A high-sensitivity optical waveguide sensor based on ALD coating and its preparation method

Abstract

The present invention relates to an optical waveguide sensor, comprising a sensor body, wherein the sensor body comprises an input single-mode optical waveguide, a multi-mode optical waveguide and an output single-mode optical waveguide which are arranged in sequence, wherein the input single-mode optical waveguide and the multi-mode optical waveguide, and the multi-mode optical waveguide and the output single-mode optical waveguide are seamlessly connected, respectively, and the multi-mode optical waveguide comprises a core layer, a sensitive layer formed on two opposite sides of the core layer, and a cladding formed on the other side of the core layer. The optical waveguide sensor of the present invention adopts an input single-mode optical waveguide-multi-mode optical waveguide-output single-mode optical waveguide sensing structure, and a sensitive layer is arranged on the side of the multi-mode optical waveguide core layer, which greatly improves the sensitivity of such sensors.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical waveguide sensing, and in particular relates to a highly sensitive optical waveguide sensor based on ALD coating and a preparation method thereof. Background Art

[0002] At present, broadband communications, big data centers and supercomputers show an urgent need for high-speed bandwidth growth. However, the electrical interconnection technology of traditional PCB (Printed Circuit Board) shows an insurmountable bottleneck at bandwidths above 108Gbps. In recent years, the interconnection technology of optical backplanes (OPCBs, Optical Printed Circuit Boards) for information interconnection, which prepares a layer of optical waveguide on conventional PCBs, has developed rapidly. Because of its many advantages such as high bandwidth, low energy consumption, no electromagnetic interference, and low cost, it is very likely to become the mainstream technology for information interconnection of high-end communication equipment in the future. With the continuous development of optical backplane technology, integrated optical waveguide technology that integrates transmission, transceiver, sensing, multiplexing / demultiplexing is the future development trend.

[0003] At present, the sensing technologies based on on-board optical waveguides mainly include micro-ring optical waveguide sensing technology, waveguide grating sensing technology, and plasma resonance optical waveguide sensing technology. However, most of these optical waveguide sensing technologies are based on single mode, and there are few reports on multimode optical waveguide sensing technologies. For multimode optical fibers, the single-mode fiber-multimode fiber-single-mode fiber (SMS) sensing structure has been a research hotspot in recent years. It is mainly based on the multi-mode interference effect generated by the optical signal during the transmission of multimode optical fibers, so as to sense the change characteristics of physical quantities such as external temperature, stress, displacement and refractive index, causing the wavelength drift of the interference peak. For example, a fiber sensor disclosed in Chinese patent CN104713660A includes a single-mode-coreless-single-mode optical fiber structure. The single-mode-coreless-single-mode optical fiber structure consists of an input optical fiber and an output optical fiber, and a coreless optical fiber arranged between the two. The connection between the coreless optical fiber and the input optical fiber and the output optical fiber is non-eccentric fusion splicing, and the coreless optical fiber uses a multimode optical waveguide or an ordinary multimode optical fiber without the cladding. However, the fiber optic sensor only uses a fiber optic structure and lacks sensitivity. In addition, the reliability of this type of fiber optic sensor is poor and it is easily affected by multiple parameters of the external environment, such as stress, temperature, gas, etc. Therefore, when measuring a single parameter of the external environment, it is difficult to eliminate the influence of other parameters. Moreover, it is difficult to integrate this type of fiber optic sensor with inter-board functional devices and is difficult to apply. Summary of the invention

[0004] The object of the present invention is to provide a highly sensitive optical waveguide sensor and a method for preparing the same in order to overcome the deficiencies of the prior art.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] An optical waveguide sensor comprises a sensor body, wherein the sensor body comprises an input single-mode optical waveguide, a multi-mode optical waveguide and an output single-mode optical waveguide which are arranged in sequence, wherein the input single-mode optical waveguide and the multi-mode optical waveguide, and the multi-mode optical waveguide and the output single-mode optical waveguide are seamlessly connected, respectively, and the multi-mode optical waveguide comprises a core layer, a sensitive layer formed on two opposite sides of the core layer, and a cladding formed on the other side of the multi-mode core layer.

[0007] In a further embodiment, the sensitive layer is formed by ALD coating technology.

[0008] In a further embodiment, the thickness of the sensitive layer is 0.1 μm-1 μm.

[0009] In a further embodiment, the height and width of the multimode optical waveguide core layer are the same or different, and the size range is 9 μm-50 μm.

[0010] In a further embodiment, the length of the multimode optical waveguide core layer is 1 cm-2 cm.

[0011] In a further embodiment, the input single-mode optical waveguide includes a core layer and a cladding formed on the outer surface of the core layer, the output single-mode optical waveguide includes a core layer and a cladding formed on the outer surface of the core layer, and the multimode optical waveguide core layer is non-eccentrically connected to the input single-mode optical waveguide core layer and the output single-mode optical waveguide core layer at the connection points.

