A silicon photon spectrum detection chip and its preparation method

Abstract

The present invention discloses a silicon photon spectrum detection chip and a preparation method thereof. An adjustable silicon optical filter is used as a filtering unit of the spectrum chip. The adjustable response characteristic of the silicon optical filter is utilized. Through an external control signal, based on a single filter, the light to be measured can be modulated multiple times. Thus, a group of modulated light responses can be obtained. The spectrum information to be measured is encoded into the output of a photodetector integrated on the chip. The spectrum to be measured is reconstructed in combination with an algorithm.

Description

Technical Field

[0001] The present invention relates to the technical field of spectrum detection, and in particular to a silicon photon spectrum detection chip and a preparation method thereof. Background Art

[0002] Spectrometers can directly reflect the spectral information of substances and obtain the existence status and material composition of the target. They are one of the most important testing instruments in the fields of material characterization and material analysis. They are widely used in life and health, food safety, environmental testing, agricultural production, and chemical process monitoring. With the widespread application of 5G technology, the Internet of Things technology has put forward higher requirements for the perception and detection of various types of information. Specifically for spectral analysis applications, the Internet of Things era requires more compact, low-cost, and low-power spectral detection equipment.

[0003] Existing spectral detection equipment has the following problems: 1) It requires precisely moved spectroscopic components, which makes the spectral detection equipment expensive and has high requirements for the test environment; 2) The maintenance cost of high-precision optical components is high; 3) Due to its spectroscopic principle, high-precision spectral detection equipment is often bulky and not portable.

[0004] The spectral detection chip mainly produces a large number of filter units with different light responses on the chip. The light to be measured passes through the array of these filter units to obtain a set of different output light responses, which are then converted into electrical signals by photodetectors and combined with algorithms to reconstruct the spectrum. This solution requires a large number of filter units with different light responses to be produced on the chip. They can be grating-based, metasurface-based, waveguide device-based, and quantum dot-based. Since the light response of each filter unit must be as different as possible to obtain an accurate spectrum to be measured through reconstruction, the structure of each filter unit also varies greatly.

[0005] Existing spectral detection chips have the following problems: 1) A large number of filter units will occupy a large amount of chip area, resulting in the spectral chip area being too large and the cost being high; 2) The various structures of the filter units mean that different processes need to be used in the processing of the chip, resulting in complex spectral chip preparation process and high processing cost.

[0006] In Chinese patent CN111811652A, a high-contrast grating is used to achieve modulation of the spectrum to be measured. Since the modulation effect of the grating on light is fixed and cannot be adjusted dynamically, a large number of gratings are required to form an array to obtain different modulation signals, and then combine the algorithm to reconstruct the spectrum. Summary of the invention

[0007] The present invention provides a silicon photon spectrum detection chip and a preparation method thereof for the chipization of a spectrometer, which has a compact structure, high integration, and low cost and can be applied to portable spectrum detection equipment.

[0008] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a silicon photonic spectral detection chip includes: an SOI substrate, an optical input interface, a filter and a photodetector. The light to be measured is coupled into the chip through the optical input interface and transmitted to the filter. Under the control of an external signal, the filter modulates the light to be measured several times in different ways and converts it into an electrical signal output through the photodetector; based on the electrical signal output after several modulations, the original spectral information can be obtained after reconstruction combined with algorithm processing.

[0009] In a preferred embodiment of the present invention, the silicon optical filter is a waveguide-type response-adjustable silicon optical filter, which is composed of a Mach-Zehnder interferometer, a microring resonant cavity, and a thermo-optical adjustment electrode.

[0010] In a preferred embodiment of the present invention, two microring resonators are coupled to each other and are respectively coupled to an interference arm of a Mach-Zehnder interferometer. An external control signal changes the phase of the Mach-Zehnder interferometer and the microring resonator through a thermo-optical adjustment electrode to adjust the filter response and realize different modulations of the light to be measured.

[0011] The present invention also provides a method for preparing a silicon photon spectrum detection chip, comprising the following steps: preparing an optical input interface, a filter, and a photodetector on the upper surface of an SOI wafer, and connecting the three in sequence; making a thermo-optical regulation electrode above the filter; making a passivation layer on the upper surface of the SOI wafer; etching a window in the electrode area to expose the electrode, and completing chip production.

