Device and method for extracting physical parameters of optical waveguide

Abstract

The invention provides an optical waveguide physical parameter extraction device and an extraction method thereof. The device comprises a laser module, a coupling input and output module, a photonic crystal micro-ring resonant cavity and a response spectrum detection module, the photonic crystal micro-ring resonant cavity is located in an adjacent area of a target optical waveguide and comprises a closed circular ring, the average width of the closed circular ring is equal to the width of the target optical waveguide, and the width is periodically modulated in the circumferential direction; the average radius is greater than a preset value. The method comprises the following steps: providing the device; continuously scanning the wavelength of the laser module, and measuring the response spectral line of the single photonic crystal micro-ring resonant cavity; obtaining the actual effective refractive index and the actual group refractive index of the target optical waveguide according to the response spectral line of the single photonic crystal micro-ring resonant cavity; pre-simulating to obtain a mapping relation between the width and the thickness of the optical waveguide and the effective refractive index and the group refractive index; based on the actual effective refractive index and the actual group refractive index, the actual width and the actual thickness of the target optical waveguide are determined through the mapping relation.

Description

Technical Field

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

[0002] Silicon-based optoelectronics is a technology that combines photonics and microelectronics by integrating photonic devices and electronic devices on a silicon-based platform. Due to its potential advantages in optical communications, optical sensing, optical interconnection, optical computing and other fields, it has attracted more and more attention from the industry and researchers in recent years. Silicon-based optoelectronic devices are compact and easy to integrate; but because their refractive index difference is quite different from that of 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). The deviation of wafer thickness in different areas and the process error during the manufacturing process will cause a huge deviation between the actual prepared device and the designed situation, and even cause the problem of unusability.

[0003] In order to solve the problem of manufacturing deviation, on the one hand, the process tolerance is considered in the design stage to improve the robustness of the device; on the other hand, the constant deviation in the manufacturing process is compensated by increasing or reducing the design size. Therefore, it is necessary to accurately extract the physical parameters of the manufactured device to provide a reference for design iteration.

[0004] In the prior art, it is generally through lossy direct observation or non-destructive optical characterization methods. Direct observation is in the form of a scanning electron microscope or a transmission electron microscope. The observation method is not only cumbersome, but also requires slicing of the prepared device. It often depends on the experience level of the operator, and the time and economic costs are high. The non-destructive optical characterization method requires the use of a two-stage MZI (Mach-Zehnder Interferometer) or two micro-ring resonators of similar sizes, and the response spectra are fitted by measuring them. The time cost of the measurement is also very high, 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 optical waveguide physical parameter extraction device and extraction method thereof, which can at least partially solve the above-mentioned technical problems existing in the prior art.

[0006] One aspect of the present application provides an optical waveguide physical parameter extraction device, 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 connection 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 through the connection optical waveguide, and the photonic crystal microring resonant cavity is used to couple with the connection 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 includes a closed annular ring, the average width of the annular 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 annular 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.

[0007] Further, the connecting optical waveguide comprises 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 a predetermined distance from the outer side of the single-mode optical waveguide.

[0008] Furthermore, the inner side or the outer side of the circular ring of the photonic crystal microring resonator has periodic modulation, and the modulation period number of the photonic crystal microring resonator is equal to twice the mode number at the position where the characteristic wavelength of the photonic crystal microring resonator is located.

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

[0010] Furthermore, 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 optical waveguide physical parameter extraction device described above; continuously scanning the wavelength of the laser module, and measuring the response spectrum 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 resonant cavity; pre-simulating and obtaining 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 through the mapping relationship based on the actual effective refractive index and the actual group refractive index of the target optical waveguide obtained.

[0012] Furthermore, 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 resonant cavity includes: obtaining the effective refractive index and the group refractive index of the single photonic crystal microring resonant cavity 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.

