An ion exchange glass-based buried segmented pattern converter

Abstract

An ion exchange glass-based buried segmented pattern spot converter, the pattern spot converter is formed by sequentially cascading n segments (n≥2) of glass-based conical waveguide chips; each segment of the glass-based conical waveguide chip is composed of a glass substrate (100) and a buried conical ion doping region (101) therein; wherein the cross-sectional dimensions of the thick end of the buried conical ion doping region (101) in the n-th segment of the glass-based conical waveguide chip match the cross-sectional dimensions of the thin end of the buried conical ion doping region (101) in the n-1st segment of the glass-based conical waveguide chip, and the thin end of the buried conical ion doping region (101) in the n-th segment of the glass-based conical waveguide chip serves as the output end of the pattern spot converter. The glass-based buried segmented pattern spot converter can achieve a larger degree of pattern spot size conversion by cascading n segments of the glass-based conical waveguide chips, improve device performance, and reduce the difficulty of design and production.

Description

Technical Field

[0001] The invention relates to an ion exchange glass-based buried segmented pattern spot converter, belonging to the field of integrated optics and optoelectronics. Background Art

[0002] Since Dr. Miller of Bell Labs in the United States proposed the concept of "integrated optics" in 1969, the theory and technology of integrated optics have developed rapidly. Some integrated optical devices, such as semiconductor lasers, optical splitters, optical modulators and optical switches, have been widely used in many fields such as optical communications, optical sensing, optical computing and optical interconnection. In particular, the application of such devices in optical interconnection has promoted the rapid development of microelectronics technology.

[0003] The refractive index difference between the core layer and the cladding layer of SOI (Silicon On Insulator) material is large, and the light confinement ability is strong. Therefore, the use of SOI material can achieve a smaller device size and realize large-scale optical device integration. Therefore, silicon-based integrated optoelectronic devices have become one of the current research hotspots in the field of microelectronics and integrated optics.

[0004] The coupling problem between optical fiber and SOI waveguide is a key issue affecting the development and application of silicon-based photonics. The core diameter of single-mode optical fiber is generally 8-10μm, while the size of SOI waveguide is generally 450nm×220nm. Therefore, the mode spot size when light is transmitted in optical fiber and the mode spot size when light is transmitted in SOI waveguide are very different. This huge mode field mismatch leads to end-face coupling loss from optical fiber to SOI waveguide of more than 20dB. Although grating coupling can be used to achieve coupling between optical fiber and silicon photonic chip, the working bandwidth of this coupling method is limited and sensitive to the polarization direction of input light. In contrast, end-face coupling can obtain higher coupling efficiency and has more advantages in working bandwidth and polarization sensitivity. It is considered by researchers to be a potential solution to solve the problem of efficient coupling between optical fiber and silicon photonic chip. In order to reduce the end-face coupling loss between optical fiber and SOI waveguide, researchers have conducted a lot of research on end-face coupling technology.

[0005] The end-face coupling between optical fiber and SOI waveguide needs to be reduced by spot size converters (SSC). Spot size converters are devices that can achieve mode field shape conversion and / or size scaling. Common spot size converters generally need to use a tapered waveguide to achieve a smooth transition of the mode field to reduce losses, and the structure of the tapered waveguide needs to meet the adiabatic transition conditions. So far, researchers have proposed various structures of silicon-based spot size converters, including: three-dimensional tapered spot size converters (Holly R, Hingerl K, etc., 2006), double-layer tapered spot size converters (Daoxin Dai, Sailing He, etc., 2006), inverted tapered spot size converters (Pavel Cheben, etc., 2010), gradient refractive index lens type spot size converters (Qian Wang, Yingyan Huang, etc., 2010), etc., and some research has also been conducted on the design and fabrication of ion-exchange glass-based spot size converters.

