Optical biosensor with micro-ring resonator structure and preparation method of optical biosensor

Abstract

The invention discloses an optical biosensor with a micro-ring resonator structure. The optical biosensor comprises a waveguide sandwich structure, a straight-through end slit waveguide, a downloading end slit waveguide, a slit micro-ring and a substrate layer, the waveguide sandwich structure, the straight-through end slit waveguide, the downloading end slit waveguide and the slit micro-ring are arranged above the substrate layer; the straight-through end slit waveguide is arranged on one side of the slit micro-ring, and the downloading end slit waveguide is arranged on the other side of the slit micro-ring; the waveguide sandwich structure is arranged in the straight-through end slit waveguide, the downloading end slit waveguide and the slit micro-ring; the waveguide interlayer structure, the straight-through end slit waveguide, the downloading end slit waveguide and the slit micro-ring form an interlayer slit waveguide structure, so that waveguide single-mode transmission can be realized; and the waveguide sandwich structure, the straight-through end slit waveguide, the downloading end slit waveguide and the slit micro-ring form a micro-ring resonator which can realize critical coupling. The optical biosensor is used for solving the problem of low sensitivity of the optical biosensor.

Description

Technical Field

[0001] The present invention relates to the field of optical biosensing and photon integrated devices, and in particular to an optical biosensor with a microring resonator structure and a preparation method thereof. Background Art

[0002] Optical biosensors have become a research hotspot due to their advantages such as rapid real-time monitoring, label-free detection, high sensitivity, and easy operation. Among them, microring resonators based on whispering gallery modes (WGMs) are widely used in biosensing due to their compact structure, high integration, flexible design, and compatibility with complementary metal-oxide-semiconductor (CMOS) processes. The principle of optical biosensors with microring resonator structures is that the biological analyte interacts with the evanescent field of the optical waveguide, causing the refractive index around the optical waveguide to change, resulting in regular changes in the intensity or position of the resonance peak of the microring resonator, thereby qualitatively or quantitatively detecting the analyte.

[0003] For optical biosensors with microring resonator structures, sensitivity is an important performance indicator. The sensitivity of conventional silicon nitride microring biosensors can only reach 246nm / RIU, while the sensitivity of conventional silicon microring biosensors can only reach 70nm / RIU, which greatly limits the application of microring resonators in the field of sensing. How to solve the low sensitivity of optical biosensors with microring resonator structures and realize highly sensitive optical biosensors with microring resonator structures has become an important scientific problem that needs to be solved urgently. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] The optical biosensor with a microring resonator structure provided by the present invention is at least used to solve the problem of low sensitivity of the above-mentioned optical biosensor.

[0006] (II) Technical solution

[0007] The embodiment of the present invention provides an optical biosensor with a microring resonator structure, comprising: a waveguide sandwich structure 1, a through-end slit waveguide 2, a download-end slit waveguide 3, a slit microring 4, and a substrate layer 5;

[0008] The waveguide sandwich structure 1, the straight-through end slot waveguide 2, the download end slot waveguide 3 and the slot microring 4 are arranged above the substrate layer 5; the straight-through end slot waveguide 2 is arranged on one side of the slot microring 4, and the download end slot waveguide 3 is arranged on the other side of the slot microring 4; the waveguide sandwich structure 1 is arranged inside the straight-through end slot waveguide 2, the download end slot waveguide 3 and the slot microring 4; the sandwich slot waveguide structure composed of the waveguide sandwich structure 1 and the straight-through end slot waveguide 2, the download end slot waveguide 3 and the slot microring 4 can realize single-mode transmission of the waveguide.

[0009] Optionally, the waveguide sandwich structure 1 has a width less than or equal to 100 nm and a thickness in the range of 220 nm-1000 nm.

[0010] Optionally, the internal slit widths of the through-end slit waveguide 2, the download-end slit waveguide 3 and the slit micro-ring 4 are in the range of 100 nm to 400 nm.

[0011] Optionally, the width of the through-end slot waveguide 2 is less than or equal to 2 μm, and the thickness ranges from 220 nm to 1000 nm.

[0012] Optionally, the width of the slot waveguide 3 at the download end is less than or equal to 2 μm, and the thickness ranges from 220 nm to 1000 nm.

[0013] Optionally, the width of the slit micro-ring 4 is less than or equal to 2 μm, the thickness ranges from 220 nm to 1000 nm, and the radius is greater than or equal to 3 μm.

[0014] Optionally, the distance between the through-end slot waveguide 2 and the slot micro-ring 4 is in the range of 0.1 μm-2.5 μm.