[0013] Furthermore, 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 a characteristic spectrum from the response spectrum of the single photonic crystal microring resonant cavity; determining a characteristic wavelength according to the position of the characteristic spectrum in the response spectrum of the photonic crystal microring resonant cavity; obtaining the effective refractive index of the photonic crystal microring resonant cavity according to the characteristic wavelength and the mode number at the position of the characteristic wavelength, wherein the mode number at the position of the characteristic wavelength is equal to one-half of the modulation period number of the photonic crystal microring resonant cavity; and obtaining the group refractive index of the photonic crystal microring resonant cavity according to the characteristic wavelength and two resonance wavelengths adjacent to the characteristic wavelength.

[0014] Furthermore, 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:

[0015]

[0016] 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.

[0017] Furthermore, 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 by the following expression:

[0018] 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.

[0019] Furthermore, the obtaining of 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 a characteristic spectrum from the response spectrum of the single photonic crystal microring resonant cavity; determining a characteristic wavelength in the response spectrum of the photonic crystal microring resonant cavity according to the position of the characteristic spectrum; determining the mode number at the position of other resonant wavelengths in the response spectrum according to the mode number at the position of the characteristic wavelength; obtaining the effective refractive index of the photonic crystal microring resonant cavity at other resonant wavelengths according to the other resonant wavelengths and the mode number at the position of the other resonant wavelengths; and obtaining the group refractive index of the photonic crystal microring resonant cavity at other resonant wavelengths according to the other resonant wavelengths and two resonant wavelengths adjacent to the other resonant wavelengths.

[0020] Furthermore, the method further comprises: forming the photonic crystal microring resonator and the target optical waveguide on the same chip unit of the same wafer.

[0021] Furthermore, the pre-simulation to obtain the mapping relationship between the width, thickness and the effective refractive index and the group refractive index of the optical waveguide includes: according to the process error range in the wafer manufacturing process, simulating the effective refractive index and the group refractive index of the optical waveguide at different widths and thicknesses by a three-dimensional finite element method to establish the mapping relationship between the width, thickness and the effective refractive index and the group refractive index of the optical waveguide.

[0022] The method and device for extracting physical parameters of an optical waveguide in one or more embodiments of the present application solve the problems of high cost, low efficiency and small monitoring range in the prior art for extracting physical parameters of a waveguide structure after manufacturing.

[0023] The method for extracting the physical parameters of an optical waveguide and the device thereof in 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 the group refractive index can be directly determined through the characteristic spectrum in the response spectrum of the single photonic crystal microring resonator, and the characteristic of a single direct measurement, that is, accuracy, can be achieved. The physical parameters of optical waveguides in different regions of a wafer can be extracted quickly, efficiently, non-destructively, and at low cost.

[0024] The method for extracting the physical parameters of an optical waveguide and the device for extracting the same in 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 the waveguide structure, simplify the test process of wafer characterization, and provide strong support for the manufacture and design of silicon-based optoelectronic chips. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 FIG. 1 is a schematic diagram of a device for extracting physical parameters of an optical waveguide according to an embodiment of the present application.

[0026] Figure 2 A schematic diagram of a photonic crystal micro-ring resonator according to an embodiment of the present application.

[0027] Figure 3 A schematic diagram of a photonic crystal micro-ring resonator according to another embodiment of the present application.

[0028] Figure 4 This is a schematic diagram of a photonic crystal micro-ring resonator according to yet another embodiment of the present application.

[0029] Figure 5 This is a schematic diagram of a photonic crystal micro-ring resonator according to another embodiment of the present application.

[0030] Figure 6 This is a response spectrum obtained during testing of a single photonic crystal micro-ring resonator according to an embodiment of the present application.

[0031] Figure 7 The flowchart is a method for extracting physical parameters of an optical waveguide according to an embodiment of the present application.

[0032] Figure 8 FIG. 1 is a schematic diagram of a cross-sectional structure of an optical waveguide according to an embodiment of the present application.

[0033] Fig. 9 This is a mapping 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 DESCRIPTION

[0034] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying 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. Instead, they are merely examples of devices consistent with some aspects of the present application as detailed in the appended claims.

[0035] The following is a detailed description of the optical waveguide physical parameter extraction device and extraction method of each embodiment of the present application in conjunction with the accompanying drawings. In the absence of conflict, the features of the following embodiments and implementations can be combined with each other.

