A dew point detection sensor, detection system and method based on microring resonator

Abstract

The present invention discloses a dew point detection sensor based on a microring resonator, a detection system and a method. The dew point detection sensor includes a semiconductor refrigerator and a microring resonator sensor chip placed thereon. The microring resonator sensor chip includes a silicon substrate and a silicon dioxide layer located on the silicon substrate. A waveguide layer is buried in the silicon dioxide layer. The waveguide layer includes a grating coupler and a microring resonator. Light in an optical fiber is coupled into the microring resonator through the grating coupler and then output from the grating coupler. The thickness of the silicon dioxide layer in the area above the microring resonator is less than the thickness of the silicon dioxide layer in other areas. The present invention uses a microring resonator to detect the dew point. The microring resonator is used as a sensor for detecting the condensation of water droplets and a sensor for recording temperature, so as to achieve rapid and accurate measurement of the condensation temperature.

Description

Technical Field

[0001] The present invention relates to the technical field of dew point detection, and in particular to a dew point detection sensor, a detection system and a method based on a microring resonator. Background Art

[0002] The accurate measurement of humidity is of great significance in daily life and industrial and agricultural production. Weather forecasting, crop growth, food storage, industrial manufacturing and other aspects all require accurate measurement and control of humidity. Humidity can be expressed as absolute humidity, relative humidity or dew point. Among them, dew point is the characterization method of humidity in most humidity standard laboratories.

[0003] When the temperature is constant, the relationship between the relative humidity in the air and the dew point temperature is uniquely determined. We can accurately calculate the relative humidity of the air by measuring the current dew point of the air. At present, most dew point sensors are made by lowering the temperature of the sensor, causing water droplets to condense on the surface of the sensor, and a certain physical quantity of the sensor changes when it encounters water. However, the condensation water detection probe and the temperature probe are separated from each other, and the temperature probe cannot quickly and accurately measure the temperature of the condensation water, resulting in a certain error in the sensor. Summary of the invention

[0004] To solve the above technical problems, the present invention provides a dew point detection sensor, a detection system and a method based on a microring resonator. A microring resonator is used to detect the dew point. The microring resonator serves as both a sensor for detecting condensation of water droplets and a sensor for recording temperature, thereby realizing fast and accurate measurement of the condensation temperature.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A dew point detection sensor based on a microring resonator comprises a semiconductor refrigerator and a microring resonator sensor chip placed thereon, wherein the microring resonator sensor chip comprises a silicon substrate and a silicon dioxide layer located on the silicon substrate, wherein a waveguide layer is buried in the silicon dioxide layer, wherein the waveguide layer comprises a grating coupler and a microring resonator, wherein light in an optical fiber is coupled into the microring resonator via the grating coupler and then output from the grating coupler; and the thickness of the silicon dioxide layer in the area above the microring resonator is less than the thickness of the silicon dioxide layer in other areas.

[0007] In the above scheme, the input end of the micro-ring resonator is connected to the grating coupler through a transmission waveguide, and the download end uses a ring waveguide as a full-strip reflector.

[0008] In the above scheme, the input end and the download end of the microring resonator are connected through a Y-type beam splitter.

[0009] In the above scheme, the waveguide material of the microring resonator is silicon nitride, the width is 1um, the height is 0.4um, the microring radius is 40um, and the coupling distance is 300nm.

[0010] In the above solution, the thickness of the silicon dioxide layer in the area above the microring resonator is 120 nm.

[0011] A dew point detection system based on a microring resonator comprises a light source, an optical fiber circulator, the dew point detection sensor as described above, and a wavelength demodulator, wherein the light source is connected to port one of the optical fiber circulator via optical fiber one, port two of the optical fiber circulator is connected to a grating coupler of a microring resonator sensor chip via optical fiber two, and port three of the optical fiber circulator is connected to the wavelength demodulator via optical fiber three.

[0012] A dew point detection method based on a microring resonator, using the above-mentioned dew point detection system, comprises the following steps:

[0013] (1) Light emitted by a light source enters port 1 of an optical fiber circulator through optical fiber 1, is output from port 2 of the optical fiber circulator, enters a microring resonator sensor chip through optical fiber 2, is coupled into the microring resonator through a grating coupler, and a semiconductor refrigerator continuously cools the microring resonator sensor chip. The reflected light enters port 2 of an optical fiber circulator through optical fiber 2, is output from port 3 of the optical fiber circulator, enters a wavelength demodulator through optical fiber 3, and the wavelength demodulator records the wavelength of the reflected light in real time.

[0014] (2) During the cooling process, due to the thermo-optical effect, the effective refractive index of the waveguide decreases, and the resonant wavelength of the microring resonator decreases accordingly. When the temperature drops to the dew point, water droplets condense on the surface of the silica layer above the microring resonator. Since the water droplets cover the surface of the waveguide, the effective refractive index of the waveguide increases, and the resonant wavelength of the microring resonator increases accordingly. Based on the wavelength recording value of the entire process, find the point where the wavelength changes from decreasing to increasing, and calculate the corresponding temperature, which is the dew point value.

