Micro-ring resonator and optical sensor

Abstract

The invention belongs to the technical field of optical switches and optical sensors, and discloses a micro-ring resonator and an optical sensor.The micro-ring resonator comprises a straight waveguide, a one-dimensional photonic crystal resonant cavity and a micro-ring resonant cavity, the one-dimensional photonic crystal resonant cavity is located between the straight waveguide and the micro-ring resonant cavity, and the one-dimensional photonic crystal resonant cavity is located between the straight waveguide and the micro-ring resonant cavity. A plurality of air holes are formed in the one-dimensional photonic crystal resonant cavity, the micro-ring resonant cavity comprises a silicon dioxide substrate, two concentric micro-rings are arranged on the silicon dioxide substrate, and a micro-groove is formed between the two micro-rings. The micro-ring resonator and the optical sensor comprising the micro-ring resonator have the advantages of being simple in structure, low in cost and high in anti-interference capacity.

Description

Technical Field

[0001] The invention belongs to the technical field of optical switches and optical sensors, and relates to a microring resonator and an optical sensor. Background Art

[0002] The microring resonator is an optical device with filtering function and strong anti-interference ability. The realization process is compatible with COMS process and is based on the design of silicon-on-insulator materials. With the realization of electromagnetic induced transparency effect in the field of optics, not only the harsh conditions for the realization of electromagnetic induced transparency effect are reduced, but also the application range of electromagnetic induced transparency effect becomes wider.

[0003] At present, the existing optical sensors realize the switching of electromagnetic induced transparency effect by changing the structural parameters, and the ability to regulate the sensing performance of the device is also limited. The optical sensor faces the problem of inconvenient regulation in actual use. Summary of the invention

[0004] In order to solve the technical problems that the switch control and sensitivity control of the electromagnetic induced transparency effect can only be achieved by changing the structural parameters, and the electronic sensor is seriously affected by electromagnetic interference, the present invention discloses a microring resonator with mature technology, simple structure, low cost and strong anti-interference ability, the microring resonator comprises a straight waveguide, a one-dimensional photonic crystal resonant cavity and a microring resonant cavity, the one-dimensional photonic crystal resonant cavity is located between the straight waveguide and the microring resonant cavity, a plurality of air holes are arranged on the one-dimensional photonic crystal resonant cavity, the microring resonant cavity comprises a silicon dioxide substrate, two concentric microrings are arranged on the silicon dioxide substrate, and a microgroove is formed between the two microrings.

[0005] Furthermore, the straight waveguide comprises a silicon dioxide substrate, two core silicon layers are arranged on the silicon dioxide substrate, and a layer of aluminum oxide is arranged between the two core silicon layers.

[0006] Furthermore, the micro-ring comprises a lower silicon layer and an upper silicon layer, a first graphene layer is provided between the lower silicon layer and the upper silicon layer, and a second graphene layer is provided on the upper surface of the upper silicon layer.

[0007] Furthermore, an aluminum oxide layer is provided above and below the first graphene layer.

[0008] Furthermore, in the microring resonator, the Fermi levels of the first graphene layer and the second graphene layer are changed by adjusting an external voltage, and the electromagnetically induced transparency effect is regulated by the changed Fermi levels.

[0009] Furthermore, the one-dimensional photonic crystal resonant cavity is a ring resonant cavity, and a plurality of the air holes are evenly arranged circumferentially on the annular surface of the ring resonant cavity.

[0010] Furthermore, in the microring resonator, the coupling strength between the straight waveguide and the one-dimensional photonic crystal resonant cavity is changed by adjusting the distance between the straight waveguide and the one-dimensional photonic crystal resonant cavity and / or the number of the air holes.

[0011] Furthermore, in the microring resonator, the coupling strength between the one-dimensional photonic crystal resonant cavity and the microring resonant cavity is changed by any one or more of the distance between the one-dimensional photonic crystal resonant cavity and the microring resonant cavity, the diameter of the microring and the width of the microgroove.

[0012] An embodiment of the present invention further provides an optical sensor, which includes the above-mentioned microring resonator.

