A silicon optical sensor with multi-parameter testing based on dynamic pattern multiplexing

Abstract

The present invention discloses a silicon optical sensor for multi-parameter testing based on dynamic mode multiplexing. The sensor comprises a silicon optical tunable filter, a silicon optical multi-order mode multiplexer / demultiplexer, and a silicon optical sensor array. The silicon optical tunable filter includes three columns of tunable cascaded microring filters and a metal heating electrode covering the microrings. The silicon optical multi-order mode multiplexer / demultiplexer connects the tunable filter and the silicon optical sensor array. The silicon optical multi-order mode multiplexer / demultiplexer is composed of pure silicon waveguides of varying widths, which are then connected together using tapered waveguides. The silicon optical sensor array comprises three different microring resonators, each responsible for implementing different sensor functions. The present invention fully utilizes the dynamic multi-order mode time-division multiplexing technology of silicon optical waveguides and introduces it into biosensors, greatly expanding the number of sensor channels and realizing an on-chip multi-parameter silicon optical sensor for large-scale parameter detection.

Description

Technical Field

[0001] The present invention relates to an optical sensor in the field of sensing, and more particularly to a silicon optical sensor with multi-parameter testing based on dynamic mode multiplexing. Background Art

[0002] With the development of information technology, such as the Internet of Things (IoT) and artificial intelligence (AI), sensors are placing higher demands on the development of sensors. Sensors, as devices that sense changes in the external environment, play a vital role in various fields. They convert external information into digital data with specific patterns, allowing us to truly live in a digital world. As a key pillar of the IoT era, sensors are developing towards being portable, multi-parameter, and high-throughput.

[0003] Optical sensing, due to its advantages such as immunity to electromagnetic interference, real-time detection, and high integration density, has found widespread application in fields such as biomolecule detection, healthcare, and environmental monitoring. Using micro-nanofabrication methods to integrate optical sensors onto chips, on-chip integrated optical sensors are created. In particular, integrated optical sensors based on silicon optical waveguides have attracted considerable attention in recent years due to the following advantages: First, the fabrication process for silicon-based optical waveguides is compatible with the established complementary metal-oxide-semiconductor (CMOS) process, and silicon is abundant on Earth, enabling large-scale, low-cost mass production. Second, silicon has a large refractive index (n = 3.478). This large refractive index difference provides strong confinement of the optical field, enabling compact waveguide devices with high integration density. Third, thanks to its application in optical interconnects, many key issues in silicon photonics technology have been thoroughly explored, such as on-chip integration of light sources and detectors, and multiplexing of multiple modes and polarization modes.

[0004] However, most current silicon photonic sensors can only detect a single parameter. A few silicon photonic sensors are capable of detecting two or more parameters, but these too have various limitations. For example, while the integrated photonic sensor array developed by Gylfason et al. can simultaneously measure changes in temperature and alcohol concentration, this sensor is limited by the use of a power splitter, which significantly reduces the light intensity received by a single sensor. Furthermore, the use of a camera is not conducive to on-chip integration. Some optical sensors display information on all parameters on the same output spectrum, which can easily interfere with each other and hinder the large-scale expansion of sensing units. Therefore, these silicon photonic sensors either can only detect one parameter or require complex off-chip systems, making them inconvenient for large-scale expansion. These optical sensors struggle to meet the practical application requirements of easily scalable sensor quantities and multi-parameter measurement. Summary of the Invention

[0005] To address, or at least partially address, the problems presented in the aforementioned background technology, the present invention proposes a multi-parameter silicon optical sensor based on dynamic mode multiplexing. This sensor utilizes a silicon optical tunable filter array to dynamically control a conventional silicon optical waveguide multi-order mode multiplexer, enabling time-division mode multiplexing without significantly degrading performance, such as loss, speed, and crosstalk. This technology also introduces mode multiplexing technology into the sensor field, enabling an on-chip multi-parameter optical sensor with easily scalable sensor capacity.

[0006] The technical solutions adopted in the present invention are as follows:

[0007] A silicon optical sensor for multi-parameter testing based on dynamic mode multiplexing includes a silicon optical tunable filter array I, a silicon optical multi-order mode multiplexer II, a silicon optical multi-order mode demultiplexer III, a silicon optical sensor array IV, and a silicon optical multi-order mode multiplexer V. The silicon optical tunable filter array I is connected to the upper silicon optical multi-order mode multiplexer II via straight waveguides 2, 3, and 4. The silicon optical multi-order mode multiplexer II is connected to the right silicon optical multi-order mode demultiplexer III via a trunk waveguide 5. The silicon optical multi-order mode demultiplexer III is connected to the lower silicon optical sensor array IV via straight waveguides 6, 7, and 8. The silicon optical sensor array IV is connected to the lower silicon optical multi-order mode multiplexer V via straight waveguides 9, 10, and 11, and then connected to a grating coupler output to a detector via a straight waveguide 12.