[0036] The present application provides a device 100 for extracting physical parameters of an optical waveguide. Figure 1 A schematic diagram of an optical waveguide physical parameter extraction device 100 according to an embodiment of the present application is disclosed. Figure 1 As shown, an optical waveguide physical parameter extraction device 100 according to an embodiment of the present application can be used to extract the physical parameters of a target optical waveguide in a wafer. The extraction device 100 includes a laser module 110, a coupling input module 120, a coupling output module 130, a single photonic crystal micro-ring resonator 140, and a response spectrum detection module 150.

[0037] Among them, the laser module 110 can be connected to the coupling input module 120 through 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 couple with the connecting optical waveguide 160.

[0038] The laser module 110 is used to provide a light source for the entire optical waveguide physical parameter extraction device 100. The laser module 110 is a tunable laser, whose wavelength is continuously adjustable, and the wavelength range of the laser module 110 covers the wavelength range of interest of the target optical waveguide.

[0039] The photonic crystal micro-ring resonator 140 is located in the vicinity of the target optical waveguide. Optionally, the photonic crystal micro-ring resonator 140 and the target optical waveguide are located on the same chip unit of the same wafer. That is, the photonic crystal micro-ring resonator 140 and the target optical waveguide can be manufactured on the same chip unit of the same wafer.

[0040] The photonic crystal micro-ring resonator 140 comprises a closed circular ring, the average width of which 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 circular ring is greater than a preset value.

[0041] The bending radius of the ring of the photonic crystal microring resonator 140 is greater than a preset value. For example, for a photonic crystal microring resonator 140 made of a 400nm thick and 800nm ​​wide silicon nitride waveguide, 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 curved waveguide is approximately equal to the effective refractive index of the straight waveguide. In addition, 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 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.

[0042] The photonic crystal micro-ring resonator 140 is the main structure of the optical waveguide physical parameter extraction device 100. In the circumferential direction of the ring of the photonic crystal micro-ring resonator 140, the inner side or the outer side of the ring has periodic modulation, and the modulation period number of the photonic crystal micro-ring resonator 140 is equal to twice the mode number at the position where the characteristic wavelength of the photonic crystal micro-ring resonator 140 is located.

[0043] Figure 2 A schematic diagram of a photonic crystal micro-ring resonator 140 according to an embodiment of the present application is disclosed. Figure 2 As shown, the modulation of the photonic crystal micro-ring resonator 140 is a sawtooth-type periodic modulation, and the modulation is applied to the outside of the ring.

[0044] Figure 3 A schematic diagram of a photonic crystal micro-ring resonator 140 according to another embodiment of the present application is disclosed. Figure 3 As shown, the modulation of the photonic crystal micro-ring resonator 140 is also a sawtooth-type periodic modulation, but Figure 2 The difference shown is that the modulation is applied to the inside of the ring.

[0045] Figure 4 A schematic diagram of a photonic crystal micro-ring resonator 140 according to another embodiment of the present application is disclosed. Figure 4 As shown, the modulation of the photonic crystal micro-ring resonator 140 is a sinusoidal periodic modulation, and the modulation is applied to the outside of the ring.

[0046] Figure 5 A schematic diagram of a photonic crystal micro-ring resonator 140 according to another embodiment of the present application is disclosed. Figure 5 As shown, the modulation of the photonic crystal micro-ring resonator 140 is also a sinusoidal periodic modulation, but Figure 4 The difference shown is that the modulation is applied to the inside of the ring.

[0047] exist Figures 2 to 5In the figure, the modulation period number of the photonic crystal micro-ring resonator 140 is 16, and the corresponding mode number at the position where the characteristic wavelength of the photonic crystal micro-ring resonator 140 is located is 8.

[0048] above Figures 2 to 5 These are only some schematic examples of modulation of the photonic crystal micro-ring resonant cavity 140 in the present application. However, it is understandable that the modulation form of the photonic crystal micro-ring resonant cavity 140 in the present application is not limited to this, and the modulation form of the ring of the photonic crystal micro-ring resonant cavity 140 can be diversified, and the modulation amplitude is much smaller than the average width of the ring, which is about tens of nanometers to hundreds of nanometers. Optionally, the modulation area may not cover the entire ring, but only a part of the ring area may be modulated.