[0015] Optionally, the distance between the download end slot waveguide 3 and the slot micro-ring 4 is in the range of 0.1 μm-2.5 μm.

[0016] Optionally, the distance between the through-end slot waveguide 2 and the slot micro-ring 4 and the distance between the download-end slot waveguide 3 and the slot micro-ring 4 may be equal or unequal.

[0017] Optionally, the waveguide sandwich structure 1 , the through-end slot waveguide 2 , the downstream-end slot waveguide 3 , and the slot micro-ring 4 may be made of the same material or different materials.

[0018] Optionally, the refractive index of the waveguide sandwich structure 1, the through-end slot waveguide 2, the download-end slot waveguide 3 and the slot micro-ring 4 is in the range of 1.5-3.5.

[0019] Optionally, the refractive index of the waveguide sandwich structure 1, the through-end slit waveguide 2, the download-end slit waveguide 3 and the slit microring 4 is greater than the refractive index of the substrate layer 5. The present invention also provides a method for preparing an optical biosensor with a microring resonator structure, comprising: S1, using a deposition process on the surface of the substrate layer 5 to obtain a waveguide material for preparing the waveguide sandwich structure 1, the through-end slit waveguide 2, the download-end slit waveguide 3 and the slit microring 4; S2, using an exposure process to pattern the waveguide sandwich structure 1, the through-end slit waveguide 2, the download-end slit waveguide 3 and the slit microring 4 above the substrate layer 5; S3, using an etching process on the basis of the patterning to obtain the waveguide sandwich structure 1, the through-end slit waveguide 2, the download-end slit waveguide 3 and the slit microring 4.

[0020] (III) Beneficial effects

[0021] 1. By arranging the sandwich structure in the slot waveguide provided by the present invention, the electric field in the slot is further enhanced on the basis of local enhancement of the electric field in the slot waveguide;

[0022] 2. The waveguide sandwich structure provided by the present invention and the sandwich slot waveguide structure composed of the through-end slot waveguide, the download-end slot waveguide and the slot micro-ring can realize single-mode transmission of the waveguide.

[0023] 3. The microring resonator composed of the waveguide sandwich structure, the through-end slot waveguide, the download-end slot waveguide and the slot microring provided by the present invention can combine the WGM of the microring resonator and the local enhancement of the electric field of the sandwich slot waveguide to achieve synergistic enhancement of the interaction between the light field and the sensing material;

[0024] 4. The wavelength sensitivity and intensity sensitivity of the optical biosensor based on the sandwich slit microring resonator structure provided by the present invention are enhanced at the same time, thereby realizing an optical biosensor with a high-sensitivity microring resonator structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of a three-dimensional structure of an optical biosensor with a microring resonator structure according to an embodiment of the present invention is shown;

[0026] Figure 2 A schematic diagram shows a front view of a sandwich slot waveguide structure at a download end in an embodiment of the present invention;

[0027] Figure 3 Schematically shows the normalized electric field diagram of the sandwich slot waveguide and the slot waveguide in the embodiment of the present invention (the width of the waveguide sandwich structure 1 is 30 nm);

[0028] Figure 4Schematically shows the wavelength position shift and intensity shift of the sandwich slit microring resonator and the slit microring resonator in the embodiment of the present invention (the width of the waveguide sandwich structure 1 is 30nm);

[0029] Figure 5 The flowchart schematically shows a method for preparing an optical biosensor with a microring resonator structure according to an embodiment of the present invention.

[0030] Explanation of the reference numerals: 1 - waveguide sandwich structure; 2 - straight-through end slot waveguide; 3 - downstream end slot waveguide; 4 - slot microring; 5 - substrate layer. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0032] See also Figure 1 , Figure 1 The structure diagram of the optical biosensor of the microring resonator structure in the embodiment of the present invention is schematically shown. The optical biosensor comprises: a waveguide sandwich structure 1, a through-end slot waveguide 2, a download-end slot waveguide 3, a slot microring 4 and a substrate layer 5; the waveguide sandwich structure 1, the through-end slot waveguide 2, the download-end slot waveguide 3 and the slot microring 4 are arranged above the substrate layer 5; the through-end slot waveguide 2 is arranged on one side of the slot microring 4, and the download-end slot waveguide 3 is arranged on the other side of the slot microring 4; the waveguide sandwich structure 1 is arranged inside the through-end slot waveguide 2, the download-end slot waveguide 3 and the slot microring 4.