[0012] In a preferred embodiment of the present invention, the optical input interface, the filter and the photodetector are connected in sequence through an optical waveguide.

[0013] In a preferred embodiment of the present invention, through holes, metal leads and metal electrodes are formed on the thermo-optical regulation electrode and the photodetector.

[0014] The present invention solves the defects existing in the background technology and has the following beneficial effects:

[0015] 1. Through the present invention, the multiple different modulations of the spectrum to be measured that originally required a filter unit array can now be completed with only one or a small number of adjustable filters, which greatly reduces the area of ​​the chip and has advantages in cost, integration and portability.

[0016] 2. Since the present invention completes multiple and different modulations of the light to be measured through an adjustable filter, compared with the existing spectral chip technical solutions, it does not need to split the light waves of the light to be measured, and the total number of photodetectors required is also relatively small, so the proportion of the light power obtained by each photodetector to the total power is higher, and therefore its signal-to-noise ratio will also be higher than that of the existing spectral chip technical solutions.

[0017] 3. The optical response of the tunable filter can be flexibly adjusted under the control signal, so its modulation effect on the measured light is more flexible and diverse. The optical response of the tunable filter can be flexibly changed and optimized according to specific application requirements, and more accurate spectral reconstruction results can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 This is a schematic diagram of the structure of a silicon photon spectrum detection chip;

[0020] Figure 2 It is a schematic diagram of the structure of a waveguide type response adjustable silicon optical filter;

[0021] Figure 3 The present invention is a flow chart of a method for preparing a spectrum detection chip;

[0022] Figure 4 Four different response spectrum examples of a waveguide-type tunable response silicon optical filter in a preferred embodiment of the present invention;

[0023] Figure 5 A schematic diagram of the chip working process in a preferred embodiment of the present invention;

[0024] In the figure: 11, SOI substrate; 12, optical input interface; 13, waveguide-type response tunable silicon optical filter; 14, photodetector; 21, Mach-Zehnder interferometer; 22, microring resonator; 23, thermo-optical regulation electrode. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. In the description of the present invention, the reference to "embodiment", "one embodiment" or "other embodiments" means that the specific features, structures or characteristics described in conjunction with the embodiment are included in at least some embodiments, but not necessarily all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0026] The present invention is based on silicon photonic technology and adopts an adjustable silicon optical filter as the filtering unit of the spectral chip. The adjustable optical response characteristic of the silicon optical filter is used to perform multiple optical modulations on the light to be detected to obtain a group of modulated optical responses. The spectral information of the light to be detected is encoded on the output optical signal of the filter, and then the optical signal is converted into the response of the detector through an integrated photodetector. The original spectral information can be reconstructed by processing the responses of each detector unit with an algorithm.

[0027] It should be noted that the adjustable silicon optical filter in the present invention is a silicon optical filter whose optical response can be changed under the control of an external signal; the Mach-Zehnder interferometer is an amplitude division interferometer, which can be used to observe the relative phase shift changes caused by a light beam emitted from a single light source being split into two collimated light beams and passing through different paths and media. When there is a phase difference, an interference waveform is generated at the output end; the microring resonant cavity is a resonant cavity device composed of a ring waveguide, which can be coupled with other resonant cavities and straight waveguides.

[0028] like Figure 1 A silicon photon spectrum detection chip is shown. The chip is based on an SOI substrate (11) and comprises an optical input interface (12), one or a group of waveguide-type adjustable response silicon optical filters (13), and one or a group of on-chip integrated photodetectors (14). The light to be measured is coupled into the chip through the optical input interface (12) and transmitted to the waveguide-type adjustable response silicon optical filter (13) via an optical waveguide. After being modulated by the filter (13), the light to be measured is transmitted to the photodetector (14) via an optical waveguide and converted into an electrical signal for output, completing one optical modulation and output. Under the control of an external signal, the waveguide-type adjustable response silicon optical filter (13) changes the response of the filter, and can modulate the light to be measured for multiple times and output it. Based on this group of modulated output electrical signals, the original spectrum information is reconstructed in combination with algorithm processing.

