Temperature-insensitive cascade double-ring detection instrument based on reflective structure

Abstract

The present invention discloses a temperature-insensitive cascade double-ring detection instrument based on a reflective structure, comprising an input light source, a fiber coupler, a detector, a space optical system, a cascade double-ring sensor and a reflective structure. The fiber coupler has multiple ports respectively connected to the space optical system and the detector; a grating coupler array is provided on the first port of the cascade double-ring sensor, wherein one ring of an unmodified biomolecular film in contact with a solution to be tested is a reference ring; another ring of a modified biomolecular film in contact with a solution to be tested is a sensing ring, and the second port of the cascade double-ring sensor is connected to the reflective structure. The present invention uses an optical system to input spatial light into a cascade double-ring sensor chip through a grating coupler, and uses a scanning reflector to realize the switching of different sensing units, thereby reducing the manufacturing cost of the sensor and increasing the utilization rate of the sensor chip. The second port of the cascade double-ring sensor is connected to the reflective structure, which increases the interaction between the resonant light and the substance to be tested and improves the detection sensitivity.

Description

Technical Field

[0001] The invention relates to a detection instrument, in particular to a temperature-insensitive cascade double-ring detection instrument based on a reflection structure. Background Art

[0002] Information acquisition technology represented by sensor technology is greatly changing our lives. As the front end of intelligent hardware, sensors have been widely studied and have made a series of progress. Optical biosensors have great potential for commercial application due to their high sensitivity, anti-electromagnetic interference, multifunctional integration and high flexibility. Optical biosensors based on on-chip integration have the characteristics of trace detection, so the cost of the detection reagents used is saved. However, because it is currently connected to the input light source with an optical fiber array, the optical fiber array and the chip need to be dissociated when detecting new biological molecules, so the experimental operation is difficult and the chip is easily damaged. In addition, the traditional cascade dual-ring sensor is easily disturbed by the external temperature, which reduces the accuracy of sensing. Summary of the invention

[0003] The object of the present invention is to provide a temperature-insensitive cascade double-ring detection instrument based on a reflection structure in view of the deficiencies of the prior art.

[0004] The technical solution adopted by the present invention to solve the technical problem is: a temperature-insensitive cascade double-ring detection instrument based on a reflective structure, comprising an input light source, a fiber coupler, a detector, a spatial optical system, a grating coupler array, a cascade double-ring sensor, a biomolecule modification part and a reflective structure;

[0005] The optical fiber coupler has four ports for intensity detection: the first port is connected to the input light source, the second port is connected to the detector one, the third port is connected to the space optical system, and the fourth port is connected to the detector two; the optical fiber coupler has three ports for wavelength detection: the first port is connected to the input light source, the second port is connected to the detector, and the third port is connected to the space optical system.

[0006] A grating coupler array is provided on the first port of the cascade double-ring sensor, and light passing through the spatial optical system enters the cascade double-ring sensor in a grating coupling manner; one ring of the cascade double-ring sensor is not modified with a biomolecular film and is in contact with a solution to be tested as a reference ring; the other ring is modified with a biomolecular film and is in contact with a solution to be tested as a sensing ring; the second port of the cascade double-ring sensor is connected to a reflective structure; the reflective structure and the light wave mode propagating in the waveguide constituting the cascade double-ring sensor are the same;

[0007] The reference ring and the sensing ring of the cascaded dual-ring sensor meet the temperature insensitivity condition: S wr ·L r =Sws ·L s ; where L r and L s are the circumferences of the reference ring and the sensor ring respectively; S wr and S ws Temperature waveguide sensitivities of the reference and sensing loops, respectively.

[0008] Furthermore, the input light source is composed of a broadband light source and a filter when intensity detection is performed; and can be a broadband light source or a tunable laser when wavelength detection is performed.

[0009] Furthermore, there are two detectors for intensity detection, namely detector one and detector two, and both detectors are optical power meters; and there is only one optical power meter for wavelength detection.

[0010] Furthermore, the reflective structure may be a reflective film plated on the second port of the cascaded double-ring sensor, or a connected annular waveguide reflective annular structure, or a single-mode optical fiber with a reflective pigtail connected to the second port of the cascaded double-ring sensor.

[0011] Furthermore, the intensity detection, when L r =L s The intensity detection sensitivity is highest.

[0012] Furthermore, the solution to be tested flows through the reference ring and the sensing ring through the microfluidic channel at the same time.

