a schematic structural diagram of the micro-ring-assisted integrated spectrum reconstruction spectrometer structure according to Example 1;

[0026] Figure 7 This is a structural schematic diagram of the micro-ring-assisted integrated spectrum reconstruction spectrometer structure of Example 2.

[0027] The accompanying drawings are labeled: incident wave 101, microring resonator 102, first waveguide 102-1, second waveguide 102-3, ring waveguide 102-2, output waveguide 103, loading waveguide 104, unloading waveguide 105, micro heating electrode 106, contact electrode 107, and spectrum reconstruction and analysis module 108. DETAILED DESCRIPTION

[0028] The structure of the microring-assisted integrated spectral reconstruction spectrometer of the present invention will be described in more detail below with reference to a schematic diagram. The schematic diagram represents a preferred embodiment of the present invention. It should be understood that those skilled in the art may modify the present invention described herein while still achieving the advantageous effects of the present invention. Therefore, the following description should be understood as a general guide for those skilled in the art and not as a limitation of the present invention.

[0029] In the description of the present invention, it should be noted that, for directional words, such as the terms "center", "horizontal", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and so on, indicating directions and positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and cannot be understood as limiting the specific scope of protection of the present invention.

[0030] The following paragraphs describe the present invention in more detail by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are greatly simplified and not to exact scale, and are provided solely for the purpose of assisting in the description of the embodiments of the present invention.

[0031] like Figure 1 As shown, the present invention provides a micro-ring assisted integrated spectrum reconstruction spectrometer structure, including an incident waveguide 101, a micro-ring resonant cavity 102, an output waveguide 103, a loading waveguide 104, a downloading waveguide 105, a micro-heating electrode 106, a contact electrode 107, and a spectrum reconstruction and analysis module 108, wherein:

[0032] The micro-ring resonator is an upload / download type micro-ring resonator, which includes a first waveguide 102-1, a second waveguide 102-3, and a ring waveguide 102-2. The first waveguide 102-1 is provided with an input port and a through port, and the second waveguide 102-3 is provided with a drop port and an add port.

[0033] The input waveguide 101 is connected to the input port of the first waveguide 102-1, and the output waveguide 103 is connected to the through port of the first waveguide 102-1;

[0034] The loading waveguide 104 is connected to the Add port on the second waveguide 102 - 3 , and the downloading waveguide 105 is connected to the Drop port on the second waveguide 102 - 3 ;

[0035] The output port of the download waveguide 105 is connected to the input port of the spectrum reconstruction and analysis module 108;

[0036] A micro heating electrode 106 is provided above the micro ring resonant cavity 102 , and the micro heating electrode 106 is connected to a contact electrode 107 .

[0037] Specifically, the incident waveguide 101 , the microring resonator 102 , the output waveguide 103 , the loading waveguide 104 , and the unloading waveguide 105 are all single-mode waveguides.

[0038] Specifically, the first waveguide 102-1 and the second waveguide 102-3 of the microring resonator 102 are respectively located on both sides of the ring waveguide 102-2; the coupling distance between the ring waveguide 102-2 and the first waveguide 102-1 is equal to the coupling distance between the ring waveguide 102-2 and the second waveguide 102-3.

[0039] Specifically, the micro-ring resonant cavity 102 may be other resonant cavities (eg, an upload / download Fabry-Perot resonant cavity) that supports multiple resonant modes.

[0040] Specifically, the free spectral range of the micro-ring resonator 102 is greater than the spectral resolution of the spectral reconstruction and analysis module 108 .

[0041] Specifically, by applying driving power to the contact electrode 107 to heat the microring resonant cavity 102 , the resonant wavelength of the microring resonant cavity 102 can be changed.

[0042] Specifically, Figure 2 The schematic diagram of spectrum recovery is as follows: by applying driving power to the contact electrode 107, inputting light s(λ) from the loading waveguide 104, and receiving light at the output waveguide 103, the comb spectrum s of the microring resonator 102 with different driving powers can be obtained. i (λ), thereby obtaining the driving power and the central wavelength and bandwidth information of the resonance peak of the microring resonator 102. The input light can be represented by multiple comb spectra s i The sum of (λ):

[0043]

[0044] Where B(λ) is the transfer function of the micro-ring, and Q is the total number of tuning states of the micro-ring.

