A chip sensing component and a trace gas detection device

Abstract

This disclosure belongs to the field of on-chip integrated sensing technology, and provides a chip sensing component and a trace gas detection device. The chip sensing component includes: a first mode field coupler, a power beam splitter, a non-uniform free spectral range microring resonator array, a power combiner, and a second mode field coupler connected in series. The non-uniform free spectral range microring resonator array is composed of N microring resonators with different resonant ring lengths connected in parallel, and the evanescent field of the ring waveguide of each microring resonator is exposed to the chip surface environment. It is used to capture the absorption information of gas molecules using multiple evanescent fields, and outputs N probe beams carrying the absorption information of gas molecules to the power combiner. By using multiple microring resonators with different ring lengths, the spectral sampling interval is effectively greatly compressed, breaking through the limitation of the free spectral range of a single microring, enabling the on-chip system to detect the narrow linewidth absorption characteristics of gas molecules.

Description

Technical Field

[0001] This application belongs to the field of on-chip integrated sensing technology, and specifically relates to a chip sensing component and a trace gas detection device. Background Technology

[0002] Trace gas monitoring has crucial applications in environmental science, industrial safety, and medical diagnostics. Laser absorption spectroscopy (LAS) technology, due to its high selectivity, rapid response, and inherently non-contact nature, has become one of the core solutions in this field. Its detection sensitivity directly depends on the path length of the effective light-gas interaction. To overcome the path limitations of traditional single-pass absorption cells, cavity-enhanced absorption spectroscopy (CEAS) technology has emerged. It utilizes a high-precision optical resonator to extend the photon lifetime by thousands to tens of thousands of times, achieving an equivalent interaction path on the order of kilometers and realizing extremely high detection sensitivity. However, this technology relies on macroscopic cavities composed of discrete precision optical lenses, making the systems typically bulky and expensive. They are also extremely sensitive to environmental vibrations and temperature drift, making it difficult to meet the demands of modern sensing devices for miniaturization, integration, robustness, and low cost.

[0003] Therefore, there is an urgent need for an innovative on-chip device architecture that can inherit the advantages of miniaturization and mass production capabilities of integrated photonics, while breaking through the limitation of excessively wide free spectral range of a single microring, and achieving high-resolution spectral measurement comparable to traditional macroscopic cavities, thereby promoting the true chip-based implementation of high-performance trace gas monitoring technology. Summary of the Invention

[0004] To address the aforementioned issues, this application provides a chip sensing component and a trace gas detection device.

[0005] This application provides a chip sensing component, comprising: a first mode field coupler, a power beam splitter, a non-uniform free-spectral-range microring resonator array, a power combiner, and a second mode field coupler connected in series; the non-uniform free-spectral-range microring resonator array is composed of N microring resonators with different resonant ring lengths connected in parallel, and the evanescent field of the ring waveguide of each microring resonator is exposed to the chip surface environment, where N is a positive integer greater than or equal to 2, wherein:

[0006] The first mode field coupler is used to couple the probe light to the input waveguide of the chip;

[0007] A power beam splitter is used to split the probe light into N paths and output them to a non-uniform free spectral range microring resonator array, wherein each path corresponds one-to-one with the N microring resonators in the array;

[0008] A non-uniform free spectral range microring resonator array is used to capture the absorption information of gas molecules using multiple evanescent fields, and outputs N probe beams carrying the absorption information of gas molecules to a power combiner.

[0009] A power combiner is used to combine N probe beams carrying absorption information of gas molecules into a single beam.

[0010] The second mode field coupler is used to couple a probe light carrying the absorption information of gas molecules to the chip's output waveguide.

[0011] Furthermore, the ring length of the i-th microring resonator in the non-uniform free spectral range microring resonator array ,in, Based on the ring length, The increment is the fixed ring length.

[0012] Furthermore, the increment of the fixed ring length is on the order of nanometers.

[0013] Furthermore, the first mode field coupler is an edge coupler, a micromirror coupler, a grating coupler, or an inverted conical coupler; the second mode field coupler is an edge coupler, a micromirror coupler, a grating coupler, or an inverted conical coupler.