[0049] Optionally, the parameters of the coupling input module 120 and the coupling output module 130 can be consistent. 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 testing, the coupling input module 120 and the coupling output module 130 can also use end-face couplers.

[0050] Continue to refer to Figure 1 The connection track between the coupling input module 120 and the coupling output module 130 through the connecting optical waveguide 160 is not limited to a straight line, but can also be a non-intersecting curve, as long as the bending waveguide loss is not significant. Optionally, the connecting optical waveguide 160 can include a single-mode optical waveguide, for example.

[0051] The photonic crystal micro-ring 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 micro-ring resonator 140 is spaced apart from the outer side of the single-mode optical waveguide by a predetermined distance. For example, the closest distance between the outer side of the photonic crystal micro-ring resonator 140 and the outer side of the single-mode optical waveguide is generally in the order of 0.1 to 1.0 microns. Of course, depending on the specific process, the closest distance between the outer side of the photonic crystal micro-ring resonator 140 and the outer side of the single-mode optical waveguide is not limited to this range.

[0052] The working wavelength range of the coupling input module 120 and the coupling output module 130 covers the wavelength range of interest of the target optical waveguide. For example, when the wavelength range of interest of the target optical waveguide is between 1550 and 1640 nm (nanometers), the working wavelength range of the coupling input module 120 and the coupling output module 130 should cover the wavelength range of 1550 to 1640 nm (nanometers).

[0053] The response spectrum detection module 150 is synchronized with the laser module 110. When the laser module 110 scans the wavelength, the response spectrum detection module 150 synchronously detects the power response through the coupling output module 130. The response spectrum detection module 150 has a power meter part and a data storage part for subsequent processing of the response spectrum line.

[0054] 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 the measurement principle is as follows: The photonic crystal micro-ring resonator 140 has a characteristic wavelength in the wavelength band of interest for the target optical waveguide. The mode number at the location 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: (1) in, is the mode number at 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 .

[0055] After transforming the above expression (1), we can get: (2)

[0056] in, is the average radius of the circular ring of the photonic crystal micro-ring resonator 140, is the modulation period number of the photonic crystal micro-ring resonator 140 .

[0057] Because the characteristic wavelength is unique, the mode number at the location of the characteristic wavelength is equal to 1 / 2 of the modulation period number of the photonic crystal microring resonator 140. Therefore, according to the characteristic wavelength and the mode number at the location of the characteristic wavelength, the effective refractive index of the photonic crystal microring resonator 140, that is, the effective refractive index of the target optical waveguide, can be quickly and accurately measured by the above expression (2).

[0058] Since the mode number at the characteristic wavelength is determined, the mode number at other resonant wavelengths near the characteristic wavelength can also be determined. For example, the mode number at the characteristic wavelength is , the wavelength is larger than the characteristic wavelength, and the number of other position modes at adjacent resonance positions is , , ,……, ; The wavelength is smaller than the characteristic wavelength, and the number of other position modes at adjacent resonance positions is , , ,……, ,in, , are the mode spacing numbers of the right and left ends with the largest distance from the characteristic wavelength, respectively. Therefore, the effective refractive index of other resonant wavelength points can also be determined according to other resonant wavelengths and the mode numbers at their locations using similar expressions as follows: (3) in, is the number of other position modes adjacent to the resonance position, For the other position mode number The resonant wavelength at the corresponding position.

[0059] Furthermore, all effective refractive indices within the working wavelength range of the entire coupling-in module 120 and the coupling-out module 130 can be obtained.