[0033] In the embodiment of the present invention, the waveguide sandwich structure 1 is arranged at the inner center of the straight-through end slot waveguide 2, the download end slot waveguide 3 and the slot microring 4, and the sandwich slot waveguide structure composed of the straight-through end slot waveguide 2, the download end slot waveguide 3 and the slot microring 4 can realize single-mode transmission of the waveguide.

[0034] In the embodiment of the present invention, the width of the waveguide sandwich structure 1 is less than or equal to 100nm, and the thickness range is 220nm-1000nm; the width of the straight-through end slot waveguide 2 is less than or equal to 2μm, and the thickness range is 220nm-1000nm; the width of the download end slot waveguide 3 is less than or equal to 2μm, and the thickness range is 220nm-1000nm; the width of the slit microring 4 is less than or equal to 2μm, the thickness range is 220nm-1000nm, and the radius is greater than or equal to 3μm.

[0035] In the embodiment of the present invention, the distance between the through-end slot waveguide 2 and the slot microring 4 can be equal to the distance between the downstream slot waveguide 3 and the slot microring 4, and the distance range is 0.1 μm-2.5 μm, so as to achieve the upper and lower symmetrical transmission and critical coupling conditions of the microring resonator.

[0036] In the embodiment of the present invention, the refractive index of the waveguide sandwich structure 1, the through-end slot waveguide 2, the download-end slot waveguide 3 and the slot microring 4 is greater than the refractive index of the substrate layer 5, and the refractive index can be in the range of 1.5-3.5, so that the waveguide sandwich structure 1, the through-end slot waveguide 2, the download-end slot waveguide 3 and the slot microring 4 constitute a sandwich slot single-mode waveguide.

[0037] More specifically, the material of the waveguide sandwich structure 1 in the embodiment of the present invention can be selected from Si, Si x N y Or SiO2, to achieve a high refractive index waveguide core layer; the material of the through end slot waveguide 2, the download end slot waveguide 3 and the slot microring 4 can be selected from Si, Si x N y Or SiO2, to achieve a high refractive index waveguide core layer; the material of the substrate layer 5 can be selected from Si x N y Or SiO2 to achieve low refractive index waveguide cladding. The above materials are selected to achieve single mode waveguide conditions.

[0038] In the embodiment of the present invention, the sandwich slot waveguide composed of the waveguide sandwich structure 1, the straight-through end slot waveguide 2, the download end slot waveguide 3 and the slot microring 4, on the one hand, constitutes a single-mode waveguide to realize the fundamental mode transmission of the waveguide, and on the other hand, after the slot waveguide is added to the sandwich, due to the electric field discontinuity, the light field is further locally enhanced in the slot, thereby realizing further enhancement of the interaction between the light field and the sensing material, that is, the same change in the refractive index of the sensing material corresponds to a larger change in the position and intensity of the resonant wavelength of the microring resonator, that is, corresponds to higher wavelength sensitivity and intensity sensitivity.

[0039] In the embodiment of the present invention, the waveguide sandwich structure 1, the through-end slot waveguide 2, the down-end slot waveguide 3 and the slot microring 4 constitute an up-down-down type microring resonator structure, which can realize up-down symmetrical transmission and critical coupling of the microring resonator on the one hand, and on the other hand, the critically coupled microring resonator has better light field binding ability, thereby enhancing the interaction between the light field and the sensing material. Similarly, it corresponds to higher sensing sensitivity.

[0040] Furthermore, the applications of the sandwich slit microring resonator implemented in the embodiments of the present invention include but are not limited to optical biosensors, photoelectric modulators, wavelength division multiplexers / demultiplexers, etc., and have important application prospects in the fields of optical interconnection, optical communication, and optical sensing.

[0041] In addition, the applications of the sandwich slit waveguide implemented in the embodiments of the present invention include but are not limited to microring resonators, multimode interference couplers, arrayed waveguide gratings, photonic crystal waveguides, and grating couplers, etc., and the applications of the corresponding optoelectronic devices implemented include but are not limited to biosensing, photoelectric detection, optical interconnection, and optical communication, etc. The sandwich slit waveguide has strong scalability and high application value.

[0042] The embodiment of the present invention also provides a method for preparing an optical biosensor with a microring resonator structure, comprising:

[0043] S1, a waveguide material for preparing a waveguide sandwich structure 1, a through-end slot waveguide 2, a download-end slot waveguide 3 and a slot microring 4 is obtained on the surface of a substrate layer 5 by a deposition process.

[0044] The waveguide materials of the waveguide sandwich structure 1, the through-end slot waveguide 2, the down-end slot waveguide 3 and the slot micro-ring 4 are prepared by a chemical vapor deposition (CVD) process.