[0014] Furthermore, the power beam splitter is a 1×N chip multimode interference beam splitter or a cascaded Y-brancher.

[0015] Furthermore, the power combiner is a multimode interference coupler, a directional coupler, or a Y-coupler.

[0016] Furthermore, the microring resonator is a silicon-based microring resonator, a silicon nitride microring resonator, or a lithium niobate microring resonator, with a quality factor greater than 1 × 10⁻⁶. 4 .

[0017] Furthermore, the chip sensing component is sealed inside the cavity, which has an air inlet and an air outlet.

[0018] This application also provides a trace gas detection device, comprising: a detection light source, an optical power amplifier, the aforementioned chip sensing component, and a photodetector connected in series.

[0019] A detection light source, used to emit detection light;

[0020] An optical power amplifier is used to amplify the probe light;

[0021] A photodetector is used to detect changes in the intensity of probe light that carries absorption information from gas molecules.

[0022] Furthermore, the photodetector is matched with the wavelength of the light source being detected, with a response range covering 1510nm-1630nm and a response frequency greater than 1MHz.

[0023] Compared with the prior art, this application has the following advantages:

[0024] 1. By connecting multiple microring resonators of different ring lengths in parallel, the spectral sampling interval is effectively and greatly compressed, breaking through the limitation of the free spectral range of a single microring, enabling the on-chip system to detect the narrow linewidth absorption characteristics of gas molecules for the first time.

[0025] 2. The cavity enhancement absorption spectroscopy function, which traditionally requires complex discrete optical components, is realized on a single photonic chip. The device has outstanding advantages such as small size, good stability, strong anti-interference ability, and easy mass production.

[0026] 3. By designing the number and ring length distribution of microring resonators, the spectral coverage and resolution can be flexibly adjusted to meet the detection needs of different gases, laying the foundation for building a multifunctional, reconfigurable on-chip spectral analysis system.

[0027] Other features and advantages of this application will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the structure of the chip sensing component of the present invention;

[0030] Figure 2 This is a single microring structure of a non-uniform free spectral range microring resonator array for the chip sensing component of the present invention;

[0031] Figure 3 This is a schematic diagram of the structure of the broadband trace gas monitoring device of the present invention;

[0032] Figure 4 This is a simulation diagram of the output signal of the broadband trace gas monitoring device of the present invention when detecting acetylene gas molecules.

[0033] In the diagram: 100, probe light source; 200, optical power amplifier; 311, first mode field coupler; 320, power beam splitter; 330, non-uniform free spectral range micro-ring resonator array; 340, power beam combiner; 312, second mode field coupler; 400, photodetector; 331, upper incident port; 332, lower incident port; 333, upper exit port; 334, lower exit port. Detailed Implementation

[0034] To address the inherent contradiction in existing high-sensitivity gas spectral monitoring devices between miniaturization, integration, and high resolution, this invention provides a wide-spectrum trace gas monitoring device based on a non-uniform free spectral range microring resonator array. This device combines the high sensitivity advantage of cavity-enhanced absorption spectroscopy with the miniaturization and scalable manufacturing characteristics of integrated photonics. By employing an on-chip non-uniform free spectral range microring resonator array structure, it effectively achieves high-density spectral sampling. This overcomes the limitation of a single microring resonator having an excessively wide free spectral range, which prevents high-resolution spectral scanning. The invention enables high-resolution, high-sensitivity measurement of gas absorption lines based on cavity-enhanced absorption spectroscopy.

[0035] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0036] like Figure 1 As shown, this is a chip sensing component according to an embodiment of the present invention, comprising: a first mode field coupler 311, a power beam splitter 320, a non-uniform free spectral range microring resonator array 330, a power combiner 340, and a second mode field coupler 312 connected in series; the non-uniform free spectral range microring resonator array is composed of N microring resonators with different resonant ring lengths connected in parallel, and the evanescent field of the ring waveguide of each microring resonator is exposed to the chip surface environment, wherein N is a positive integer greater than or equal to 2, where:

[0037] The first mode field coupler 311 is used to couple the probe light to the input waveguide of the chip;

[0038] The power beam splitter 320 is implemented using a multimode interference coupler such as a 1×N multimode interference coupler or a cascaded Y-brancher, and is used to split the probe light into N paths and output them to the non-uniform free spectral range microring resonator array 330, wherein each path corresponds one-to-one with the N microring resonators of the array.