[0006] Teem Photonics of France has launched an ion exchange glass-based spot converter product (https: / / www.teemphotonics.com / integrated-optics / waft-interface-products / ), such as Figure 1 As shown. This mold spot converter is made by glass-based ion exchange optical waveguide technology, which has the unique advantages of simple process and low cost. By controlling the shape of the ion exchange window during the waveguide formation process, a buried conical ion doping area (101) is obtained in the glass substrate (100) to achieve the mold spot conversion function. This mold spot converter can change the mold spot size from 10.8×10μm at the input end to 2 Reduced to 4.1×3.1μm at the output 2 , the insertion loss is below 1.0dB, which can significantly reduce the coupling difficulty between optical fiber and SOI waveguide.

[0007] The size of the mold spot at the output end of the mold spot converter is an important performance indicator of the mold spot converter, but based on the existing glass-based mold spot converter manufacturing technology, it is very difficult to achieve a greater reduction in the mold spot size. The reason is that in the process of forming the mold spot converter by diffusion of doped ions, the size difference of the waveguide core layer at the input end and the output end of the mold spot converter is controlled by the width of the ion exchange window, but limited by the characteristics of the glass-based ion exchange technology, the diffusion depth and lateral broadening of the doped ions in the glass substrate (100) are mainly determined by the diffusion coefficient (related to temperature and ion concentration) and the diffusion time. The existing technology is difficult to achieve a large change from the mold spot size at the input end of the mold spot converter to the mold spot size at the output end. Therefore, using the existing mold spot converter manufacturing technology, further reducing the mold spot size at the output end (for example, 3μm or less) faces technical challenges in design and manufacturing. Summary of the invention

[0008] The present invention provides an ion exchange glass-based buried segmented pattern spot converter, which can achieve a greater reduction in pattern spot size through a segmented structure, improve device performance, and reduce the difficulty of design and production.

[0009] The ion exchange glass-based buried segmented pattern spot converter proposed by the present invention is formed by sequentially cascading n segments (n≥2) of glass-based conical waveguide chips. Each segment of the glass-based conical waveguide chip is composed of a glass substrate (100) and a buried conical ion doped region (101) therein. The cross-sectional dimensions of the thick end of the buried conical ion doping region (101) in the first glass-based conical waveguide chip match the core of the optical fiber and serve as the input end of the spot converter; the cross-sectional dimensions of the thick end of the buried conical ion doping region (101) in the second glass-based conical waveguide chip match the cross-sectional dimensions of the thin end of the buried conical ion doping region (101) in the first glass-based conical waveguide chip; and so on; the cross-sectional dimensions of the thick end of the buried conical ion doping region (101) in the nth glass-based conical waveguide chip match the cross-sectional dimensions of the thin end of the buried conical ion doping region (101) in the n-1th glass-based conical waveguide chip, and the thin end of the buried conical ion doping region (101) in the nth glass-based conical waveguide chip serves as the output end of the spot converter. The relative positions of adjacent glass-based conical waveguide chips are fixed by ultraviolet curing glue whose refractive index matches that of the glass substrate (100).

[0010] The basic structural unit of the ion exchange glass-based buried segmented spot converter described in the present invention is a glass-based conical waveguide chip. The size difference between the thick end and the thin end of the buried conical ion doping region (101) in the glass-based conical waveguide chip is controlled by the shape of the ion exchange window formed by the mask (200) on the surface of the glass substrate (100). The shape of the ion exchange window formed by the mask (200) on the surface of the glass substrate (100) is realized by the waveguide pattern on the mask. Figure 3 As shown, the light-transmitting area on the mask is a conical structure, with a thick end width of W1, a thin end width of W2, and a length of L.

[0011] Each section of glass-based tapered waveguide chip is made using thermal ion exchange-electric field assisted ion migration technology, including: Figure 4 The first step is coating, using sputtering or thermal evaporation technology to make a mask (200) on the surface of a clean glass substrate (100); the second step is photolithography, using standard photolithography, etching and other micro-processing processes to transfer the waveguide pattern on the mask to the mask (200) on the surface of the glass substrate (100) to form an ion exchange window; the third step is thermal ion exchange, immersing the glass substrate (100) in a molten salt containing doped ions at high temperature, and the doped ions in the molten salt enter through the ion exchange window formed by the mask (200) on the surface of the glass substrate (100). The invention relates to a method for manufacturing a glass substrate (100) and a method for manufacturing a glass substrate (100) comprising: firstly, a surface-type conical ion-doped region (102) is formed by ion-doping the surface-type conical ion-doped region (102) and then, the surface-type conical ion-doped region (102) is formed by ion-doping the surface-type conical ion-doped region (102) and then, the surface-type conical ion-doped region (102) is formed by ion-doping the surface-type conical ion-doped region (102) and then, the surface-type conical ion-doped region (102) is formed by ion-doping the surface-type conical ion-doped region (101) and then, the glass substrate (100) and the buried conical ion-doped region (101) constitute a glass-based conical waveguide chip.

