Adjustable single-channel time domain sampling filter, spectrograph and detection method

Abstract

The invention discloses an adjustable single-channel time domain sampling filter, a spectrometer and a detection method, and relates to the technical field of computational reconstruction type spectrometers, the adjustable single-channel time domain sampling filter comprises N stages of cascaded asymmetric interference units, and each asymmetric interference unit comprises a first waveguide light splitting element arranged at an input end and used for dividing input light into two paths for output; the two interference arms are respectively used for receiving light output by the two paths of the first waveguide light splitting element; the two interference arms respectively have different arm lengths; the second waveguide light splitting element is used for combining the output light of the two interference arms to generate optical interference; wherein at least three asymmetric interference units are provided with phase modulators on interference arms; when the adjustable single-channel time domain sampling filter is used, optical channels with different spectral responses are formed in a time sequence by tuning the phase modulators located in the different cascaded asymmetric interference units. The invention has the advantages of small occupied volume, high integration level, high signal-to-noise ratio, high detection precision and high detection speed.

Description

Technical Field

[0001] The present invention relates to the technical field of computational reconstruction spectrometers, and in particular to an adjustable single-channel time-domain sampling filter, a spectrometer and a detection method. Background Art

[0002] As one of the most basic detection equipment, spectrometer can effectively use the spectral information of matter to analyze its physical properties and chemical composition, so it is widely used in many fields.

[0003] Traditional spectral detection technologies mainly include dispersive spectrometers based on prisms or narrowband filters and Fourier transform spectrometers based on Michelson interferometers. However, these spectrometers have shortcomings in terms of energy loss, volume, cost, and computational complexity, making it difficult to meet the current market demand for miniaturized and low-cost spectral detection devices.

[0004] In recent years, computational spectrometer has attracted widespread attention from academia and industry as a new spectral detection method. Its basic principle is to input the unknown spectrum into multiple pre-calibrated sampling filters, and then use photodetectors to detect the filtered light intensity signals one by one. Based on these pre-calibrated filters and the detected intensity signals, an underdetermined set of equations can be constructed, and the input spectrum can be reversely solved through related algorithms. Unlike traditional dispersive spectrometers where each pixel needs to be sampled separately, the core advantage of computational spectrometers is that through appropriate sampling filter combinations, a large number of pixels in the spectral frequency domain can be solved with fewer sampling times, thereby greatly improving the detection efficiency.

[0005] However, currently common computational spectrometers all construct multiple independent sampling channels in the spatial domain, that is, the power of the incident spectrum is evenly divided into multiple parts, and then input into the corresponding sampling channels one by one for detection. This inevitably leads to very limited power allocated to each channel, thereby reducing the signal-to-noise ratio of the system. In addition, constructing multiple spatial sampling channels will occupy a larger volume and consume more resources, which is not conducive to the miniaturization of the device. These shortcomings are particularly obvious for on-chip integrated devices, so it is necessary to develop a sampling filter and spectrometer that occupies a small volume, is easy to integrate, and has a high signal-to-noise ratio. Summary of the invention

[0006] The present invention aims to solve one of the technical problems in the related art to a certain extent. To this end, the present invention provides an adjustable single-channel time-domain sampling filter, a spectrometer and a detection method, which have the advantages of small footprint, high integration, high signal-to-noise ratio, high detection accuracy and fast detection speed.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] An adjustable single-channel time-domain sampling filter is configured in an on-chip computational reconstruction spectrometer when in use, comprising N-stage cascaded asymmetric interference units, N≥3; the asymmetric interference unit comprises:

[0009] A first waveguide splitter element is provided at the input end and is used to split the input light into two output paths according to a preset splitting ratio;

[0010] Two interference arms, respectively receiving the light outputted from two paths of the first waveguide light splitting element; the two interference arms respectively have arm lengths of different lengths; and,

[0011] A second waveguide beam splitter element, used for combining the output lights of the two interference arms to generate optical interference;

[0012] Wherein, at least three asymmetric interference units are provided with phase modulators on the interference arms;

[0013] In two adjacent asymmetric interference units, the output light of the second waveguide beam splitter element in the previous stage is used as the input light of the first waveguide beam splitter element in the next stage;

[0014] When in use, the adjustable single-channel time-domain sampling filter forms optical channels with different spectral responses in time sequence by tuning the phase modulators in different cascaded asymmetric interference units.