[0013] Furthermore, the spatial optical system includes a collimating mirror, a scanning reflector and a focusing and beam collecting optical system, and the switching of different cascaded dual-ring sensors on the same chip is achieved through the angular scanning of the scanning reflector; the focusing and beam collecting optical system can gather the energy of the incident light and then incident on the grating coupler array.

[0014] Furthermore, during intensity detection, a portion of the input light of the input light source enters detector one through the optical fiber coupler to monitor the input optical power stability, and the other portion enters the cascaded dual-ring sensor through the spatial optical system using grating coupling. The reflective structure connected to the second port of the cascaded dual-ring sensor returns the light along the original path and finally enters detector two.

[0015] When the biological molecules in the test solution are adsorbed on the biological molecule membrane, the effective refractive index of the sensing ring waveguide will change, the transmission spectrum of the cascade double-ring sensor will drift, the transmission spectrum within the input light wavelength range will move, and the optical power of the output light will change. The optical power received by detector one and detector two after the test solutions containing different concentrations of the test substance are passed through the cascade double-ring sensor is recorded, and the optical power of detector two and detector one is normalized to measure the content of the test substance in the test solution.

[0016] The beneficial effects of the present invention are as follows: the temperature-insensitive cascade double-ring detection instrument based on a reflective structure of the present invention can be detected by wavelength detection and intensity detection, and the test method is flexible, wherein the intensity detection cost is relatively low; by building a spatial optical system for light alignment, the service life of the cascade double-ring optical chip is improved, wherein the scanning reflector can realize the rapid scanning of multi-path sensing units; microfluidic channels are added to the reference ring and the sensing ring, and the solution to be tested is introduced at the same time, thereby reducing the influence of the external environment temperature on the sensing signal; the cascade double-ring sensor is connected to the reflective structure, which not only improves the sensitivity of the cascade double-ring sensor, but also enables the sensor input light and output light to share the same optical path, thereby simplifying the light alignment optical path of the sensing system; and through the structural design of the sensing ring and the reference ring, a temperature-insensitive sensor is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of a cascade double-loop detection instrument based on a reflection structure;

[0018] Figure 2 It is a schematic diagram of the structure of the modified part of the biological molecule;

[0019] Figure 3 Schematic diagram of the radius of the sensing ring and its change with the waveguide width;

[0020] Figure 4 Schematic diagram of the relationship between the output spectrum of the cascaded double-ring sensor and the temperature;

[0021] Figure 5 Schematic diagram of the cascaded double-ring output spectrum and the cascaded double-ring output spectrum based on the reflection structure;

[0022] Figure 6 Schematic diagram of the output spectrum of the cascade double-ring detection instrument based on the reflection structure;

[0023] Figure 7 The relationship between the effective refractive index of the sensing ring and the power ratio (PR) of detector one to detector two was measured for the cascaded dual-ring sensor (CMRR) and the cascaded dual-ring sensor based on a reflection structure (RCMRR) under intensity detection. DETAILED DESCRIPTION

[0024] The following are specific embodiments of the present invention, which further illustrate the present invention. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application.

[0025] like Figure 1As shown, the present embodiment provides a temperature-insensitive cascade dual-ring detection instrument based on a reflective structure, comprising an input light source 1, a fiber coupler 2, a detector 3, a space optical system 4, a grating coupler array 5, a cascade dual-ring sensor 6, a biomolecule modification part 7 and a reflective structure 8; the fiber coupler 2 uses four ports for intensity detection: the first port 21 is connected to the input light source 1, the second port 22 is connected to the detector one 31, the third port 23 is connected to the space optical system 4, and the fourth port 24 is connected to the detector two 32; the fiber coupler 2 uses three ports for wavelength detection: the first port 21 is connected to the input light source 1, the second port 22 is connected to the detector 31, and the third port 23 is connected to the space optical system 4. A grating coupler array 5 is provided on the first port 61 of the cascade double-ring sensor, and light passing through the spatial optical system 4 enters the cascade double-ring sensor 6 in a grating coupling manner; one ring of the cascade double-ring sensor 6 does not modify the biomolecular film and is in contact with the solution to be tested, serving as a reference ring 62; the other ring modifies the biomolecular film and is in contact with the solution to be tested, serving as a sensing ring 63; the second port 64 of the cascade double-ring sensor is connected to the reflective structure 8; the reflective structure 8 has the same light wave mode propagating in the waveguide constituting the cascade double-ring sensor.