[0045] Specifically, by inputting light from the loading waveguide 104 and receiving light at the output port of the spectrum reconstruction and analysis module 108, the response matrix 1 of the spectrum reconstruction and analysis module 108 can be obtained. However, this response matrix contains the direct spectrum information of the microring resonator 102, which needs to be removed. By applying a suitable driving power to the contact electrode 107, the response matrix 2 of the spectrum reconstruction and analysis module 108 can be obtained. By comparing the response matrix 1 and the response matrix 2, the direct spectrum information of the microring resonator 102 can be removed to obtain the true response matrix p(λ, j) of the spectrum reconstruction and analysis module 108. An unknown light is input to the incident waveguide 101, and the optical power I is received at the output port of the spectrum reconstruction and analysis module 108. i (j). Therefore,

[0046]

[0047] where λ min and λ max are the minimum and maximum operating wavelengths, M is the number of physical channels of the spectrum reconstruction and analysis module, and i is the i-th tuning state. Written in discrete form as

[0048] I i，M×1 =p M×N s i，N×1 #(3)

[0049] Where N is the number of sampled wavelength points. Since the comb spectrum of the Drop port of the second waveguide 102-3 of the microring resonator can be expressed as the sum of several Lorentz functions, Figure 3 is the resonance peak of the microring and the corresponding Lorentz fitting.

[0050] s i，N×1 =Φ i，N×K t i，K×1 #(4)

[0051] where t i，K×1 is the weight factor, Φ iN×K Each column of is a Lorentz function. So we have

[0052] I i，M×1 =Θ i，M×K t i，K×1 #(5)

[0053] where Θ i，M×K =p M×N Φ i，N×KThen, the weight factor t of the comb spectrum of the microring resonator 102 corresponding to each driving power can be recovered by linear regression algorithm and regularization. i，K ×1

[0054] Minimize||I i -Θ i ·t i || 2 +α||t i || 2 subject to 0≤t i ≤1 #(6)

[0055] Figure 4 is the comb spectrum of the microring and the reconstructed weight factor, and then all the comb spectra are obtained according to formula (4). By combining the download spectra of all the microring resonators 102 with formula (1), the input unknown spectrum s(λ) can be reconstructed.

[0056] Figure 5 are the input spectrum and the reconstructed broad spectrum.

[0057] Two embodiments of the filter structure of the present invention are given below.

[0058] Example 1

[0059] A microring-assisted integrated spectral reconstruction spectrometer structure was fabricated on a 220nm silicon-on-insulator platform. The input waveguide 101, microring resonator 102, and output waveguide 103 are 500nm wide, strip-shaped, with an etch depth (waveguide height) of 220nm. The microring resonator radius is 15μm. The coupling distance between the input waveguide 101, output waveguide 103, and microring resonator 102 is 250nm. The center of the microheating electrode coincides with the center of the microring resonator, and the width of the microheating electrode is 3μm.

[0060] like Figure 6 As shown, Example 1 and Figure 1 The difference from the general structure diagram is that the spectrum reconstruction and analysis module 108 can adopt a multi-level Y-branch tree 109 and a random grating 110.

[0061] Example 2

[0062] like Figure 7 As shown, the difference between Example 2 and Example 1 is that the spectrum reconstruction and analysis module 108 can use a meandering waveguide 109 and a waveguide array 110.

[0063] In addition, for ordinary technicians in this technical field, without departing from the principles of the present invention, they can also make several improvements and modifications, using other integrated optical platforms, such as a silicon-on-insulator platform, an inorganic chalcogenide glass platform, a titanium oxide platform, a silicon nitride platform, a lithium niobate-on-insulator platform, and a III-V indium phosphide platform, etc.; using different optical working bands, such as the ultraviolet band, the visible light band, the near-infrared waveguide, the mid-infrared waveguide, and the far-infrared band, etc.

[0064] Those skilled in the art will understand that the foregoing descriptions are merely preferred embodiments of the invention and are not intended to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, those skilled in the art will still be able to modify the technical solutions described in the foregoing examples or substitute equivalents for some of the technical features therein. Any modifications, equivalent substitutions, etc. made within the spirit and principles of the invention shall be included within the scope of protection of the invention.

