Device and method for extracting physical parameters of optical waveguide

Abstract

The present application provides an extraction device and an extraction method for physical parameters of an optical waveguide. The device includes a laser module, a coupling input / output module, a photonic crystal microring resonator, and a response spectrum detection module. The photonic crystal microring resonator is located in the adjacent area of the target optical waveguide. It includes a closed ring, the average width of which is equal to the width of the target optical waveguide but is periodically modulated along the circumferential direction, and the average radius is greater than a preset value. The method includes: providing the device; continuously scanning the wavelength of the laser module and measuring the response spectrum line of a single photonic crystal microring resonator; obtaining the actual effective refractive index and the actual group refractive index of the target optical waveguide according to the response spectrum line of the single photonic crystal microring resonator; pre-simulating the mapping relationship between the width and thickness of the optical waveguide and the effective refractive index and the group refractive index; and determining the actual width and actual thickness of the target optical waveguide based on the actual effective refractive index and the actual group refractive index through the mapping relationship.

Description

Technical Field

[0001] The present application relates to the field of optoelectronic information technology, and particularly to an apparatus and method for extracting physical parameters of an optical waveguide. Background Art

[0002] Silicon-based optoelectronic technology is a technology that combines photonics and microelectronics, integrating photonic devices and electronic devices on a silicon-based platform. Due to its potential advantages in the fields of optical communication, optical sensing, optical interconnection, optical computing, etc., it has received increasing attention from the industry and researchers in recent years. Silicon-based optoelectronic devices are structurally compact and easy to integrate; however, due to the large difference in refractive index between the waveguide and the cladding material, the performance of waveguide devices, especially interference devices, is very sensitive to the physical parameters of the optical waveguide (effective refractive index, group refractive index, width, thickness, tilt angle). Deviations in wafer thickness in different regions and process errors during the manufacturing process will result in a huge deviation between the actually fabricated device and the designed situation, and even cause problems that make the device unusable.

[0003] Regarding the problem of manufacturing deviations, on the one hand, process tolerances are considered in the design stage to improve the robustness of the device; on the other hand, the constant deviation during the manufacturing process is compensated by increasing or decreasing the design size. Therefore, it is necessary to accurately extract the physical parameters of the fabricated device to provide a reference basis for design iteration.

[0004] In the prior art, generally, there are lossy direct observation or non-destructive optical characterization methods. Direct observation is carried out in the form of a scanning electron microscope or a transmission electron microscope. The observation means is not only cumbersome, but also requires slicing the fabricated device, and often depends on the experience level of the operator, with high time cost and economic cost. The non-destructive optical characterization method requires using a two-stage MZI (Mach-Zehnder Interferometer) or two microring resonators with similar sizes, and fitting the measured response spectra to obtain the results. The measurement time cost is also very large, and it is impossible to measure devices with large deviations. Summary of the Invention

[0005] The purpose of the present application is to provide an apparatus and method for extracting physical parameters of an optical waveguide, which can at least partially solve the above technical problems existing in the prior art.

[0006] One aspect of the present application provides an extraction device for physical parameters of an optical waveguide, which is used to extract the physical parameters of a target optical waveguide in a wafer. The extraction device includes a laser module, a coupling input module, a coupling output module, a connecting optical waveguide, a single photonic crystal microring resonator, and a response spectrum detection module. The laser module is connected to the coupling input module, the response spectrum detection module is connected to the coupling output module, the coupling input module and the coupling output module are connected by the connecting optical waveguide, and the photonic crystal microring resonator is used to couple with the connecting optical waveguide. Among them, the photonic crystal microring resonator is located in the adjacent area of the target optical waveguide. The photonic crystal microring resonator includes a closed ring, the average width of the ring is equal to the width of the target optical waveguide but is periodically modulated along the circumferential direction, and the average radius of the ring is greater than a preset value; the laser module is used to provide a light source for the extraction device, the wavelength of the laser module is continuously adjustable, and the wavelength range of the laser module covers the wavelength range concerned by the target optical waveguide and the characteristic wavelength of the photonic crystal microring resonator.

[0007] Further, the connecting optical waveguide includes a single-mode optical waveguide, the photonic crystal microring resonator is located on one side of the connecting path of the single-mode optical waveguide, and the outer side of the photonic crystal microring resonator is spaced from the outer side of the single-mode optical waveguide by a predetermined distance.

[0008] Further, the inner side or the outer side of the ring of the photonic crystal microring resonator has a periodic modulation, and the number of modulation periods of the photonic crystal microring resonator is equal to twice the number of modes at the position where the characteristic wavelength of the photonic crystal microring resonator is located.

[0009] Further, the coupling input module and the coupling output module are grating couplers or free-form surface couplers. For non-wafer-level testing, an end-face coupler can also be used.