[0060] For example, in an actual experimental measurement example, the photonic crystal micro-ring resonator 140 uses a silicon nitride waveguide and Figure 4 In the modulation type, the center 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 cycles is 680, the number of modes at the corresponding characteristic wavelength position is 340, and the modulation amplitude is 60 nanometers. Figure 6 The response spectrum of the single photonic crystal micro-ring resonator 140 obtained during the test is disclosed. Figure 6 As shown, the response spectrum is a typical optical microcavity coupling spectrum. For the photonic crystal microring resonator 140, there is also a unique characteristic spectrum. Figure 6 It can be seen that at the wavelength of 1523.3nm, the extinction ratio of the transmission spectrum is significantly different from that at other resonance positions, and two modes with close frequencies appear at this characteristic wavelength, that is, one mode is split into two, and the size of the split is proportional to the amplitude of the modulation. According to the intrinsic properties of the photonic crystal microring resonator 140, the number of modes at the position of the characteristic wavelength is exactly equal to half of the number of modulation cycles of the photonic crystal microring resonator 140, that is, 340. Therefore, the effective refractive index at the characteristic wavelength can be obtained to be 1.633102. When the wavelength is larger than the characteristic wavelength, the number of modes at other positions adjacent to the resonance position is 339, 338, 337, 336, ...; when the wavelength is smaller than the characteristic wavelength, the number of modes at other positions adjacent to the resonance position is 340, 341, 342, 343, .... Therefore, all effective refractive indices within the working wavelength range of the entire coupling input module 120 and the coupling output module 130 can be obtained.

[0061] Furthermore, the group refractive index of the photonic crystal micro-ring resonator 140 at the characteristic wavelength can be obtained based on the characteristic wavelength and the two resonance wavelengths adjacent to the characteristic wavelength based on the following expression (4): (4) in, is the group refractive index of the photonic crystal micro-ring resonator 140, is the characteristic wavelength, , are the two resonance wavelengths adjacent to the characteristic wavelength, is the average radius of the circular ring of the photonic crystal micro-ring resonator 140 .

[0062] The group refractive index of the photonic crystal micro-ring resonator 140 at other resonant wavelengths can also be obtained according to other resonant wavelengths and two resonant wavelengths adjacent to the other resonant wavelengths through the following similar expressions: (5) in, For other resonance wavelengths, , are two resonance wavelengths adjacent to other resonance wavelengths.

[0063] Thus, the group refractive index of the coupling-in module 120 and the coupling-out module 130 in the entire operating wavelength range can be extracted.

[0064] The present application also provides a method for extracting physical parameters of an optical waveguide. Figure 7 A flow chart of a method for extracting physical parameters of an optical waveguide according to an embodiment of the present application is disclosed. Figure 7 As shown, a method for extracting physical parameters of an optical waveguide according to an embodiment of the present application may include steps S1 to S5.

[0065] In step S1, the optical waveguide physical parameter extraction device 100 described above is provided.

[0066] Optionally, the photonic crystal micro-ring resonator 140 in the extraction device 100 and the target optical waveguide may be formed on the same chip unit of the same wafer.

[0067] In step S2 , the wavelength of the laser module 110 is continuously scanned, and the response spectrum line of a single photonic crystal micro-ring resonator 140 is measured by the response spectrum detection module 150 in the extraction device 100 .

[0068] 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 of the single photonic crystal micro-ring resonator 140 measured in step S2.

[0069] How to obtain the actual effective refractive index and the actual group refractive index of the target optical waveguide based on the response spectrum of a single photonic crystal microring resonator 140 will be described in detail below.

[0070] 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 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.

[0071] In some embodiments, step S3 may further include steps S31 to S34.

[0072] In step S31, a characteristic spectrum line can be found from the response spectrum line of a single photonic crystal micro-ring resonator 140, such as Figure 6 The longest spectral line shown in is the characteristic spectral line.

[0073] In step S32, in the response spectrum of the photonic crystal micro-ring resonator 140, the characteristic wavelength is determined according to the position of the characteristic spectrum. Figure 6 The characteristic spectral lines in the spectrum can determine that the characteristic wavelength is 1523.3nm.

[0074] In step S33, the effective refractive index of the photonic crystal micro-ring resonator 140 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 resonator 140, that is, For example, for Figure 6 For example, the modulation period of the photonic crystal micro-ring resonator 140 is 680 for testing. Therefore, accordingly, Figure 6 The mode number at the position where the characteristic wavelength of the photonic crystal micro-ring resonator 140 is located is 340.

