CN111323120A - High-resolution spectrometer based on etched diffraction grating - Google Patents
High-resolution spectrometer based on etched diffraction grating Download PDFInfo
- Publication number
- CN111323120A CN111323120A CN201811535909.1A CN201811535909A CN111323120A CN 111323120 A CN111323120 A CN 111323120A CN 201811535909 A CN201811535909 A CN 201811535909A CN 111323120 A CN111323120 A CN 111323120A
- Authority
- CN
- China
- Prior art keywords
- waveguide
- output
- waveguides
- spectrometer
- reflection grating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 230000005540 biological transmission Effects 0.000 claims abstract description 18
- 239000000758 substrate Substances 0.000 claims abstract description 16
- 230000003287 optical effect Effects 0.000 claims abstract description 9
- 238000003384 imaging method Methods 0.000 claims description 5
- 238000005259 measurement Methods 0.000 claims description 5
- 238000000034 method Methods 0.000 claims description 5
- 238000000206 photolithography Methods 0.000 claims description 3
- 230000008878 coupling Effects 0.000 description 4
- 238000010168 coupling process Methods 0.000 description 4
- 238000005859 coupling reaction Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 2
- 238000010183 spectrum analysis Methods 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 238000004611 spectroscopical analysis Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/12—Generating the spectrum; Monochromators
- G01J3/18—Generating the spectrum; Monochromators using diffraction elements, e.g. grating
- G01J3/1895—Generating the spectrum; Monochromators using diffraction elements, e.g. grating using fiber Bragg gratings or gratings integrated in a waveguide
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/28—Investigating the spectrum
- G01J3/2823—Imaging spectrometer
Landscapes
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- General Physics & Mathematics (AREA)
- Optical Integrated Circuits (AREA)
Abstract
The invention provides a high-resolution spectrometer based on an etched diffraction grating, which comprises a substrate, wherein an input waveguide, a free transmission area, a reflection grating and an output waveguide are integrated on the substrate; the input waveguide is used for receiving an optical signal to be detected and transmitting the optical signal to the free transmission area; the free transmission area is used for transmitting the light to be measured which is emitted from the input waveguide and is reflected by the reflection grating; the reflection grating is used for reflecting the optical signal to be measured to the incident end of the output waveguide so that the reflected light meets the condition of interference phase growth at the incident end of the output waveguide; the output waveguide is a dense array waveguide which is formed by circularly arranging a plurality of waveguides with different widths, each waveguide is an output channel, and each output channel outputs light with different wavelengths. Compared with a spectrometer using an array waveguide with the same width as an output waveguide, the spectrometer has the advantages that the number of output channels is more, the distance between the output channels is smaller, and the resolution of the spectrometer is higher under the condition of the same spectrometer device size.
Description
Technical Field
The invention belongs to the technical field of optics, and particularly relates to a high-resolution spectrometer based on an etched diffraction grating.
Background
The spectrometer has very important significance in the aspects of chemical and biological sensing, material analysis and light source characterization, and the high-resolution on-chip spectrometer provides a spectral analysis technology with low cost and compact structure for portable sensing. In recent years, Silicon-On-Insulator (SOI) integrated platforms have attracted attention due to their advantages of compactness, reliable performance, high sensitivity, etc., and become ideal platforms for implementing On-chip spectrometers and On-chip laboratory systems.
In the prior art, the on-chip spectrometer generally adopts a traditional array waveguide with equal width as an output waveguide, the width of each output channel of the output waveguide is the same, the distance between adjacent output channels can reach 2.5um, and when the distance is continuously reduced, the crosstalk phenomenon between the output channels affects the resolution ratio. The resolution of the on-chip spectrometer is higher when the spacing between output channels is smaller, and the spacing requirement for equal-width output channels makes it more difficult to improve the resolution of the device.
Therefore, those skilled in the art are devoted to develop a high resolution spectrometer based on etched diffraction grating, so that under the condition of the same spectrometer device size, the number of output channels can be increased, the output channel spacing can be further reduced, and the resolution of the spectrometer can be improved.