[0008] As a further improvement, the silicon photonic tunable filter array I described in the present invention is composed of three groups of tunable filters and metal heating electrodes covering their upper surfaces. Each group of tunable filters is composed of three microring resonators connected in series. The three groups of tunable filters are connected to the silicon photonic multi-order mode multiplexer II through waveguides 2, 3 and 4 respectively.

[0009] As a further improvement, the silicon photonic multi-order mode multiplexer II, silicon photonic multi-order mode demultiplexer III and silicon photonic multi-order mode multiplexer V described in the present invention have the same structure, all consisting of three pure silicon waveguides of different widths, and the silicon waveguides of different widths are connected by tapered waveguides. The silicon photonic multi-order mode multiplexer II and the silicon photonic multi-order mode demultiplexer III are connected by a wide waveguide 5, and the silicon photonic multi-order mode demultiplexer III is connected to the silicon photonic sensor array IV through waveguides 6, 7 and 8.

[0010] As a further improvement, the silicon optical sensor array IV of the present invention is composed of three sensors, each of which is connected to the silicon optical multi-order mode multiplexer V through waveguides 9, 10 and 11 respectively.

[0011] As a further improvement, the silicon optical sensor array IV of the present invention is implemented by using microring resonators as sensor units, the resonant rings 421 and 422 are ordinary buried silicon optical waveguide structures, and the resonant ring 423 is a slot waveguide structure.

[0012] As a further improvement, the waveguide 1 described in the present invention is connected to the waveguide 114 in the silicon optical tunable filter array I as an input waveguide, and the waveguide 12 is connected to the waveguide 519 in the silicon optical multi-order mode multiplexer V as an output waveguide.

[0013] The beneficial effects of the present invention are:

[0014] The silicon photonic sensor is connected by a silicon photonic tunable filter I and a silicon photonic multi-order mode multiplexer II. The silicon photonic tunable filter allows for the free switching of multiple parameters, enabling a single light source to switch different filters at different times, controlled by a metal heating motor. After passing through each filter, multiple light paths are formed and can continue to be transmitted through the same waveguide. After being transmitted to the silicon photonic multi-order mode demultiplexer III, the light can be transmitted to the corresponding sensor units in the silicon photonic sensor array IV, achieving multi-parameter measurement. After further transmission to the silicon photonic multi-order mode multiplexer V, a single detector can be used to measure multiple parameters in the silicon photonic sensor array IV.

[0015] This invention introduces adjustable functionality into multi-order mode multiplexing technology, achieving a dynamic mode multiplexing technique. This dynamic mode multiplexing technique is then incorporated into silicon optical sensors, enabling a multi-parameter silicon optical sensor. This allows for the detection of multiple parameters (such as multiple protein molecules, concentration, and temperature) using a single chip, a single light source, and a single detector. This invention significantly expands the number of sensor channels, enabling an on-chip multi-parameter optical sensor with easily scalable sensor capacity. It also significantly reduces the cost of multi-parameter measurements, paving the way for even higher-level full-chip integration (where both the light source and detector are integrated on the sensor chip) and its applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the structure of a silicon optical sensor for multi-parameter testing based on dynamic mode multiplexing provided by the present invention;

[0017] 1 is the input waveguide, 12 is the output waveguide, 2-11 are all waveguides;

[0018] I is a silicon photonic tunable filter array, II is a silicon photonic multi-order mode multiplexer, III is a silicon photonic multi-order mode demultiplexer, IV is a silicon photonic sensor array, and V is a silicon photonic multi-order mode multiplexer.

[0019] Figure 2 This is a schematic diagram of the structure of the silicon optical tunable filter array provided by the present invention;

[0020] 131-139 are all microring resonators, 124-126 are curved waveguides, 111-113 are straight waveguides, 121-123 are all curved waveguides, 115 and 116 are curved waveguides, and 117 is a straight waveguide.

