Chalcogenide micro-ring resonator cavity structure based on fano resonance

Abstract

The application discloses a chalcogenide micro-ring resonator structure based on Fano resonance, which comprises a substrate layer and a chalcogenide material waveguide layer arranged on the substrate layer, wherein the chalcogenide material waveguide layer comprises a strip waveguide and a ring waveguide, the strip waveguide is tangent to the ring waveguide and is arranged at intervals, and the shortest distance between the strip waveguide and the ring waveguide is a first gap; the strip waveguide is symmetrically provided with a first grating and a second grating on two sides relative to the ring waveguide, thereby forming an FP cavity between the first grating and the second grating, so that discrete light in the strip waveguide and continuous light in the ring waveguide are superposed to generate Fano resonance. The discrete resonance mode of the FP cavity formed between the two gratings of the straight strip waveguide and the continuous transmission mode of the micro-ring are superimposed and interfered with each other to generate Fano resonance, so that the key performance indicators of the optical sensor are better than those of a traditional micro-ring resonator, and the optical performance such as loss, quality factor, sensitivity, extinction ratio and the like is reduced.

Description

Technical Field

[0001] This invention belongs to the field of optical devices, and particularly relates to a chalcogenide microring resonator structure based on Fano resonance. Background Technology

[0002] Traditional chalcogenide microring resonators are special inorganic amorphous materials formed by combining chalcogen elements (S, Se, Te) with other low electronegativity elements. Compared with conventional optical media, chalcogenide glasses have a broad spectrum of light transmission covering the entire visible to mid-infrared band, flexible and adjustable refractive index parameters, and possess both ultra-high third-order nonlinearity and negligible two-photon absorption effects.

[0003] Existing chalcogenide microring resonator structures include racetrack-shaped and ridge-shaped waveguide structures. The racetrack-shaped structure, composed of a combination of arc-shaped and straight waveguides, allows for efficient optical coupling by adjusting the coupling spacing and waveguide dimensions. The ridge-shaped waveguide structure is formed through reactive ion etching, combined with thermosetting polymer cladding annealing, which reduces surface roughness from 0.62 nm to 0.24 nm, significantly reducing transmission loss. The high thermo-optic coefficients of chalcogenide materials make them extremely sensitive to temperature changes. In integrated photonic devices, due to their compact internal layout, spatiotemporal variations in local temperature significantly alter their refractive index. For example, temperature fluctuations in high-Q (Quality Factor) microring resonators can lead to large wavelength shifts, even rendering the photonic device malfunction.

[0004] It is evident that traditional chalcogenide microcavities suffer from high losses, low quality factors, and poor optical performance, failing to meet the application requirements of large-scale photonic integrated devices. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of traditional chalcogenide microcavities in the prior art, such as high loss, low quality factor and poor optical performance, and to provide a chalcogenide microring resonant cavity structure based on Fano resonance.

[0006] The present invention solves the above-mentioned technical problems through the following technical solution:

[0007] In a first aspect, a chalcogenide microring resonant cavity structure based on Fano resonance is provided, comprising:

[0008] Substrate layer;

[0009] A chalcogenide waveguide layer is disposed on the substrate layer. The chalcogenide waveguide layer includes a strip waveguide and an annular waveguide. The strip waveguide and the annular waveguide are tangent to each other and spaced apart. The shortest distance between the strip waveguide and the annular waveguide is a first gap.

[0010] The strip waveguide is symmetrically provided with a first grating and a second grating on both sides of the ring waveguide, thereby forming an FP cavity between the first grating and the second grating, so that the discrete light in the strip waveguide is superimposed with the continuous light in the ring waveguide to generate Fano resonance.

[0011] Optionally, the period of both the first grating and the second grating is 385nm-395nm, the duty cycle of both the first grating and the second grating is 30%-50%, and the number of gratings of the first grating and the second grating is 195-205.