Disclosure of Invention
In view of the above drawbacks of the prior art, an embodiment of the present invention provides a high resolution spectrometer based on an etched diffraction grating, including:
the input waveguide, the free transmission area, the reflection grating and the output waveguide are integrated on the substrate;
the input waveguide is used for receiving an optical signal to be detected and transmitting the optical signal to the free transmission area;
the free transmission area is used for transmitting the light to be measured which is emitted from the input waveguide and is reflected by the reflection grating;
the reflection grating is used for reflecting the optical signal to be measured to the incident end of the output waveguide so that the reflected light meets the condition of interference phase growth at the incident end of the output waveguide;
the output waveguide is a dense array waveguide which is formed by circularly arranging a plurality of waveguides with different widths, each waveguide is an output channel, and each output channel outputs light with different wavelengths.
Further, the substrate is an SOI substrate, and the input waveguide, the reflection grating and the output waveguide are fabricated on the substrate by a photolithography method.
Furthermore, the reflection grating is a Bragg grating, and the position of the reflection grating is calculated by a double perfect imaging point method, so that the reflected light meets the condition of interference phase length at the incident ends of different output channels of the output waveguide.
Further, the dense array waveguide is composed of a plurality of waveguides with different widths, and the waveguides with different widths are used to reduce crosstalk between adjacent waveguides, and preferably, the dense array waveguide is composed of 3 waveguides with different widths, and the number of the waveguides is determined by required resolution and measurement bandwidth. The crosstalk between two adjacent waveguides is represented by the formula:
determining where P is1→2Representing the energy, P, coupled into the waveguide 2 from the waveguide 11Representing the energy in waveguide 1, Δ β representing the difference between the propagation constants of the two waveguides,. kappa the coupling strength between the waveguides, and L the coupling length from the equation it can be seen that the larger Δ β, the smaller the crosstalk between the two waveguides, and Δ β the difference Δ n between the equivalent refractive indices of the fundamental modes of the two adjacent waveguideseff(λ) determining:
Δβ＝k0*Δneff(λ)
wherein k is0Is the wave vector in vacuum. Equivalent refractive index n of fundamental mode of waveguideeff(lambda) varies with the waveguide width, and the waveguide width is selected so that the difference between the equivalent refractive indices of the fundamental modes of adjacent waveguides is aneff(λ) is maximized, thereby achieving less crosstalk.
The light to be measured with the wavelength of lambda enters a free transmission area through an input waveguide, and the equivalent refractive index of the light to be measured in the free transmission area is neff(λ), via different paths Lini，Lini+jReflected by the gratings at different positions to form a reflected light path LoutiAnd Louti+jReaching the output waveguide, reflected light beams of different wavelengths satisfy interference phase long-wave conditions at different output waveguide positions:
neff(λ)(Lini+j+Louti+j-Lini-Louti) Jm lambda (m is an integer)
When the reflected light satisfies the condition of constructive interference at the incident end of the output channel, the reflected light can be output from the output channel.
The invention has the advantages that the output waveguide is designed into the dense array waveguide, compared with the traditional array waveguide with the same width, the output channel spacing of the dense array waveguide is smaller, the crosstalk can be kept lower, under the condition that the device size is the same, the number of the output channels is more, the spacing between the adjacent output channels is smaller, and the higher resolution ratio can be achieved.
Drawings
FIG. 1 is a schematic structural diagram of a preferred embodiment of a high resolution spectrometer based on an etched diffraction grating according to the present invention;
FIG. 2 is a side view of a preferred embodiment of a high resolution spectrometer based on etched diffraction gratings in accordance with the present invention;
FIG. 3 is a partial enlarged view of an input waveguide and an output waveguide of a preferred embodiment of the high resolution spectrometer based on the etched diffraction grating of the present invention;
FIG. 4 is a partial enlarged view of the input end of the output waveguide of the preferred embodiment of the high resolution spectrometer based on etched diffraction grating according to the present invention;
FIG. 5 is a graph of the waveguide fundamental mode equivalent refractive index as a function of waveguide width in accordance with the present invention;
FIG. 6 is a partially enlarged view of a reflection grating in accordance with a preferred embodiment of the high resolution spectrometer of the present invention;
FIG. 7 is a schematic diagram of the spectroscopy of a high resolution spectrometer based on an etched diffraction grating according to the present invention;
FIG. 8 is a graph of the calculation of the output of the high resolution spectrometer based on the etched diffraction grating according to the present invention;
FIG. 9 is a graph of a test of the output of a high resolution spectrometer based on etched diffraction gratings according to the present invention.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited thereto.