[0021] Figure 3 This is a schematic diagram of the structure of the silicon photonic multi-order mode multiplexer provided by the present invention;

[0022] 211, 212, and 213 are waveguides, 231 and 232 are tapered waveguides, 221-223 are curved waveguides, and 214-216 are straight waveguides;

[0023] Figure 4 This is a schematic diagram of the structure of the silicon photonic multi-order mode demultiplexer provided by the present invention;

[0024] 315, 317, 319 are output waveguides, 311, 312, 313 are waveguides, 331, 332 are tapered waveguides, 321-326 are curved waveguides, and 314, 316, 318 are straight waveguides;

[0025] Figure 5 This is a schematic diagram of the silicon light sensor array structure provided by the present invention;

[0026] 411-413 are straight waveguides, 421-423 are microrings;

[0027] Figure 6 This is a schematic diagram of the structure of the silicon photonic multi-order mode multiplexer provided by the present invention;

[0028] 511, 513, 515 are input waveguides, 517, 518, 519 are straight waveguides, 531, 532 are tapered waveguides, 512, 514, 516 are straight waveguides, and 521-526 are curved waveguides. DETAILED DESCRIPTION

[0029] The structure of the present invention is as follows Figure 1As shown, a silicon optical sensor comprises a silicon optical tunable filter, a silicon optical multi-order mode multiplexer / demultiplexer, and a silicon optical sensor array. The silicon optical tunable filter array includes three sets of filters, each corresponding to a respective sensing unit. The filters are composed of three cascaded microring resonators, which achieve a flat-top spectral output. The silicon optical filter can also be tuned by heating metal electrodes. The light output from the filters is then coupled via waveguides to the silicon optical multi-order mode multiplexer / demultiplexer for transmission, ultimately reaching the sensor unit for detection of the object under test. The silicon optical sensor array also consists of three sensor units, responsible for long-range concentration sensing, temperature sensing, and high-precision concentration sensing, respectively. These sensor units are constructed from three different microring resonator structures: a conventional buried silicon optical waveguide structure for long-range concentration sensing and temperature sensing, and a slit waveguide structure for high-precision concentration sensing. To achieve a specific sensor function, simply turn on the corresponding filter switch, and all three sensors can perform simultaneous sensing and measurement.

[0030] The metal heating electrode is completely covered on the upper surface of the filter micro-ring waveguide by sputtering.

[0031] The silicon photonics multi-mode multiplexer / demultiplexer is primarily implemented using waveguides of varying widths. As the waveguide width increases, higher-order modes emerge. Phase matching is used to convert the fundamental TE mode to higher-order modes, allowing the different modes to propagate through the waveguide without interfering with each other. Similarly, the silicon photonics multi-mode demultiplexer also uses phase matching to convert higher-order modes to lower-order modes. Waveguides of varying widths are connected via tapered waveguides to form a single straight waveguide, facilitating light transmission.

[0032] The silicon optical sensor with multi-parameter test based on dynamic mode multiplexing is implemented on silicon-on-insulator (SOI) material, and the thickness of the pure silicon waveguide is 220 nm.

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments of a silicon optical sensor based on multi-parameter testing using dynamic mode multiplexing, but the present invention is not limited to the following embodiments.

[0034] like Figure 1 As shown, an embodiment of the present invention provides a silicon optical sensor for multi-parameter testing based on dynamic mode multiplexing, wherein the silicon optical sensor includes: an input waveguide 1 of a light source, a silicon optical tunable filter array I composed of three groups of cascaded microring resonators, silicon optical multi-order mode multiplexers II and V composed of waveguides of different widths, a silicon optical multi-order mode demultiplexer III composed of waveguides of different widths, a silicon optical sensor array IV composed of three groups of all-pass microring resonators, and an output waveguide 12 of the sensor device.

[0035] In the figure, each module is connected by straight waveguides. Among them, input waveguide 1 is connected to silicon optical tunable filter array I; waveguides 2, 3, and 4 respectively connect silicon optical tunable filter array I to silicon optical multi-order mode multiplexer II; waveguide 5 connects silicon optical multi-order mode multiplexer II to silicon optical multi-order mode demultiplexer III; waveguides 6, 7, and 8 respectively connect silicon optical multi-order mode demultiplexer III to silicon optical sensor array IV; waveguides 9, 10, and 11 respectively connect silicon optical sensor array IV to silicon optical multi-order mode multiplexer V; waveguide 12 is the output waveguide, connected to the photodetector;

[0036] like Figure 2 As shown, the silicon optical tunable filter array I comprises three groups of filters. The first group consists of three microring resonators 131, 132, and 133 connected in series; the second group consists of microring resonators 134, 135, and 136; and the third group consists of microring resonators 137, 138, and 139. For the microrings, the input waveguides are curved waveguides 124, 125, and 126, which couple more light into the microrings. Each section of curved waveguides 124, 125, and 126 is connected by curved waveguides 115 and 116, with waveguide 114 connecting to the input waveguide 1 of the light source. The output waveguides of the filters consist of straight waveguides and curved waveguides. The output waveguides of the first group consist of curved waveguide 121 and straight waveguide 111; the output waveguides of the second group consist of curved waveguide 122 and straight waveguide 112; and the output waveguides of the third group consist of curved waveguide 123 and straight waveguide 113. 117 is an extended waveguide to prevent light from being reflected back to the filter from the cross section.