[0012] The matching of the optical waveguide mode spot size at the connection between adjacent glass-based tapered waveguide chips is achieved by controlling the thick end width W1 and the thin end width W2 on each section of the glass-based tapered waveguide chip and the process parameters of thermal ion exchange-electric field assisted ion migration.

[0013] Finally, the glass-based tapered waveguide chips of various sections are aligned in sequence, and the relative positions of adjacent glass-based tapered waveguide chips are fixed by using ultraviolet curing glue whose refractive index matches that of the glass substrate (100).

[0014] The glass substrate (100) in the spot converter may be made of silicate glass, borate glass or phosphate glass; the doping ions in the buried conical ion doping region (101) may be Ag. + , Tl + , K+ , Rb + or Cs + .

[0015] The advantage of the ion exchange glass-based buried segmented pattern spot converter described in the present invention is that compared with the existing glass-based pattern spot converter, the glass-based buried segmented pattern spot converter described in the present invention can achieve a larger degree of pattern spot size conversion through the cascading of n segments of glass-based conical waveguide chips, thereby improving device performance and reducing the difficulty of design and production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the structure of the ion exchange glass-based spot converter launched by Teem Photonics.

[0017] Figure 2 It is a structural schematic diagram of the ion exchange glass-based buried segmented pattern spot converter described in the present invention.

[0018] Figure 3 This is a schematic diagram of the mask pattern used for the production of glass-based tapered waveguide chips.

[0019] Figure 4 This is a process flow chart for manufacturing glass-based tapered waveguide chips.

[0020] Figure 5 It is a structural schematic diagram of the ion exchange glass-based buried two-stage pattern spot converter described in the present invention.

[0021] Figure 6 It is a schematic structural diagram of the ion exchange glass-based buried three-stage pattern spot converter described in the present invention.

[0022] 100: Glass substrate.

[0023] 101: buried conical ion-doped region.

[0024] 102: Surface type conical ion doped region.

[0025] 200: Mask. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0027] Example 1: Design and fabrication of an ion exchange glass-based buried two-stage pattern converter

[0028] The ion exchange glass-based buried two-stage spot converter is composed of two sections of glass-based tapered waveguide chips cascaded together, such as Figure 5As shown. Each section of the glass-based conical waveguide chip is composed of a glass substrate (100) and a buried conical ion-doped region (101) therein. The cross-sectional dimensions of the thick end of the buried conical ion-doped region (101) in the first section of the glass-based conical waveguide chip match those of the optical fiber core, and serve as the input end of the pattern spot converter; the cross-sectional dimensions of the thick end of the buried conical ion-doped region (101) in the second section of the glass-based conical waveguide chip match those of the thin end of the buried conical ion-doped region (101) in the first section of the glass-based conical waveguide chip, and the thin end of the buried conical ion-doped region (101) in the second section of the glass-based conical waveguide chip serves as the output end of the pattern spot converter. The relative positions of the two sections of the glass-based conical waveguide chips are fixed by ultraviolet curing glue whose refractive index matches that of the glass substrate (100).