[0013] Compared with the prior art, the beneficial effects that can be achieved by at least one of the above-mentioned technical solutions adopted in the embodiments of this specification include at least the following: the microring resonator of the present invention can achieve resonance between multiple energy levels through the design of straight waveguide, one-dimensional photonic crystal resonant cavity and microring resonant cavity and the change of graphene Fermi level, and at the same time, near-field coupling occurs between the electric fields to generate detection fields and control fields. By regulating the electromagnetic induced transparency effect and the depth of the electromagnetic induced transparency effect window, the environmental refractive index can be changed to simulate the sensitivity of the device, thereby realizing the evaluation of the sensing performance of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 A schematic diagram of a microring resonator disclosed in an embodiment of the present invention;

[0016] Figure 2 A schematic diagram of a straight waveguide disclosed in an embodiment of the present invention;

[0017] Figure 3 A schematic diagram of a microring resonant cavity disclosed in an embodiment of the present invention;

[0018] Figure 4 A schematic diagram of three energy levels of a microring resonator disclosed in an embodiment of the present invention;

[0019] Figure 5 A schematic diagram of evanescent wave propagation disclosed in an embodiment of the present invention;

[0020] Among them, 1. straight waveguide; 12. core layer silicon; 13. aluminum oxide; 2. one-dimensional photonic crystal resonant cavity; 21. air hole; 3. microring resonant cavity; 31. microring; 311. lower silicon layer; 312. upper silicon layer; 32. microgroove; 313. first graphene layer; 314. second graphene layer; 315. aluminum oxide layer; 4. silicon dioxide substrate. DETAILED DESCRIPTION

[0021] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0022] The following describes the implementation methods of the present application through specific specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and the features of the embodiments can be combined with each other in the absence of conflict. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0023] In the description of this embodiment, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the invention.

[0024] In addition, the terms "first", "second", "third", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more features. In the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0025] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present disclosure. The illustrations only show components related to the present disclosure rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0026] The embodiment of the present invention discloses a microring resonator, see Figure 1 , Figure 2 and Figure 3 As shown, the microring resonator includes a straight waveguide 1, a one-dimensional photonic crystal resonant cavity 2 and a microring resonant cavity 3, wherein the one-dimensional photonic crystal resonant cavity 2 is located between the straight waveguide 1 and the microring resonant cavity 3, wherein the one-dimensional photonic crystal resonant cavity 2 is provided with a plurality of air holes 21, wherein the microring resonant cavity 3 includes a silicon dioxide substrate 4, wherein two concentric microrings 31 are provided on the silicon dioxide substrate 4, and a microgroove 32 is formed between the two microrings 31.

[0027] In the specific implementation, the three parts of the microring resonator are mainly made of silicon on insulator. The production process of the device is compatible with the CMOS process, and 12 mask plates are required, of which the substrate is silicon dioxide. At the same time, in order to reduce the difficulty of implementing the process, the present invention directly replaces the one-dimensional photonic crystal of the one-dimensional photonic crystal resonant cavity 2 with an air hole 21 instead of filling it with other materials with different refractive indices. At the same time, by using two microrings 31 and a microgroove 32 between the two microrings 31 to form a microring resonant cavity 3 of a groove-type microring, the light coupled into the microring resonant cavity 3 can be well controlled, and the microring resonator can also be fully integrated with the surrounding medium.

[0028] In the specific implementation, the light source is used as the main signal, and light interferes between the parts to form near-field coupling. The light resonates in the microring resonator, and then light of different wavelengths is selected. According to the different wavelengths and the wavelength required for coupling, the strength of the detection field and the control field is changed to achieve the switch regulation of the electromagnetic induced transparency effect. Furthermore, when the light is transmitted in the microring resonator 3, the microgroove 32 can well limit the light, thereby improving the utilization rate of the light. At the same time, the microgroove 32 is filled with the medium to be measured. Since the refractive index of the medium to be measured is different from that of silicon, when the light is transmitted in the microgroove 32, a large number of evanescent waves will be generated, and the light will fully contact the medium to be measured, thereby improving the sensing performance of the device.

[0029] Further, see Figure 2 As shown, the straight waveguide 1 includes a silicon dioxide substrate 4, on which two core silicon layers 12 are arranged, and between which a layer of aluminum oxide 13 is arranged. Aluminum oxide 13, as an insulating material, can ensure the high mobility of graphene in the micro-ring resonant cavity 3. At the same time, graphene, silicon and aluminum oxide form a capacitor structure, which can better transmit light in the straight waveguide 1 and the one-dimensional photonic crystal resonant cavity 2, and make the light more fully coupled in the micro-ring resonant cavity 3.