Examples
As shown in fig. 1 and 2, a high resolution spectrometer based on an etched diffraction grating includes a substrate 1, an input waveguide 2, a free transmission region 3, a reflection grating 4 and an output waveguide 5. An input waveguide 2, a free transmission area 3, a reflection grating 4 and an output waveguide 5 are integrated on a substrate 1. In this embodiment, the substrate 1 is an SOI substrate, the substrate thickness is preferably 220nm, the input waveguide 2, the reflection grating 3, and the output waveguide 5 are fabricated on the substrate by a photolithography method, and the remaining region is the free transmission region 3.
Fig. 3 is a partially enlarged view of an input waveguide and an output waveguide of a preferred embodiment of the high-resolution spectrometer based on the etched diffraction grating of the present invention, where the input and the output are grating-coupled, and as shown in the figure, the output waveguide 31 is a dense array waveguide and is composed of a plurality of waveguides, each waveguide is an output channel, and each output channel outputs light with different wavelengths. Light to be measured is guided in from an input waveguide incident end 34, enters a free transmission area from an input waveguide emergent end 35, is reflected by a reflection grating at the tail end of the free transmission area, reflected light enters from an output waveguide incident end 32, the reflected light with different wavelengths meets the condition of constructive interference at different output channels, and is output 33 from different output channels, so that the light splitting effect is achieved.
Fig. 4 is a partial enlarged view of an output waveguide of the present invention, and as shown in the figure, the output waveguide is composed of a plurality of waveguides with different widths, in this embodiment, the output waveguide is composed of 3 waveguides with different widths, and the crosstalk between two adjacent waveguides is represented by the following formula:
determining where P is1→2Representing the energy, P, coupled into the waveguide 2 from the waveguide 11Represents the energy in waveguide 1, Δ β represents the difference between the propagation constants of the two waveguides, κ represents the coupling strength between the waveguides, and L is the coupling lengthIn the formula, the larger the difference delta β between the propagation constants is, the smaller the crosstalk between the two waveguides is, delta β is the difference delta n between the equivalent refractive indexes of the fundamental modes of the two adjacent waveguideseff(λ) determining:
Δβ＝k0*Δneff(λ)
wherein k is0Is the wave vector in vacuum.
As shown in FIG. 5, the equivalent refractive index n of the fundamental mode of the waveguideeff(lambda) will vary with the waveguide width, and according to the variation curve, the appropriate waveguide width is selected to make the difference delta n between the equivalent refractive indexes of the fundamental modes of the adjacent waveguideseff(λ) is maximized, thereby achieving less crosstalk.
In this embodiment, it is preferable that the waveguides with different widths in 3 are circularly arranged according to size, the widths are w1, w2 and w3, the number of waveguides is determined by the required resolution and the measurement bandwidth, and the larger the number of waveguides is, the larger the measurement bandwidth is. According to the equivalent refractive index n of the fundamental mode of the waveguideeff(λ) is a curve that varies with the waveguide width, preferably w 1-420 nm, w 2-480 nm, and w 3-590 nm, where crosstalk between adjacent waveguides is minimized. The number of the waveguides is preferably 121, namely 121 output channels, and the spacing between the waveguides is 1 um.
Fig. 6 is a partial enlarged view of the reflection grating of the present invention, wherein the reflection grating is formed by a plurality of grating units arranged and combined according to a period, and the period is determined by bragg conditions:
2neffT＝mλ
wherein, the period T is 480nm, and the grating order m is 1.