[0039] The non-uniform free-spectral-range microring resonator array 330 has its input terminals connected to N output terminals of a power beamsplitter 320, and its output terminals connected to N input terminals of a power beam combiner 340. This array is used to capture the absorption information of gas molecules using multiple evanescent fields, and outputs N probe beams carrying the absorption information of the gas molecules to the power beam combiner. The waveguide design of each microring resonator exposes its evanescent field to the chip surface environment to interact with the gas being measured. A key design feature of this non-uniform free-spectral-range microring resonator array 330 is that the resonant ring length of each microring is precisely designed to be different, forming a sequence of ring lengths.

[0040] The power combiner 340, unlike the power splitter 320, adopts an N×1 structure to combine N paths of detection light carrying absorption information of gas molecules into one path.

[0041] The second mode field coupler 312 is used to couple a probe light carrying absorption information of gas molecules to the output waveguide of the chip.

[0042] Preferably, the ring length of the i-th microring resonator in the non-uniform free spectral range microring resonator array is... ,in, Based on the ring length, The increment is the fixed ring length.

[0043] Preferably, the increment of the fixed ring length is on the order of nanometers.

[0044] Preferably, the first mode field coupler 311 is an edge coupler, a micromirror coupler, a grating coupler, or an inverted conical coupler; the second mode field coupler is an edge coupler, a micromirror coupler, a grating coupler, or an inverted conical coupler.

[0045] Preferably, the power beam splitter 320 is a 1×N chip multimode interference beam splitter or a cascaded Y-brancher.

[0046] Preferably, the power combiner 340 is a multimode interference coupler, a directional coupler, or a Y-coupler.

[0047] Preferably, the microring resonator is a silicon-based microring resonator, a silicon nitride microring resonator, or a lithium niobate microring resonator, with a quality factor greater than 1×10⁻⁶. 4 .

[0048] Preferably, the chip sensing component can be directly measured in the gas to be measured, or it can be sealed inside the cavity and have inlet and outlet ports, and the gas inlet and outlet can be controlled by microfluidics and other technologies.

[0049] like Figure 2The single microring structure of the non-uniform free spectral range microring resonator array of the wide-spectrum trace gas monitoring device of the present invention is shown. It consists of two parallel straight-guided waves and a ring resonant cavity located between the two straight-guided waves. There are two pairs of input and output ports. In this case, the light enters from the input port 332, and the outgoing light coupled into the microring exits from the port 333. The port 334 is also an output port, and the output is the light that has not been coupled into the microring. It can also generally be used as a light intensity monitoring port for gas concentration inversion.

[0050] like Figure 3 As shown, this is a trace gas detection device according to an embodiment of the present invention, comprising: a detection light source 100, an optical power amplifier 200, a chip sensing component 300, and a photodetector connected in series; wherein, the chip sensing component can be monolithically integrated on the same photonic chip;

[0051] The detection light source 100 is used to emit detection light; preferably, a wavelength-tunable laser is used, and its tuning range should cover one or more characteristic absorption peaks of the target gas to be tested.

[0052] The optical power amplifier 200 is used to amplify the probe light to compensate for the power loss introduced by beam splitting, coupling and other processes in the subsequent link, so as to ensure the strength of the sensing signal.

[0053] The photodetector 400 is used to receive the synthesized optical signal carrying absorption information of gas molecules output from the power combiner 340, and convert it into an electrical signal for subsequent analysis and processing. This detector can be an off-chip demodulation device or a photodiode heterogeneously integrated with the photonic chip.

[0054] Preferably, the detection light source is a commercially available broadband tunable continuous light source with a wavelength range covering 1510-1630nm, used to detect vibrational-rotational transition absorption of gas molecules.