[0010] Further, the photonic crystal microring resonator and the target optical waveguide are located on the same chip unit of the same wafer.

[0011] Another aspect of the present application provides a method for extracting physical parameters of an optical waveguide. The method includes: providing the device for extracting physical parameters of the optical waveguide as described above; continuously scanning the wavelength of the laser module, and measuring the response spectrum line of a single photonic crystal microring resonator through the response spectrum detection module in the extraction device; obtaining the actual effective refractive index and actual group refractive index of the target optical waveguide according to the response spectrum line of the single photonic crystal microring resonator; pre-simulating the mapping relationship between the width and thickness of the optical waveguide and the effective refractive index and group refractive index; and determining the actual width and actual thickness of the target optical waveguide based on the obtained actual effective refractive index and actual group refractive index of the target optical waveguide through the mapping relationship.

[0012] Further, the obtaining the actual effective refractive index and actual group refractive index of the target optical waveguide according to the response spectrum line of the single photonic crystal microring resonator includes: obtaining the effective refractive index and group refractive index of the single photonic crystal microring resonator according to the response spectrum line of the single photonic crystal microring resonator, wherein the actual effective refractive index and actual group refractive index of the target optical waveguide are equal to the effective refractive index and group refractive index of the photonic crystal microring resonator.

[0013] Further, the obtaining the effective refractive index and group refractive index of the single photonic crystal microring resonator according to the response spectrum line of the single photonic crystal microring resonator includes: finding a characteristic spectrum line from the response spectrum line of the single photonic crystal microring resonator; determining a characteristic wavelength according to the position of the characteristic spectrum line in the response spectrum line of the photonic crystal microring resonator; obtaining the effective refractive index of the photonic crystal microring resonator according to the characteristic wavelength and the mode number at the position where the characteristic wavelength is located, wherein the mode number at the position where the characteristic wavelength is located is equal to half of the modulation period number of the photonic crystal microring resonator; and obtaining the group refractive index of the photonic crystal microring resonator according to the characteristic wavelength and two resonance wavelengths adjacent to the characteristic wavelength.

[0014] Further, the effective refractive index of the photonic crystal microring resonator at the characteristic wavelength is obtained according to the characteristic wavelength and the mode number at the position where the characteristic wavelength is located through the following expression:

[0015]

[0016]

[0017] Wherein, is the effective refractive index of the photonic crystal microring resonator, is the characteristic wavelength of the photonic crystal microring resonator, is the mode number at the position where the characteristic wavelength is located, is the modulation period number of the photonic crystal microring resonator, is the average radius of the ring of the photonic crystal microring resonator.

[0018] Further, the group refractive index of the photonic crystal microring resonator at the characteristic wavelength is obtained according to the characteristic wavelength and two resonance wavelengths adjacent to the characteristic wavelength through the following expression:

[0019]

[0020] wherein, is the group refractive index of the photonic crystal microring resonator, is the characteristic wavelength of the photonic crystal microring resonator, and are respectively two resonance wavelengths adjacent to the characteristic wavelength, is the average radius of the ring of the photonic crystal microring resonator.

[0021] Further, obtaining the effective refractive index and group refractive index of a single photonic crystal microring resonator according to the response spectrum of a single photonic crystal microring resonator includes: finding a characteristic spectrum line from the response spectrum of a single photonic crystal microring resonator; in the response spectrum of the photonic crystal microring resonator, determining the characteristic wavelength according to the position where the characteristic spectrum line is located; according to the mode number at the position where the characteristic wavelength is located, the mode numbers at the positions of other resonance wavelengths in the response spectrum can be determined; obtaining the effective refractive index of the photonic crystal microring resonator at other resonance wavelengths according to the other resonance wavelengths and the mode numbers at the positions of the other resonance wavelengths; obtaining the group refractive index of the photonic crystal microring resonator at other resonance wavelengths according to the other resonance wavelengths and two resonance wavelengths adjacent to the other resonance wavelengths.

[0022] Further, the method further includes: forming the photonic crystal microring resonator and the target optical waveguide on the same chip unit of the same wafer.

[0023] Further, the pre-simulation to obtain the mapping relationship between the width and thickness of the optical waveguide and the effective refractive index and group refractive index includes: according to the process error range in the wafer manufacturing process, simulating the effective refractive index and group refractive index at different widths and different thicknesses of the optical waveguide by three-dimensional finite element method to establish the mapping relationship between the width and thickness of the optical waveguide and the effective refractive index and group refractive index.

[0024] The method and device for extracting physical parameters of an optical waveguide according to one or more embodiments of the present application solve the problems of high cost, low efficiency, and small monitoring range in extracting the physical parameters of a waveguide structure after manufacturing in the prior art.

