Micro-ring resonator and optical sensor

Abstract

The application belongs to the technical field of optical switch and optical sensor, and discloses a micro-ring resonator and an optical sensor, wherein 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; a plurality of air holes are arranged on 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-slot is formed between the two micro-rings. The micro-ring resonator and the optical sensor containing the micro-ring resonator have the characteristics of simple structure, low cost and strong anti-interference ability.

Description

Technical Field

[0001] This invention belongs to the field of optical switch and optical sensor technology, and relates to a microring resonator and optical sensor. Background Technology

[0002] Microring resonators are optical devices with strong filtering capabilities and anti-interference abilities. Their fabrication process is compatible with CMOS technology and is based on silicon-on-insulator (SiI) designs. The realization of electromagnetically induced transparency (EMI) in optics has not only reduced the stringent conditions for achieving EMI but also broadened its application range.

[0003] Currently, existing optical sensors achieve electromagnetically induced transparency by changing structural parameters, and their ability to control the sensing performance of the device is also limited. In practical use, these optical sensors face the problem of inconvenient control. Summary of the Invention

[0004] To address the technical problems of requiring structural parameter changes to achieve electromagnetically induced transparency effect switching and sensitivity control, as well as the severe electromagnetic interference affecting electronic sensors, this invention discloses a microring resonator with mature technology, simple structure, low cost, and strong anti-interference capability. The microring resonator includes a straight waveguide, a one-dimensional photonic crystal resonator, and a microring resonator. The one-dimensional photonic crystal resonator is located between the straight waveguide and the microring resonator and has multiple air holes. The microring resonator includes a silicon dioxide substrate, on which two concentric microrings are formed, with a microgroove between the two microrings.

[0005] Furthermore, the straight waveguide includes a silicon dioxide substrate, on which two core silicon layers are disposed, and an aluminum oxide layer is disposed between the two core silicon layers.

[0006] Furthermore, the microring comprises a lower silicon layer and an upper silicon layer, with a first graphene layer disposed between the lower silicon layer and the upper silicon layer, and a second graphene layer disposed on the upper surface of the upper silicon layer.

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

[0008] Furthermore, in the micro-ring resonator, the Fermi levels of the first and second graphene layers are changed by adjusting the external voltage, and the electromagnetically induced transparency effect is modulated by the changed Fermi levels.

[0009] Furthermore, the one-dimensional photonic crystal resonator is a ring resonator, and the ring resonator has a plurality of air holes uniformly arranged circumferentially on its ring surface.

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

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

[0012] This invention also provides an optical sensor, which includes the aforementioned 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, through the design of a straight waveguide, a one-dimensional photonic crystal resonator and a microring resonator, and the change of the graphene Fermi level, can realize resonance between multiple energy levels, and at the same time enable near-field coupling between various electric fields to generate a detection field and a control field. By controlling the electromagnetic induced transparency effect and the depth of the electromagnetic induced transparency effect window, the refractive index of the environment can be changed to simulate the sensitivity of the device, thereby realizing the evaluation of the sensing performance of the device. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

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

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

[0017] Figure 3 This is a schematic diagram of the microring resonator disclosed in an embodiment of the present invention;

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

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

[0020] Among them, 1. Straight waveguide; 12. Core silicon; 13. Alumina; 2. One-dimensional photonic crystal resonator; 21. Air hole; 3. Micro-ring resonator; 31. Micro-ring; 311. Lower silicon; 312. Upper silicon; 32. Microgroove; 313. First graphene layer; 314. Second graphene layer; 315. Alumina layer; 4. Silicon dioxide substrate. Detailed Implementation

[0021] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0022] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features of the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this 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", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They 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, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the invention.

