A method for manufacturing a black phosphorus integrated fiber coupler

Abstract

The application discloses a kind of black phosphorus integrated optical fiber coupler manufacturing method, belong to optical sensing technical field, it is characterized as follows: a kind of black phosphorus integrated optical fiber coupler is by light source (1), incident single-mode optical fiber (2), black phosphorus integrated optical fiber coupler (3), output single-mode optical fiber (4), optical spectrum analyzer (5) composition.The black phosphorus integrated optical fiber coupler (3) is made by optical fiber fusion taper, and black phosphorus film on the surface of coupler is deposited on the surface of optical fiber coupler using layer-by-layer deposition method.Coupler is connected with light source by incident single-mode optical fiber, and is connected with optical spectrum analyzer by output single-mode optical fiber.The optical fiber sensor adopts two-dimensional material black phosphorus and optical fiber coupler structure combination, utilizes the excellent molecular adsorption performance of black phosphorus and its large specific surface area characteristics, so that the sensitivity of optical fiber coupler is further improved, and the sensor also has the characteristics such as simple structure, low manufacturing cost, etc., provides new direction for optical fiber sensing and biological detection.

Description

Technical Field

[0001] This invention belongs to the field of optical sensing technology, specifically relating to a method for fabricating a black phosphorus integrated fiber optic coupler. Background Technology

[0002] Fiber optic sensor technology utilizes optical properties for sensing and detection, offering advantages such as short response time, small size, simple structure, and immunity to electromagnetic interference, playing a crucial role in numerous fields. Tapered fiber optic sensors are relatively simple to fabricate, low in cost, and highly sensitive compared to other fiber optic sensors. However, due to their small waist diameter, this type of sensor exhibits relatively poor stability. Fiber optic couplers, made by fused and tapered two optical fibers, allow for a larger waist diameter without sacrificing sensitivity, resulting in better stability compared to tapered sensors made from a single fiber. Furthermore, the output spectrum of a fiber optic coupler structure exhibits a vernier effect, significantly increasing sensitivity several times compared to sensors without this effect. However, traditional fiber optic couplers have limitations, hindering the specific detection of particular molecules. Additionally, the sensing sensitivity of a single coupler is limited, leaving considerable room for improvement. Surface functionalization of optical fibers can greatly promote the realization of fiber-optic specific sensing and improve its sensitivity. Recent studies have shown that combining two-dimensional layered materials with optical fiber sensors can effectively improve sensor sensitivity, and the interaction with the analyte can also effectively improve the sensor's specific detection performance. This can be used in practical applications such as gas detection, temperature and humidity detection, and biosensors. Black phosphorus, due to its unique structure, has a larger specific surface area, higher hole mobility, and excellent molecular adsorption capacity compared to other two-dimensional materials. The superior performance of black phosphorus makes it a very promising nanomaterial, widely used in photodetectors, modulators, chemical sensors, and biochemical detection. It provides a suitable platform for the functionalization of optical fiber sensors. By combining optical fiber sensors with two-dimensional materials, and fully leveraging the advantages of both, a new direction for biosensing using optical fiber sensors is provided, which has significant research value and application prospects in enhancing the sensitivity and specific detection of optical fiber sensors. Summary of the Invention

[0003] The purpose of this invention is to combine the two-dimensional material black phosphorus with an optical fiber sensor, fully leveraging the advantages of both to improve the sensitivity of the optical fiber sensor while providing a new direction for the functionalization of optical fiber surfaces. By depositing a black phosphorus thin film in the uniform waist-cone region of the optical fiber coupler, the high-sensitivity detection of the optical fiber sensor is achieved by utilizing the large specific surface area and excellent molecular adsorption capacity of black phosphorus.

[0004] The technical solution adopted to achieve the above technical objectives is as follows:

[0005] A black phosphorus integrated fiber optic coupler comprises a light source (1), an incident single-mode fiber (2), a black phosphorus integrated fiber optic coupler (3), an output single-mode fiber (4), and a spectrometer (5). The black phosphorus integrated fiber optic coupler (3) is connected to the light source (1) through the incident single-mode fiber (2) and to the spectrometer (5) through the output single-mode fiber (4).

[0006] Furthermore, the fiber coupler (3) integrated with black phosphorus is fabricated by fiber fusion taper, and the specific fabrication method includes the following steps:

[0007] 1) Remove the coating from the single-mode fiber 101 using fiber optic pliers, clean the fiber surface with alcohol, and cut the end face flat with a fiber optic cleaver. Treat the coreless fiber 102 in the same way, align the two fiber segments, and fusion splice them.

[0008] 2) Remove the coating from the single-mode fiber 103 using fiber optic pliers, clean the fiber surface with alcohol, and cut the end face flat with a fiber optic cleaver. Align it with the other end of the coreless fiber from step 1) and perform fusion splicing.

[0009] 3) Use fiber optic pliers to strip the coating from the middle part of the single-mode fiber 104 and clean it with alcohol. Wrap the part with the stripped coating together with the coreless fiber 102 part from step 2).

[0010] 4) Fix the two strands of optical fiber together with a clamp, and use a flame tapering machine to heat the stranded part for flame heating tapering.