[0015] In the above scheme, the adjustable single-channel time-domain sampling filter adopts a single-channel structure, which can not only reduce the space volume and improve the integration, but also the power of the incident spectrum does not need to be divided again, and can completely enter the single-channel filter, eliminating the loss in the transmission process. The final output spectrum power is still greatly improved compared to the existing scheme where the input power is divided equally by multiple channels. In this way, when the same photodetector is used for reception, its signal-to-noise ratio will increase, thereby improving the detection accuracy. At the same time, since the phase modulation of the on-chip waveguide can be easily achieved at the millisecond or even microsecond level, it has an extremely high detection speed.

[0016] It is further preferred that the phase modulator is arranged on one or two interference arms in the asymmetric interference unit.

[0017] The present invention is further preferably configured such that the phase modulator has at least three different phase adjustment states.

[0018] Through the phase modulator, the spectral phase on the interference arm can be adjusted to change its spectral response; and by controlling the phase modulators in asymmetric interference units located at multiple different cascade levels, more combinations can be achieved and the randomness of the output spectrum can be increased.

[0019] It is further preferred that the present invention has a splitting ratio between the first waveguide splitting element and the second waveguide splitting element in a range of 0.05 to 0.3.

[0020] Since the waveguide splitter element has two input ports and two output ports, its splitting ratio is the ratio of the powers of its two output ports. The spectrum will be attenuated when it is transmitted from the previous asymmetric interference unit to the next asymmetric interference unit, and the attenuation will gradually accumulate as the number of stages increases. After experiments and simulations, the splitting ratio is designed to be between 0.05 and 0.3 in this scheme, which can only ensure that the two interference arms in each cascade can split the light and generate a randomly disturbed spectrum at the output end of the filter, and can also control the loss of the spectrum in the multi-stage transmission process within an acceptable range.

[0021] It is further preferred that in two adjacent asymmetric interference units, the second waveguide beam splitter element in the previous asymmetric interference unit and the first waveguide beam splitter element in the next asymmetric interference unit reuse the same waveguide beam splitter element.

[0022] It is further preferred that the splitting ratio of the waveguide splitting elements multiplexed in two adjacent asymmetric interference units is 0.05 to 0.95.

[0023] For the multiplexed waveguide splitter element, since its splitter element is multiplexed by adjacent interferometers (asymmetric interference units), its system response cannot be mathematically described by the cumulative multiplication of the independent transmission spectra of multiple interferometers. Through numerical simulation, its system transmission response can still be easily obtained. The simulation results show that its splitting ratio ρ can achieve a relatively ideal perturbation effect in a large range of 0.05 to 0.95.

[0024] It is further preferred that in the present invention, in the same asymmetric interference unit, the difference in arm length between the two interference arms is in the range of 1 μm to 600 μm.

[0025] By adjusting the arm length difference, the perturbation effect of the filter output spectrum can be adjusted. At the same time, the larger the arm length difference, the smaller the resolution of the spectrum will be. When one of the arm length differences in the filter reaches 600μm, the speed of light in the SiN waveguide is about 1.5*10 8 m / s, 600um divided by the speed of light is 0.004ns, so the period on the spectrum is approximately its reciprocal 250GHz, which is approximately 0.8nm in the C-band 100GHz, so the spectrum period is approximately 2nm. Corresponding to this period, the resolution that the spectrometer can achieve is approximately 20pm to 100pm. Considering actual needs, this resolution is currently applicable to the detection of all material contents.

[0026] According to a further preferred embodiment of the present invention, the asymmetric interference unit is a Mach-Zehnder interferometer structure.

[0027] It is further preferred that the present invention has at least one of the asymmetric interference units be a passive Mach-Zehnder interferometer structure.

[0028] In addition, the present invention also provides a computational reconstruction spectrometer, which includes a light source, a photodetector, and the aforementioned adjustable single-channel time-domain sampling filter. The computational reconstruction spectrometer provided by the present invention has a similar reasoning process to the beneficial effects of the aforementioned adjustable single-channel time-domain sampling filter, which will not be repeated here.

[0029] Furthermore, the present invention also provides a spectrum detection method, which uses the above-mentioned computational reconstruction spectrometer to obtain a spectrum response matrix and an underdetermined set of equations.

[0030] At the same time, the present invention also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor implements any of the above-mentioned spectral detection methods when executing the computer program.