[0024] Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more features. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0025] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this disclosure. The illustrations only show the components related to this disclosure and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

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

[0027] In practical implementation, the three parts of the microring resonator are primarily made of silicon-on-insulator (SiI). The device's fabrication process is compatible with CMOS technology and requires 12 photomasks, with the substrate being silicon dioxide. To reduce the complexity of the fabrication process, this invention directly replaces the one-dimensional photonic crystal of the one-dimensional photonic crystal resonator 2 with air holes 21, instead of filling it with other materials of different refractive indices. Furthermore, by using two microrings 31 and a microgroove 32 between them to form a grooved microring microring, the light coupled into the microring resonator 3 can be well controlled, and the microring resonator can be fully integrated with the surrounding medium.

[0028] In practical implementation, the light source serves as the primary signal, and interference occurs between different parts, forming near-field coupling. The light resonates within the micro-ring resonator, selecting different wavelengths. Based on these wavelengths and the wavelengths required for coupling, the strength of the detection and control fields is altered, enabling the switching and control of the electromagnetically induced transparency effect. Furthermore, when light propagates within the micro-ring resonator 3, the micro-groove 32 effectively confines the light, improving its utilization. Simultaneously, the micro-groove 32 is filled with the medium under test. Due to the difference in refractive index between the medium under test and silicon, a large number of evanescent waves are generated when light propagates within the micro-groove 32, ensuring sufficient contact between the light and the medium under test and enhancing the device's sensing performance.

[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 disposed, and an aluminum oxide layer 13 is disposed between the two core silicon layers 12. The aluminum oxide 13, as an insulating material, ensures the high mobility of graphene in the microring resonant cavity 3. Simultaneously, graphene, silicon, and aluminum oxide constitute a capacitor structure, allowing light to propagate better in the straight waveguide 1 and the one-dimensional photonic crystal resonant cavity 2, and enabling more complete coupling of light in the microring 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 disposed between the lower silicon layer 311 and the upper silicon layer 312, and a second graphene layer 314 is disposed 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 graphene can be changed by adjusting the Fermi level of graphene. Generally speaking, when graphene is a single-layer structure, it is considered to have no dangling bonds and charge traps, and can be regarded as a two-dimensional structure. In this case, the conductivity of graphene can be replaced by surface conductivity. As the Fermi level of graphene increases, its surface conductivity will increase accordingly. Thus, when light couples between the one-dimensional photonic crystal resonant cavity 2 and the microring resonant cavity 3, more light will couple into the microring resonant cavity 3, thereby changing the mechanism for achieving electromagnetically induced transparency and realizing the switching control of the electromagnetically induced transparency effect.

[0031] Furthermore, see Figure 3 As shown, aluminum oxide layers 315 are provided above and below the first graphene layer 313.

[0032] Furthermore, in the micro-ring resonator, the Fermi level of the first graphene layer 313 and the second graphene layer 314 is changed by adjusting the external voltage, and the electromagnetically induced transparency effect is modulated by the changed Fermi level.

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

[0034] In this invention, the straight waveguide 1, one-dimensional photonic crystal resonator 2, and micro-ring resonator 3 of the micro-ring resonator can be compared to a three-level atomic structure. The coupling strength between these parts can be enhanced or weakened by changing the distance, radius, and number of air holes 21. By altering the coupling strength, the strength of the detection field and control field can be adjusted, thereby enabling the switching and control of the electromagnetically induced transparency effect. A schematic diagram of the three levels of the micro-ring resonator is shown below. Figure 4 As shown. Specifically, in the microring resonator, the coupling strength between the straight waveguide 1 and the one-dimensional photonic crystal resonator 2 is changed by the distance between the straight waveguide 1 and the one-dimensional photonic crystal resonator 2 and / or the number of air holes 21. In the microring resonator, the coupling strength between the one-dimensional photonic crystal resonator 2 and the microring resonator 3 is changed by any one or more of the distance between the one-dimensional photonic crystal resonator 2 and the microring resonator 3, the diameter of the microring 31, and the width of the microgroove 32.

