Miniature computational spectrometer based on disordered photonic molecules

Abstract

A miniature computational spectrometer based on disordered photonic molecules includes: a substrate, four microdisks disposed thereon, two waveguides, a heating layer on top, and a pair of metal electrodes. The two waveguides for inputting and outputting optical signals are located outside the four microdisks, which are coupled in pairs to form a photonic molecule system. The heating layer is located on top of the four microdisks and connected to the pair of metal electrodes located outside the waveguides. This invention, based on a disordered photonic molecule structure, uses multi-body electromagnetic coupling as a medium to generate a quasi-disordered spectral response matrix. While achieving compact physical dimensions, it also enables high bandwidth and high resolution spectral analysis, exhibiting a near-infinite free spectral range (FSR) and a high Q value (>7.74 × 10⁻⁶). 5 It can exhibit spectral analysis performance with a high bandwidth of 100nm and a high resolution of 8pm.

Description

Technical Field

[0001] This invention relates to a technology in the field of spectrometers, specifically a miniature computational spectrometer based on disordered photonic molecules. Background Technology

[0002] In scientific research and industrial fields involving material analysis, spectral analysis is an important research tool, and the development of portable platforms has created an increasingly urgent need for miniaturized spectrometers. Due to their physical size and characteristics, the encoders in existing spectrometers encode redundant spectral information, leading to a decrease in reconstruction efficiency and performance, or requiring a centimeter-scale footprint to accumulate sufficient optical path difference. This forces existing computational spectrometers to make trade-offs between performance and physical size. Summary of the Invention

[0003] This invention addresses the shortcomings of existing spectrometers, such as the difficulty in balancing physical size and spectral analysis performance, and the periodic redundancy in the encoded information of computational spectrometers. It proposes a miniature computational spectrometer based on disordered photonic molecules. Utilizing a disordered photonic molecule structure and employing many-body electromagnetic coupling as a medium, a quasi-disordered spectral response matrix is ​​generated. This achieves both compact physical size and high bandwidth and high resolution spectral analysis, exhibiting a near-infinite free spectral range (FSR) and a high Q value (>7.74 × 10⁻⁶). 5 It can exhibit spectral analysis performance with a high bandwidth of 100nm and a high resolution of 8pm.

[0004] This invention is achieved through the following technical solution:

[0005] This invention relates to a micro-computational spectrometer based on disordered photonic molecules, comprising: a substrate layer, four microdisks disposed thereon, two waveguides, a heating layer located on the top layer, and a pair of metal electrodes, wherein: the two waveguides for inputting and outputting optical signals are respectively located outside the four microdisks that are coupled in pairs to form a photonic molecule system, and the heating layer is located on top of the four microdisks and connected to the pair of metal electrodes located outside the waveguides.

[0006] The photonic molecular system is preferably quadrilateral in shape.

[0007] The SOI wafer comprises, from bottom to top, a silicon substrate layer, a silicon dioxide layer, and a silicon layer.

[0008] The first and third microdisks are coupled to the first waveguide in parallel direction; the first and second microdisks are coupled in the vertical direction; the second and fourth microdisks are coupled to the second waveguide in parallel direction; and the third and fourth microdisks are coupled in the vertical direction.

[0009] In the aforementioned coupling, the coupling spacing between each microdisk is equal.

[0010] This embodiment relates to an encoding method for optical signals based on the aforementioned micro-computational spectrometer. The spectral signal is input into the waveguide through the input port of the first waveguide, and after being coupled into a photonic molecular system composed of four microdisks for quasi-disorder encoding, it is coupled into the second waveguide through the microdisks and output. The input spectral signal is then reconstructed after the spectral correlation function curve is calculated and plotted. Technical effect

[0011] This invention generates a quasi-random response matrix by coupling multiple microdisk photonic atoms of different sizes in pairs to form a heteronuclear photonic molecular structure. This generates a large number of disordered supermodes distributed across the spectrum. Compared to existing technologies, this invention completely eliminates mode degeneracy, greatly enriching the number of photonic molecular orbitals participating in mode hybridization, thereby generating a large number of disordered supermodes in the spectrum. This significantly reduces the natural periodicity of resonant cavity devices to an extremely low level. Based on this response matrix, experiments have demonstrated the performance of an ultra-high resolution and wide bandwidth spectrometer. Attached Figure Description

[0012] Figure 1 This is a three-dimensional structural schematic diagram of the miniature computational spectrometer of the present invention;

[0013] In the figure: 1. Silicon dioxide substrate, 2, 3, 4, 5. Silicon microdisk, 6, 7. Silicon waveguide, 8. Waveguide in input port, 9. Waveguide output port, 10. Titanium nitride heating layer, 11, 12.