[0026] like Figure 2 As shown, the biomolecule modification part 7 includes: a biomolecule film 71, a biomolecule receptor 72, a biomolecule to be detected 73, and a solution to be detected 74. At the same time, the solution to be detected 74 is introduced into the microfluidic channel and flows through the reference ring 62 and the sensing ring 63, and the biomolecule receptor 72 on the biomolecule film 71 on the sensing ring 63 will specifically adsorb the biomolecule to be detected 73 in the solution to be detected 74, thereby changing the effective refractive index of the sensing ring 63 for sensing.

[0027] The temperature-insensitive cascade double-ring detection instrument based on a reflective structure of the present invention greatly reduces the sensing error caused by the temperature difference before and after the solution 74 to be tested flows through the reference ring 62 and the sensing ring 63 at the same time.

[0028] like Figure 3 As shown, when the reference ring 62 has a radius of 123 μm, a height of 220 nm, and a width of 550 nm, in order to realize that the sensor is not disturbed by the external temperature, the values ​​of the radius of the sensing ring 63 and the waveguide width correspond to the temperature insensitive condition. The substrate material of the reference ring 62 and the sensing ring 63 is SiO2, and the waveguide core material is Si.

[0029] according to:

[0030]

[0031]

[0032]

[0033] It can be deduced that:

[0034]

[0035] Where: S is the sensitivity of a single loop; ΔT is when the external temperature changes; Δλ is the wavelength drift of the output spectrum resonance peak; S w is the waveguide sensitivity; λ is the central wavelength; n g is the group refractive index; S CMRR is the sensitivity of the cascaded double-loop sensor; S r is the reference loop temperature sensitivity; S s is the temperature sensitivity of the sensing ring; FSR is the free spectral range; FSR r and FSR s are the free spectral ranges of the reference ring and the sensing ring, respectively; L is the circumference of the ring; S wr , L r 、n gr are the temperature waveguide sensitivity, circumference and group refractive index of the reference ring respectively; S ws , L s 、n gs are the temperature waveguide sensitivity, circumference and group refractive index of the sensing ring, respectively.

[0036] From formula (4), we can get S CMRR =0 temperature insensitive condition is:

[0037] S wr ·L r =S ws ·L s (5)

[0038] In the temperature-insensitive cascade dual-ring detection instrument based on a reflective structure of the present invention, the design of the reference ring 62 and the sensing ring 63 meets the temperature-insensitive condition, which greatly reduces the external temperature interference caused by the thermo-optical effect of the Si material during the detection of biological molecules.

[0039] like Figure 4 As shown, the reference ring 62 has a radius of 123 μm, a height of 220 nm, and a width of 550 nm; the sensing ring 63 has a radius of 122 μm, a height of 220 nm, and a width of 560.5 nm. The cascaded double-ring sensor that meets the temperature insensitivity condition has only discrete peaks in the output spectrum that move with temperature changes at 20°C, 34°C, and 48°C, while the output spectrum envelope does not move with temperature changes, shielding the interference of external temperature.

[0040] like Figure 5 As shown, the double ring parameters are Figure 4Similarly, the radius of the reference ring 62 is 123 μm, the radius of the sensing ring 63 is 122 μm, the effective refractive index of the reference ring is 1.9093, the effective refractive index of the sensing ring 63 is 1.7505, and R is 0.96.

[0041] The output spectrum amplitude transmittance of the cascaded double-ring detection instrument based on the reflection structure is:

[0042]

[0043] where κ r1 , κ r2 are the amplitude coupling coefficients of the upper and lower coupling regions of the reference ring, t r1 ,t r2 are the amplitude transmission coefficients of the upper and lower coupling regions of the reference ring, κ s1 , κ s2 are the amplitude coupling coefficients of the upper and lower coupling regions of the sensor ring, t s1 ,t s2 are the amplitude transmission coefficients of the upper and lower coupling regions of the sensor ring, j is an imaginary unit, R r , R s are the reference ring radius and the sensing ring radius, β r , β s are the propagation constants of the reference loop and the sensing loop, respectively, r , α s are the losses of the reference loop and the sensing loop, respectively; R is the reflectivity of the reflection structure; and exp(·) is an exponential function with e as the base.

[0044] Compared with the output spectrum of the traditional cascade double-ring sensor, the cascade double-ring detection instrument based on the reflection structure of the present invention has greatly improved contrast of the output spectrum and greatly improved sharpness of its envelope peak, which will greatly improve the sensitivity during intensity detection and reduce the error caused by envelope fitting during wavelength detection.

[0045] like Figure 6 As shown, its double ring parameters are Figure 4 When the temperature is 20°C, the concentration of the biomolecule 73 to be tested in the test solution 74 is changed (the refractive index of the test solution 74 changes by Δn c ), the output spectrum envelope moves significantly, while when the concentration of the biological molecules 73 to be tested in the test solution 74 is not changed and the temperature is changed to 34°C, the output spectrum envelope does not change, and only the discrete peaks in the envelope move.

