Ion-exchange-based adjustable optical splitter and its manufacturing process

Abstract

The present invention relates to the field of integrated optical splitters, and discloses a tunable optical splitter based on ion exchange and its manufacturing process, which mainly includes a glass substrate, metal electrodes, and glass-based waveguides. The manufacturing process of the optical splitter based on ion exchange mainly includes the following two steps. The first step is to perform a secondary mixed molten salt ion exchange process above the glass-based PLC (planar lightwave circuit) device; the second step is to fabricate metal electrodes on the surface of the secondary ion exchange region by using the Lift-off process. The tunable optical splitter in the present invention can regulate the ion exchange process in the waveguide region of the glass-based PLC (planar lightwave circuit) through the heat generated by the metal thermal electrode or the capacitive electric field formed by two metal electrodes, so as to achieve the purpose of modulating the propagation mode of the waveguide in the ion exchange region and the splitting ratio of the optical splitter.

Description

Technical Field

[0001] The present invention relates to the field of integrated optical splitters, and particularly to a modifiable optical splitter based on ion exchange and a preparation process thereof. Background Art

[0002] With the continuous progress and development of science and technology, significant breakthroughs have been made in the research of communication technologies. As the key to the basic network, optical communication networks occupy a core position in the communication network. Among them, optical transmission technology is a new generation of network communication technology with both information transmission functions and independent storage and exchange functions, playing an important role in optical communication networks. In optical communication and optical transmission networks, optical splitters are usually used to achieve functions such as changing the transmission direction of optical signals and distributing the optical signal power of different branches, and are indispensable key integrated optical devices in FTTH (Fiber To The Home) of FTTx (Fiber To The x) fiber access network technology.

[0003] Planar monolithic integrated photon technology is also known as Planar lightwave circuit (PLC). Due to its low loss, excellent uniformity, small footprint, easy integration and processing, long-term reliability, and low cost within the working wavelength range, glass-based PLC (Planar lightwave waveguide) devices have attracted extensive interest from researchers. Currently, there are mainly several process technologies for preparing optical waveguides on a planar glass substrate, including ion exchange, plasma-enhanced chemical vapor deposition (PECVD), sol-gel spin coating, and flame hydrolysis. Among these processes, ion exchange technology not only has many advantages such as low cost and stable process, but also has a high refractive index contrast between the prepared waveguide and the glass substrate. The glass-based PLC (Planar lightwave waveguide) optical waveguide fabricated by this process is located several micrometers below the glass substrate surface, which can not only ensure the stability of the waveguide structure, but also greatly reduce the optical transmission loss in the waveguide and maintain a low polarization correlation of the waveguide, achieving the purpose of supporting defined modes, and at the same time, it can also have good compatibility with the optical fiber transmission system.

[0004] With the rapid development of the big data era and 5G communication technology, glass-based PLC (Planar lightwave waveguide) optical splitters have been widely used in data center optical interconnection networks and communication base station construction, and have become one of the most critical passive devices in passive optical transmission networks, and are the core devices connecting optical network terminals and optical network units. However, due to the lack of modulation means, glass-based PLC (Planar lightwave waveguide) optical splitters are difficult to meet the requirements of various application scenarios. Most current solutions use overall heating of glass-based PLC (Planar lightwave waveguide) devices. This solution has a single modulation means, cannot accurately control the splitting ratio of glass-based PLC (Planar lightwave waveguide) optical splitters, and generates high power consumption during the modulation process. Summary of the Invention

[0005] The object of the present invention is to overcome the defects of the above-mentioned prior art and provide a tunable optical splitter based on ion exchange and its manufacturing process. The optical splitter can regulate the ion exchange process in the waveguide region of a glass-based PLC (planar lightwave circuit) through the heat generated by a metal thermal electrode or the capacitive electric field formed by two metal electrodes, so as to achieve the purpose of modulating the propagation mode of the waveguide in the ion exchange region and the splitting ratio of the optical splitter.

[0006] To achieve the above object, the present invention is achieved through the following three technical solutions:

[0007] A tunable optical splitter based on ion exchange, comprising a glass substrate, a metal thermal electrode, a secondary ion exchange region, and a glass-based waveguide, wherein the glass-based waveguide is buried in the glass substrate; the secondary ion exchange region is located on the upper surface of the glass-based waveguide; the metal thermal electrode is located on the upper surface of the secondary ion exchange region.

[0008] A tunable optical splitter based on ion exchange, comprising a glass substrate, a metal first driver, a secondary ion exchange region, a glass-based waveguide, and a metal second driver electrode, wherein the metal second driver electrode is located on the lower surface of the glass substrate; the glass-based waveguide is buried in the glass substrate; the secondary ion exchange region is located on the upper surface of the glass-based waveguide; the metal first driver is located on the upper surface of the secondary ion exchange region, and the metal first driver and the metal second driver electrode are externally connected to a power supply to form a capacitive electric field.