[0012] Optionally, the straight waveguide region between the first and second gratings of the strip waveguide constitutes the cavity length of the FP cavity, and the cavity length of the FP cavity is 4.9. m-5.1 m.

[0013] Optionally, the first gap is 195nm-210nm.

[0014] Optionally, the outer diameter of the annular waveguide is 18 mm. m-24 m.

[0015] Optionally, one side of the strip waveguide is the incident light side, and the incident light satisfies the TE0 fundamental mode condition.

[0016] Optionally, the incident light is 1500nm-1600nm. After the discrete light in the strip waveguide is coupled with the continuous light in the ring waveguide, they interfere and cancel each other out to form a symmetrical Lorentz curve.

[0017] Optionally, the substrate layer is SiO2, and the thickness of the substrate layer is 2. m-4 m.

[0018] Optionally, the chalcogenide waveguide layer is Ge 28 Sb 12 Se 60 The thin film material has a height of 290nm-310nm and a width of 590nm-610nm.

[0019] Optionally, when the resonant wavelength is 1550nm, the waveguide height of the strip waveguide is 300nm, the waveguide width is less than 740nm, and the strip waveguide is in single-mode operation; the single-mode operation is used to characterize the operating state that supports the transmission of incident light of a set frequency in the optical fiber.

[0020] The significant advantages of this invention are as follows: It provides a chalcogenide microring resonator structure based on Fano resonance. A chalcogenide waveguide layer is disposed on a substrate, comprising a strip waveguide and a ring waveguide. The strip waveguide and the ring waveguide are tangential and spaced apart, with the shortest distance between them forming a first gap. A first grating and a second grating are symmetrically arranged on both sides of the strip waveguide relative to the ring waveguide, forming a Fano cavity between them. This allows the discrete light in the strip waveguide to superimpose with the continuous light in the ring waveguide to generate Fano resonance. This invention generates Fano resonance through the superposition and interference of the discrete resonance mode of the Fano cavity formed between the two gratings of the strip waveguide and the continuous transmission mode of the microring. This results in key performance indicators of the optical sensor being superior to those of traditional microring resonators, reducing losses and improving optical performance such as quality factor, sensitivity, and extinction ratio. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the chalcogenide microring resonator based on Fano resonance in Embodiment 1 of the present invention.

[0022] Figure 2 This is a schematic diagram of the MRR transmission spectrum of the chalcogenide microring resonator structure based on Fano resonance in Embodiment 1 of the present invention.

[0023] Figure 3 This is a schematic diagram of the transmission spectrum of the FP cavity based on the Fano resonance microring resonator structure of Embodiment 1 of the present invention.

[0024] Figure 4 This is a schematic diagram of the transmission spectrum obtained by combining the MRR and FP cavities of the chalcogenide microring resonator structure based on Fano resonance in Embodiment 1 of the present invention.

[0025] Figure 5 This is a schematic diagram of the electric field distribution of the FP cavity coupled microring in the chalcogenide microring resonant cavity structure based on Fano resonance in Embodiment 1 of the present invention.

[0026] Figure 6 This is a schematic diagram of the slope distribution of the FP cavity coupled microring in the chalcogenide microring resonant cavity structure based on Fano resonance in Embodiment 1 of the present invention.

[0027] Figure 7 This is a schematic diagram of the sensitivity distribution of the FP cavity coupled microring in the chalcogenide microring resonator structure based on Fano resonance in Embodiment 1 of the present invention. Detailed Implementation

[0028] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0029] Example 1

[0030] This embodiment provides a chalcogenide microring resonant cavity structure based on Fano resonance, such as... Figure 1 As shown, the chalcogenide microring resonator structure includes:

[0031] Substrate layer;

[0032] A chalcogenide waveguide layer is disposed on a substrate layer. The chalcogenide waveguide layer includes a strip waveguide 10 and an annular waveguide 20. The strip waveguide 10 and the annular waveguide 20 are tangent to each other and spaced apart. The shortest distance between the strip waveguide 10 and the annular waveguide 20 is a first gap 13.

