Novel on-chip Fourier transform spectrometer structure

Abstract

The invention discloses a novel on-chip Fourier transform spectrometer structure which comprises an input waveguide coupler, a 1 * N power divider, an asymmetric orthogonal Mach-Zehnder interferometer array and a photoelectric detector which are connected through single-mode waveguides. The 1 * N power divider is formed by cascading 1 * 2 power dividers. The asymmetric orthogonal Mach-Zehnder interferometer comprises a 1 * 2 power divider, a reference arm waveguide, an interference arm waveguide and a 90-degree optical mixer, the 1 * 2 power divider is used for distributing signal light into the reference arm waveguide and the interference arm waveguide, and the 90-degree optical mixer combines optical signals transmitted by the reference arm waveguide and the interference arm waveguide into interference signals. According to the novel on-chip Fourier transform spectrometer, an output coupler of a traditional Mach-Zehnder interferometer is replaced by the 90-degree optical mixer, an effective output channel can be doubled on the premise that the number of interferometers is not increased, the amount of spectrum sampling information is increased, and the novel on-chip Fourier transform spectrometer is a feasible scheme for improving the spectral resolution.

Description

Technical Field

[0001] The present application relates to a spectrometer structure, and in particular to a novel on-chip Fourier transform spectrometer structure. Background Art

[0002] As a key analytical tool for analyzing the composition and structure of substances, spectrometers play a vital role in many fields, including but not limited to chemical engineering, material analysis, astronomical science, medical diagnosis and biosensing. However, although traditional spectrometers can provide high spectral resolution, they are bulky and cannot meet the application requirements of miniaturization and portability. With the advancement of science and technology and the growth of application needs, the demand for integrated, miniaturized and portable spectrometers is becoming increasingly urgent. This type of spectrometer can not only break through the traditional application limitations, but also significantly reduce costs. It is of great significance to promote industries closely related to national economy and people's livelihood, such as safe production, food testing, and medical analysis.

[0003] In the process of realizing on-chip spectrometers, silicon-based manufacturing and integration technology has shown its unique advantages. This technology has become an ideal choice for developing new spectrometers with its compact structure, good compatibility and low cost. In particular, the Fourier transform spectrometer based on Mach-Zehnder interferometer has attracted much attention due to its large light flux and high signal-to-noise ratio. However, the limitation of the traditional Mach-Zehnder interferometer structure is that it has a limited number of output ports, and usually only one effective output port can be provided, which limits the increase in the spectral sampling information volume and the improvement in resolution of the spectrometer. Therefore, while maintaining the performance indicators of the spectrometer such as high resolution and large bandwidth, achieving compactness of the device structure is the focus of the current research on the structure of on-chip spectrometers. Summary of the invention

[0004] In view of the problems existing in the prior art solutions, the present invention proposes a novel on-chip Fourier transform spectrometer structure. The core component of the structure is an asymmetric orthogonal Mach-Zehnder interferometer. By replacing the beam combiner at the output end of the traditional Mach-Zehnder interferometer with a 90° optical mixer, two mutually orthogonal effective output ports are realized to increase the amount of spectral sampling information, thereby effectively improving the resolution of the spectrometer while keeping the number of interferometers unchanged.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a novel on-chip Fourier transform spectrometer structure, comprising:

[0006] An input waveguide coupler for introducing signal light;

[0007] 1×N power divider, used to divide the signal light into N equal parts and introduce them into the asymmetric orthogonal Mach-Zehnder interferometer array;

[0008] An asymmetric orthogonal Mach-Zehnder interferometer array is used to combine signal lights to obtain interference signals under different optical path differences;

[0009] Photoelectric detector, used to measure the interference signal formed by the change of the optical path difference of the signal light.

[0010] Furthermore, the input waveguide coupler, 1×N power divider, asymmetric orthogonal Mach-Zehnder interferometer array and photodetector included in the novel on-chip Fourier transform spectrometer structure are connected to each other through a single-mode waveguide.

[0011] Furthermore, the structure of the input waveguide coupler adopts a grating coupler structure that supports C-band operation.

[0012] Furthermore, the 1×N power divider is composed of It is composed of two identical 1×2 power dividers cascaded.

[0013] Furthermore, the asymmetric orthogonal Mach-Zehnder interferometer is composed of a 1×2 power divider, a reference arm waveguide, an interference arm waveguide and a 90° optical mixer.