[0012] In a further embodiment, the height and width of the input single-mode optical waveguide core layer are the same or different, and the size range is 1 μm to 9 μm; the height and width of the output single-mode optical waveguide core layer are the same or different, and the size range is 1 μm to 9 μm.

[0013] In a further embodiment, the lengths of the input single-mode optical waveguide core layer and the output single-mode optical waveguide core layer are respectively greater than 1 cm.

[0014] In a further embodiment, the optical waveguide sensor further comprises a substrate, and the sensor body is fixedly disposed on the substrate.

[0015] Another technical solution adopted by the present invention is: a method for preparing an optical waveguide sensor, the preparation method includes preparing a multimode optical waveguide, and the preparation method of the multimode optical waveguide includes the following steps:

[0016] (1) Spin coating a layer of cladding glue on the surface of the substrate, heating and curing, and forming a lower cladding layer on the surface of the substrate;

[0017] (2) spin coating a layer of core layer glue on the surface of the lower cladding layer prepared in step (1), heating and curing, and forming a core layer on the lower cladding layer;

[0018] (3) Spin-coating a layer of cladding glue on the surface of the core layer obtained in step (2), heating and curing, forming an upper cladding layer on the core layer, and preparing a multimode optical waveguide semi-finished product, wherein the multimode optical waveguide semi-finished product comprises a lower cladding layer, a core layer, and an upper cladding layer sequentially formed on the substrate;

[0019] (4) placing light shielding plates on both sides of the upper cladding layer of the optical waveguide semi-finished product obtained in step (3), and then performing exposure using ultraviolet photolithography;

[0020] (5) removing the unexposed upper cladding layer, core layer and lower cladding layer treated in step (4) using a developer;

[0021] (6) A layer of sensitive film is coated on two opposite side walls of the multimode optical waveguide semi-finished product after being processed in step (5) by using ALD coating technology to obtain the multimode optical waveguide.

[0022] In a further embodiment, the method for preparing the optical waveguide sensor further comprises the following steps:

[0023] A. Spin-coat a layer of cladding glue on the prepared multimode optical waveguide sample;

[0024] B. injecting core layer glue on the substrate and at two ends of the multimode optical waveguide respectively by using a 3D direct writing process;

[0025] C. Expose the sample to ultraviolet light to solidify the cladding adhesive and the core adhesive, thereby preparing an input single-mode optical waveguide and an output single-mode optical waveguide.

[0026] In step A, the thickness of the spin-coated encapsulation layer is approximately equal to the thickness of the multimode optical waveguide.

[0027] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0028] The optical waveguide sensor of the present invention adopts an input single-mode optical waveguide-multi-mode optical waveguide-output single-mode optical waveguide sensing structure, and a sensitive layer is arranged on the side of the multi-mode optical waveguide core layer, which greatly improves the sensitivity of such sensors.

[0029] The optical waveguide sensor of the present invention organically integrates the optical waveguide preparation technology and combines the industry's advanced ALD coating technology to improve process compatibility, and can be organically integrated on an optical backplane to form a functional module, which is beneficial to improving the integration of optical waveguide functional devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1A highly sensitive optical waveguide sensor based on ALD coating according to an embodiment of the present invention;

[0031] Figure 2 A schematic diagram of the structure of an ALD-coated multi-mode optical waveguide according to an embodiment of the present invention;

[0032] Figure 3 A schematic diagram of the preparation process of an ALD-coated multimode optical waveguide according to an embodiment of the present invention;

[0033] Figure 4 A schematic diagram of the preparation process of an input single-mode optical waveguide and an output single-mode optical waveguide according to an embodiment of the present invention;

[0034] The names represented by the numbers in the figure are:

[0035] 01. Input single-mode optical waveguide; 02. Multi-mode optical waveguide; 03. Input single-mode optical waveguide;

[0036] 1. Substrate; 2. Lower cladding; 3. Core layer; 4. Upper cladding; 5. Sensitive layer; 6. Environmental layer; 7. 3D direct writing equipment. DETAILED DESCRIPTION

[0037] The specific implementation of the present invention is further described in detail below in conjunction with specific embodiments, but the implementation and protection scope of the present invention are not limited thereto.

[0038] like Figures 1 to 3 The high-sensitivity optical waveguide sensor based on ALD coating shown in the figure includes a substrate 1 and a sensor body fixedly arranged on the substrate 1, and the sensor body includes an input single-mode optical waveguide 01, a multi-mode optical waveguide 02 and an output single-mode optical waveguide 03 arranged in sequence, and the input single-mode optical waveguide 01 and the multi-mode optical waveguide 02, and the multi-mode optical waveguide 02 and the output single-mode optical waveguide 03 are seamlessly connected respectively.