[0031] These features and advantages of the present invention will be disclosed in detail in the following specific embodiments and drawings. The best embodiments or means of the present invention will be described in detail in conjunction with the drawings, but they are not intended to limit the technical solutions of the present invention. In addition, there are multiple features, elements, and components that appear in each of the following texts and drawings, and different symbols or numbers are marked for convenience, but they all represent components with the same or similar structures or functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be further described below in conjunction with the accompanying drawings:

[0033] Figure 1 It is a structural block diagram of the spectrometer described in the present invention.

[0034] Figure 2 It is a structural schematic diagram of the first two asymmetric interference units of the adjustable single-channel time-domain sampling filter in the present invention using independent type splitting elements.

[0035] Figure 3a-3c Schematic diagram of the phase modulator being arranged on the interference arm in different ways in some embodiments.

[0036] Figure 4 The figure is an example of the spectrum response of a time domain sampling channel modulated by an adjustable single-channel time domain sampling filter.

[0037] Figure 5 for Figure 4 A magnified view of the spectrum response within the dashed box.

[0038] Figure 6This is an experimental effect diagram of using the computational reconstruction spectrometer and spectrum detection method of the present invention to compute and reconstruct a spectrum.

[0039] Figure 7 It is a schematic diagram of the structure of the first two asymmetric interference units of the adjustable single-channel time-domain sampling filter in the present invention using multiplexed light-splitting elements.

[0040] Among them, 100 is a light source; 200 is an adjustable single-channel time-domain sampling filter; 210 is an asymmetric interference unit; 211 is a first light-splitting element; 212 is an interference arm; 213 is a second light-splitting element; 214 is a phase modulator; and 300 is a photodetector. DETAILED DESCRIPTION

[0041] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments in the implementation manner are intended to be used to explain the present invention and should not be construed as limiting the present invention.

[0042] References in this specification to "one embodiment" or "an example" or "an example" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment itself may be included in at least one embodiment of the present patent disclosure. The appearance of the phrase "in one embodiment" in various places in the specification does not necessarily refer to the same embodiment.

[0043] The present invention provides an adjustable single-channel time-domain sampling filter, a spectrometer and a detection method, wherein the adjustable single-channel time-domain sampling filter and the spectrometer are based on an integrated optical platform, and utilize optical waveguides and optical waveguide devices to construct three or more levels of asymmetric Mach-Zehnder interferometers (or asymmetric interference units), thereby forming an adjustable sampling filter.

[0044] The integrated optical platforms here include silicon-based optical platforms (pure silicon or silicon germanium platforms), silicon nitride (SiN, Silicon Nitride) optical platforms, indium phosphide (InP, Indium Phosphide) or indium arsenide (InAs, IndiumArsenide) and other III-V optical platforms, lithium phosphate (LN, Lithium Niobate) optical platforms, and even various hybrid integrated platforms. Among them, the selection of different platforms has different advantages and disadvantages. For example, the silicon-based platform has the advantages of small device size, high thermal-optical efficiency and mature process, while the lithium phosphate platform has the advantages of high electro-optical efficiency and suitability for high-speed modulation. You can make a choice according to actual needs without restriction.

[0045] Each interferometer consists of a corresponding waveguide beam splitter and two interferometer arms of different lengths. The phase of each interferometer can be actively modulated by a phase modulator set on its interferometer arm, thereby realizing the change of the overall spectral response of its sampling filter, and then realizing the sampling of unknown spectrum in time sequence.

[0046] Asymmetric Mach-Zehnder interferometer (or asymmetric interference unit) can be realized by different optical waveguide device designs, for example, its beam splitter element can be a multimode interferometer, a directional coupler or a Y-splitter, etc. At the same time, there can be many different types of connections between these beam splitters. Specifically, the beam splitters between adjacent interferometers can be independent of each other or can be reused. For the convenience of description, they can be referred to as independent type and reused type.

[0047] In addition, the phase modulation of each Mach-Zehnder interferometer can also be implemented in a variety of ways. For example, its phase modulator can be based on the thermo-optic effect, electro-optic effect or nonlinear effect of the waveguide to achieve phase control. At the same time, due to the trade-off between modulation efficiency and device complexity, the phase modulator can be deployed on both arms of each interferometer at the same time, or it can be deployed on only one of the arms. In addition, in the sampling filter composed of multiple-stage Mach-Zehnder interferometers, several levels of passive Mach-Zehnder interferometers that do not have phase modulation capabilities can also be mixed in.