[0035] Electromagnetic induced transparency (EET) is a nonlinear optical phenomenon originating from a quantum destructive interference effect of multi-level excitation. It manifests as a narrow transparent window within a broad absorption spectrum, thus exhibiting significant dispersion characteristics. Furthermore, EET significantly reduces photon velocity, making it promising for applications in full-light devices. Therefore, this invention also provides an optical sensor comprising the aforementioned microring resonator. This optical sensor can be used in optical sensing, optical switching, and slow-light devices. When applied to sensing, the large full width at half maximum (FWHM) of EET results in high sensitivity, exhibiting high sensitivity to the analyte and thus superior sensing performance. Moreover, the slotted design of the microring resonator 3 further enhances the sensing performance of the device.

[0036] Optical devices, widely used in the field of sensing, are inextricably linked to evanescent waves. For example... Figure 5 As shown, evanescent waves are a portion of light that escapes without total internal reflection at the interface between media with different refractive indices when propagating through them. This portion of light reflects back and forth between the two media, but also attenuates during propagation. This invention generates an electromagnetically induced transparency effect through the coupling between the straight waveguide 1 and the one-dimensional photonic crystal resonator, and between the one-dimensional photonic crystal resonator 3 and the micro-ring resonator 3. Using optical devices to achieve the electromagnetically induced transparency effect solves the two conditions required in the traditional atomic field: extremely low experimental temperature and extremely high-intensity light source. Specifically, when the micro-ring resonator 3 is in complete contact with the test medium, the test medium fills the micro-groove 32. When light propagates in the micro-groove 32, due to the difference in refractive indices between the test medium and the silicon waveguide, a large number of evanescent waves are generated, causing sufficient contact between the light and the test medium, thus changing the output spectrum of the micro-ring resonator. Since the light reacts fully with the medium under test, the device is very sensitive to the refractive index of the medium under test. The sensitivity of the device can be calculated by combining the output spectrum of the micro-ring resonator 3 with the change in the refractive index of the medium under test.

[0037] The microring resonator of this invention, through the design of a straight waveguide, a one-dimensional photonic crystal resonator, and a microring resonator, as well as the alteration of the graphene Fermi level, can achieve resonance between multiple energy levels. At the same time, it enables near-field coupling between various electric fields to generate a detection field and a control field. By controlling the electromagnetically induced transparency effect and the depth of the electromagnetically induced transparency effect window, the refractive index of the environment can be changed to simulate the sensitivity of the device, thereby enabling the evaluation of the sensing performance of the device.

[0038] By modifying the structure of the microring resonator and altering the Fermi level of graphene, the window of the electromagnetically induced transparency effect can be controlled, enabling the interconversion between the electromagnetically induced transparency effect and the Fano and Lorentz effects. This has broad application prospects in the field of optical switches. Furthermore, due to the small full width at half maximum (FWHM) and large free spectral range of the electromagnetically induced transparency effect, higher sensitivity can be achieved, providing a feasible solution for sensor development.

[0039] Obviously, those skilled in the art should understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Various modifications and variations of the embodiments of the present invention are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0040] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A micro-ring resonator, characterized by, The micro-ring resonator comprises a straight waveguide (1), a one-dimensional photonic crystal resonant cavity (2) and a micro-ring resonant cavity (3), the one-dimensional photonic crystal resonant cavity (2) is located between the straight waveguide (1) and the micro-ring resonant cavity (3), the one-dimensional photonic crystal resonant cavity (2) is a ring resonant cavity, a plurality of air holes (21) are uniformly arranged on the ring surface of the ring resonant cavity in the circumferential direction, and the micro-ring resonant cavity (3) comprises a silicon dioxide substrate (4), two concentric micro-rings (31) are arranged on the silicon dioxide substrate (4), and a micro-slot (32) is formed between the two micro-rings (31). The micro-ring (31) comprises lower-layer silicon (311) and upper-layer silicon (312), a first graphene layer (313) is arranged between the lower-layer silicon (311) and the upper-layer silicon (312), a second graphene layer (314) is arranged on the upper surface of the upper-layer silicon (312), and alumina layers (315) are arranged above and below the first graphene layer (313). The straight waveguide (1) comprises a silicon dioxide substrate (4), two core-layer silicons (12) are arranged on the silicon dioxide substrate (4), and an alumina layer (13) is arranged between the two core-layer silicons (12). The coupling strength between the straight waveguide (1) and the one-dimensional photonic crystal resonant cavity (2) and the coupling strength between the one-dimensional photonic crystal resonant cavity (2) and the micro-ring resonant cavity (3) in the micro-ring resonator can be adjusted by adjusting an external voltage to change a Fermi energy level to control an electromagnetically induced transparency effect.