[0025] The method and device for extracting physical parameters of an optical waveguide according to one or more embodiments of the present application only need to test the response spectrum of a single photonic crystal microring resonator. The effective refractive index and group refractive index can be directly determined through the characteristic spectrum in the response spectrum of the single photonic crystal microring resonator. It can achieve the characteristics of single direct measurement and accuracy, and can quickly, efficiently, non-destructively, and at low cost extract the physical parameters of optical waveguides in different regions of a wafer.

[0026] The method and device for extracting physical parameters of an optical waveguide according to one or more embodiments of the present application can quickly and accurately extract the physical parameters of the optical waveguide without damaging the chip and waveguide structure of the wafer, simplify the test process of wafer characterization, and provide strong support for the manufacturing and design of silicon-based optoelectronic chips. Description of the Drawings

[0027] Figure 1 It is a schematic diagram of a device for extracting physical parameters of an optical waveguide according to an embodiment of the present application.

[0028] Figure 2 It is a schematic diagram of a photonic crystal microring resonator according to an embodiment of the present application.

[0029] Figure 3 It is a schematic diagram of a photonic crystal microring resonator according to another embodiment of the present application.

[0030] Figure 4 It is a schematic diagram of a photonic crystal microring resonator according to still another embodiment of the present application.

[0031] Figure 5 It is a schematic diagram of a photonic crystal microring resonator according to yet another embodiment of the present application.

[0032] Figure 6 It is the response spectrum obtained when testing a single photonic crystal microring resonator according to an embodiment of the present application.

[0033] Figure 7 It is a flowchart of a method for extracting physical parameters of an optical waveguide according to an embodiment of the present application.

[0034] Figure 8 It is a schematic cross-sectional structure diagram of an optical waveguide according to an embodiment of the present application.

[0035] Figure 9 It is a mapping relationship diagram of the width, thickness, effective refractive index, and group refractive index of an optical waveguide according to an embodiment of the present application. Detailed implementation manners

[0036] Here, exemplary embodiments will be described in detail, and examples thereof are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices consistent with some aspects of the present application as detailed in the appended claims.

[0037] Next, with reference to the drawings, an apparatus and method for extracting physical parameters of an optical waveguide according to each embodiment of the present application will be described in detail. Without conflict, the features in the following embodiments and implementation manners can be combined with each other.

[0038] The present application provides an apparatus 100 for extracting physical parameters of an optical waveguide. Figure 1 A schematic diagram of an apparatus 100 for extracting physical parameters of an optical waveguide according to an embodiment of the present application is disclosed. As Figure 1 shown, an apparatus 100 for extracting physical parameters of an optical waveguide according to an embodiment of the present application can be used to extract physical parameters of a target optical waveguide in a wafer. The extraction apparatus 100 includes a laser module 110, a coupling input module 120, a coupling output module 130, a single photonic crystal microring resonator 140, and a response spectrum detection module 150.

[0039] Among them, the laser module 110 can be connected to the coupling input module 120 through an optical fiber; the response spectrum detection module 150 is connected to the coupling output module 130; the coupling input module 120 and the coupling output module 130 are connected through a connecting optical waveguide 160, and the photonic crystal microring resonator 140 is used to be coupled with the connecting optical waveguide 160.

[0040] The laser module 110 is used to provide a light source for the entire apparatus 100 for extracting physical parameters of an optical waveguide. The laser module 110 is a tunable laser, its wavelength is continuously tunable, and the wavelength range of the laser module 110 covers the wavelength range concerned by the target optical waveguide.

[0041] The photonic crystal microring resonator 140 is located in the adjacent area of the target optical waveguide. Optionally, the photonic crystal microring resonator 140 and the target optical waveguide are on the same chip unit of the same wafer. That is, the photonic crystal microring resonator 140 and the target optical waveguide can be fabricated on the same chip unit of the same wafer.

[0042] The photonic crystal microring resonator 140 includes a closed ring, the average width of the ring is equal to the width w of the target optical waveguide but the width is periodically modulated along the circumferential direction, and the average radius of the ring is greater than a preset value.

[0043] The bending radius of the ring of the photonic crystal microring resonator 140 is greater than a preset value. For example, for the photonic crystal microring resonator 140 made of a silicon nitride waveguide with a thickness of 400 nm and a width of 800 nm, when the bending radius of the ring of the photonic crystal microring resonator 140 is greater than about 40 microns, the effective refractive index of the bent waveguide is approximately equal to the effective refractive index of the straight waveguide. And, by setting the average width of the ring of the photonic crystal microring resonator 140 to the width w of the target optical waveguide, the effective refractive index of the photonic crystal microring resonator 140 is made equal to the effective refractive index of the target optical waveguide. Furthermore, the present application can obtain the effective refractive index of the target optical waveguide by measuring the effective refractive index of the photonic crystal microring resonator 140.