[0029] like Figure 2The structure of a waveguide-type response adjustable silicon optical filter is shown. The waveguide-type silicon optical filter is composed of a Mach-Zehnder interferometer (21), a micro-ring resonant cavity (22), and a thermo-optical adjustment electrode (23). Two micro-ring resonators (22) are coupled to each other and are respectively coupled to an interference arm of the Mach-Zehnder interferometer (21). An external control signal changes the phase of the Mach-Zehnder interferometer (21) and the micro-ring resonator (22) through the thermo-optical adjustment electrode (23), thereby completing the adjustment of the filter response and realizing different modulations of the light to be measured.

[0030] like Figure 4 as well as Figure 5 Four different response spectrum examples and a workflow example in one embodiment are shown. Originally, a filter unit array was required to complete multiple different modulations of the spectrum to be measured. The present invention only requires one or a small number of adjustable filters to complete it, which greatly reduces the chip area and has advantages in cost, integration, and portability.

[0031] Moreover, since the present invention completes multiple and different modulations of the light to be measured through an adjustable filter, compared with the existing spectral chip technical solutions, there is no need to split the light waves of the light to be measured, and the total number of photodetectors required is also relatively small, so the proportion of the light power obtained by each photodetector to the total power is higher, and therefore its signal-to-noise ratio will also be higher than that of the existing spectral chip technical solutions.

[0032] In addition, the optical response of the tunable filter can be flexibly adjusted under the action of the control signal, so its modulation effect on the light to be measured is more flexible and diverse. The optical response of the tunable filter can be flexibly changed and optimized according to specific application requirements, and more accurate spectral reconstruction results can be obtained.

[0033] The chip preparation method of the present invention is as follows Figure 3 As shown, the method includes the following steps: preparing an SOI wafer; preparing an optical input interface, a waveguide-type tunable response silicon optical filter, and a photodetector on the upper surface of the SOI wafer; connecting the optical input interface with the input end of the waveguide-type tunable response silicon optical filter through an optical waveguide; the waveguide-type tunable response silicon optical filter is composed of a Mach-Zehnder interferometer and a microring resonant cavity; connecting the output end of the waveguide-type tunable response silicon optical filter with the photodetector through an optical waveguide; making a thermo-optical adjustment electrode above the tunable response silicon optical filter; making through holes, metal leads, and metal electrodes on the thermo-optical adjustment electrode and the photodetector; making a passivation layer on the upper surface of the wafer; etching a window in the electrode area to expose the electrode, and completing chip manufacturing.

[0034] The above is based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A silicon photon spectrum detection chip, include: SOI substrate, optical input interface, filter and photodetector, characterized in that: The light to be measured is coupled into the chip through the optical input interface and transmitted to the filter. Under the control of an external signal, the filter modulates the light to be measured several times in different ways and converts it into an electrical signal output through the photodetector. The original spectral information can be obtained by combining the algorithm processing and reconstructing the output electrical signal after several modulations. The silicon optical filter is a waveguide type response adjustable silicon optical filter, which is composed of a Mach-Zehnder interferometer, a micro-ring resonant cavity, and a thermo-optical adjustment electrode; The two microring resonators are coupled to each other and to one interference arm of the Mach-Zehnder interferometer respectively. The external control signal changes the phase of the Mach-Zehnder interferometer and the microring resonator through the thermo-optic adjustment electrode, thereby adjusting the filter response and realizing different modulations of the light to be measured.

2. A method for preparing a silicon photon spectrum detection chip according to claim 1, It is characterized in that The following steps are involved: An optical input interface, a filter, and a photodetector are prepared on the upper surface of the SOI wafer, and the three are connected in sequence; a thermo-optical adjustment electrode is prepared above the filter; and a passivation layer is prepared on the upper surface of the SOI wafer; A window is etched in the electrode area to expose the electrode, completing chip production.

3. The method for preparing a silicon photon spectrum detection chip according to claim 2, Features: The optical input interface, the filter and the photodetector are connected in sequence through the optical waveguide.

4. The method for preparing a silicon photon spectrum detection chip according to claim 2, Features: The thermo-optical regulating electrode and the photoelectric detector are both provided with through holes, metal leads and metal electrodes.

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