[0015] Through the above technical solution, the dew point detection sensor, detection system and method based on microring resonator provided by the present invention have the following beneficial effects:

[0016] 1. The present invention uses a microring resonator to detect the dew point. The microring resonator serves as both a sensor for detecting the condensation of water droplets and a sensor for recording temperature, thereby realizing rapid and accurate measurement of the condensation temperature.

[0017] 2. The present invention utilizes a semiconductor refrigerator to continuously cool the microring resonator sensor chip, records the value of the reflected wavelength during the cooling process, finds the point where the wavelength changes from decreasing to increasing, and calculates the corresponding temperature as the dew point value. This method makes full use of the change of the refractive index of the waveguide with temperature and the influence of water droplets on the refractive index of the waveguide. This method is simple, convenient and highly accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0019] Figure 1 A partially cutaway schematic diagram of a dew point detection sensor based on a microring resonator disclosed in an embodiment of the present invention;

[0020] Figure 2 A plan view of the microring resonator disclosed in Example 1 of the present invention;

[0021] Figure 3 A cross-sectional view of a microring resonator sensor chip disclosed in Embodiment 1 of the present invention;

[0022] Figure 4 A plan view of a microring resonator disclosed in Example 2 of the present invention;

[0023] Figure 5 A cross-sectional view of a microring resonator sensor chip disclosed in Embodiment 2 of the present invention;

[0024] Figure 6 A diagram of a dew point detection system based on a microring resonator disclosed in the present invention;

[0025] Figure 7 is the relationship between the resonant wavelength and temperature;

[0026] Figure 8 This is the effect of water layer thickness on the effective refractive index;

[0027] Fig. 9 This is a graph showing the change in resonant wavelength during the cooling process.

[0028] In the figure, 1. semiconductor refrigerator; 2. microring resonator sensor chip; 3. silicon substrate; 4. silicon dioxide layer; 5. grating coupler; 6. microring resonator; 7. Y-type beam splitter; 8. light source; 9. fiber circulator; 10. ring waveguide; 11. wavelength demodulator; 12. optical fiber one; 13. optical fiber two; 14. optical fiber three; 15. transmission waveguide. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0030] The present invention provides a dew point detection sensor based on a microring resonator, such as Figure 1 As shown, it includes a semiconductor refrigerator 1 and a microring resonator sensor chip 2 placed thereon, the semiconductor refrigerator 1 is used to cool the microring resonator sensor chip 2, so that water vapor condenses above the surface of the microring resonator 6. A layer of thermal conductive silicone grease is applied between the two.

[0031] like Figure 3 and Figure 5 As shown, the microring resonator sensor chip 2 includes a silicon substrate 3 and a silicon dioxide layer 4 located on the silicon substrate 3, wherein a waveguide layer ( Figure 1 The waveguide layer includes a grating coupler 5 and a microring resonator 6. The microring resonator 6 is a reflective microring resonator. The light in the optical fiber is coupled into the microring resonator 6 through the grating coupler 5, and then output from the grating coupler 5 after passing through the microring resonator.

[0032] The thickness of the silicon dioxide layer 4 in the area above the microring resonator 6 is less than that in other areas. In this embodiment, the thickness of the silicon dioxide layer 4 in the area above the microring resonator 6 is 120 nm, which can ensure that water droplets can condense on the surface of the silicon dioxide layer 4 above the microring resonator.

[0033] The microring resonator 6 in the present invention has two structures, wherein the structure of the embodiment 1 is as follows: Figure 2 and Figure 3 As shown, the input end of the micro-ring resonator 6 is connected to the grating coupler 5 through the transmission waveguide 15, and the download end is connected to the ring waveguide 10 through the transmission waveguide 15, and the ring waveguide 10 serves as a full-strip reflector. Light is input from the input end A, coupled to the download end B through the micro-ring, and the light at the download end B is reflected by the ring waveguide 10 and returns to the input end A along the original path. Therefore, input-output multiplexing is realized at the input end A of the micro-ring resonator 6.

[0034] The structure of Example 2 is as follows Figure 4 and Figure 5 As shown, the input end A and the download end B of the microring resonator 6 are connected through a Y-type beam splitter 7 to realize single-channel input and output. The input light is divided into two parts through the Y-type beam splitter 7, one part passes through the microring from the input end A and returns to the Y-type beam splitter 7 at the download end, and the other part passes through the microring from the download end B and returns to the Y-type beam splitter 7 at the input end A. The two beams of returned light are combined in the Y-type beam splitter 7 and then returned.

[0035] The waveguide material of the micro-ring resonator 6 is silicon nitride, the width is 1 um, the height is 0.4 um, the micro-ring radius is 40 um, and the coupling distance is 300 nm.

[0036] The present invention also discloses a dew point detection system based on a microring resonator, such as Figure 6 As shown, it includes a light source 8, an optical fiber circulator 9, the dew point detection sensor as above, and a wavelength demodulator 11. The light source 8 is connected to port one a of the optical fiber circulator 9 through an optical fiber one 12, port two b of the optical fiber circulator 9 is connected to the grating coupler 5 of the microring resonator sensor chip 2 through an optical fiber two 13, and port three c of the optical fiber circulator 9 is connected to the wavelength demodulator 11 through an optical fiber three 14.