[0055] Preferably, the photodetector is matched with the wavelength of the detection light source, with a response range covering 1510nm-1630nm and a response frequency greater than 1MHz.

[0056] The operation of the aforementioned trace gas detection device is as follows: The broadband tunable laser emitted by the probe light source is amplified by an optical power amplifier and then injected into the on-chip waveguide by a first mode field coupler. Subsequently, the light is uniformly distributed by a power beam splitter to a non-uniform free spectral range microring resonator array—this array consists of dozens to hundreds of microring resonators with different resonant ring lengths connected in parallel. The evanescent field of each microring is exposed to the gas environment to be measured. Because the ring lengths of each microring are precisely designed and different from each other, their resonance peaks are distributed at different intervals on the frequency axis. These resonance peaks intersect and are closely arranged, thus forming an equivalent, high-density "comb" transmission spectrum within the target spectral range. This design compresses the frequency interval of the effective spectral sampling points from the free spectral range of a single microring on the order of hundreds of GHz to GHz or even below, achieving high-resolution coverage of the fine absorption spectra of gas molecules. After the light-matter interaction is enhanced by the micro-ring array, the light signal carrying gas absorption information is collected and converged by the power combiner, and finally converted into an electrical signal by the photodetector for demodulation and analysis, thereby retrieving the concentration of trace gases.

[0057] The working principle and high-resolution mechanism of this embodiment are as follows:

[0058] The free spectral range (FSR) of a single microring resonator is very large (typically >100 GHz), making it impossible to finely resolve narrow absorption lines of gas molecules (typically on the order of GHz). This invention addresses this problem by introducing a non-uniform free spectral range microring resonator array (330), where the ring length of the i-th microring is designed as follows: ,in Based on the ring length, The increments are fixed at the nanometer scale. Since the FSR is inversely proportional to the ring length, the resonant peaks of each microring are located at different positions on the frequency axis. When dozens to hundreds of microrings are connected in parallel, their resonant peaks interweave across a broadband spectral range to form a highly dense network of equivalent frequency sampling points. This makes the effective spectral sampling interval of the entire device much smaller than the FSR of a single microring, reaching GHz or even sub-GHz levels, thus enabling high-resolution scanning of gas absorption spectra.

[0059] During operation, the probe light is uniformly distributed across all the parallel-connected microrings. When the laser wavelength scans to near the resonant wavelength of a particular microring, the light beam resonates strongly within the cavity, resulting in intense characteristic absorption by gas molecules on the microring surface, causing a decrease in the transmitted light intensity of that channel. Because the array provides dense spectral sampling, the system can record the complete profile of the gas absorption spectrum with high fidelity. The transmitted light from all microring channels is combined and uniformly received by the photodetector 400. By analyzing the detector signal's wavelength variation curve and fitting it to a standard absorption library (such as HITRAN), the type and concentration of trace gases can be accurately determined.

[0060] In this invention, addressing the challenges of integrating bulky discrete cavities in traditional cavity-enhanced absorption spectroscopy and the insufficient spectral resolution of individual on-chip microrings due to their short cavity lengths and wide free spectral ranges (typically reaching hundreds of GHz), a chip-based sensing component is proposed. Its core lies in coupling the amplified probe light to a non-uniform free spectral range microring resonator array composed of hundreds of microrings of varying lengths via a power beam splitter. The resonant peaks of these microrings intersect each other on the frequency axis, effectively compressing the effective spectral sampling point spacing from the hundreds of GHz level of a single microring to below GHz, thereby achieving high-resolution spectral absorption measurement comparable to traditional cavity-enhanced techniques within a miniaturized on-chip system. The trace gas detection device incorporating this chip-based sensing component combines the high selectivity of gas absorption spectra with the miniaturization and large-scale integration advantages of on-chip photonic circuits, providing a new approach for developing high-performance, portable trace gas monitoring systems.