[0030] Further, see Figure 3As shown, the microring 31 includes a lower silicon layer 311 and an upper silicon layer 312, a first graphene layer 313 is provided between the lower silicon layer 311 and the upper silicon layer 312, and a second graphene layer 314 is provided on the upper surface of the upper silicon layer 312. By integrating two layers of graphene (including the first graphene layer 313 and the second graphene layer 314) in the microring resonant cavity 3, the conductivity of the graphene can be changed by adjusting the Fermi level of the graphene. Generally speaking, when the graphene is a single-layer structure, it is considered that it has no dangling bonds and charge traps, and it can be regarded as a two-dimensional structure. At this time, the conductivity of the graphene can be replaced by the surface conductivity. As the Fermi level of graphene increases, its surface conductivity will increase accordingly. In this way, when light is coupled between the one-dimensional photonic crystal resonant cavity 2 and the microring resonant cavity 3, more light will be coupled into the microring resonant cavity 3, thereby changing the realization of the electromagnetically induced transparency effect, and realizing the switch regulation of the electromagnetically induced transparency effect.

[0031] Further, see Figure 3 As shown, an aluminum oxide layer 315 is disposed above and below the first graphene layer 313 .

[0032] Furthermore, in the microring resonator, the Fermi levels of the first graphene layer 313 and the second graphene layer 314 are changed by adjusting an external voltage, and the electromagnetically induced transparency effect is regulated by the changed Fermi levels.

[0033] Further, see Figure 1 As shown, the one-dimensional photonic crystal resonant cavity 2 is a ring resonant cavity, and a plurality of air holes 21 are evenly arranged circumferentially on the ring surface of the ring resonant cavity.

[0034] The straight waveguide 1, the one-dimensional photonic crystal resonant cavity 2 and the microring resonant cavity 3 in the microring resonator of the present invention can be compared with a three-level atomic structure. The coupling strength between the parts can be enhanced or weakened by changing the distance, radius and number of air holes 21 between the parts. By changing the coupling strength, the detection field and the control field strength can be adjusted, thereby realizing the switch control of the electromagnetic induced transparency effect. The three-level schematic diagram of the microring resonator is shown in FIG. Figure 4 Specifically, in the microring resonator, the coupling strength between the straight waveguide 1 and the one-dimensional photonic crystal resonant cavity 2 is changed by the distance between the straight waveguide 1 and the one-dimensional photonic crystal resonant cavity 2 and / or the number of the air holes 21. In the microring resonator, the coupling strength between the one-dimensional photonic crystal resonant cavity 2 and the microring resonant cavity 3 is changed by any one or more of the distance between the one-dimensional photonic crystal resonant cavity 2 and the microring resonant cavity 3, the diameter of the microring 31, and the width of the microgroove 32.

[0035] Electromagnetically induced transparency is a kind of nonlinear optics, which originates from a quantum destructive interference effect of multi-level excitation, and is manifested as a narrow transparent window in a wide absorption spectrum. Therefore, the electromagnetically induced transparency effect has significant dispersion characteristics, and the electromagnetically induced transparency effect has a significant effect on reducing the speed of photons, so it has broad application prospects in the field of full-light devices. Therefore, an embodiment of the present invention also provides an optical sensor, which includes the above-mentioned microring resonator, and the optical sensor can be used in the fields of optical sensing, optical switching, and slow-light devices. By applying it to the field of sensing, since the electromagnetically induced transparency has a large half-height full width value, the device has a higher sensitivity and shows a higher sensitivity to the substance to be measured, making the sensing performance of the device more superior. In addition, by designing the microring resonant cavity 3 into a groove shape, it is also beneficial to improve the sensing performance of the device.