[0009] A tunable optical splitter based on ion exchange, comprising a glass substrate, a metal thermal electrode, and a glass-based waveguide, wherein the glass-based waveguide is buried in the glass substrate; the metal thermal electrode is located on the upper surface of the glass substrate and above the glass-based waveguide.

[0010] The structure of the glass-based waveguide in the above three technical solutions can be fabricated into a Mach-Zehnder interferometer, a directional coupler, or a Y-branch.

[0011] The metal thermal electrode and the metal first driver electrode in the above three technical solutions are fabricated by electron beam thermal evaporation process and Lift-off process (metal stripping process).

[0012] The secondary ion exchange region in the first and second solutions is fabricated by photolithography and wet etching process.

[0013] The metal second driver electrode in the second solution is fabricated by electron beam thermal evaporation process.

[0014] In the second solution, the metal first driving electrode and the metal second driving electrode are respectively bonded to a PCB (printed circuit board) by means of probes or leads. The probes or leads can be connected to any position of the metal electrodes. The metal first driving electrode is externally connected to the positive pole of a power supply; the metal second driving electrode is externally connected to the negative pole of the power supply.

[0015] The components of the metal thermal electrode and the metal first driving electrode are made of exactly the same process and materials. Only because of their different functions in the technical solutions, two different names are used.

[0016] Each structure in the three technical solutions is formed into a whole by an integration method, and the integration method means the usual meaning of the integration method used in the integrated circuit semiconductor microfabrication process in this field.

[0017] Working principle of the first technical solution: The metal thermal electrode is electrically heated, and the heat transferred through the metal thermal electrode drives the ions in the glass-based waveguide and the secondary ion exchange region to diffuse, so as to achieve the purpose of modulating the glass-based PLC (planar light waveguide) waveguide and the splitting ratio of the optical splitter.

[0018] Working principle of the second technical solution: The capacitive electric field formed by two metal driving electrodes drives the ions in the glass-based waveguide and the secondary ion exchange region to diffuse, so as to achieve the purpose of modulating the glass-based PLC (planar light waveguide) waveguide and the splitting ratio of the optical splitter.

[0019] Working principle of the third technical solution: The metal thermal electrode is electrically heated, and the heat transferred through the metal thermal electrode drives the ions in the glass-based waveguide to diffuse, so as to achieve the purpose of modulating the glass-based PLC (planar light waveguide) waveguide and the splitting ratio of the optical splitter.

[0020] All three technical solutions use metal electrodes to control ion diffusion so as to achieve the control of the splitting ratio of the device. The control methods are specifically divided into two types: metal resistance heat and electric field drive.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: Compared with the current modulation method for glass-based PLC optical splitters (heating the whole device), this modulation scheme is likely to cause instability of the glass substrate, and it is difficult to achieve accurate control of the branch optical power distribution, and a relatively high power consumption is generated during the modulation process. The ion-exchange-based tunable optical splitter of the present invention can drive the ions to diffuse directionally through the heat transferred by the metal thermal electrode or the capacitive electric field formed by two metal driving electrodes, so as to achieve the purpose of modulating the glass-based waveguide and the splitting ratio of the optical splitter. This technical means can avoid heating the glass substrate and has a relatively low power consumption, solving the problem that the existing modulation means of glass-based PLC optical splitters are single and difficult to meet the requirements of various application scenarios. Brief Description of the Drawings

[0022] Figure 1 FIG. is a schematic cross-sectional structure diagram of a tunable optical splitter based on ion exchange in Embodiment 1 of the present invention;

[0023] Figure 2 FIG. is a schematic cross-sectional structure diagram of a tunable optical splitter based on ion exchange in Embodiment 2 of the present invention;

[0024] Figure 3 FIG. is a schematic cross-sectional structure diagram of a tunable optical splitter based on ion exchange in Embodiment 3 of the present invention;

[0025] Figure 4 FIG. is a schematic top view structure diagram of a Mach-Zehnder interferometer optical splitter in Embodiment 1 of the present invention;

[0026] Figure 5 FIG. is a schematic three-dimensional structure diagram of a Mach-Zehnder interferometer optical splitter in Embodiment 2 of the present invention;

[0027] Figure 6 FIG. is a schematic three-dimensional structure diagram of a directional coupler optical splitter in Embodiment 2 of the present invention;

[0028] Figure 7 FIG. is a schematic three-dimensional structure diagram of a Y-branch optical splitter in Embodiment 2 of the present invention.