[0048] Based on the above-mentioned adjustable single-channel time-domain sampling filter (optical path) and combined with a photodetector, a chip-level computational spectrometer can be created, which has the advantages of small footprint, high integration, high signal-to-noise ratio, high detection accuracy and fast detection speed.

[0049] The photodetector here can be integrated with the designed adjustable single-channel time-domain sampling filter (optical path) on the same chip, such as an on-chip integrated germanium or III-V photodetector, or it can be external to the chip, such as a patch photodetector, or a photosensitive element such as a charge-coupled device (CCD) and a complementary metal-oxide-semiconductor (CMOS).

[0050] This on-chip integrated adjustable single-channel time-domain spectrometer does not need to split light in the spatial domain, so the device has extremely low insertion loss and a high signal-to-noise ratio. At the same time, since only one physical optical channel is required, the device is compact and relatively simple, and its volume and hardware resource consumption are much smaller than traditional spatial domain spectrometers. In addition, since the phase modulation of the on-chip waveguide can be easily achieved at the millisecond or even microsecond level, this spectrometer has an extremely high detection speed.

[0051] The following will describe in detail two implementation modes of the independent type and the multiplexed type of the light splitting element in the adjustable single-channel time-domain spectrometer in combination with specific embodiments.

[0052] Embodiment 1:

[0053] like Figure 1 As shown, an on-chip computational reconstruction spectrometer is shown, including a light source 100, an adjustable single-channel time-domain sampling filter 200, and a photodetector 300. The light source 100 provides an input spectrum for the adjustable single-channel time-domain sampling filter 200. When used, the adjustable single-channel time-domain sampling filter 200 can form optical channels with different spectral responses in time sequence, so as to obtain a spectral response matrix and an underdetermined set of equations in the process of computationally reconstructing the spectrum. The photodetector 300 receives the spectrum output by the adjustable single-channel time-domain sampling filter and samples it to obtain corresponding light intensity information.

[0054] Specifically, the adjustable single-channel time-domain sampling filter 200 includes N-stage cascaded asymmetric interference units 210 , where N≥3 and N is an integer. The asymmetric interference unit 210 includes a first waveguide beam splitter element 211 , two interference arms 212 and a second waveguide beam splitter element 212 .

[0055] In an asymmetric interference unit 210, a first waveguide beam splitter 211 is disposed at the input end to split the input light into two output paths. Two interference arms 212 respectively receive the two output lights of the first waveguide beam splitter 211. A second waveguide beam splitter 213 is used to combine the output lights of the two interference arms to generate optical interference.

[0056] It should be noted that the two interference arms here have arm lengths of different lengths, or in other words, there is an arm length difference between the two interference arms to form an asymmetric structure.

[0057] Specifically, the first spectroscopic element here can adopt a structure with two input ports and two output ports, or a structure with only one input port and two output ports. The specific selection is made according to the position of the first spectroscopic element in the asymmetric interference unit. For example, the first spectroscopic element in the first-stage asymmetric interference unit can adopt a structure with only one input port, and the first spectroscopic element in the asymmetric interference unit after the first stage can adopt a structure with two input ports.

[0058] The second beam splitter element can be similar or identical to the first beam splitter element, the difference between the two being that the input port and the output port are interchanged when used. Similarly, the second beam splitter element in the last-stage asymmetric interference unit can be a structure with only one output port.

[0059] In addition to the above consideration that the structures of the first spectrometer and the second spectrometer need to be adaptively adjusted according to the position, in some embodiments, a dual input port and dual output port structure can be uniformly adopted, but when in use, only one of the ports can be selected according to the position of the spectrometer, and the other port is left hanging. For the above-mentioned spectrometer with a dual output port structure, its splitting ratio is the ratio of the powers of its two output ports. The splitting ratio of the first waveguide spectrometer 211 and the second waveguide spectrometer 213 is between 0.05 and 0.3. It can be implemented in a variety of ways, such as a multimode interferometer, a directional coupler or a Y-splitter, etc., and those skilled in the art can choose according to the specific situation without limitation.

[0060] In the cascaded Mach-Zehnder interferometer structure proposed in this solution, each interferometer (ie, the asymmetric interference unit 210 ) may have a pair of independent beam splitting elements, namely, a first waveguide beam splitting element 211 and a second waveguide beam splitting element 213 .