[0011] Furthermore, the single-mode fiber has a cladding diameter of 125 μm, a core diameter of 9 μm, a length of 30 cm for single-mode fiber 101, a length of 30 cm for single-mode fiber 103, and a cladding outer diameter of 125 μm, an inner diameter of 62.5 μm, and a length of 1 cm for the coreless fiber.

[0012] Furthermore, the fiber optic coupler has a transition cone region length of 8 mm, a uniform lumbar region length of 8 mm, and a diameter of 6 μm.

[0013] Furthermore, the flame conical heating time is 180 seconds.

[0014] Furthermore, the black phosphorus thin film in the black phosphorus integrated optical fiber coupler (3) is prepared by multiple depositions using a black phosphorus solution. The specific preparation method includes the following steps:

[0015] 1) The fiber optic coupler was immersed in a piranha solution for 1 hour to enrich the fiber optic surface with -OH groups, and then thoroughly washed with distilled water and anhydrous ethanol.

[0016] 2) The silanized fiber coupler was incubated in a freshly prepared 10% APTES solution for two hours to form Si-O-Si bonds and leave -NH2 on the fiber surface for the next reaction. Then it was thoroughly washed with distilled water and anhydrous ethanol.

[0017] 3) Fix the fiber optic coupler in the microchannel container and carefully add 30 μL of black phosphorus solution to it, waiting for the ethanol solvent in the black phosphorus solution to gradually evaporate completely.

[0018] 4) Subsequently, the black phosphorus molecules that were not completely fixed on the fiber surface were washed with distilled water and anhydrous ethanol, and a second deposition cycle was performed. A total of 3 deposition cycles were performed, each lasting 40 minutes. After the deposition cycle was completed, black spots could be observed on the surface of the fiber sensor, indicating that the black phosphorus film (6) on the surface of the fiber coupler was deposited.

[0019] Furthermore, the piranha solution is prepared by mixing concentrated sulfuric acid and 30% hydrogen peroxide in a 7:3 ratio.

[0020] Furthermore, the thickness of the black phosphorus film on the surface of the fiber coupler is 300 nm.

[0021] The black phosphorus-integrated fiber optic coupler proposed in this invention is relatively simple to fabricate, low in cost, and highly sensitive. Depositing a black phosphorus solution onto the fiber optic coupler allows for a larger sensing area and effectively enhances the sensor's molecular adsorption performance. Furthermore, the specific binding of black phosphorus with certain materials enables specific detection. When the black phosphorus film deposited on the fiber adsorbs sensing ions, the evanescent field around the fiber changes, leading to a change in the output spectrum. Observing this change in the output spectrum allows for effective analysis of the analyte's information. Combining black phosphorus with a fiber optic coupler effectively improves the sensor's accuracy and sensitivity, opens up new research directions, and provides new research ideas for the field of optical sensing. Attached Figure Description

[0022] Figure 1 The diagram shows a black phosphorus integrated fiber optic coupler detection device provided by the present invention.

[0023] Figure 2 This is a schematic diagram of the sensing region structure of the fiber optic coupler provided by the present invention.

[0024] Figure 3 The transmission spectrum during the fabrication of the fiber optic coupler provided by this invention. Detailed Implementation

[0025] This example utilizes a black phosphorus-integrated fiber optic coupler. A black phosphorus film is deposited on the fiber optic coupler, and the large specific surface area and excellent molecular adsorption properties of the black phosphorus film are used to achieve high sensitivity and high accuracy of fiber optic coupler sensing.

[0026] In this embodiment, P1 is selected as the input port and P3 is selected as the output port. The output power of the output port can be expressed as:

[0027]

[0028] Among them, P 1x and P 1y These represent the input optical power of input port P1 in the X and Y polarization directions, respectively. The phase difference accumulated in the odd and even modes can be represented as:

[0029]

[0030]

[0031] in, These represent the effective refractive indices of the even-mode X / Y polarization states, respectively. λ and L represent the effective refractive indices of the odd-mode X / Y polarization states, respectively. λ is the incident light wavelength, and L represents the length of the uniform waist region of the coupler.

[0032] The working principle of this invention is as follows: When X / Y polarized light is incident on the coupler port through the input fiber, the odd-numbered and even-numbered supermodes are excited in the cone region. According to supermode theory, the two parallel micro / nano fibers can be regarded as a new type of waveguide. When the two modes propagate along the uniform waist, they couple. Since X-polarization and Y-polarization produce a certain phase difference during propagation, they superimpose during propagation in the coupling cone region. Therefore, an envelope spectrum with a vernier effect can be observed at the output port. When the environment around the fiber changes, the output spectrum also changes accordingly. By observing the changes in the spectrum, changes in the external environment can be reflected.

[0033] Combined with appendix Figure 1 A black phosphorus integrated fiber optic coupler comprises a light source (1), an incident single-mode fiber (2), a black phosphorus integrated fiber optic coupler (3), an output single-mode fiber (4), and a spectrometer (5). The black phosphorus integrated fiber optic coupler (3) is connected to the light source (1) through the incident single-mode fiber (2) and to the spectrometer (5) through the output single-mode fiber (4).