[0044] The photonic crystal microring resonator 140 is the main structure of the extraction device 100 for the physical parameters of the optical waveguide. In the circumferential direction of the ring of the photonic crystal microring resonator 140, there is a periodic modulation on the inner or outer side of the ring, and the number of modulation periods of the photonic crystal microring resonator 140 is equal to twice the number of modes at the position of the characteristic wavelength of the photonic crystal microring resonator 140.

[0045] Figure 2 Disclosed is a schematic diagram of the photonic crystal microring resonator 140 according to an embodiment of the present application. As Figure 2 shown, the modulation of the photonic crystal microring resonator 140 is a zigzag periodic modulation, and the modulation is applied to the outer side of the ring.

[0046] Figure 3 Disclosed is a schematic diagram of the photonic crystal microring resonator 140 according to another embodiment of the present application. As Figure 3 shown, the modulation of the photonic crystal microring resonator 140 is also a zigzag periodic modulation, but the difference from Figure 2 that shown is that the modulation is applied to the inner side of the ring.

[0047] Figure 4 Disclosed is a schematic diagram of the photonic crystal microring resonator 140 according to still another embodiment of the present application. As Figure 4 shown, the modulation of the photonic crystal microring resonator 140 is a sinusoidal periodic modulation, and the modulation is applied to the outer side of the ring.

[0048] Figure 5 Disclosed is a schematic diagram of the photonic crystal microring resonator 140 according to yet another embodiment of the present application. As Figure 5 shown, the modulation of the photonic crystal microring resonator 140 is also a sinusoidal periodic modulation, but the difference from Figure 4 that shown is that the modulation is applied to the inner side of the ring.

[0049] In Figures 2 to 5Among them, the modulation period number of the photonic crystal microring resonator 140 is 16, and the number of modes at the position of the characteristic wavelength of the corresponding photonic crystal microring resonator 140 is 8.

[0050] The above Figures 2 to 5 are only some schematic examples of the modulation of the photonic crystal microring resonator 140 in this application. However, it can be understood that the modulation form of the photonic crystal microring resonator 140 in this application is not limited to this. The modulation form of the ring of the photonic crystal microring resonator 140 can be diversified, and the modulation amplitude is much smaller than the average width of the ring, about dozens of nanometers to hundreds of nanometers. Optionally, the modulation region may not cover the entire ring, but only modulate a partial region of the ring.

[0051] Optionally, the parameters of the coupling input module 120 and the coupling output module 130 can be the same. In one embodiment, the coupling input module 120 and the coupling output module 130 can be a pair of grating couplers. In another embodiment, the coupling input module 120 and the coupling output module 130 can be a pair of free-form surface couplers. The coupling input module 120 and the coupling output module 130 are adapted to the wafer-level test process. For non-wafer-level tests, the coupling input module 120 and the coupling output module 130 can also use end-face couplers.

[0052] Continue to refer to Figure 1 , the connection trajectory of the coupling input module 120 and the coupling output module 130 connected by the connecting optical waveguide 160 is not limited to a straight line, and can also be a non-crossing curve, as long as the bending waveguide loss is not significant. Optionally, the connecting optical waveguide 160 can include, for example, a single-mode optical waveguide.

[0053] The photonic crystal microring resonator 140 is located on one side of the connection path of the single-mode optical waveguide, and the outer side of the photonic crystal microring resonator 140 is spaced a predetermined distance from the outer side of the single-mode optical waveguide. For example, the closest distance between the outer side of the photonic crystal microring resonator 140 and the outer side of the single-mode optical waveguide is generally on the order of 0.1 to 1.0 micrometers. Of course, according to the specific process, the closest distance between the outer side of the photonic crystal microring resonator 140 and the outer side of the single-mode optical waveguide is not limited to this range.

[0054] The operating wavelength range of the coupling input module 120 and the coupling output module 130 covers the wavelength range concerned by the target optical waveguide. For example, when the wavelength range concerned by the target optical waveguide is in the range of 1550 to 1640 nm (nanometers), then the operating wavelength range of the coupling input module 120 and the coupling output module 130 should cover the wavelength band range of 1550 to 1640 nm (nanometers).

[0055] The response spectrum detection module 150 is synchronized with the laser module 110. While the laser module 110 performs wavelength scanning, the response spectrum detection module 150 synchronously detects the power response passing through the coupling output module 130. The response spectrum detection module 150 has a power meter section and a data storage section for subsequent processing of the response spectrum line.