[0029] In the figure: 101 is a glass substrate; 102A is a metal thermal electrode; 102B is a metal first driving electrode; 103 is a secondary ion exchange region; 104 is a glass-based waveguide; 105 is a metal second driving electrode. Detailed Embodiments

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0031] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the structure or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0032] The present invention relates to an ion-exchange-based tunable optical splitter and its manufacturing process, specifically including three different optical splitter structures and corresponding manufacturing process flows. The specific implementation schemes of these three different optical splitters and their manufacturing processes will be introduced separately below.

[0033] Example 1:

[0034] An ion-exchange-based tunable optical splitter (as Figure 1 shown) includes a glass substrate 101, a metal thermal electrode 102A, a secondary ion-exchange region 103, and a glass-based waveguide 104. The glass-based waveguide 104 is buried in the glass substrate 101. The secondary ion-exchange region 103 is located on the upper surface of the glass-based waveguide 104, and the metal thermal electrode 102A is located on the upper surface of the secondary ion-exchange region 103. For the top view of this structure, please refer to Figure 4 . Heat transferred through the metal thermal electrode drives the diffusion of ions in the glass-based waveguide and the secondary ion-exchange region, thereby achieving the purpose of modulating the glass-based PLC (Planar Lightwave Circuit) waveguide and the splitting ratio of the optical splitter.

[0035] The manufacturing process flow of the tunable optical splitter in this example is as follows:

[0036] The first step is to deposit a hard mask aluminum film on the surface of the glass-based PLC device;

[0037] The second step is to prepare an ion-exchange window through photolithography and wet etching processes;

[0038] The third step is to place the glass-based PLC device with the ion-exchange window in a molten salt containing doped ions at a high temperature for ion exchange;

[0039] The fourth step is to remove the mask through wet etching and then prepare a metal thermal electrode window through a photolithography process again;

[0040] The fifth step is to deposit a metal thermal electrode thin film through electron beam thermal evaporation and use the Lift-off process to strip the metal thin film except for the thermal electrode to obtain the metal thermal electrode.

[0041] Example 2:

[0042] An ion-exchange-based tunable optical splitter (as Figure 2As shown in the figure, it includes a glass substrate 101, a metal first driving electrode 102B, a secondary ion exchange region 103, a glass-based waveguide 104, and a metal driving electrode 105. The metal second driving electrode 105 is located on the lower surface of the glass substrate 101. The glass-based waveguide 104 is buried in the glass substrate 101. The secondary ion exchange region 103 is located on the upper surface of the glass-based waveguide 104. The metal first driving electrode 102B is located on the upper surface of the secondary ion exchange region 103. The metal first driving electrode 102B and the metal second driving electrode 105 are externally connected to a power supply to form a capacitive electric field. The structure of the glass-based waveguide 104 can be fabricated into a Mach-Zehnder interferometer (3D

[0043] The three-dimensional perspective view is as Figure 5 shown), a directional coupler (the three-dimensional perspective view is as Figure 6 shown), or a Y-branch (the three-dimensional perspective view is as Figure 7 shown). The metal first driving electrode 102B and the metal second driving electrode 105 are respectively bonded to a PCB (printed circuit board) by means of probes or leads. The probes or leads can be connected to any position of the metal electrodes. The metal first driving electrode 102B is externally connected to the positive pole of the power supply, and the metal second driving electrode 105 is externally connected to the negative pole of the power supply. The capacitive electric field formed by the two metal electrodes drives the ions in the glass-based waveguide and the secondary ion exchange region to diffuse, thereby achieving the purpose of modulating the glass-based PLC (planar lightwave circuit) waveguide and the splitting ratio of the optical splitter.

[0044] The preparation process flow of the tunable optical splitter in this embodiment is as follows:

[0045] The first step is to deposit a mask on the surface of the glass-based PLC device;

[0046] The second step is to fabricate an ion exchange window through photolithography and wet etching processes;

[0047] The third step is to place the glass-based PLC device with the ion exchange window in a molten salt containing doped ions at a high temperature for ion exchange;

[0048] The fourth step is to remove the mask through wet etching and then fabricate a metal driving electrode window on the upper surface of the glass-based PLC device through a photolithography process;

[0049] The fifth step is to deposit a metal driving electrode thin film on the upper surface of the glass-based PLC device through electron beam thermal evaporation, and use the Lift-off process to strip the metal thin film except for the driving electrode to fabricate the metal first driving electrode;

[0050] The sixth step is to deposit a metal driving electrode thin film on the lower surface of the glass-based PLC device through electron beam thermal evaporation to fabricate the metal second driving electrode.

[0051] Embodiment 3:

[0052] A modifiable optical splitter based on ion exchange (as Figure 3 shown), comprising a glass substrate 101, a metal thermal electrode 102A and a glass-based waveguide 104. The glass-based waveguide 104 is buried in the glass substrate 101, and the metal thermal electrode 102A is located on the upper surface of the glass substrate 101 and above the glass-based waveguide 104. The heat transferred through the metal thermal electrode drives the diffusion of ions in the glass-based waveguide, thereby achieving the purpose of modulating the glass-based PLC (planar optical waveguide) waveguide and the splitting ratio of the optical splitter.