[0036] Optical devices can be widely used in the field of sensing, which is closely related to evanescent waves. Figure 5 As shown, the evanescent wave is a part of the light that overflows without total reflection at the interface of the two materials when the light is transmitted in the medium with different refractive indexes. This part of the light will be reflected back and forth between the two media, but at the same time it will also be attenuated during the propagation process. The electromagnetic induced transparency effect is generated by coupling the light between the straight waveguide 1 and the one-dimensional photonic crystal resonant cavity and between the one-dimensional photonic crystal resonant cavity 3 and the microring resonant cavity 3. The use of optical devices to achieve the electromagnetic induced transparency effect solves the two conditions that the extremely low experimental environment temperature and the extremely high intensity light source must be met to achieve the electromagnetic induced transparency effect in the traditional atomic field. Specifically, when the microring resonant cavity 3 is in full contact with the medium to be measured, the medium to be measured will fill the microgroove 32. When the light is transmitted in the microgroove 32, due to the different refractive indices of the medium to be measured and the silicon waveguide, a large number of evanescent waves will be generated, resulting in full contact between the light and the medium to be measured, so that the output spectrum of the microring resonator changes. Since the light fully reacts with the medium to be measured, the device is very sensitive to the refractive index of the medium to be measured. The sensitivity of the device can be calculated by combining the output spectrum of the micro-ring resonator 3 and the change of the refractive index of the medium to be measured.

[0037] The microring resonator of the present invention can realize resonance between multiple energy levels through the design of straight waveguide, one-dimensional photonic crystal resonant cavity and microring resonant cavity and the change of graphene Fermi level, and at the same time, near-field coupling occurs between various electric fields to generate detection field and control field. By regulating the electromagnetic induced transparency effect and the depth of the electromagnetic induced transparency effect window, the environmental refractive index can be changed to realize the simulation of the device sensitivity, thereby realizing the evaluation of the sensing performance of the device.

[0038] By changing the structure of the microring resonator and the Fermi level of graphene, the window of electromagnetically induced transparency can be controlled, and the mutual conversion between electromagnetically induced transparency effect and Fano effect and Lorentz effect can be realized, which has broad application prospects in the field of optical switching. In addition, since the half-width of electromagnetically induced transparency effect is small and the free spectrum range is large, high sensitivity can be achieved, providing a feasible solution for the development of sensors.

[0039] Obviously, those skilled in the art should understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the embodiments of the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0040] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A microring resonator, characterized in that: The invention comprises a straight waveguide (1), a one-dimensional photonic crystal resonant cavity (2) and a microring resonant cavity (3); the one-dimensional photonic crystal resonant cavity (2) is located between the straight waveguide (1) and the microring resonant cavity (3); the one-dimensional photonic crystal resonant cavity (2) is provided with a plurality of air holes (21); the microring resonant cavity (3) comprises a silicon dioxide substrate (4); two concentric microrings (31) are provided on the silicon dioxide substrate (4); a microgroove (32) is formed between the two microrings (31).

2. The microring resonator according to claim 1, characterized in that: The straight waveguide (1) comprises a silicon dioxide substrate (4), two core silicon layers (12) are arranged on the silicon dioxide substrate (4), and a layer of aluminum oxide (13) is arranged between the two core silicon layers (12).

3. The microring resonator according to claim 1, characterized in that: The micro-ring (31) comprises a lower silicon layer (311) and an upper silicon layer (312), a first graphene layer (313) is provided between the lower silicon layer (311) and the upper silicon layer (312), and a second graphene layer (314) is provided on the upper surface of the upper silicon layer (312).

4. The microring resonator according to claim 3, characterized in that: Aluminum oxide layers (315) are provided above and below the first graphene layer (313).

5. The microring resonator according to claim 3, characterized in that: The Fermi energy levels of the first graphene layer (313) and the second graphene layer (314) are changed by adjusting an external voltage, and the electromagnetically induced transparency effect is regulated by the changed Fermi energy levels.

6. The microring resonator according to claim 1, characterized in that: The one-dimensional photonic crystal resonant cavity (2) is a ring resonant cavity, and a plurality of air holes (21) are evenly arranged circumferentially on the annular surface of the ring resonant cavity.

7. The microring resonator according to any one of claims 1 to 6, characterized in that: The coupling strength between the straight waveguide (1) and the one-dimensional photonic crystal resonant cavity (2) is changed by adjusting the distance between the straight waveguide (1) and the one-dimensional photonic crystal resonant cavity (2) and / or the number of the air holes (21).

8. The microring resonator according to any one of claims 1 to 6, characterized in that: The coupling strength between the one-dimensional photonic crystal resonant cavity (2) and the microring resonant cavity (3) is changed by any one or more of the distance between the one-dimensional photonic crystal resonant cavity (2) and the microring resonant cavity (3), the diameter of the microring (31) and the width of the microgroove (32).

9. An optical sensor, characterized in that: The invention comprises the microring resonator as claimed in any one of claims 1 to 8.

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