[0014] Figure 2 This is a light field distribution diagram of the photonic molecular system at different wavelengths in the miniature computational spectrometer of this invention;

[0015] Figure 3 This is a transmission intensity distribution diagram of the miniature computational spectrometer of the present invention under different heating powers;

[0016] Figure 4 This is a graph of the spectral correlation function of the miniature computational spectrometer of the present invention;

[0017] Figure 5 This is a diagram showing the reconstruction results of monochromatic light signals by the miniature computational spectrometer of this invention;

[0018] Figure 6 This is a diagram showing the reconstruction results of a high-bandwidth constructed spectrum by the miniature computational spectrometer of this invention;

[0019] Figure 7 This diagram illustrates the highest resolution spectral reconstruction using the miniature spectrometer of this invention. Detailed Implementation

[0020] like Figure 1 As shown in the figure, this embodiment relates to a micro-computational spectrometer based on disordered photonic molecules fabricated on an SOI wafer, comprising: a substrate layer 1, four microdisks 2, 3, 4, 5 disposed thereon, two waveguides 6, 7, a heating layer 10 located on the top layer, and a pair of metal electrodes 11, 12, wherein: the two waveguides 6, 7 used for input and output optical signals are respectively located outside the four microdisks 2, 3, 4, 5 that are coupled in pairs to form a photonic molecule system, and the heating layer 10 is located on top of the four microdisks and connected to the pair of metal electrodes located outside the waveguides 6, 7.

[0021] The SOI wafer comprises, from bottom to top, a silicon substrate layer, a silicon dioxide layer, and a silicon layer, with a total thickness of 220 nm.

[0022] The diameters of the first to fourth microdisks 2-5 are 14μm, 13μm, 10μm and 18μm respectively. The technical details of their position setting are as follows: the four microdisks are arranged in pairs and coupled to each other: the first and third microdisks 2 and 4 are coupled in the parallel direction and are also coupled to the first waveguide 6 respectively; the first and second microdisks 2 and 3 are coupled in the vertical direction; the second and fourth microdisks 3 and 5 are coupled in the parallel direction and are also coupled to the second waveguide 7 respectively; the third and fourth microdisks 4 and 5 are coupled in the vertical direction.

[0023] The coupling spacing between the microdisks is equal.

[0024] The first waveguide 6 has a width of 450nm, and its coupling distance with the first and third microdisks 2 and 4 is 180nm; the second waveguide 7 has a width of 450nm, and its coupling distance with the second and fourth microdisks 3 and 5 is 180nm.

[0025] The heating layer 10 is made of rectangular titanium nitride with a size of 85×35μm and is located directly above the four micro disks. A pair of metal electrodes 11 and 12 are used to apply voltage and ground, respectively.

[0026] This embodiment relates to an encoding method for optical signals based on the aforementioned micro-computational spectrometer. The spectral signal is input to waveguide 6 through waveguide in port 8 and coupled into a photonic molecular system composed of four microdisks 2, 3, 4, and 5. Coupling and light interactions occur within the photonic molecular system. The four microdisks 2, 3, 4, and 5 have different diameters, resulting in more diverse phenomena of light coupling and interaction between the microdisks, such as… Figure 2As shown, the light field distribution of light of different wavelengths is different in the photonic molecular system, thereby realizing quasi-disordered encoding of the light signal. After quasi-disordered encoding, the light signal entering the photonic molecular system is coupled into the waveguide 7 through the second and fourth microdisks 3 and 5, and transmitted to the waveguide output port 9 for output. After further calculating and plotting its spectral correlation function curve through the spectral correlation function, the input spectral information is reconstructed.

[0027] The aforementioned quasi-disordered encoding involves the heating layer 10 controlling the heating efficiency by applying a voltage, thereby applying different heating effects to the photonic molecular system to change the coupling and interaction of the photonic molecular system, and thus changing the encoding method of the optical signal.

[0028] like Figure 3 As shown, the heating power of the heating layer 10 is between 0-55mW. The transmission intensity distribution of light with a wavelength range of 1500nm-1600nm in the photonic molecular system is used as a pre-set optical response matrix to encode the input optical signal.

[0029] The theoretical resolution of the spectrometer can be estimated by the full width at half maximum (FWHM) of the curve, such as... Figure 4 As shown, the theoretical resolution of the computational spectrometer involved in this embodiment is 8 pm.