[0033] A first grating 11 and a second grating 12 are symmetrically arranged on both sides of the strip waveguide 10 relative to the ring waveguide 20, thereby forming an FP cavity 14 between the first grating 11 and the second grating 12, so that the discrete light in the strip waveguide 10 and the continuous light in the ring waveguide 20 are superimposed to generate Fano resonance.

[0034] In this design, the strip waveguide 10 is linear. A first grating 11 is placed on the left side of the strip waveguide 10, and an identical second grating 12 is symmetrically placed on the right side of the strip waveguide 10. The annular waveguide 20 is circular. The strip waveguide 10 and the annular waveguide 20 are located in the same plane. The gratings in the strip waveguide 10 form an FP cavity, achieving an optimized design for the traditional chalcogenide waveguide. The two gratings diffract the transmitted light, and part of the transmitted light is reflected back into the strip waveguide 10. The two gratings act like mirrors in a traditional FP cavity, and the straight waveguide region between the first grating 11 and the second grating 12 constitutes the cavity length of the FP cavity.

[0035] Specifically, according to the principle of interference, the optical path difference of the propagating light traveling one round trip within the FP cavity satisfies the following calculation formula. L represents the effective refractive index of light propagating in the strip waveguide 10, and L represents the cavity length.

[0036]

[0037] When the incident light enters from the strip waveguide 10 ( Figure 1 (Input arrow indicator shown) Part of the incident light enters the microring through coupling, and the light propagates along the annular path within the microring. This occurs when the circumference of the microring satisfies C=2. (R represents the radius of the micro-ring), meaning that when the resonance condition is met, the incident light will form a stable resonance within the micro-ring, and the resonant light can be coupled back to the strip waveguide 10 for output via an evanescent wave. Figure 1 (Indicates Through arrow). The phase relationship between the discrete resonant mode of the FP cavity and the continuous transmission mode of the microring results in an asymmetric linearity after superposition. When the phases of the two modes are close, constructive interference occurs, and the transmittance increases; when the phases of the two modes differ significantly, destructive interference occurs, the transmittance decreases, and an asymmetric Fano resonance peak is generated.

[0038] In one embodiment, the periods of both the first grating 11 and the second grating 12 are 385nm-395nm, the duty cycles of both are 30%-50%, and the number of gratings in both gratings is 195-205. The straight waveguide region between the first grating 11 and the second grating 12 of the strip waveguide 10 constitutes the cavity length of the FP cavity 14, which is 4.9 nm. m-5.1 m.

[0039] In this scheme, the grating period, grating duty cycle, number of gratings, and cavity length of the FP cavity are adjusted using a parameter scanning method to obtain the optimal structural parameters of the chalcogenide microring resonator. When the two symmetrical gratings have a period of approximately 390 nm, a grating duty cycle of approximately 40%, a number of gratings of approximately 200, and a first gap of approximately 200 nm, the wavelength of the incident light is around 1550 nm and the slope of the Fano line reaches its maximum. The aforementioned design parameters improve the extinction ratio and sensitivity of the optical sensor.

[0040] In one embodiment, the first gap 13 is 195nm-210nm.

[0041] In this scheme, the first coupling gap between each strip waveguide 10 and the ring waveguide 20 is set at about 200nm, which ensures a high quality factor, Q value and extinction ratio, and improves the reliability of the measurement results.

[0042] In one embodiment, the outer diameter of the annular waveguide 20 is 18 mm. m-24 m.

[0043] In this design, the outer part of the ring waveguide 20 is set at 20. To improve the extinction ratio and sensitivity of the optical sensor, the measurement should be around m.

[0044] In one embodiment, one side of the strip waveguide 10 is the incident light side, and the incident light satisfies the TE0 fundamental mode condition.