[0039] In this example, the multimode optical waveguide 02 includes a lower cladding 2 formed on a substrate 1, a core layer 3 formed on the lower cladding 2, an upper cladding 4 formed on the surface of the core layer 3, and a sensitive layer 5 formed on two opposite side surfaces of the core layer 3, and the sensitive layer 5 also extends up and down to the side surfaces of the upper cladding 4 and the lower cladding 2.

[0040] The sensitive layer 5 is formed by ALD coating technology, and has a thickness of 0.1 μm-1 μm. The sensitive layer 5 can be used as a sensitive layer or as a multimode waveguide cladding. The sensitive layer 5 is relatively thin, and the mode field energy can penetrate the sensitive layer 5 to fully sense changes in external environmental parameters, such as changes in external gas and external liquid.

[0041] The height and width of the multimode optical waveguide core layer 3 are the same or different, and the size range is 9 μm-50 μm. The length of the multimode optical waveguide core layer 3 is 1 cm-2 cm. The thickness of the lower cladding layer 2 and the upper cladding layer 4 is >9 μm.

[0042] In this example, the input single-mode optical waveguide 01 includes a core layer and a cladding formed on the outer surface of the core layer, the output single-mode optical waveguide 03 includes a core layer and a cladding formed on the outer surface of the core layer, and the multimode optical waveguide core layer is non-eccentrically connected to the input single-mode optical waveguide core layer and the output single-mode optical waveguide core layer at the connection points.

[0043] The height and width of the input single-mode optical waveguide core layer are the same or different, and the size range is 1μm ~ 9μm; the height and width of the output single-mode optical waveguide core layer are the same or different, and the size range is 1m ~ 9μm. The length of the input single-mode optical waveguide core layer and the output single-mode optical waveguide core layer is 1cm-2cm.

[0044] Referring to Figures 3 and 4, the optical waveguide sensor is prepared by the following preparation method:

[0045] 1) Preparation of multimode optical waveguide

[0046] (1) Spin coating a layer of cladding glue on the surface of the cleaned substrate 1, heating and curing, and forming a lower cladding layer 2 on the surface of the substrate 1;

[0047] (2) Spin coating a layer of core layer glue on the surface of the lower cladding layer 2 prepared in step (1), heating and curing, and forming a core layer 3 on the lower cladding layer 2;

[0048] (3) Spin coating a cladding glue on the surface of the core layer 3 obtained in step (2), heating and curing, forming an upper cladding layer 4 on the core layer 3, and preparing a multimode optical waveguide semi-finished product, the multimode optical waveguide semi-finished product comprising a lower cladding layer 2, a core layer 3 and an upper cladding layer 4 formed in sequence on a substrate 1;

[0049] (4) placing light shielding plates on both sides of the upper cladding layer 4 of the multimode optical waveguide semi-finished product obtained in step (3), and then performing exposure by ultraviolet photolithography;

[0050] (5) Using a developer, remove the unexposed upper cladding layer 4, core layer 3 and lower cladding layer 2 treated in step (4), such as Figure 3 As shown, in the y direction, there are only the core layer 3 and the environmental layer 6 structure, and in the x direction, there are the lower cladding layer 2, the core layer 3, the upper cladding layer 4 and the environmental layer 6 structure in sequence;

[0051] (6) A sensitive layer 5 is coated on two opposite side walls of the multimode optical waveguide semi-finished product after the treatment in step (5) by using ALD coating technology to obtain a multimode optical waveguide, that is, a sensitive film is coated on the side wall of the core layer 3 in the y direction.

[0052] 2) Preparation of optical waveguide sensor

[0053] (1) Spin-coating a layer of cladding glue on the prepared multimode optical waveguide sample, the thickness of which is approximately equal to the thickness of the multimode optical waveguide;

[0054] (2) using a 3D direct writing device 7 to inject core layer glue on the substrate and at both ends of the multimode optical waveguide;

[0055] (3) The sample is exposed to ultraviolet light to solidify the cladding adhesive and the core adhesive, thereby preparing an input single-mode optical waveguide and an output single-mode optical waveguide.

[0056] In this example, the materials used to prepare the core layer, upper cladding layer and lower cladding layer of the multimode optical waveguide are all photosensitivity and are all negative resists.

[0057] EXEMPLARY EMBODIMENTS

[0058] In this example, the substrate is made of ordinary PCB material; the material for preparing the multimode core layer of the multimode optical waveguide is LightLink™ XP-6701A; the height, width and length of the multimode core layer are 50μm, 50μm and 1cm respectively; the material for preparing the upper cladding and the lower cladding is LightLink™ XH-100145; the material of the sensitive layer is SnO2 / SiO2 composite sensitive film with a thickness of 0.5μm.