The position of the reflection grating is designed according to a double perfect imaging method, so that the reflected light and the light to be measured corresponding to the reflected light are guided out in the output wave to meet the condition of interference constructive, and then are output from the output waveguide. In this embodiment, the number of output channels is preferably 121, then according to the double perfect imaging method, two perfect imaging points of the spectrometer are located at the 30 th and 90 th channels, the input waveguide and the 30 th output waveguide are used as two foci of the first set of ellipses, the input waveguide and the 60 th output waveguide are used as two foci of the second set of ellipses, the length of the long axis of each ellipse is determined according to the interference constructive condition and the interference order, and the interference order of EDG (etched diffraction Grating) is 15. The selection of the interference order needs to be satisfied
Wherein λminAnd λmaxMinimum and maximum wavelength, n, respectively, in the measurement rangeeff1And neff2Respectively when the wavelength is lambdaminAnd λmaxThe equivalent refractive index of (a).
A series of ellipses are obtained, and the intersection point of the two groups of ellipses is taken to obtain the position of the reflection grating.
As shown in FIG. 7, light to be measured with a wavelength λ enters a free transmission region through an input waveguide, and an equivalent refractive index n in the free transmission regioneff(λ), via different paths Lini，Lini+jReflected by the gratings at different positions and via a path LoutiAnd Louti+jWhen the reflected light reaches the output waveguide position, the reflected light with different wavelengths meets the condition of interference constructive at different output waveguide positions:
neff(λ)(Lini+j+Louti+j-Lini-Louti)＝jmλ
when the reflected light satisfies the condition of constructive interference at the incident end of the output channel, the reflected light can be output from the output channel.
FIG. 8 is a graph of a calculated output of a high resolution spectrometer based on an etched diffraction grating according to the present invention, wherein the crosstalk is-20 dB at a resolution of 0.5 nm. FIG. 9 is a graph of the output result of a high resolution spectrometer based on an etched diffraction grating according to the present invention, which is used to perform spectral analysis on the light to be measured with a center wavelength of 1550nm, thereby achieving a spectral resolution of 0.5nm and crosstalk of-4.3 dB.
The embodiments described above can be further combined or replaced, and the embodiments are only described as preferred examples of the patent of the present invention, and do not limit the concept and scope of the patent of the present invention, and various changes and modifications of the technical solution of the patent of the present invention made by those skilled in the art without departing from the design concept of the patent of the present invention belong to the protection scope of the present invention.
Claims (4)
1. A high resolution spectrometer based on an etched diffraction grating, comprising:
the input waveguide, the free transmission area, the reflection grating and the output waveguide are integrated on the substrate;
the input waveguide is used for receiving an optical signal to be detected and transmitting the optical signal to the free transmission area;
the free transmission area is used for transmitting the light to be measured which is emitted from the input waveguide and is reflected by the reflection grating;
the reflection grating is used for reflecting the optical signal to be measured to the incident end of the output waveguide so that the reflected light meets the condition of interference phase growth at the incident end of the output waveguide;
the output waveguide is a dense array waveguide which is formed by circularly arranging a plurality of waveguides with different widths, each waveguide is an output channel, and each output channel outputs light with different wavelengths.
2. The spectrometer of claim 1, wherein the substrate is an SOI substrate, and the input waveguide, the reflection grating and the output waveguide are fabricated on the substrate by a photolithography method.
3. The high resolution spectrometer based on the etched diffraction grating as claimed in claim 1, wherein the reflection grating is a bragg grating, and the position of the reflection grating is calculated by a double perfect imaging point method, so that the reflected light meets the condition of constructive interference at the incident ends of different output channels of the output waveguide.