[0037] like Figure 3 As shown, the silicon photonic multi-mode multiplexer II is composed of three waveguides of different widths 211, 212, and 213, connected by tapered waveguides 231 and 232. The input waveguides of the multi-mode multiplexer are composed of curved waveguides and straight waveguides: curved waveguide 221 and straight waveguide 214, curved waveguide 222 and straight waveguide 215, and curved waveguide 223 and straight waveguide 216. The input light is in the fundamental TE mode, modulated by the filter. For the silicon photonic multi-mode multiplexer II, the input waveguides are waveguides 221, 222, and 223, each connected to the three sets of tunable filters described above.

[0038] like Figure 4As shown, the structure of the silicon photonic multi-mode demultiplexer III is identical to that of the aforementioned silicon photonic multi-mode demultiplexer II, simply inverted for symmetry. The silicon photonic multi-mode demultiplexer comprises three waveguides of varying widths, 311, 312, and 313, connected by tapered waveguides 331 and 332. The output waveguides of the multi-mode demultiplexer consist of curved waveguides 321-326 and straight waveguides 314-319. Output waveguides 315, 317, and 319 connect to three sensing units in the silicon photonic sensor array IV, specifically to straight waveguides 411, 412, and 413, respectively.

[0039] like Figure 5 As shown, the silicon optical sensor array IV is composed of three groups of all-through microring resonators. The first group of sensors consists of a straight waveguide 411 and a microring 421, the second group of sensors consists of a straight waveguide 412 and a microring 422, and the third group of sensors consists of a straight waveguide 413 and a microring 423. The first two groups of microring structures are conventional buried silicon optical waveguide structures, while the third group of microring structures is a slot waveguide structure.

[0040] like Figure 6 As shown, the input waveguides of the multi-order mode multiplexer V are straight waveguides 511, 513, and 515, respectively. Their upper ends are connected to the three groups of silicon optical sensors described above, specifically to waveguides 411, 412, and 413. Light is then coupled into the multi-order mode multiplexer via curved waveguides 521-526 and straight waveguides 512, 514, and 516. Utilizing the specificity of mode coupling, light of different modes propagates through the multiplexer without interfering with each other. The mode multiplexer is composed of straight waveguides 517, 518, and 519 of varying widths, which are further connected by tapered waveguides 531 and 532. The wide waveguide 519 connects to the output waveguide 12 of the sensor device. Light is then output from the output waveguide and ultimately received by a photodetector.

[0041] The specific embodiments of the present invention and their implementation are as follows:

[0042] First, light is coupled into the silicon nanowire dielectric waveguide 1 from the top surface using a grating coupler. The input light mode is the TE0 mode. The light then passes through the tunable filter array I and is coupled into the main waveguide by filters 131-133, 134-136, and 137-139. The filters are composed of microrings in a series arrangement of pure silicon waveguides, which enable broadband bandpass filtering. The filter tunability is achieved by heating the metal to determine whether light is coupled into the main waveguide through each filter, transforming the static filter into a dynamically tunable broadband bandpass filter. When a filter is in the on state, the output light from the drop terminals (drop ports) 111, 112, and 113 enters the main waveguide through silicon optical mode multiplexer II. This is achieved by designing the width of the main waveguide at the corresponding filter position so that the equivalent refractive index of a certain order of optical mode within it matches the mode of the single-mode waveguide at the drop terminal. Phase matching is achieved, enabling optical coupling and mode conversion.