[0014] Furthermore, the reference arm waveguide and the interference arm waveguide in the asymmetric orthogonal Mach-Zehnder interferometer are connected to the first input port and the third input port of the 90° optical mixer respectively.

[0015] Furthermore, by changing the length difference between the reference arm waveguide and the interference arm waveguide in the asymmetric orthogonal Mach-Zehnder interferometer to ΔL, 2ΔL, 3ΔL...NΔL in sequence, a linear change of the optical path difference of the entire interferometer system can be achieved.

[0016] Furthermore, the transmission functions of the first output port and the third output port of the interferometer are orthogonal to each other, which can effectively increase the amount of information of spectral sampling while keeping the size and number of optical path differences unchanged, thereby improving the resolution of the spectrometer.

[0017] Compared with the prior art, the present invention has the following advantages: the novel on-chip Fourier transform spectrometer structure adopts an asymmetric orthogonal Mach-Zehnder interferometer structure as a core part, and replaces the output end combiner of the traditional Mach-Zehnder interferometer with a 90° optical mixer to obtain two output ports whose transmission functions are orthogonal to each other; by reasonably designing the arm length difference of the orthogonal Mach-Zehnder interferometer, the transmission functions of each output port in the spectrometer structure can be made orthogonal to each other, thereby achieving the doubling of effective output ports while keeping the size and number of optical path differences unchanged, effectively increasing the amount of information of spectral sampling, and achieving the improvement of spectral resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings:

[0019] Figure 1 A schematic structural diagram of a novel on-chip Fourier transform spectrometer in an embodiment of the present invention is shown.

[0020] In the figure: 100, input waveguide coupler; 200, 1×N power divider; 300, asymmetric orthogonal Mach-Zehnder interferometer array; 400, photodetector; 201, power divider cascaded to form a 1×N power divider; 301, power divider constituting an asymmetric orthogonal Mach-Zehnder interferometer; 302, reference arm waveguide constituting an asymmetric orthogonal Mach-Zehnder interferometer; 303, interference arm waveguide constituting an asymmetric orthogonal Mach-Zehnder interferometer; 304, 90° optical mixer constituting an asymmetric orthogonal Mach-Zehnder interferometer. DETAILED DESCRIPTION

[0021] In order to illustrate the present invention in more detail, the technical solution of the present invention is further described below in conjunction with preferred embodiments and drawings.

[0022] like Figure 1 As shown, a novel on-chip Fourier transform spectrometer structure includes an input waveguide coupler (100), a 1×N power divider (200), an asymmetric orthogonal Mach-Zehnder interferometer array and a photodetector (400).

[0023] Furthermore, the input waveguide coupler (100), the 1×N power divider (200), the asymmetric orthogonal Mach-Zehnder interferometer array and the photodetector (400) included in the novel on-chip Fourier transform spectrometer structure are connected to each other via a single-mode waveguide.

[0024] Furthermore, the structure of the input waveguide coupler (100) adopts a broadband end face coupler structure or a grating coupler structure.

[0025] Furthermore, the 1×N power divider (200) is composed of a plurality of identical 1×2 power dividers connected in cascade.

[0026] Furthermore, the asymmetric orthogonal Mach-Zehnder interferometer is composed of a 1×2 power divider, a reference arm waveguide (302), an interference arm waveguide (303) and a 90° optical mixer (304).

[0027] Furthermore, the reference arm waveguide (302) and the interference arm waveguide (303) in the asymmetric orthogonal Mach-Zehnder interferometer are respectively connected to the first input port and the third input port of the 90° optical mixer (304).

[0028] Furthermore, by changing the length difference between the reference arm waveguide (302) and the interference arm waveguide (303) in the asymmetric orthogonal Mach-Zehnder interferometer array to ΔL, 2ΔL, 3ΔL...NΔL in sequence, a linear change of the optical path difference of the entire interferometer system is achieved.

[0029] Furthermore, since a 90° optical mixer (304) is used to replace the beam combiner at the output end of the conventional Mach-Zehnder interferometer, according to the interference principle and the working principle of the optical mixer, the phase difference between the interference data obtained at the four output ports of the asymmetric orthogonal Mach-Zehnder interferometer can be obtained. And the correlation of the corresponding transfer functions is shown in the following table.