[0061] The multi-stage asymmetric interference units are connected in series in sequence. In two adjacent asymmetric interference units, the output light of the second waveguide beam splitter element in the previous stage is used as the input light of the first waveguide beam splitter element in the next stage.

[0062] More specifically, if Figure 2As shown, taking the first-stage asymmetric interference unit and the second-stage asymmetric interference unit as examples, in the first-stage asymmetric interference unit, the light source is connected to the input port of the first waveguide spectrometer through a waveguide element, one end of the two interference arms is respectively connected to the two output ports of the first waveguide spectrometer, and the other ends of the two interference arms are respectively connected to the two input ports of the second waveguide spectrometer. An input port of the first waveguide spectrometer in the second-stage asymmetric interference unit is connected to an output port of the second waveguide spectrometer in the first-stage asymmetric interference unit, and the other input port of the first waveguide spectrometer in the second-stage asymmetric interference unit and the other output port of the second waveguide spectrometer in the first-stage asymmetric interference unit are both suspended. Similarly, the connections of other cascaded asymmetric interference units are not described one by one.

[0063] Due to this connection method, one output port of the second waveguide splitter element connected to the next level in each asymmetric interference unit is suspended, resulting in a certain loss of the spectrum during transmission, that is, attenuation. As the number of levels increases, the attenuation will gradually accumulate. After experiments and simulations, the splitting ratio is designed to be between 0.05 and 0.3 in this scheme, which can only ensure that the two interference arms in each cascade can split the light and generate a randomly disturbed spectrum at the output end of the filter, and can also control the loss of the spectrum in the multi-level transmission process within an acceptable range.

[0064] In addition to the above connection method, in an alternative embodiment, the two input ports of the first waveguide beam splitter element in the second-stage asymmetric interference unit can be connected to the two output ports of the second waveguide beam splitter element in the first-stage asymmetric interference unit one by one, which is equivalent to multiplexing a waveguide beam splitter element. See Examples 2 and Figure 7 .

[0065] In this embodiment, a phase modulator 214 is provided on the interference arm 212 of the asymmetric interference unit 210. The phase modulator can be implemented in a variety of ways, such as a phase modulator based on the thermo-optic effect of waveguide, a phase modulator based on the electro-optic effect or nonlinear effect, etc.

[0066] At the same time, due to the trade-off between device complexity and power consumption, there are also multiple options for the number of phase modulators. Those skilled in the art can make a choice based on actual conditions. For example, in some exemplary embodiments, Figure 3a As shown, they are distributed on the two arms of each interferometer, and can also be Figure 3b The distribution is shown on each arm of the interferometer. Figure 3c Shown are several levels of the distribution multi-level structure.

[0067] In order to achieve a better perturbation effect for the output spectrum (i.e., the exit spectrum) and to form sufficient optical channels with different spectral responses in timing when establishing the spectral response matrix and the underdetermined equation group, in this embodiment, at least three asymmetric interference units are provided with phase modulators on the interference arms, and the phase modulators have at least three different phase adjustment states.

[0068] From the perspective of parameter design, there are differences between independent and multiplexed beam splitters. In the design using independent beam splitters, the spectrum response of the interferometer follows a trigonometric periodic oscillation relationship, as shown in the following formula:

[0069] T i =ρ 2 +(1-ρ) 2 -2ρ(1-ρ)cos(βΔL i +δ i )

[0070] Among them, T i refers to the transmission spectrum of the i-th interferometer, ρ is the splitting ratio of the splitting structure in the interferometer (which can be a multimode interference coupler or a directional coupler, etc.), ΔL i is the difference in arm length between the two interference arms, and δ i This is the phase of the interferometer, which can be adjusted by the phase modulator. In order to achieve a more ideal filtering effect for the system as a whole, the splitting ratio ρ of each interferometer can be set between 0.05 and 0.3, and the arm length difference ΔL of each interferometer i The value can be between one micron and six hundred microns.

[0071] In the time domain, by adjusting the phase δ in different interferometers i The corresponding spectral response can be shifted by modulation, so that the spectra of the entire system after cascading are different in the time domain. Since the phase of each interferometer can modulate multiple states, and the system contains multiple interferometers, this single-channel integrated optical circuit can easily construct an exponential number of time-series sampling filter channels, and the number satisfies the following formula:

[0072] N 总通道数 =P 相位状态 ^N 级数

[0073] That is, the total number of time-domain channels is equal to a power series with the number of interferometers with adjustable phase as the index and the number of phases modulated by the user at each interferometer as the base. For example, when this tunable filter has 6 interferometers, and the user modulates 4 phases for each interferometer, such as 0, π / 2, π, and 3π / 2 respectively, then 4 to the power of 6 combinations can be constructed, that is, 4096 sampling channels in the time domain.