[0056] The photonic crystal micro-ring resonator 140 of the present application can directly measure the effective refractive index and group refractive index of the target optical waveguide, and its measurement principle is as follows:

[0057] The photonic crystal micro-ring resonator 140 has characteristic wavelengths within the wavelength band of interest of the target optical waveguide. The number of modes at the position of the characteristic wavelength is 1 / 2 of the modulation period number of the photonic crystal micro-ring resonator 140. The characteristic wavelength of the photonic crystal micro-ring resonator 140 satisfies the following expression:

[0058] (1)

[0059] Where, is the number of modes at the position of the characteristic wavelength, is the characteristic wavelength of the photonic crystal micro-ring resonator 140, is the effective refractive index of the waveguide of the photonic crystal micro-ring resonator 140, is the circumference of the ring of the photonic crystal micro-ring resonator 140.

[0060] By converting the above expression (1), we can obtain:

[0061] (2)

[0062]

[0063] Where, is the average radius of the ring of the photonic crystal micro-ring resonator 140, is the modulation period number of the photonic crystal micro-ring resonator 140.

[0064] Because the characteristic wavelength is unique and the number of modes at the position of the characteristic wavelength is equal to 1 / 2 of the modulation period number of the photonic crystal micro-ring resonator 140, therefore, based on the characteristic wavelength and the number of modes at the position of the characteristic wavelength, the effective refractive index of the photonic crystal micro-ring resonator 140, that is, the effective refractive index of the target optical waveguide, can be measured quickly and accurately through the above expression (2).

[0065] Since the number of modes at the position of the characteristic wavelength is determined, the number of modes at the positions of other resonance wavelengths adjacent to the characteristic wavelength can also be determined. For example, the number of modes at the position of the characteristic wavelength is , the wavelength is longer than the characteristic wavelength, and the number of other position modes at adjacent resonance positions are successively , , , ……, ; when the wavelength is shorter than the characteristic wavelength, the number of other position modes at adjacent resonance positions are successively , , , ……, , where , are respectively the mode interval numbers with the largest distance from the characteristic wavelength at the right end and the left end. Therefore, the effective refractive index of other resonance wavelength points can also be determined by using the following similar expressions according to other resonance wavelengths and the number of modes at their positions:

[0066] (3)

[0067] where is the number of other position modes at adjacent resonance positions, is the resonance wavelength at the position corresponding to this number of other position modes .

[0068] Furthermore, all the effective refractive indices within the working wavelength range of the entire coupling input module 120 and coupling output module 130 can be obtained.

[0069] For example, in an actual experimental measurement example, the photonic crystal microring resonator 140 uses a silicon nitride waveguide and Figure 4 the modulation type in Figure 6 . The central radius of the ring of the photonic crystal microring resonator 140 is 50.5 microns, the average width of the ring is 1 micron, the number of modulation periods is 680, the number of modes at the position of the corresponding characteristic wavelength is 340, and the modulation amplitude is 60 nanometers. Figure 6 reveals the response spectrum obtained when testing this single photonic crystal microring resonator 140. As Figure 6As can be seen, at the wavelength of 1523.3 nm, the extinction ratio of the transmission spectrum has a significant difference compared with other resonance positions, and at this characteristic wavelength position, two modes with close frequencies appear, that is, one mode splits into two, and the splitting size is proportional to the modulation amplitude. According to the intrinsic property of the photonic crystal microring resonator 140, the number of modes at the position of this characteristic wavelength is exactly equal to half of the modulation period number of the photonic crystal microring resonator 140, which is 340. Therefore, the effective refractive index at the characteristic wavelength can be obtained as 1.633102. When the wavelength is larger than this characteristic wavelength, the number of modes at other positions of adjacent resonance positions are 339, 338, 337, 336, …… in turn; when the wavelength is smaller than this characteristic wavelength, the number of modes at other positions of adjacent resonance positions are 340, 341, 342, 343, …… in turn. Therefore, all the effective refractive indices within the working wavelength range of the entire coupling input module 120 and coupling output module 130 can be obtained.

[0070] Furthermore, based on the following expression (4), the group refractive index of the photonic crystal microring resonator 140 at the characteristic wavelength can be obtained according to the characteristic wavelength and two resonance wavelengths adjacent to the characteristic wavelength:

[0071] (4)

[0072] where, is the group refractive index of the photonic crystal microring resonator 140, is the characteristic wavelength, 、 are two resonance wavelengths adjacent to the characteristic wavelength respectively, is the average radius of the ring of the photonic crystal microring resonator 140.

[0073] The group refractive index of the photonic crystal microring resonator 140 at other resonance wavelengths can also be obtained according to other resonance wavelengths and two resonance wavelengths adjacent to other resonance wavelengths through the following similar expression:

[0074] (5)

[0075] where, is other resonance wavelength, 、 are two resonance wavelengths adjacent to other resonance wavelength.