[0053] The preparation process flow of the modifiable optical splitter in this embodiment is as follows:

[0054] The first step is to spin-coat photoresist above the glass-based PLC device;

[0055] The second step is to prepare a metal thermal electrode deposition window through a photolithography process;

[0056] The third step is to deposit a metal thermal electrode thin film by electron beam thermal evaporation and use a Lift-off process to strip the metal thin film other than the thermal electrode to obtain the metal thermal electrode.

[0057] The glass-based PLC devices in the above-mentioned first embodiment, second embodiment and third embodiment refer to the whole formed by burying the glass-based waveguide in the glass substrate, and can be specifically divided into Mach-Zehnder interferometers, directional couplers or Y-branches.

[0058] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A modifiable optical splitter based on ion exchange, comprising a glass substrate (101), a metal thermal electrode (102A), a secondary ion exchange region (103), and a glass-based waveguide (104), characterized in that: The glass-based waveguide (104) is buried in the glass substrate (101); the secondary ion exchange region (103) is located on the upper surface of the glass-based waveguide (104); the metal thermal electrode (102A) is located on the upper surface of the secondary ion exchange region (103).

2. A modifiable optical splitter based on ion exchange, comprising a glass substrate (101), a first metal driving electrode (102B), a secondary ion exchange region (103), a glass-based waveguide (104) and a second metal driving electrode (105), characterized in that, The metal second driving electrode (105) is located on the lower surface of the glass substrate (101); the glass-based waveguide (104) is buried in the glass substrate (101); the secondary ion exchange region (103) is located on the upper surface of the glass-based waveguide (104); the metal first driving electrode (102B) is located on the upper surface of the secondary ion exchange region (103), and the metal first driving electrode (102B) and the metal second driving electrode (105) are externally connected to a power supply to form a capacitive electric field.

3. The ion-exchange-based adjustable optical splitter according to claim 1 or 2, characterized in that The structure of the glass-based waveguide (104) can be fabricated into a Mach-Zehnder interferometer, a directional coupler, or a Y-branch.

4. The ion-exchange-based adjustable optical splitter according to claim 1 or 2, characterized in that, The secondary ion exchange region (103) is fabricated by photolithography and wet etching processes.

5. The ion-exchange-based adjustable optical splitter according to claim 1 or 2, characterized in that The metal thermal electrode (102A) or the metal first driving electrode (102B) is fabricated by electron beam thermal evaporation process and Lift-off process.

6. The modifiable optical splitter based on ion exchange according to claim 2, characterized in that The metal second driving electrode (105) is fabricated by electron beam thermal evaporation process; the metal first driving electrode (102B) and the metal second driving electrode (105) are respectively bonded to the PCB (printed circuit board) by means of probes or leads, and the probes or leads can be connected to any position of the metal electrode. The metal first driving electrode (102B) is externally connected to the positive pole of the power supply; the metal second driving electrode (105) is externally connected to the negative pole of the power supply.

7. The preparation process of a modifiable optical splitter based on ion exchange according to claim 1, characterized in that: Including the following steps: 7.1), In the first step, deposit a hard mask aluminum film on the surface of the glass-based PLC device; 7.2), In the second step, prepare an ion exchange window through photolithography and wet etching processes; 7.3), In the third step, place the glass-based PLC device with the ion exchange window in a molten salt containing doped ions at a high temperature for ion exchange; 7.4), In the fourth step, remove the mask by wet etching and then prepare a metal thermal electrode window through photolithography process; 7.5), In the fifth step, deposit a metal thermal electrode thin film by electron beam thermal evaporation and adopt the Lift-off process to strip the metal thin film except the thermal electrode to obtain the metal thermal electrode.

8. The preparation process of a modifiable optical splitter based on ion exchange according to claim 2, characterized in that: Including the following steps: 8.1), In the first step, deposit a mask on the surface of the glass-based PLC device; 8.2), In the second step, prepare an ion exchange window through photolithography and wet etching processes; 8.3), In the third step, place the glass-based PLC device with the ion exchange window in a molten salt containing doped ions at a high temperature for ion exchange; 8.4), In the fourth step, remove the mask by wet etching and then prepare a metal driving electrode window on the upper surface of the glass-based PLC device through photolithography process; 8.5), In the fifth step, deposit a metal driving electrode thin film on the upper surface of the glass-based PLC device by electron beam thermal evaporation, and adopt the Lift-off process to strip the metal thin film except the driving electrode to obtain the metal first driving electrode. 8.6), The sixth step is to deposit a metal driving electrode thin film on the lower surface of the glass-based PLC device by electron beam thermal evaporation to obtain the second metal driving electrode.

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