[0046] The cascade double-ring detection instrument based on the reflection structure of the present invention can realize the quantitative detection of the biological molecules 73 to be detected in the solution 74 to be detected with different concentrations while ensuring that it is insensitive to the external temperature.

[0047] like Figure 7As shown, its structural parameters are Figure 5 The same. Generally, the largest slope is selected as the maximum sensitivity of the sensor under intensity detection, so the sensitivity of the cascaded double-loop sensor is obtained: S CMRR =2806.2dB / RIU, the sensitivity of the cascaded double-loop detection instrument based on the reflection structure: S RCMRR =8347.31dB / RIU.

[0048] The cascade double-ring detection instrument based on the reflection structure of the present invention has an intensity detection sensitivity increased by 2.975 times compared with the traditional cascade double-ring sensor with the same structural parameters.

[0049] The above embodiments are used to explain the present invention, rather than to limit the present invention. Any modification and change made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A temperature-insensitive cascade double-ring detection instrument based on a reflective structure, characterized in that: It includes an input light source, a fiber coupler, a detector, a space optical system, a grating coupler array, a cascaded double-ring sensor, a biomolecule modification part and a reflection structure; The fiber coupler has four ports for intensity detection: the first port is connected to the input light source, the second port is connected to the detector 1, the third port is connected to the space optical system, and the fourth port is connected to the detector 2; the fiber coupler has three ports for wavelength detection: the first port is connected to the input light source, the second port is connected to the detector 1, and the third port is connected to the space optical system; A grating coupler array is provided on the first port of the cascaded dual-ring sensor, and light passing through the spatial optical system enters the cascaded dual-ring sensor in a grating coupling manner; One ring in the cascade double-ring sensor does not modify the biomolecule membrane and is in contact with the solution to be tested as a reference ring; The other ring modifies the biomolecule membrane and contacts with the solution to be tested, serving as a sensing ring; The second port of the cascaded double-ring sensor is connected to a reflective structure; the reflective structure has the same light wave mode as that propagated in the waveguide constituting the cascaded double-ring sensor; The reference ring and the sensing ring of the cascaded dual-ring sensor meet the temperature insensitivity condition: S wr ·L r =S ws ·L s ; where L r and L s are the circumferences of the reference ring and the sensor ring respectively; S wr and S ws Temperature waveguide sensitivities of the reference and sensing loops, respectively.

2. A temperature-insensitive cascade double-ring detection instrument based on a reflective structure according to claim 1, characterized in that: The input light source is composed of a broadband light source and a filter when detecting intensity; and the input light source is a tunable laser when detecting wavelength.

3. The temperature-insensitive cascade double-ring detection instrument based on a reflective structure according to claim 1, characterized in that: There are two detectors for intensity detection, namely detector 1 and detector 2, both of which are optical power meters; there is only one detector for wavelength detection, which is an optical power meter.

4. The temperature-insensitive cascade double-ring detection instrument based on a reflective structure according to claim 1, characterized in that: The reflective structure is a reflective film plated on the second port of the cascaded double-ring sensor, or a connected annular waveguide reflective annular structure, or a single-mode optical fiber with a reflective pigtail connected to the second port of the cascaded double-ring sensor.

5. The temperature-insensitive cascade double-loop detection instrument based on a reflective structure according to claim 1, characterized in that: For intensity detection, when L r =L s The intensity detection sensitivity is highest.

6. The temperature-insensitive cascade double-ring detection instrument based on a reflective structure according to claim 1, characterized in that: The solution to be tested flows through the reference ring and the sensing ring simultaneously through the microfluidic channel.

7. The temperature-insensitive cascade double-loop detection instrument based on a reflective structure according to claim 1, characterized in that: The spatial optical system includes a collimating mirror, a scanning reflector and a focusing and beam collecting optical system. By scanning the scanning reflector at an angle, the switching of different cascaded dual-ring sensors on the same chip is realized; the focusing and beam collecting optical system can gather the energy of the incident light and then incident on the grating coupler array.

8. The temperature-insensitive cascade double-loop detection instrument based on a reflective structure according to claim 1, characterized in that: During intensity detection, part of the input light of the input light source enters detector one through the optical fiber coupler to monitor the input optical power stability, and the other part enters the cascaded dual-ring sensor through the spatial optical system using grating coupling. The reflective structure connected to the second port of the cascaded dual-ring sensor returns the light to its original path and finally enters detector two.

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