[0076] Thus, the group refractive index within the entire working wavelength range of the coupling input module 120 and coupling output module 130 can be extracted.

[0077] This application also provides a method for extracting physical parameters of an optical waveguide. Figure 7The flowchart of the method for extracting the physical parameters of an optical waveguide according to an embodiment of the present application is disclosed. As Figure 7 shown, the method for extracting the physical parameters of an optical waveguide according to an embodiment of the present application may include steps S1 to S5.

[0078] In step S1, the extraction device 100 for the physical parameters of the optical waveguide described above is provided.

[0079] Optionally, the photonic crystal microring resonator 140 in the extraction device 100 may be formed on the same chip unit of the same wafer as the target optical waveguide.

[0080] In step S2, the wavelength of the laser module 110 is continuously scanned, and the response spectrum line of a single photonic crystal microring resonator 140 is measured by the response spectrum detection module 150 in the extraction device 100.

[0081] In step S3, the actual effective refractive index and the actual group refractive index of the target optical waveguide are obtained according to the response spectrum line of the single photonic crystal microring resonator 140 measured in step S2.

[0082] Hereinafter, how to obtain the actual effective refractive index and the actual group refractive index of the target optical waveguide according to the response spectrum line of the single photonic crystal microring resonator 140 will be introduced in detail.

[0083] In step S3, the effective refractive index and the group refractive index of the single photonic crystal microring resonator 140 can be obtained according to the response spectrum line of the single photonic crystal microring resonator 140, wherein the actual effective refractive index and the actual group refractive index of the target optical waveguide are equal to the effective refractive index and the group refractive index of the photonic crystal microring resonator 140.

[0084] In some embodiments, step S3 may further include steps S31 to S34.

[0085] In step S31, a characteristic spectrum line can be found from the response spectrum line of the single photonic crystal microring resonator 140. For example, Figure 6 the longest spectrum line shown in is the characteristic spectrum line.

[0086] In step S32, in the response spectrum line of the photonic crystal microring resonator 140, the characteristic wavelength is determined according to the position where the characteristic spectrum line is located. For example, according to Figure 6 the characteristic spectrum line in, the characteristic wavelength can be determined to be 1523.3 nm.

[0087] In step S33, the effective refractive index of the photonic crystal microring resonator 140 is obtained according to the characteristic wavelength and the number of modes at the position where the characteristic wavelength is located, wherein the number of modes at the position where the characteristic wavelength is located is equal to half of the modulation period number of the photonic crystal microring resonator 140, that is For example, for Figure 6 , the test is carried out with the modulation period number of the photonic crystal microring resonator 140 being 680. Accordingly, Figure 6 the number of modes at the position of the characteristic wavelength of the photonic crystal microring resonator 140 in

[0088] In some embodiments, the effective refractive index of the photonic crystal microring resonator 140 at the characteristic wavelength can be obtained from the above expression (2) according to the characteristic wavelength and the number of modes at the position of the characteristic wavelength.

[0089] In some embodiments, according to the number of modes at the position of the characteristic wavelength, the number of modes at the positions of other resonance wavelengths in the response spectrum can be determined. Then, the effective refractive index of the photonic crystal microring resonator 140 at the other resonance wavelengths can be obtained from the above expression (3) according to the other resonance wavelengths and the number of modes at the positions of the other resonance wavelengths.

[0090] Thus, all the effective refractive indices of the photonic crystal microring resonator 140 within the entire operating wavelength range of the coupling input module 120 and the coupling output module 130 can be determined.

[0091] In step S34, the group refractive index of the photonic crystal microring resonator 140 is obtained according to the characteristic wavelength and two resonance wavelengths adjacent to the characteristic wavelength.

[0092] In some embodiments, the group refractive index of the photonic crystal microring resonator 140 at the characteristic wavelength can be obtained from the above expression (4) according to the characteristic wavelength and two resonance wavelengths adjacent to the characteristic wavelength.

[0093] In other embodiments, the group refractive index of the photonic crystal microring resonator 140 at the other resonance wavelengths can be obtained from the above expression (5) according to the other resonance wavelengths and two resonance wavelengths adjacent to the other resonance wavelengths.

[0094] Thus, all the group refractive indices of the photonic crystal microring resonator 140 within the entire operating wavelength range of the coupling input module 120 and the coupling output module 130 can be determined.

[0095] In step S4, the mapping relationship between the width w and thickness h of the optical waveguide and the effective refractive index and group refractive index is pre-simulated.