Claims

1. A micro-ring-assisted integrated spectrum reconstruction spectrometer structure, characterized in that: The invention comprises an incident waveguide (101), a micro-ring resonant cavity (102), an output waveguide (103), a loading waveguide (104), a downloading waveguide (105), a micro-heating electrode (106), a contact electrode (107), and a spectrum reconstruction and analysis module (108), wherein: The micro-ring resonant cavity (102) is an upload / download type micro-ring resonant cavity, which includes a first waveguide (102-1), a second waveguide (102-3) and a ring waveguide (102-2). An input port and a through port are provided on the first waveguide (102-1), and a drop port and an add port are provided on the second waveguide (102-3). The incident waveguide (101) is connected to the input port on the first waveguide (102-1), and the output waveguide (103) is connected to the through port on the first waveguide (102-1); The loading waveguide (104) is connected to the Add port on the second waveguide (102-3), and the downloading waveguide (105) is connected to the Drop port on the second waveguide (102-3); The output port of the download waveguide (105) is connected to the input port of the spectrum reconstruction and analysis module (108); A micro-heating electrode (106) is provided above the micro-ring resonant cavity (102), and the micro-heating electrode (106) is connected to a contact electrode (107); The first waveguide (102-1) and the second waveguide (102-3) of the micro-ring resonant cavity (102) are respectively located on both sides of the ring waveguide (102-2); the coupling distance between the ring waveguide (102-2) and the first waveguide (102-1) is equal to the coupling distance between the ring waveguide (102-2) and the second waveguide (102-3); The free spectral range of the micro-ring resonant cavity (102) is greater than the spectral resolution of the spectral reconstruction and analysis module (108).

2. The micro-ring-assisted integrated spectrum reconstruction spectrometer structure according to claim 1, characterized in that: The incident waveguide (101), the micro-ring resonant cavity (102), the output waveguide (103), the loading waveguide (104) and the unloading waveguide (105) are all single-mode waveguides.

3. The micro-ring-assisted integrated spectrum reconstruction spectrometer structure according to claim 1 or 2, characterized in that: The micro-ring resonant cavity (102) adopts an upload-download Fabry-Perot resonant cavity and supports multiple resonant modes.

4. The micro-ring-assisted integrated spectrum reconstruction spectrometer structure according to claim 1 or 2, characterized in that: By applying driving power to the contact electrode (107), the microring resonant cavity (102) is heated, thereby changing the resonant wavelength of the microring resonant cavity (102).

5. The micro-ring-assisted integrated spectrum reconstruction spectrometer structure according to claim 1 or 2, characterized in that: By applying driving power to the contact electrode (107), inputting light s(λ) from the loading waveguide (104), and receiving light at the output waveguide (103), comb spectra si(λ) of the microring resonant cavity (102) with different driving powers are obtained, thereby obtaining driving power and central wavelength and bandwidth information of the resonance peak of the microring resonant cavity (102); the input light is represented as the sum of multiple comb spectra si(λ): Where B(λ) is the transfer function of the micro-ring, and Q is the total number of tuning states of the micro-ring.

6. The micro-ring-assisted integrated spectrum reconstruction spectrometer structure according to claim 1 or 2, characterized in that: Light is input from the loading waveguide (104), and light is received at the output port of the spectrum reconstruction and analysis module (108), thereby obtaining a response matrix 1 of the spectrum reconstruction and analysis module (108). However, the response matrix carries the direct spectrum information of the microring resonant cavity (102), which needs to be removed. A response matrix 2 of the spectrum reconstruction and analysis module (108) is obtained by applying a suitable driving power to the contact electrode (107). By comparing the response matrix 1 and the response matrix 2, the direct spectrum information of the microring resonant cavity (102) is removed, thereby obtaining a true response matrix p(λ, j) of the spectrum reconstruction and analysis module (108). Finally, unknown light is input to the incident waveguide (101), and the optical power Ii(j) is received at the output port of the spectrum reconstruction and analysis module (108). Therefore, Where λmin and λmax are the minimum and maximum operating wavelengths, M is the number of physical channels of the spectrum reconstruction and analysis module, and i is the i-th tuning state; Written as a discrete expression I i，M×1 =p M×N s i，N×1 #(3) Where N is the number of wavelength points sampled; since the comb spectrum of the download port of the microring is expressed as the sum of several Lorentz functions, we have s i，N×1 =Φ i，N×K t i，K×1 #(4) Where ti, K×1 is the weight factor, and each column of Φi, N×K is a Lorentz function; therefore, I i，M×1 =Θ i，M×K t i，K×1 #(5) Where Θi,M×K=pm×NΦ i , N×K, and then recover the weight factor ti, K×1 of the comb hanging spectrum of the micro-ring resonator (102) corresponding to each driving power by linear regression algorithm and regularization Minimize||I i -Θ i ·t i || 2 +α||t i || 2 subject to 0≤t i ≤1 #(6) Then, all the comb spectra are obtained according to formula (4), and the input unknown spectrum s(λ) is reconstructed by combining the download spectra of all the micro-ring resonators (102) with formula (1).

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