[0045] In this scheme, the incident light is input into a strip waveguide from one end face, and the polarization characteristics, angle characteristics, and spot shape characteristics of the incident light are carefully adjusted so that it can completely excite the most basic and stable transverse electric mode in the strip waveguide 10, namely the TE0 fundamental mode, which can avoid exciting unwanted higher-order modes and ensure efficient and low-loss single-mode transmission of optical signals.

[0046] In one embodiment, the incident light is 1500nm-1600nm. After the discrete light in the strip waveguide 10 couples with the continuous light in the ring waveguide layer, interference cancellation occurs to form an asymmetric Fano resonance peak.

[0047] In this plan, such as Figure 2 As shown, the horizontal axis represents the wavelength of the incident light, and the vertical axis represents the transmittance of the chalcogenide microring resonator structure based on Fano resonance. When the incident light is 1500nm-1600nm, the radius is 20. When the annular waveguide and the strip waveguide are coupled, the incident light undergoes destructive interference at a specific wavelength, forming an asymmetric Fano resonance peak at the resonant wavelength.

[0048] In one embodiment, the substrate is SiO2, and the thickness of the substrate is 2. m-4 m.

[0049] In this scheme, a complete optical sensor structure is formed by setting a SiO2 substrate layer below the chalcogenide waveguide layer, which ensures the reliability and effectiveness of the chalcogenide microring resonator structure based on Fano resonance.

[0050] In one embodiment, the chalcogenide waveguide layer is Ge. 28 Sb 12 Se 60 The height of the chalcogenide waveguide layer is 290nm-310nm and the width is 590nm-610nm.

[0051] In this scheme, the chalcogenide material is chalcogenide glass. Compared with traditional semiconductor materials (such as silicon and germanium), chalcogenide glass has a wider band gap, thus exhibiting a lower two-photon absorption effect, ensuring the reliability of the optical sensor and improving its optical performance.

[0052] In one embodiment, when the resonant wavelength is 1550nm, the waveguide height of the strip waveguide is 300nm, the waveguide width is less than 740nm, and the strip waveguide is in single-mode operation; the single-mode operation is used to characterize the operating state that supports the transmission of incident light of a set frequency in the optical fiber.

[0053] In this scheme, for the strip waveguide 10, the waveguide height and waveguide width jointly determine the number of modes. When the waveguide height is greater than 300nm, higher-order modes will appear when the waveguide width is greater than 740nm. In order to meet the theoretical critical value of TE0 fundamental mode single-mode transmission, the waveguide width is set to less than 740nm and the waveguide height is set to 300nm, which significantly reduces the multimode risk caused by the fluctuation of optical sensor process.

[0054] like Figure 3 As shown, the horizontal axis represents the wavelength of the incident light, and the vertical axis represents the transmittance of the chalcogenide microring resonator structure based on Fano resonance. When the incident light is in the 1500nm-1600nm wavelength range, the two gratings have a period of 385nm, and the duty cycle of the two gratings is 30%-50%, the two gratings and the linear waveguide resonate to form a "w"-shaped transmission spectrum with a bandwidth of 19nm and an extinction ratio of 52dB.

[0055] like Figure 4 As shown, the horizontal axis represents the wavelength of the incident light, and the vertical axis represents the transmittance of the chalcogenide microring resonator structure based on Fano resonance. When the incident light is in the 1500nm-1600nm wavelength range, the transmission spectrum obtained by coupling the microring with the Fano cavity is shown in the figure. Figure 4 In this process, the original continuous state of the micro-ring is broken, and the incident light undergoes coherent superposition at the resonant wavelength of 1552nm-1560nm to produce Fano resonance, which meets the design requirements of optical sensors.

[0056] like Figure 5 As shown, the horizontal axis represents the X direction and the vertical axis represents the Y direction. This is a schematic diagram of the electric field distribution generated by the simulation design after the FP cavity and the micro-ring resonator are coupled when the incident light is 1559nm. The incident light is coupled from the FP cavity into the micro-ring resonator.