[0074] like Figure 4 As shown, several examples of the spectrum response of a time domain sampling channel modulated by the above-mentioned adjustable single-channel time domain sampling filter are shown. Among them, Figure 5 for Figure 4 A local enlarged view of its spectral response within the middle dashed box.

[0075] Specifically, Figure 4 and 5 The spectral response in is an example of a system with six-stage Mach-Zehnder interferometers, independent type, where the splitting ratio ρ of each interferometer is 0.1, and the bandwidth range is from 1410nm to 1610nm, a total of 200nm. The difference in the length of the two arms of the interferometer is set between 100 and 600 microns, and each interferometer is set to have three different phase states, namely 0, π / 3, and 2π / 3. It can be seen that with different phase settings, the spectral response of this filter shows completely different spectral shapes, so different sampling effects can be obtained.

[0076] This embodiment also provides a spectrum detection method for the above-mentioned on-chip computational reconstruction spectrometer, which is used to obtain the detection data required for the spectral response matrix and the underdetermined equation group through the on-chip computational reconstruction spectrometer during the process of calculating and reconstructing the spectrum.

[0077] When used specifically, the adjustable single-channel time-domain sampling filter is first calibrated in advance to obtain the transmission matrix in the time domain (i.e., the spectral response matrix). After that, the unknown spectrum is input, and the pre-calibrated sampling channels are modulated in turn in the time domain to obtain the light intensity information of the corresponding photodetector. Using the pre-calibrated transmission matrix and the detected light intensity information vector, the information of the incident spectrum in the frequency domain can be reversely solved, thereby achieving the purpose of spectral detection. Mathematically speaking, this process can be expressed as follows: Assuming that N time-series filter sampling channels are constructed, the spectral response function of each channel is H i (λ)(i=1,2,...,N), where λ represents the wavelength of light. Assuming the input spectrum is S(λ), after passing through a certain filtering channel, the corresponding light intensity value Y measured by the photodetector is i It can be expressed as:

[0078] Y i =∫S(λ)*H i (λ)dλ

[0079] Here, i = 1, 2, ..., N. Therefore, for N time-series filter channels, the measured light intensity Y i A vector Y (of size N×1) can be formed. By combining all the time series filter channel response functions H i(λ) forms a matrix H (size is N×M) and discretizes the input spectrum S(λ) into a vector S (size is M×1), where M is the number of spectral pixels. The above equation can be transformed into a linear equation system:

[0080] S M×1 =H M×N Y N×1

[0081] By solving this set of linear equations using mathematical algorithms, such as convex optimization algorithms and machine learning, we can obtain the information of the input spectrum S(λ), thereby achieving the purpose of spectral detection.

[0082] like Figure 6 As shown in FIG. 1 , an experimental result of using the on-chip computational reconstruction spectrometer and spectrum detection method to calculate and reconstruct a spectrum is shown. Here, a system with six independent Mach-Zehnder interferometers is used as an example. It can be seen that the recovered spectrum is highly consistent with the actual input spectrum, indicating the high accuracy of its spectrum detection.

[0083] Specifically, in this experiment, the user built a six-stage adjustable Mach-Zehnder interferometer on a silicon nitride (SiN) integrated platform, and set three different phase states for each interferometer, namely 0, π / 3, and 2π / 3. Therefore, a total of 3 to the power of 6, or 729 time-domain sampling filter channels, were constructed.

[0084] The experimental results show that the bandwidth of this time-domain computational spectrometer reaches 200nm and the accuracy reaches 0.01nm, that is, more than 20,000 spectral pixels are obtained in the measured wavelength range of 1410nm-1610nm. The total detection time is less than 0.8 seconds.

[0085] At the same time, this embodiment also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the above-mentioned spectrum detection method. Here, the steps of the spectrum detection method can be the steps in the memory analysis method of each of the above-mentioned embodiments.

[0086] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. Accordingly, the computer program can be stored in a non-volatile computer-readable storage medium, and when the computer program is executed, the method of any one of the above-mentioned embodiments can be implemented.