2. The micro-ring resonator according to claim 1, wherein, The Fermi energy level of the first graphene layer (313) and the second graphene layer (314) is changed by adjusting an external voltage, and the electromagnetically induced transparency effect is controlled by the changed Fermi energy level.

3. The micro-ring resonator according to claim 1 or 2, characterized in that, 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 air holes (21).

4. The micro-ring resonator according to claim 1 or 2, characterized in that, The coupling strength between the one-dimensional photonic crystal resonant cavity (2) and the micro-ring resonant cavity (3) is changed by any one or more of the distance between the one-dimensional photonic crystal resonant cavity (2) and the micro-ring resonant cavity (3), the diameter of the micro-ring (31) and the width of the micro-slot (32).

5. An optical sensor, characterized by The micro-ring resonator comprises a straight waveguide (1), a one-dimensional photonic crystal resonant cavity (2) and a micro-ring resonant cavity (3), the one-dimensional photonic crystal resonant cavity (2) is located between the straight waveguide (1) and the micro-ring resonant cavity (3), the one-dimensional photonic crystal resonant cavity (2) is a ring resonant cavity, a plurality of air holes (21) are uniformly arranged on the ring surface of the ring resonant cavity in the circumferential direction, and the micro-ring resonant cavity (3) comprises a silicon dioxide substrate (4), two concentric micro-rings (31) are arranged on the silicon dioxide substrate (4), and a micro-slot (32) is formed between the two micro-rings (31). The micro-ring (31) comprises lower-layer silicon (311) and upper-layer silicon (312), a first graphene layer (313) is arranged between the lower-layer silicon (311) and the upper-layer silicon (312), a second graphene layer (314) is arranged on the upper surface of the upper-layer silicon (312), and alumina layers (315) are arranged above and below the first graphene layer (313). The straight waveguide (1) comprises a silicon dioxide substrate (4), two core-layer silicons (12) are arranged on the silicon dioxide substrate (4), and an alumina layer (13) is arranged between the two core-layer silicons (12). The coupling strength between the straight waveguide (1) and the one-dimensional photonic crystal resonant cavity (2) and the coupling strength between the one-dimensional photonic crystal resonant cavity (2) and the micro-ring resonant cavity (3) in the micro-ring resonator can be adjusted by adjusting an external voltage to change a Fermi energy level to control an electromagnetically induced transparency effect. The Fermi energy level of the first graphene layer (313) and the second graphene layer (314) is changed by adjusting an external voltage, and the electromagnetically induced transparency effect is controlled by the changed Fermi energy level. 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 air holes (21). The coupling strength between the one-dimensional photonic crystal resonant cavity (2) and the micro-ring resonant cavity (3) is changed by any one or more of the distance between the one-dimensional photonic crystal resonant cavity (2) and the micro-ring resonant cavity (3), the diameter of the micro-ring (31) and the width of the micro-slot (32). The micro-ring resonator comprises a straight waveguide (1), a one-dimensional photonic crystal resonant cavity (2) and a micro-ring resonant cavity (3), the one-dimensional photonic crystal resonant cavity (2) is located between the straight waveguide (1) and the micro-ring resonant cavity (3), the one-dimensional photonic crystal resonant cavity (2) is a ring resonant cavity, a plurality of air holes (21) are uniformly arranged on the ring surface of the ring resonant cavity in the circumferential direction, and the micro-ring resonant cavity (3) comprises a silicon dioxide substrate (4), two concentric micro-rings (31) are arranged on the silicon dioxide substrate (4), and a micro-slot (32) is formed between the two micro-rings (31).

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