[0096] Figure 8 Reveals a schematic cross-sectional structure diagram of an optical waveguide according to an embodiment of the present application. As Figure 8As shown, the optical waveguide includes a cladding material and a core material located within the cladding material. The optical waveguide has a width w and a thickness h. In an embodiment of the present application, the width w of the optical waveguide may refer to the widest width of the core material.

[0097] Figure 9 A mapping relationship diagram of the width w, thickness h of the optical waveguide in an embodiment of the present application with the effective refractive index and group refractive index is disclosed. As Figure 9 shown, in some embodiments, according to the process error range in the wafer manufacturing process, the effective refractive index and group refractive index at different widths w and different thicknesses h of the optical waveguide can be simulated by three-dimensional finite element method, so that the mapping relationship between the width w, thickness h of the optical waveguide and the effective refractive index and group refractive index can be established.

[0098] In step S5, based on the mapping relationship obtained in step S4 with the actual effective refractive index and actual group refractive index of the target optical waveguide obtained in step S3, the actual width and actual thickness of the target optical waveguide can be determined.

[0099] By repeating the above steps, the target optical waveguides in different regions on the wafer can be tested respectively, so that the statistical laws of the physical parameters of the optical waveguides in different regions of the entire wafer can be extracted.

[0100] The method and extraction device 100 for extracting the physical parameters of the optical waveguide of the present application solve the problems of high cost, low efficiency, and small monitoring range in extracting the physical parameters of the waveguide structure after manufacturing in the prior art.

[0101] Compared with the prior art, the method and extraction device 100 for extracting the physical parameters of the optical waveguide of the present application only need to test the response spectrum of a single photonic crystal microring resonator 140. The effective refractive index and group refractive index can be directly determined through the characteristic spectrum in the response spectrum of the single photonic crystal microring resonator 140. It has the characteristics of accurate single direct measurement, and can quickly, efficiently, non-destructively, and low-costly extract the physical parameters of the optical waveguides in different regions of the wafer.

[0102] The method and extraction device 100 for extracting the physical parameters of the optical waveguide of the present application can quickly and accurately extract the physical parameters of the optical waveguide without damaging the chip and waveguide structure of the wafer, simplify the test process of wafer characterization, and provide strong support for the manufacturing and design of silicon-based optoelectronic chips.

[0103] The above has introduced in detail the apparatus and method for extracting the physical parameters of the optical waveguide provided by the embodiments of the present application. Specific examples are used herein to elaborate on the apparatus and method for extracting the physical parameters of the optical waveguide in the embodiments of the present application. The description of the above embodiments is only used to help understand the core idea of the present application and is not intended to limit the present application. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the spirit and principle of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications should also fall within the protection scope of the appended claims of the present application.

Claims

1. An optical waveguide physical parameter extraction device, used to extract the physical parameters of a target optical waveguide in a wafer, characterized in that: The extraction device comprises a laser module, a coupling input module, a coupling output module, a connecting optical waveguide, a single photonic crystal microring resonant cavity and a response spectrum detection module, wherein the laser module is connected to the coupling input module, the response spectrum detection module is connected to the coupling output module, the coupling input module and the coupling output module are connected via the connecting optical waveguide, and the photonic crystal microring resonant cavity is used to couple with the connecting optical waveguide, wherein the photonic crystal microring resonant cavity is located in the vicinity of the target optical waveguide, the photonic crystal microring resonant cavity comprises a closed circular ring, the average width of the circular ring is equal to the width of the target optical waveguide but the width is periodically modulated along the circumferential direction, and the average radius of the circular ring is greater than a preset value; the laser module is used to provide a light source for the extraction device, the wavelength of the laser module is continuously adjustable, and the wavelength range of the laser module covers the wavelength range of interest of the target optical waveguide and the characteristic wavelength of the photonic crystal microring resonant cavity.

2. The extraction device according to claim 1, characterized in that: The connecting optical waveguide comprises a single-mode optical waveguide, the photonic crystal microring resonator is located at one side of the connecting path of the single-mode optical waveguide, and the outer side of the photonic crystal microring resonator is spaced a predetermined distance from the outer side of the single-mode optical waveguide.

3. The extraction device according to claim 1, characterized in that: The inner side or the outer side of the circular ring of the photonic crystal micro-ring resonant cavity has periodic modulation, and the modulation period number of the photonic crystal micro-ring resonant cavity is equal to twice the mode number at the position where the characteristic wavelength of the photonic crystal micro-ring resonant cavity is located.

4. The extraction device according to claim 1, characterized in that: The coupling-in module and the coupling-out module are grating couplers or free-form surface couplers.

5. The extraction device according to claim 1, characterized in that: The photonic crystal micro-ring resonant cavity and the target optical waveguide are located on the same chip unit of the same wafer.