[0045] S2, patterning the waveguide sandwich structure 1, the through-end slot waveguide 2, the download-end slot waveguide 3 and the slot micro-ring 4 by using an exposure process above the substrate layer 5 and the waveguide material.

[0046] The waveguide sandwich structure 1, the through-end slot waveguide 2, the down-end slot waveguide 3 and the slot micro-ring 4 are patterned by electron beam lithography (EBL) process.

[0047] S3, based on the above-mentioned patterning, an etching process is adopted to obtain a waveguide sandwich structure 1, a through-end slot waveguide 2, a download-end slot waveguide 3 and a slot micro-ring 4.

[0048] The waveguide sandwich structure 1, the through-end slot waveguide 2, the download-end slot waveguide 3 and the slot micro-ring 4 are obtained by using an inductively coupled plasma (ICP) etching process.

[0049] The method for preparing an optical biosensor with a microring resonator structure provided in an embodiment of the present invention, the size parameters and material types of each structure in the preparation process, etc., please refer to the above structural embodiment part, which will not be repeated here.

[0050] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An optical biosensor with a microring resonator structure, characterized in that: include: A waveguide sandwich structure (1), a through-end slot waveguide (2), a download-end slot waveguide (3), a slot microring (4), and a substrate layer (5); The waveguide sandwich structure (1), the through-end slot waveguide (2), the download-end slot waveguide (3) and the slot micro-ring (4) are arranged above the substrate layer (5); The through-end slot waveguide (2) is arranged on one side of the slot micro-ring (4), and the download-end slot waveguide (3) is arranged on the other side of the slot micro-ring (4); the waveguide sandwich structure (1) is arranged inside the through-end slot waveguide (2), the download-end slot waveguide (3) and the slot micro-ring (4).

2. The optical biosensor of the microring resonator structure according to claim 1, characterized in that: The waveguide sandwich structure (1) has a width less than or equal to 100 nm and a thickness ranging from 220 nm to 1000 nm.

3. The optical biosensor of the microring resonator structure according to claim 1, characterized in that: The internal slit widths of the through-end slit waveguide (2), the download-end slit waveguide (3) and the slit micro-ring (4) are in the range of 100 nm to 400 nm.

4. The optical biosensor of the microring resonator structure according to claim 1, characterized in that: The width of the through-end slot waveguide (2) is less than or equal to 2 μm, and the thickness ranges from 220 nm to 1000 nm.

5. The optical biosensor of the microring resonator structure according to claim 1, wherein: The width of the download end slot waveguide (3) is less than or equal to 2 μm, and the thickness ranges from 220 nm to 1000 nm.

6. The optical biosensor of the microring resonator structure according to claim 1, characterized in that: The slit micro-ring (4) has a width less than or equal to 2 μm, a thickness ranging from 220 nm to 1000 nm, and a radius greater than or equal to 5 μm.

7. The optical biosensor of the microring resonator structure according to claim 1, characterized in that: The distance between the through-end slot waveguide (2) and the slot micro-ring (3) is in the range of 0.1 μm to 2.5 μm.

8. The optical biosensor of the microring resonator structure according to claim 1, characterized in that: The distance between the through-end slot waveguide (2) and the slot micro-ring (4) is in the range of 0.1 μm to 2.5 μm.

9. The optical biosensor of the microring resonator structure according to claim 1, characterized in that: The refractive index of the waveguide sandwich structure (1), the through-end slot waveguide (2), the download-end slot waveguide (3) and the slot micro-ring (4) is in the range of 1.5-3.5; The refractive index of the waveguide sandwich structure (1), the through-end slot waveguide (2), the download-end slot waveguide (3) and the slot micro-ring (4) is greater than the refractive index of the substrate layer (5).

10. A method for preparing an optical biosensor having a microring resonator structure according to any one of claims 1 to 9, characterized in that: The preparation method comprises: S1, using a deposition process on the surface of the substrate layer (5) to obtain a waveguide material for preparing the waveguide sandwich structure (1), the through-end slot waveguide (2), the download-end slot waveguide (3) and the slot microring (4); S2, patterning the waveguide sandwich structure (1), the through-end slit waveguide (2), the download-end slit waveguide (3), and the slit micro-ring (4) by using an exposure process above the substrate layer (5) and the waveguide material; S3, based on the patterning, an etching process is used to obtain the waveguide sandwich structure (1), the through-end slit waveguide (2), the download-end slit waveguide (3), and the slit microring (4).

Images