[0029] Each segment of the glass-based conical waveguide chip of the ion exchange glass-based buried two-segment spot converter is manufactured by using the thermal ion exchange-electric field assisted ion migration technology. The glass substrate (100) is made of soda-lime glass, which is processed into a disc with a diameter of 100 mm and a thickness of 1.5 mm. The manufacturing process of the glass-based conical waveguide chip specifically includes the following steps: Figure 4 The first step is coating, using thermal evaporation technology to make an aluminum mask (200) with a thickness of 100-300 nm on the surface of a clean glass substrate (100); the second step is photolithography, using standard photolithography, etching and other micro-processing processes to transfer the waveguide pattern on the mask to the aluminum mask (200) on the surface of the glass substrate (100) to form an ion exchange window; the third step is Ag + -Na + Thermal ion exchange, immersing the glass substrate (100) in a mixed molten salt composed of NaNO3, Ca(NO3)2, and AgNO3 at high temperature, during which the Ag in the molten salt is + The ions enter the interior of the glass substrate (100) through the ion exchange window formed by the aluminum mask (200) on the surface of the glass substrate (100), and diffuse to form a surface-type conical ion doping region (102); the fourth step is to remove the mask, and use an acid corrosion method to remove the aluminum mask (200) on the surface of the glass substrate (100), and clean the glass substrate (100); the fifth step is electric field assisted ion migration, under the action of high temperature and direct current electric field, the surface-type conical ion doping region (102) migrates into the interior of the glass substrate (100), forming a buried conical ion doping region (101), and the glass substrate (100) and the buried conical ion doping region (101) constitute a glass-based conical waveguide chip. The specific design and manufacturing parameters of each section of the glass-based conical waveguide chip of the ion exchange glass-based buried two-section spot converter are shown in Table 1.

[0030] Table 1 Design and fabrication parameters of ion exchange glass-based buried two-stage spot converter

[0031]

[0032] Finally, the glass substrate (100) is sliced ​​and the end surface is ground and polished to obtain two sections of glass-based tapered waveguide chips. The two sections of glass-based tapered waveguide chips are cut into two sections according to the Figure 5 The thick end of the buried conical ion doped region (101) in the second glass-based conical waveguide chip is aligned with the thin end of the buried conical ion doped region (101) in the first glass-based conical waveguide chip, and the relative position between the two glass-based conical waveguide chips is fixed by using an ultraviolet curing glue whose refractive index matches that of the glass substrate (100).

[0033] The ion exchange glass-based buried two-stage pattern spot converter manufactured according to the above method has a pattern spot size of about 10.8×10μm at the input end. 2 The mode field size at the output end can be reduced to 3.6 (± 0.3) × 2.5 (± 0.2) μm 2 .

[0034] Example 2: Design and fabrication of an ion exchange glass-based buried three-stage pattern converter

[0035] The ion exchange glass-based buried three-segment spot converter is composed of three sections of glass-based tapered waveguide chips cascaded together, such as Figure 6 As shown. Each section of the glass-based conical waveguide chip is composed of a glass substrate (100) and a buried conical ion-doped region (101) therein. The cross-sectional dimensions of the thick end of the buried conical ion-doped region (101) in the first section of the glass-based conical waveguide chip match the core of the optical fiber and serve as the input end of the pattern spot converter; the cross-sectional dimensions of the thick end of the buried conical ion-doped region (101) in the second section of the glass-based conical waveguide chip match the cross-sectional dimensions of the thin end of the buried conical ion-doped region (101) in the first section of the glass-based conical waveguide chip; the cross-sectional dimensions of the thick end of the buried conical ion-doped region (101) in the third section of the glass-based conical waveguide chip match the cross-sectional dimensions of the thin end of the buried conical ion-doped region (101) in the second section of the glass-based conical waveguide chip, and the thin end of the buried conical ion-doped region (101) in the third section of the glass-based conical waveguide chip serves as the output end of the pattern spot converter. The relative position between two adjacent sections of glass-based tapered waveguide chips is fixed by ultraviolet curing glue whose refractive index matches that of the glass substrate (100).