[0059] The materials used to prepare the input single-mode optical waveguide core layer and the output single-mode optical waveguide core layer are both LightLink™ XP-6701A, and the height, width, and length of the input single-mode optical waveguide core layer and the output single-mode optical waveguide core layer are 9μm, 9μm, and 1cm, respectively; the materials used to prepare the input single-mode optical waveguide cladding and the output single-mode optical waveguide cladding are LightLink™ XH-100145, respectively.

[0060] Comparative Example

[0061] The optical waveguide sensor provided in this comparative example has the same structure as that of exemplary embodiment 1, except that no ALD coating process is performed.

[0062] Through simulation analysis, it is known that the sensitivity of the optical waveguide sensor of the exemplary embodiment 1 used for gas or liquid detection is as high as 2000nm / re, which is much better than the sensitivity of the general single-mode fiber-multimode fiber-single-mode fiber sensor. However, the sensitivity of the optical waveguide sensor of the comparative example used for gas or liquid detection is only 1200nm / re.

[0063] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an optical waveguide sensor, characterized in that: The preparation method includes the preparation of a multimode optical waveguide, and the preparation method of the multimode optical waveguide includes the following steps: (1) Spin coating a layer of cladding glue on the surface of the substrate, heating and curing, and forming a lower cladding layer on the surface of the substrate; (2) spin coating a layer of core layer glue on the surface of the lower multimode cladding layer obtained in step (1), heating and curing, and forming a core layer on the lower cladding layer; (3) spin coating a cladding glue on the surface of the core layer obtained in step (2), heating and curing, forming an upper cladding layer on the core layer, and preparing a multimode optical waveguide semi-finished product, wherein the multimode optical waveguide semi-finished product comprises a lower cladding layer, a core layer, and an upper cladding layer sequentially formed on the substrate; (4) placing light shielding plates on both sides of the upper cladding layer of the multimode optical waveguide semi-finished product obtained in step (3), and then performing exposure by ultraviolet photolithography; (5) removing the unexposed upper cladding layer, core layer and lower cladding layer treated in step (4) using a developer; (6) using ALD coating technology to coat a layer of sensitive film on two opposite side walls of the optical waveguide semi-finished product treated in step (5) to obtain the multimode optical waveguide, that is, coating a layer of sensitive film on the side wall in the y direction; The method for preparing the optical waveguide sensor further comprises the following steps: A. Spin-coat a layer of cladding glue on the prepared multimode optical waveguide sample; B. injecting core layer glue on the substrate and at two ends of the multimode optical waveguide respectively by using a 3D direct writing process; C. Expose the sample to ultraviolet light to solidify the cladding adhesive and the core adhesive, thereby preparing an input single-mode optical waveguide and an output single-mode optical waveguide.

2. An optical waveguide sensor, manufactured by the method for manufacturing an optical waveguide sensor according to claim 1, comprising a sensor body, characterized in that: The sensor body includes an input single-mode optical waveguide, a multi-mode optical waveguide and an output single-mode optical waveguide which are arranged in sequence. The input single-mode optical waveguide and the multi-mode optical waveguide, as well as the multi-mode optical waveguide and the output single-mode optical waveguide are seamlessly connected respectively. The multi-mode optical waveguide includes a core layer, a sensitive layer formed on two opposite sides of the core layer, and a multi-mode cladding formed on the other side of the core layer.

3. The optical waveguide sensor according to claim 2, characterized in that: The sensitive layer is formed by adopting ALD coating technology.

4. The optical waveguide sensor according to claim 2, characterized in that: The thickness of the sensitive layer is 0.1 μm-1 μm.

5. The optical waveguide sensor according to claim 2, characterized in that: The height and width of the core layer are the same or different, and the size range is 9 μm-50 μm.

6. The optical waveguide sensor according to claim 2, characterized in that: The length of the multimode optical waveguide is 1 cm-2 cm.

7. The optical waveguide sensor according to claim 2, characterized in that: The input single-mode optical waveguide includes a core layer and a cladding formed on the outer surface of the core layer, the output single-mode optical waveguide includes a core layer and a cladding formed on the outer surface of the core layer, and the multi-mode optical waveguide core layer is non-eccentrically connected to the input single-mode optical waveguide core layer and the output single-mode optical waveguide core layer at the connection point.

8. The optical waveguide sensor according to claim 2, characterized in that: The height and width of the input single-mode optical waveguide core layer are the same or different, and the size range is 1 μm to 9 μm; the height and width of the output single-mode optical waveguide core layer are the same or different, and the size range is 1 μm to 9 μm.

9. The optical waveguide sensor according to claim 2, characterized in that: The optical waveguide sensor further comprises a substrate, and the sensor body is fixedly arranged on the substrate.

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