4. The spectrometer of claim 1, wherein the dense array of waveguides is comprised of a plurality of waveguides of different widths, preferably 3 widths, in a circular arrangement, the number of waveguides being determined by the required resolution and measurement bandwidth.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811535909.1A CN111323120A (en) | 2018-12-17 | 2018-12-17 | High-resolution spectrometer based on etched diffraction grating |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811535909.1A CN111323120A (en) | 2018-12-17 | 2018-12-17 | High-resolution spectrometer based on etched diffraction grating |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111323120A true CN111323120A (en) | 2020-06-23 |
Family
ID=71165034
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201811535909.1A Pending CN111323120A (en) | 2018-12-17 | 2018-12-17 | High-resolution spectrometer based on etched diffraction grating |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111323120A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115165102A (en) * | 2022-09-02 | 2022-10-11 | 之江实验室 | Large-bandwidth high-resolution compact on-chip spectrometer and detection method |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104570200A (en) * | 2014-12-19 | 2015-04-29 | 南京大学 | Silicon-based waveguide-improved silicon dioxide-based array waveguide grating device and manufacturing method thereof |
| CN105474057A (en) * | 2013-08-13 | 2016-04-06 | 华为技术有限公司 | Compact optical waveguide arrays and optical waveguide spirals |
| CN105547478A (en) * | 2016-01-27 | 2016-05-04 | 浙江大学 | Imaging spectrometer on the basis of etched diffraction grating |
| CN209400083U (en) * | 2018-12-17 | 2019-09-17 | 绍兴图聚光电科技有限公司 | A kind of high resolution spectrometer based on etched diffraction grating |
-
2018
- 2018-12-17 CN CN201811535909.1A patent/CN111323120A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105474057A (en) * | 2013-08-13 | 2016-04-06 | 华为技术有限公司 | Compact optical waveguide arrays and optical waveguide spirals |
| CN104570200A (en) * | 2014-12-19 | 2015-04-29 | 南京大学 | Silicon-based waveguide-improved silicon dioxide-based array waveguide grating device and manufacturing method thereof |
| CN105547478A (en) * | 2016-01-27 | 2016-05-04 | 浙江大学 | Imaging spectrometer on the basis of etched diffraction grating |
| CN209400083U (en) * | 2018-12-17 | 2019-09-17 | 绍兴图聚光电科技有限公司 | A kind of high resolution spectrometer based on etched diffraction grating |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115165102A (en) * | 2022-09-02 | 2022-10-11 | 之江实验室 | Large-bandwidth high-resolution compact on-chip spectrometer and detection method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR100839969B1 (en) | Micro resonator sensor | |
| US6278813B1 (en) | Wavelength division multi/demultiplexer | |
| US9574941B2 (en) | Dispersed fourier transform spectrometer, methods and systems | |
| EP0444817B1 (en) | Optical multiplexer/demultiplexer | |
| US9052291B2 (en) | Optical sensor based on a broadband light source and cascaded waveguide filters | |
| Kodate et al. | Compact spectroscopic sensor using an arrayed waveguide grating | |
| JPH01124723A (en) | Spectrograph | |
| Zou et al. | Silicon-based arrayed waveguide gratings for WDM and spectroscopic analysis applications | |
| JP2006267961A (en) | Optical demultiplexing device and optical monitoring device | |
| US20120177060A1 (en) | Optical apparatus, method, and applications | |
| EP3792661A1 (en) | High resolution and high efficiency photonic air data detection | |
| US20060072114A1 (en) | Apparatus and mehod for sensing with metal optical filters | |
| CN113701884B (en) | Spectrum or spectrum analysis system on broadband filtering type sheet based on sub-wavelength structure | |
| US9976919B2 (en) | Fiber-optic sensor assembly | |
| CN102902010A (en) | Waveguide grating device with uniform channel loss | |
| CN111323120A (en) | High-resolution spectrometer based on etched diffraction grating | |
| CN112305668B (en) | Array waveguide grating with double-layer structure | |
| CN110044484B (en) | Cascaded dual-ring enhanced Fourier transform spectrometer | |
| El Ahdab et al. | Wide-band silicon photonic MOEMS spectrometer requiring a single photodetector | |
| CN209400083U (en) | A kind of high resolution spectrometer based on etched diffraction grating | |
| US6636660B2 (en) | Monochrometer and wavelength division multiplexer comprising said monochrometer | |
| Zhuang et al. | On-Chip Sub-Picometer Continuous Wavelength Fiber-Bragg-Grating Interrogator | |
| Rasras et al. | Lab-on-chip silicon photonic sensor | |
| JPH07117612B2 (en) | Optical multiplexer / demultiplexer | |
| Mendez-Astudillo et al. | Phase-shifted multimode bragg gratings in silicon-on-insulator for sensing applications |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20200623 |
|
| WD01 | Invention patent application deemed withdrawn after publication |