[0037] A dew point detection method based on a microring resonator, using the above-mentioned dew point detection system, comprises the following steps:

[0038] (1) The light emitted by the light source 8 enters the port a of the optical fiber circulator 9 through the optical fiber 12, is output from the port b of the optical fiber circulator 9, enters the microring resonator sensor chip 2 through the optical fiber 13, and is coupled into the microring resonator 6 through the grating coupler 5. The resonant wavelength formula of the microring resonator 6 is: Where R is the radius of the microring, m is the resonance order, and n is eff is the waveguide effective refractive index;

[0039] The semiconductor refrigerator 1 continuously cools the microring resonator sensor chip 2, and the reflected light enters the port 2 b of the optical fiber circulator 9 through the optical fiber 2 13, and finally is output from the port 3 c of the optical fiber circulator 9, and enters the wavelength demodulator 11 through the optical fiber 3 14, and the wavelength demodulator 11 records the wavelength of the reflected light in real time;

[0040] (2) During the cooling process, due to the thermo-optical effect, the effective refractive index of the waveguide decreases, and the resonant wavelength of the microring resonator 6 decreases accordingly. The relationship between the resonant wavelength and temperature is shown in the figure below: Figure 7 When the temperature drops to the dew point, water droplets condense on the surface of the silicon dioxide layer 4 above the microring resonator 6. Since the water droplets cover the waveguide surface, the effective refractive index of the waveguide increases, and the resonant wavelength of the microring resonator 6 increases accordingly. The relationship between the effective refractive index of the waveguide and the thickness of the water layer is as follows: Figure 8 As shown; during the entire cooling process, the resonant wavelength of the microring resonator 6 first decreases and then increases, as shown in Fig. 9 shown.

[0041] According to the wavelength change curve recorded during the entire cooling process, the wavelength turning point is selected, and the corresponding temperature calculated according to the wavelength is the dew point value.

[0042] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A dew point detection sensor based on a microring resonator, characterized in that: The invention comprises a semiconductor refrigerator and a micro-ring resonator sensor chip placed thereon. The micro-ring resonator sensor chip comprises a silicon substrate and a silicon dioxide layer located on the silicon substrate. A waveguide layer is buried in the silicon dioxide layer. The waveguide layer comprises a grating coupler and a micro-ring resonator. Light in an optical fiber is coupled into the micro-ring resonator through the grating coupler and then output from the grating coupler. The thickness of the silicon dioxide layer in the area above the micro-ring resonator is less than that in other areas. The input end of the micro-ring resonator is connected to the grating coupler through a transmission waveguide, and the download end uses a ring waveguide as a full-band reflector. Alternatively, the input end and the download end of the micro-ring resonator are connected through a Y-type beam splitter.

2. A dew point detection sensor based on a microring resonator according to claim 1, characterized in that: The waveguide material of the micro-ring resonator is silicon nitride, the width is 1um, the height is 0.4um, the radius of the micro-ring is 40um, and the coupling distance is 300nm.

3. A dew point detection sensor based on a microring resonator according to claim 1, characterized in that: The thickness of the silicon dioxide layer in the area above the microring resonator is 120 nm.

4. A dew point detection system based on a microring resonator, characterized in that: The invention comprises a light source, an optical fiber circulator, the dew point detection sensor as claimed in claim 1, and a wavelength demodulator, wherein the light source is connected to port one of the optical fiber circulator through optical fiber one, port two of the optical fiber circulator is connected to a grating coupler of a microring resonator sensor chip through optical fiber two, and port three of the optical fiber circulator is connected to the wavelength demodulator through optical fiber three.

5. A dew point detection method based on a microring resonator, using the dew point detection system as claimed in claim 4, characterized in that: The steps include: (1) The light emitted by the light source enters port 1 of the optical fiber circulator through optical fiber 1, is output from port 2 of the optical fiber circulator, enters the microring resonator sensor chip through optical fiber 2, is coupled into the microring resonator through the grating coupler, and the semiconductor refrigerator continuously cools the microring resonator sensor chip. The reflected light enters port 2 of the optical fiber circulator through optical fiber 2, and is finally output from port 3 of the optical fiber circulator, enters the wavelength demodulator through optical fiber 3, and the wavelength demodulator records the wavelength of the reflected light in real time. (2) During the cooling process, due to the thermo-optical effect, the effective refractive index of the waveguide decreases, and the resonant wavelength of the microring resonator decreases accordingly. When the temperature drops to the dew point, water droplets condense on the surface of the silica layer above the microring resonator. Since the water droplets cover the surface of the waveguide, the effective refractive index of the waveguide increases, and the resonant wavelength of the microring resonator increases accordingly. Based on the wavelength recording value of the entire process, find the point where the wavelength changes from decreasing to increasing, and calculate the corresponding temperature, which is the dew point value.

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