[0043] In this sensor, three transverse-electric modes (TE0, TE1, and TE2) are considered in the trunk waveguide. When light in a certain mode passes through the trunk waveguide and reaches sensor array IV, it passes through demultiplexer III, corresponding to mode multiplexer II, and is reconverted to the TE0 mode and downloaded to the corresponding optical sensor microrings 421, 422, and 423. Due to the specificity of mode coupling, light in that mode can only be downloaded to a specific sensor, thus achieving a one-to-one correspondence between the microring resonators 131-133, 134-136, and 137-139 in tunable filter I, the trunk waveguide mode, and the microrings 421, 422, and 423 in sensor unit IV. Light passing through the sensor unit, composed of an all-pass microring resonator, undergoes a resonance effect. When external conditions change, the spectrum modulated by the microring resonator also changes. The change in the resonant wavelength can be used to infer the change in external conditions. This sensor array consists of three microring sensing units—microrings 421, 422, and 423—that perform three distinct functions: wide-range concentration sensing, temperature sensing, and high-precision concentration sensing. Microring 423, the high-precision concentration sensor, utilizes a slit waveguide structure, while the others utilize conventional buried silicon optical waveguides. Finally, after the light carrying the measured parameter information is output from each sensor, it is converted by a silicon optical mode multiplexer V to another trunk waveguide 12 and ultimately output to the detector. Because the sensors operate in a time-sharing manner, only a single detection unit is required to detect all sensor information. This ultimately creates a multi-parameter silicon optical sensor.

[0044] The above description of the embodiments is intended to facilitate understanding and application of the present invention by those skilled in the art. It is apparent that those skilled in the art can readily make various modifications to the above embodiments and apply the general principles described herein to other embodiments without requiring creative effort. Therefore, the present invention is not limited to the above embodiments. Any improvements or modifications made by those skilled in the art based on the disclosure of the present invention should fall within the scope of protection of the present invention.

Claims

1. A silicon optical sensor with multi-parameter testing based on dynamic mode multiplexing, characterized by: The invention comprises a silicon optical tunable filter array (I), a first silicon optical multi-order mode multiplexer (II), a silicon optical multi-order mode demultiplexer (III), a silicon optical sensor array (IV) and a second silicon optical multi-order mode multiplexer (V). The silicon optical tunable filter array (I) is composed of three groups of tunable filters and metal heating electrodes covering the upper surface thereof. Each group of tunable filters is composed of three micro-ring resonators connected in series. The three groups of tunable filters are connected to the first silicon optical multi-order mode multiplexer (II) above through a first straight waveguide (2), a second straight waveguide (3) and a third straight waveguide (4). ), the first silicon optical multi-order mode multiplexer (II) is connected to the right silicon optical multi-order mode demultiplexer (III) through the trunk waveguide (5), the silicon optical multi-order mode demultiplexer (III) is connected to the silicon optical sensor array (IV) below through the fourth straight waveguide (6), the fifth straight waveguide (7), and the sixth straight waveguide (8), the silicon optical sensor array (IV) consists of three sensors, and the three sensors are respectively connected to the second silicon optical multi-order mode multiplexer (V) below through the seventh straight waveguide (9), the eighth straight waveguide (10), and the ninth straight waveguide (11), the silicon optical sensor array (IV) is realized by a microring resonator as a sensor unit, the second silicon optical multi-order mode multiplexer (V) is connected to the output straight waveguide (12), and the output straight waveguide (12) is connected to the grating coupler output to the detector; the sensor unit consists of a straight waveguide and a microring.

2. The silicon optical sensor with multi-parameter testing based on dynamic mode multiplexing according to claim 1, characterized in that: The first silicon photonic multi-order mode multiplexer (II), the silicon photonic multi-order mode demultiplexer (III) and the second silicon photonic multi-order mode multiplexer (V) have the same structure and are all composed of three pure silicon waveguides of different widths. The silicon waveguides of different widths are connected by tapered waveguides. The first silicon photonic multi-order mode multiplexer (II) and the silicon photonic multi-order mode demultiplexer (III) are connected through a trunk waveguide (5), and the silicon photonic multi-order mode demultiplexer (III) is connected to the silicon photonic sensor array (IV) through a fourth straight waveguide (6), a fifth straight waveguide (7) and a sixth straight waveguide (8).

3. The silicon optical sensor with multi-parameter testing based on dynamic mode multiplexing according to claim 1, characterized in that: The first microring (421) and the second microring (422) in the silicon optical sensor array (IV) are common buried silicon optical waveguide structures, while the third microring (423) is a slit waveguide structure.

4. The silicon optical sensor with multi-parameter testing based on dynamic mode multiplexing according to claim 3, characterized in that: The input waveguide (1) is connected to the waveguide (114) in the silicon optical tunable filter array (I) as an input waveguide, and the output straight waveguide (12) is connected to the tenth straight waveguide (519) in the second silicon optical multi-order mode multiplexer (V) as an output waveguide.

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