[0075] In some embodiments, the effective refractive index of the photonic crystal micro-ring resonator 140 at the characteristic wavelength can be obtained by the above expression (2) according to the characteristic wavelength and the mode number at the position where the characteristic wavelength is located.

[0076] In some embodiments, the mode number at the location of other resonant wavelengths in the response spectrum can be determined based on the mode number at the location of the characteristic wavelength. Then, the effective refractive index of the photonic crystal microring resonator 140 at other resonant wavelengths can be obtained based on the other resonant wavelengths and the mode numbers at the locations of other resonant wavelengths through the above expression (3).

[0077] Thus, all effective refractive indices of the photonic crystal micro-ring resonator 140 within the entire operating wavelength range of the coupling-in module 120 and the coupling-out module 130 can be determined.

[0078] In step S34, the group refractive index of the photonic crystal micro-ring resonator 140 is obtained according to the characteristic wavelength and two resonance wavelengths adjacent to the characteristic wavelength.

[0079] In some embodiments, the group refractive index of the photonic crystal micro-ring resonator 140 at the characteristic wavelength can be obtained by the above expression (4) according to the characteristic wavelength and two resonance wavelengths adjacent to the characteristic wavelength.

[0080] In other embodiments, the group refractive index of the photonic crystal micro-ring resonator 140 at other resonant wavelengths can be obtained according to other resonant wavelengths and two resonant wavelengths adjacent to the other resonant wavelengths through the above expression (5).

[0081] Thus, all group refractive indices of the photonic crystal micro-ring resonator 140 within the entire operating wavelength range of the coupling-in module 120 and the coupling-out module 130 can be determined.

[0082] In step S4, a mapping relationship between the width w and thickness h of the optical waveguide and the effective refractive index and group refractive index is obtained in advance by simulation.

[0083] Figure 8 The cross-sectional structure diagram of an optical waveguide according to an embodiment of the present application is disclosed. Figure 8 As shown, the optical waveguide includes a cladding material and a core material located in the cladding material. The optical waveguide has a width w and a thickness h. In the embodiment of the present application, the width w of the optical waveguide may refer to the widest width of the core material.

[0084] Fig. 9 The mapping relationship between the width w, thickness h, effective refractive index, and group refractive index of an optical waveguide according to an embodiment of the present application is disclosed. Fig. 9 As shown, in some embodiments, 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 w and different thicknesses h can be simulated by the three-dimensional finite element method, so that the mapping relationship between the width w and thickness h of the optical waveguide and the effective refractive index and the group refractive index can be established.

[0085] In step S5, based on the mapping relationship between the actual effective refractive index and the actual group refractive index of the target optical waveguide obtained in step S3 and obtained in step S4, the actual width and actual thickness of the target optical waveguide can be determined.

[0086] 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.

[0087] The optical waveguide physical parameter extraction method and extraction device 100 of the present application solve the problems of high cost, low efficiency and small monitoring range in the prior art for extracting the physical parameters of the waveguide structure after manufacturing.

[0088] Compared with the prior art, the optical waveguide physical parameter extraction method and extraction device 100 of the present application only need to test the response spectrum of a single photonic crystal microring resonator 140. The effective refractive index and the group refractive index can be directly determined through the characteristic spectrum in the response spectrum of the single photonic crystal microring resonator 140, which can achieve the characteristic of accurate single direct measurement, and can extract the physical parameters of optical waveguides in different regions of the wafer quickly, efficiently, non-destructively and at low cost.

[0089] The optical waveguide physical parameter extraction method and extraction device 100 of the present application can quickly and accurately extract the physical parameters of the optical waveguide without damaging the chip and waveguide structure, simplify the test process of wafer characterization, and provide strong support for the manufacture and design of silicon-based optoelectronic chips.

[0090] The above is a detailed introduction to the optical waveguide physical parameter extraction device and extraction method provided in the embodiment of the present application. This article uses specific examples to illustrate the optical waveguide physical parameter extraction device and extraction method of the embodiment of the present application. The description of the above embodiment 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 pointed out that for ordinary technicians 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 scope of protection of the claims attached to 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 actual group refractive index of the target optical waveguide through the mapping relationship.

7. The extraction method according to claim 6, characterized in that: 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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