6. A method for extracting physical parameters of an optical waveguide, characterized in that: include: Providing an optical waveguide physical parameter extraction device as claimed in claim 1; Continuously scanning the wavelength of the laser module, and measuring the response spectrum line of a single photonic crystal microring resonant cavity through the response spectrum detection module in the extraction device; Obtaining the actual effective refractive index and the actual group refractive index of the target optical waveguide according to the response spectrum of the single photonic crystal microring resonator; Pre-simulation to obtain the mapping relationship between the width and thickness of the optical waveguide and the effective refractive index and group refractive index; The actual width and the actual thickness of the target optical waveguide are determined based on the obtained actual effective refractive index and the actual group refractive index of the target optical waveguide through the mapping relationship.

7. The extraction method according to claim 6, wherein: The step of obtaining the actual effective refractive index and the actual group refractive index of the target optical waveguide according to the response spectrum of the single photonic crystal microring resonator comprises: The effective refractive index and group refractive index of a single photonic crystal microring resonant cavity are obtained according to the response spectrum of the single photonic crystal microring resonant cavity, wherein the actual effective refractive index and the actual group refractive index of the target optical waveguide are equal to the effective refractive index and the group refractive index of the photonic crystal microring resonant cavity.

8. The extraction method according to claim 7, characterized in that: The step of obtaining the effective refractive index and the group refractive index of a single photonic crystal microring resonant cavity according to the response spectrum of the single photonic crystal microring resonant cavity comprises: Finding characteristic spectral lines from the response spectral lines of a single photonic crystal microring resonator; In the response spectrum of the photonic crystal micro-ring resonator, determining a characteristic wavelength according to the position of the characteristic spectrum; The effective refractive index of the photonic crystal micro-ring resonant cavity is obtained according to the characteristic wavelength and the mode number at the position where the characteristic wavelength is located, wherein the mode number at the position where the characteristic wavelength is located is equal to one half of the modulation period number of the photonic crystal micro-ring resonant cavity; The group refractive index of the photonic crystal micro-ring resonant cavity is obtained according to the characteristic wavelength and two resonance wavelengths adjacent to the characteristic wavelength.

9. The extraction method according to claim 8, characterized in that: According to the characteristic wavelength and the mode number at the position where the characteristic wavelength is located, the effective refractive index of the photonic crystal microring resonator at the characteristic wavelength is obtained by the following expression: in, is the effective refractive index of the photonic crystal microring resonator, is the characteristic wavelength of the photonic crystal microring resonator, is the mode number at the location of the characteristic wavelength, is the modulation period number of the photonic crystal microring resonator, is the average radius of the circular ring of the photonic crystal microring resonator.

10. The extraction method according to claim 8, characterized in that: According to the characteristic wavelength and two resonance wavelengths adjacent to the characteristic wavelength, the group refractive index of the photonic crystal microring resonator at the characteristic wavelength is obtained by the following expression: in, is the group refractive index of the photonic crystal microring resonator, is the characteristic wavelength of the photonic crystal microring resonator, , are two resonant wavelengths adjacent to the characteristic wavelength, is the average radius of the circular ring of the photonic crystal microring resonator.

11. The extraction method according to claim 8, characterized in that: The step of obtaining the effective refractive index and the group refractive index of a single photonic crystal microring resonant cavity according to the response spectrum of the single photonic crystal microring resonant cavity comprises: Finding characteristic spectral lines from the response spectral lines of a single photonic crystal microring resonator; In the response spectrum of the photonic crystal micro-ring resonator, determining a characteristic wavelength according to the position of the characteristic spectrum; The mode number at the position of other resonant wavelengths in the response spectrum can be determined according to the mode number at the position of the characteristic wavelength; Obtaining the effective refractive index of the photonic crystal microring resonator at other resonant wavelengths according to the other resonant wavelengths and the mode numbers at the positions where the other resonant wavelengths are located; The group refractive index of the photonic crystal micro-ring resonator at the other resonant wavelength is obtained according to the other resonant wavelength and two resonant wavelengths adjacent to the other resonant wavelength.

12. The extraction method according to claim 6, characterized in that: Also includes: The photonic crystal micro-ring resonator and the target optical waveguide are formed on the same chip unit of the same wafer.

13. The extraction method according to claim 6, characterized in that: The mapping relationship between the width and thickness of the optical waveguide and the effective refractive index and the group refractive index obtained by the pre-simulation includes: According to the process error range in the wafer manufacturing process, the effective refractive index and the group refractive index of the optical waveguide with different widths and thicknesses are simulated by the three-dimensional finite element method to establish the mapping relationship between the width and thickness of the optical waveguide and the effective refractive index and the group refractive index.

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