[0087] Embodiment 2:

[0088] This embodiment shows an adjustable single-channel time-domain sampling filter of another structure. The main difference between this embodiment and the adjustable single-channel time-domain sampling filter in Embodiment 1 is that in this embodiment, in two adjacent asymmetric interference units, the second waveguide splitter element in the previous asymmetric interference unit and the first waveguide splitter element in the next asymmetric interference unit reuse the same waveguide splitter element.

[0089] Specifically, the first-stage asymmetric interference unit and the second-stage asymmetric interference unit are taken as examples for explanation. Figure 7 As shown, the first-level asymmetric interference unit and the second-level asymmetric interference unit reuse the same waveguide splitter element, and the reused waveguide splitter element has two input ports and two output ports, the two input ports are respectively connected to the interference arms in the first-level asymmetric interference unit, and the two output ports are respectively connected to the interference arms in the second-level asymmetric interference unit. At this time, the reused waveguide splitter element can be regarded as the second waveguide splitter element of the first-level asymmetric interference unit, and can also be regarded as the first waveguide splitter element of the second-level asymmetric interference unit.

[0090] Since the waveguide transmission structure has less loss, the splitting ratio of the waveguide splitting element multiplexed in the adjacent two-stage asymmetric interference units can be set to 0.05 to 0.95 as needed.

[0091] The remaining features and structures are similar or identical to those of Example 1 and will not be described in detail here.

[0092] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes but is not limited to the contents described in the drawings and the above specific embodiments. Any modification that does not deviate from the functional and structural principles of the present invention will be included in the scope of the claims.

Claims

1. An adjustable single-channel time-domain sampling filter, configured in an on-chip computational reconstruction spectrometer when in use, characterized in that: The invention comprises N-stage cascaded asymmetric interference units, where N≥3; the asymmetric interference unit comprises: A first waveguide light splitting element is arranged at the input end and is used to split the input light into two output paths; Two interference arms, respectively receiving the light outputted from two paths of the first waveguide light splitting element; the two interference arms respectively have arm lengths of different lengths; and, A second waveguide beam splitter element, used for combining the output lights of the two interference arms to generate optical interference; Wherein, at least three asymmetric interference units are provided with phase modulators on the interference arms; In two adjacent asymmetric interference units, the output light of the second waveguide beam splitter element in the previous stage is used as the input light of the first waveguide beam splitter element in the next stage; When in use, the adjustable single-channel time-domain sampling filter forms optical channels with different spectral responses in time sequence by tuning the phase modulators in different cascaded asymmetric interference units.

2. The adjustable single-channel time-domain sampling filter according to claim 1, characterized in that: The phase modulator is arranged on one or two interference arms of the asymmetric interference unit.

3. The adjustable single-channel time-domain sampling filter according to claim 1, characterized in that: The phase modulator has at least three different phase adjustment states.

4. The adjustable single-channel time-domain sampling filter according to claim 1, characterized in that: The splitting ratio of the first waveguide splitting element and the second waveguide splitting element is in a range of 0.05 to 0.

3.

5. The adjustable single-channel time-domain sampling filter according to claim 1, characterized in that: In two adjacent asymmetric interference units, the second waveguide beam splitter element in the previous asymmetric interference unit and the first waveguide beam splitter element in the next asymmetric interference unit reuse the same waveguide beam splitter element.

6. The adjustable single-channel time-domain sampling filter according to claim 5, characterized in that: The splitting ratio of the waveguide splitting elements multiplexed in two adjacent asymmetric interference units is 0.05 to 0.

95.

7. The adjustable single-channel time-domain sampling filter according to any one of claims 1 to 6, characterized in that: In the same asymmetric interference unit, the difference in arm length between the two interference arms is between 1μm and 600μm.

8. The adjustable single-channel time-domain sampling filter according to claim 1, characterized in that: The asymmetric interference unit is a Mach-Zehnder interferometer structure.

9. The adjustable single-channel time-domain sampling filter according to claim 8, characterized in that: At least one of the asymmetric interference units is a passive Mach-Zehnder interferometer structure.

10. An on-chip computational reconstruction spectrometer, characterized in that: The invention comprises a light source, a photodetector and an adjustable single-channel time-domain sampling filter as claimed in any one of claims 1 to 9.

11. A spectrum detection method, characterized in that: The spectral response matrix and the underdetermined equation set are obtained using a computational reconstruction spectrometer as described in claim 10.

12. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, the spectrum detection method described in claim 11 is implemented.

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