[0030] like Figures 5-7 As shown, the reconstruction refers to: encoding the input spectral information through a photonic molecular system and then outputting it, using a regularization algorithm to calculate and reconstruct the spectral information to obtain the reconstructed spectrum.

[0031] The regularization algorithm specifically includes: transforming the discrete inverse problem into a convex optimization problem. in: Let I represent the reconstructed spectrum, T be the measured spectrum, S be the energy measurement value, and ||…||2 represent the l2 norm. When processing sparse discrete signals, the Lasso algorithm is used to introduce α1||I||1 as a regularization term, where α1 is the weight and ||…||1 represents the l1 norm. When processing continuous signals, the general Tikhonov algorithm is used to introduce…||I||1 as a regularization term. As a regularization term, α2 and α3 are weights, and D represents taking the first-order difference; when processing step signals, the total variation (TV) algorithm and the general Tikhonov algorithm are used to introduce regularization. As a regularization term, α4 is the weight.

[0032] like Figure 5 The image shown is a reconstruction result of the spectrometer on a monochromatic light signal, demonstrating that the spectrometer has the capability to perform spectral reconstruction analysis on monochromatic spectra.

[0033] like Figure 6 The image shows the reconstruction results of a high-bandwidth continuous spectrum, demonstrating that the spectrometer possesses at least the capability to perform spectral reconstruction analysis on a high-bandwidth (100 nm) continuous spectrum with a wavelength range of 1500 nm–1600 nm. Figure 7 The image shown illustrates the highest resolution of the spectrometer's spectral reconstruction, demonstrating that the spectrometer can achieve a maximum resolution of 8 pm.

[0034] Compared to existing technologies, this method, based on heteronuclear photonic molecular structures, generates a large number of disordered supermodes distributed across the spectrum, thereby producing a quasi-random response matrix. This is the first time that quasi-randomness has been achieved in a simple and compact resonant cavity structure and applied to the field of computational spectrometry. Because it approximates randomness while preserving the high Q-values ​​of the microdisk resonant cavity, the spectrometer benefits from a near-infinite FSR over a large measurable bandwidth, achieving ultra-high spectral resolution while being integrated into a relatively small footprint. This invention significantly improves the bandwidth-to-resolution ratio per unit area. A photonic molecular system composed of four cascaded microdisks is used as a pre-coded detector to encode the input spectrum in a quasi-random manner. A regularization algorithm is then used to reconstruct the spectral information from the encoded information, achieving high bandwidth and high resolution spectral analysis performance within a compact physical size.

[0035] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.

Claims

1. A miniature computational spectrometer based on disordered photonic molecules, characterized in that, include: The substrate consists of four microdisks disposed thereon, two waveguides, a heating layer on top, and a pair of metal electrodes. The two waveguides for inputting and outputting optical signals are located outside the four microdisks that are coupled in pairs to form a photonic molecular system. The heating layer is located on top of the four microdisks and is connected to a pair of metal electrodes located outside the waveguides.

2. The micro-computational spectrometer based on disordered photonic molecules according to claim 1, characterized in that, The photonic molecular system is quadrilateral in shape.

3. The micro-computational spectrometer based on disordered photonic molecules according to claim 1, characterized in that, The SOI wafer comprises, from bottom to top, a silicon substrate layer, a silicon dioxide layer, and a silicon layer.

4. The micro-computational spectrometer based on disordered photonic molecules according to claim 1, characterized in that, The first and third microdisks are coupled to the first waveguide in parallel direction; the first and second microdisks are coupled in the vertical direction; the second and fourth microdisks are coupled to the second waveguide in parallel direction; and the third and fourth microdisks are coupled in the vertical direction.

5. The micro-computational spectrometer based on disordered photonic molecules according to claim 4, characterized in that, In the aforementioned coupling, the coupling spacing between each microdisk is equal.

6. The micro-computational spectrometer based on disordered photonic molecules according to claim 1 or 4, characterized in that, The diameters of the first to fourth microdisks are 14μm, 13μm, 10μm and 18μm respectively, and the coupling spacing is 180nm.

7. A method for encoding optical signals based on the micro-computational spectrometer described in any one of claims 1-6, characterized in that, The spectral signal is input into the waveguide through the input port of the first waveguide. After being coupled into the photonic molecular system composed of four microdisks for quasi-disorder encoding, it is coupled into the second waveguide through the microdisks and output. The spectral correlation function curve is then calculated and plotted to reconstruct the input spectral signal.

8. The encoding method according to claim 7, characterized in that, The reconstruction refers to: encoding the input spectral information through a photonic molecular system and then outputting it, using a regularization algorithm to calculate and reconstruct the spectral information to obtain the reconstructed spectrum.

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