[0036] Each segment of the glass-based conical waveguide chip of the ion exchange glass-based buried three-segment spot converter is manufactured by using the thermal ion exchange-electric field assisted ion migration technology. The glass substrate (100) is made of soda-lime glass, which is processed into a disc with a diameter of 100 mm and a thickness of 1.5 mm. The manufacturing process of the glass-based conical waveguide chip specifically includes the following steps: Figure 4 The first step is coating, using thermal evaporation technology to make an aluminum mask (200) with a thickness of 100-300 nm on the surface of a clean glass substrate (100); the second step is photolithography, using standard photolithography, etching and other micro-processing processes to transfer the waveguide pattern on the mask to the aluminum mask (200) on the surface of the glass substrate (100) to form an ion exchange window; the third step is Ag + -Na + Thermal ion exchange, immersing the glass substrate (100) in a mixed molten salt composed of NaNO3, Ca(NO3)2, and AgNO3 at high temperature, during which the Ag in the molten salt is + The ions enter the interior of the glass substrate (100) through the ion exchange window formed by the aluminum mask (200) on the surface of the glass substrate (100), and diffuse to form a surface-type conical ion doping region (102); the fourth step is to remove the mask, and use an acid corrosion method to remove the aluminum mask (200) on the surface of the glass substrate (100), and clean the glass substrate (100); the fifth step is electric field assisted ion migration, under the action of high temperature and direct current electric field, the surface-type conical ion doping region (102) migrates into the interior of the glass substrate (100), forming a buried conical ion doping region (101), and the glass substrate (100) and the buried conical ion doping region (101) constitute a glass-based conical waveguide chip. The specific design and manufacturing parameters of each section of the glass-based conical waveguide chip of the ion exchange glass-based buried three-section spot converter are shown in Table 2.

[0037] Table 2 Design and fabrication parameters of ion exchange glass-based buried three-stage spot converter

[0038]

[0039]

[0040] Finally, the glass substrate (100) is sliced ​​and the end surface is ground and polished to obtain three sections of glass-based tapered waveguide chips. Figure 6The thick end of the buried conical ion doping region (101) in the second glass-based conical waveguide chip is aligned with the thin end of the buried conical ion doping region (101) in the first glass-based conical waveguide chip, and the thick end of the buried conical ion doping region (101) in the third glass-based conical waveguide chip is aligned with the thin end of the buried conical ion doping region (101) in the second glass-based conical waveguide chip. The relative positions of the two adjacent glass-based conical waveguide chips are fixed by using an ultraviolet curing adhesive having a refractive index matching that of the glass substrate (100).

[0041] The ion exchange glass-based buried three-stage pattern spot converter manufactured according to the above method has a pattern spot size of about 10.8×10μm at the input end. 2 The mode field size at the output end can be reduced to 3.2 (± 0.2) × 2.2 (± 0.2) μm 2 .

[0042] The above specific implementation modes are used to explain the present invention rather than to limit the present invention. Any modification and change made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

Claims

1. An ion exchange glass-based buried segmented spot converter, characterized in that: The spot converter is formed by sequentially cascading n glass-based conical waveguide chips, wherein n≥2; each glass-based conical waveguide chip is formed by a glass substrate (100) and a buried conical ion-doped region (101) therein; wherein the cross-sectional dimensions of the thick end of the buried conical ion-doped region (101) in the first glass-based conical waveguide chip match the core of the optical fiber, and serve as the input end of the spot converter; the cross-sectional dimensions of the thick end of the buried conical ion-doped region (101) in the second glass-based conical waveguide chip match the cross-sectional dimensions of the buried conical ion-doped region (101) in the first glass-based conical waveguide chip; and the cross-sectional dimensions of the thick end of the buried conical ion-doped region (101) in the second glass-based conical waveguide chip match the cross-sectional dimensions of the buried conical ion-doped region (101) in the first glass-based conical waveguide chip. The cross-sectional dimensions of the thick end of the buried conical ion-doped region (101) in the nth glass-based conical waveguide chip match the cross-sectional dimensions of the thin end of the buried conical ion-doped region (101) in the n-1th glass-based conical waveguide chip, and the thin end of the buried conical ion-doped region (101) in the nth glass-based conical waveguide chip serves as the output end of the pattern spot converter; the relative positions of adjacent glass-based conical waveguide chips are fixed by ultraviolet curing glue having a refractive index that matches that of the glass substrate (100); The glass substrate (100) is made of silicate glass material, borate glass material or phosphate glass material; The doping ions in the buried conical ion doping region (101) are Ag. + , Tl + , K + , Rb + or Cs + .

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