[0057] like Figure 6 As shown, the horizontal axis represents the wavelength of the incident light, and the vertical axis represents the transmittance of the chalcogenide microring resonator structure based on Fano resonance. Figure 7 As shown, the horizontal axis represents the refractive index of the environment, and the vertical axis represents the transmittance.

[0058] Figure 6 , Figure 7 Analysis shows that when the ambient refractive index changes from 1 RIU to 1.0008 RIU and the incident light wavelength is 1559.18 nm, the extinction ratio changes from -4.3 dB to -32.7 dB. The intensity detection sensitivity is calculated to be 3.32 × 10⁻⁶ based on fitting. 4 dB / RIU corresponds to a Fano line slope of 256.7 dB / nm.

[0059] The extinction ratio is 28.4 dB. Therefore, as the refractive index of the environment increases, the slope of the FP cavity coupled microring increases, the sensitivity increases, the extinction ratio increases, and the sensitivity of the FP cavity coupled microring increases. It is evident that the optical sensor based on Fano resonance significantly outperforms traditional microring resonators in key performance indicators such as sensitivity, Q value (quality factor), and extinction ratio.

[0060] In this embodiment, the discrete resonant mode of the FP cavity formed between the two gratings of the straight waveguide is superimposed and interfered with the continuous transmission mode of the microring to generate Fano resonance. This makes the key performance indicators of the optical sensor superior to those of the traditional microring resonator, reducing losses and improving optical performance such as quality factor, sensitivity, and extinction ratio.

[0061] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A chalcogenide microring resonant cavity structure based on Fano resonance, characterized in that, include: Substrate layer; A chalcogenide waveguide layer is disposed on the substrate layer. The chalcogenide waveguide layer includes a strip waveguide and an annular waveguide. The strip waveguide and the annular waveguide are tangent to each other and spaced apart. The shortest distance between the strip waveguide and the annular waveguide is a first gap. The strip waveguide is symmetrically provided with a first grating and a second grating on both sides of the ring waveguide, thereby forming an FP cavity between the first grating and the second grating, so that the discrete light in the strip waveguide is superimposed with the continuous light in the ring waveguide to generate Fano resonance. The periods of the first grating and the second grating are both 385nm-395nm, the duty cycles of the first grating and the second grating are both 30%-50%, and the number of gratings of the first grating and the second grating is 195-205. The straight waveguide region between the first and second gratings of the strip waveguide constitutes the cavity length of the FP cavity, which is 4.9 μm-5.1 μm. The first gap is 195nm-210nm; The outer diameter of the annular waveguide is 18μm-24μm; The substrate layer is SiO2, and the thickness of the substrate layer is 2μm-4μm; The chalcogenide waveguide layer is Ge. 28 Sb 12 Se 60 The thin film material has a height of 290nm-310nm and a width of 590nm-610nm.

2. The chalcogenide microring resonant cavity structure based on Fano resonance as described in claim 1, characterized in that, One side of the strip waveguide is the incident light side, and the incident light satisfies the TE0 fundamental mode condition.

3. The chalcogenide microring resonant cavity structure based on Fano resonance as described in claim 1, characterized in that, The incident light is 1500nm-1600nm. After the discrete light in the strip waveguide is coupled with the continuous light in the ring waveguide, they interfere and cancel each other out to form an asymmetric Fano resonance peak.

4. The chalcogenide microring resonant cavity structure based on Fano resonance as described in claim 1, characterized in that, When the resonant wavelength is 1550nm, the waveguide height of the strip waveguide is 300nm, the waveguide width is less than 740nm, and the strip waveguide is in single-mode operation; the single-mode operation is used to characterize the operating state that supports the transmission of incident light of a set frequency in the optical fiber.

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