[0030]

[0031] Furthermore, there is a situation in which the phase difference of interference data in the output end of the asymmetric orthogonal Mach-Zehnder interferometer is an odd multiple of π / 2, which means that there are output ports whose transmission functions are orthogonal to each other; for example, the transmission functions of the first output port and the third output port are orthogonal to each other, that is, these two ports can both be used as effective output ports of the spectrometer. Compared with the Fourier transform spectrometer based on the traditional Mach-Zehnder interferometer structure, the Fourier transform spectrometer can effectively increase the sampling amount of spectral information without increasing the number of interferometers, thereby achieving an improvement in the resolution of the spectrometer.

[0032] Finally, it should be explained that the above-described embodiments are merely preferred examples for clearly illustrating the present invention, but they are not limitations on the implementation schemes of the present invention. Those skilled in the art should understand that other different forms of modifications or equivalent replacements of some technical features can be made on the basis of the above-mentioned specific implementation schemes. It is impossible to list all implementation schemes here. Therefore, all modifications, improvements, equivalent replacements, etc. derived from the technical solutions of the present invention within the spirit and principles of the present invention should be within the technical scope of the present invention.

Claims

1. A novel on-chip Fourier transform spectrometer structure, characterized in that: include An input waveguide coupler (100) for introducing signal light; A 1×N power divider (200) is used to divide the signal light into N equal parts and introduce the parts into an asymmetric orthogonal Mach-Zehnder interferometer array; An asymmetric orthogonal Mach-Zehnder interferometer array (300) is used to combine signal lights to obtain interference signals under different optical path differences; The photoelectric detector (400) is used to measure the interference signal formed by the change of the optical path difference of the signal light.

2. The novel on-chip Fourier transform spectrometer structure according to claim 1, characterized in that: The input waveguide coupler (100), the 1×N power divider (200), the asymmetric orthogonal Mach-Zehnder interferometer array (300) and the photodetector (400) are integrated in a silicon-on-insulator material, the substrate material and the cladding material are silicon dioxide, and the waveguide material is silicon.

3. The novel on-chip Fourier transform spectrometer structure according to claim 1, characterized in that: The output end of the waveguide input coupler (100) is connected to the input end of the 1×N optical beam splitter (200), the N output ends of the 1×N optical beam splitter (200) are respectively connected to the input end of the asymmetric orthogonal Mach-Zehnder interferometer array (300), and the output ends of the asymmetric orthogonal Mach-Zehnder interferometer array (300) are respectively connected to the photodetector (400).

4. The novel on-chip Fourier transform spectrometer structure according to claim 2, characterized in that: The structure of the input waveguide coupler (100) adopts a grating coupler structure whose working band covers the C band.

5. The novel on-chip Fourier transform spectrometer structure according to claim 2, characterized in that: The asymmetric orthogonal Mach-Zehnder interferometer array (300) comprises N asymmetric orthogonal Mach-Zehnder interferometers with different arm length differences, wherein a single interferometer structure comprises a 1×2 power divider (301), a reference arm waveguide (302), an interference arm waveguide (303) and a 90° optical mixer (304).

6. The novel on-chip Fourier transform spectrometer structure according to claim 5, characterized in that: The output end of the 1×2 power divider (301) is respectively connected to the reference arm waveguide (302) and the interference arm waveguide (303) through a single-mode waveguide, each reference arm waveguide (302) output end is connected to the first input port of the 90° optical mixer (304), and each interference arm waveguide (303) output end is connected to the third input port of the 90° optical mixer (304).

7. The novel on-chip Fourier transform spectrometer structure according to claim 6, characterized in that: The reference arm waveguide (302) and the interference arm waveguide (303) are both single-mode waveguides with the same cross-sectional structure, but have different lengths to provide different optical path differences.

8. The novel on-chip Fourier transform spectrometer structure according to claim 1, characterized in that: The arm length differences in the asymmetric orthogonal Mach-Zehnder interferometer (300) array are ΔL, 2ΔL, 3ΔL, ... NΔL in sequence, so as to achieve a linear change in the optical path difference of the entire interferometer system.

9. The novel on-chip Fourier transform spectrometer structure according to claim 8, characterized in that: The transmission functions of the first output port and the third output port of the interferometer are orthogonal to each other, which can effectively increase the amount of information of spectral sampling while keeping the size and number of optical path differences unchanged, thereby improving the resolution of the spectrometer.

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