[0061] The following is an example of measurement parameters for acetylene gas that absorbs near 1530 nm:

[0062] In one specific embodiment, to achieve the monitoring of acetylene gas in the near-infrared band, the device parameters can be designed as follows:

[0063] Number of microrings ;

[0064] Basic ring length ;

[0065] Ring length increment (Achieved through high-precision photolithography).

[0066] With this design, the array can achieve an equivalent spectral sampling interval of about 1.5 GHz near the 1530 nm band, which is sufficient to resolve the absorption linewidth of gases at room temperature and pressure (about 20 GHz to 4 GHz).

[0067] The detection light source 100 is a broadband continuously tunable external cavity semiconductor laser. The laser wavelength is scanned to cover the molecular absorption lines, and the intensity changes of the light emitted through port 333 are detected and collected by the detector. The acetylene gas concentration is set to 10%, and the simulation results are as follows: Figure 4 As shown. Figure 4 The output port data of the microring at port 333 shows that, in particular, gas absorption causes losses, and the light intensity of the microring resonant output is weakened. The amount of weakening can be used to infer the gas concentration based on laser infrared absorption spectroscopy.

[0068] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A chip sensing component, characterized in that, include: The system consists of a first mode field coupler, a power beam splitter, a non-uniform free-spectral-range microring resonator array, a power combiner, and a second mode field coupler, connected in series. The non-uniform free-spectral-range microring resonator array comprises N microring resonators with different ring lengths connected in parallel. The evanescent field of the ring waveguide of each microring resonator is exposed to the chip surface environment to interact with the gas under test. The resonant peaks of the N microring resonators with different ring lengths intersect each other on the frequency axis, where N is a positive integer greater than or equal to 2. The first mode field coupler is used to couple the probe light to the input waveguide of the chip; The power beam splitter is used to split the probe light into N paths and output them to a non-uniform free spectral range microring resonator array, wherein each path corresponds one-to-one with the N microring resonators of the array. The non-uniform free spectral range microring resonator array is used to capture the absorption information of gas molecules using multiple evanescent fields and output N probe beams carrying the absorption information of gas molecules to the power combiner. The power combiner is used to combine N paths of probe light carrying absorption information of gas molecules into one path. The second mode field coupler is used to couple a probe light carrying the absorption information of gas molecules to the chip's output waveguide.

2. The chip sensing component according to claim 1, characterized in that, a ring length of an i-th micro-ring resonator in the array of micro-ring resonators in the non-uniform free spectral range wherein, is a base ring length, is a fixed ring length increment.

3. The chip sensing component according to claim 2, characterized in that, The increment of the fixed ring length is on the order of nanometers.

4. The chip sensing component according to claim 1, characterized in that, The first mode field coupler is an edge coupler, a micromirror coupler, a grating coupler, or an inverted conical coupler; the second mode field coupler is an edge coupler, a micromirror coupler, a grating coupler, or an inverted conical coupler.

5. The chip sensing component according to claim 1, characterized in that, The power beam splitter is a 1×N chip multimode interference beam splitter or a cascaded Y-brancher.

6. The chip sensing component according to claim 1, characterized in that, The power combiner is a multimode interference coupler, a directional coupler, or a Y-coupler.

7. The chip sensing component according to claim 1, characterized in that, The micro-ring resonator is a silicon-based micro-ring resonator, a silicon nitride micro-ring resonator or a lithium niobate micro-ring resonator, and the quality factor value is greater than 1x10 4 .

8. The chip sensing component according to claim 1, characterized in that, The chip sensing component is sealed inside a cavity, which has an air inlet and an air outlet.

9. A trace gas detection device, characterized in that, include: The detection light source, the optical power amplifier, the chip sensing component according to any one of claims 1-8, and the photodetector are connected in series. The detection light source is used to emit detection light; The optical power amplifier is used to amplify the probe light; The photodetector is used to detect changes in the intensity of detection light carrying absorption information of gas molecules.

10. The trace gas detection device according to claim 9, characterized in that, The photodetector is matched with the wavelength of the light source, with a response range covering 1510nm-1630nm and a response frequency greater than 1MHz.

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