[0034] Combined with appendix Figure 2A black phosphorus integrated optical fiber coupler (3) is formed by sequentially fusing a single-mode fiber 101, a coreless fiber 102, and a single-mode fiber 103 together at one end of the optical fiber coupler. It is wound together with another single-mode fiber 104 and made by flame taper.

[0035] Combined with appendix Figure 2 A black phosphorus integrated optical fiber coupler (3) The specific steps of black phosphorus deposition are as follows:

[0036] 1) The fiber optic coupler was immersed in a piranha solution for 1 hour to enrich the fiber optic surface with -OH groups, and then thoroughly washed with distilled water and anhydrous ethanol.

[0037] 2) The silanized fiber coupler is incubated in a freshly prepared 10% APTES solution for two hours to form Si-O-Si bonds, and then thoroughly washed with distilled water and anhydrous ethanol.

[0038] 3) Fix the fiber optic coupler in the microchannel container and carefully add 30 μL of black phosphorus solution to it, waiting for the ethanol solvent in the black phosphorus solution to gradually evaporate completely.

[0039] 4) Subsequently, the black phosphorus molecules that were not completely fixed on the surface of the optical fiber were cleaned with distilled water and anhydrous ethanol, and a second deposition cycle was performed. A total of 3 deposition cycles were performed, with each deposition cycle lasting 40 minutes.

[0040] In summary, the black phosphorus integrated fiber optic coupler of this invention has a stable structure, low manufacturing cost, and high sensitivity. By utilizing the high sensitivity of the fiber optic coupler and the specificity of black phosphorus, it provides a new direction for fiber optic sensing and biological detection.

Claims

1. A black phosphorus integrated fiber coupler, characterized in that it comprises a light source (1), an incident single-mode fiber (2), a black phosphorus integrated fiber coupler (3), an output single-mode fiber (4), and a spectrometer (5). The black phosphorus integrated fiber coupler (3) is composed of an incident single-mode fiber, a coreless fiber, and an output single-mode fiber fused together in sequence. The coreless fiber is wound together with another single-mode fiber and made by flame taper. Its structure includes a transition cone region and a uniform waist cone region connected in sequence. The uniform waist cone region has a length of 8 mm and a diameter of 6 μm. A black phosphorus film (6) is fixed on the surface of the uniform waist cone region by silanization treatment and layer-by-layer deposition. The thickness of the black phosphorus film is 300 nm. The black phosphorus integrated fiber coupler (3) is connected to the light source (1) through the incident single-mode fiber (2) and to the spectrometer (5) through the output single-mode fiber (4).

2. The black phosphorus integrated fiber coupler according to claim 1, characterized in that, The fiber optic coupler fabrication method includes the following steps: 1) Remove the coating from the single-mode fiber with fiber pliers, clean the fiber surface with alcohol, and cut the end face flat with a fiber cleaver. Treat both ends of the coreless fiber in the same way, and align the two fiber segments for fusion splicing. 2) Remove the coating from the single-mode fiber with fiber pliers, clean the fiber surface with alcohol, and cut the end face flat with a fiber cleaver. Align it with the other end of the coreless fiber from step 1) and fusion splice it. 3) Use fiber optic pliers to strip the coating from the middle part of the single-mode fiber and clean it with alcohol. Wrap the part with the stripped coating together with the coreless fiber (102) part from step 2). 4) Fix the two strands of optical fiber together with a clamp, and use a flame melting tapering machine to heat the stranded part for flame heating tapering.

3. The black phosphorus integrated fiber coupler according to claim 1, characterized in that, The preparation method of the black phosphorus film (6) includes the following steps: 1) Immerse the fiber optic coupler in piranha solution for 1 hour, then clean it to enrich its surface with -OH groups; 2) Immerse the treated fiber coupler in a 10% APTES solution for 2 hours to form Si-O-Si bonds and introduce -NH2 groups on its surface, then clean it. 3) Fix the fiber optic coupler in the microchannel container, add 30 μL of black phosphorus solution, and wait for the solvent to evaporate; 4) Repeat step (3) 3 times, each time for 40 minutes, to form a black phosphorus film with a thickness of 300 nm.

4. The fiber optic coupler according to claim 1 or 2, characterized in that: The single-mode fiber has a cladding diameter of 125 μm and a core diameter of 9 μm; the lengths of the incident single-mode fiber and the output single-mode fiber are both 30 cm; the coreless fiber has a cladding outer diameter of 125 μm, an inner diameter of 62.5 μm, and a length of 1 cm.

5. The fiber optic coupler according to claim 1 or 2, characterized in that, The heating time of the flame-drawn cone is 180 seconds to form an optical fiber coupler structure with a transition cone region length of 8 mm, a uniform waist cone region length of 8 mm, and a diameter of 6 μm.

6. The fiber optic coupler according to claim 1 or 2, characterized in that, The thickness of the black phosphorus film can be controlled by the number of deposition layers. The prepared black phosphorus film has a thickness of about 300 nm. The piranha solution is prepared by mixing concentrated sulfuric acid and 30% hydrogen peroxide in a volume ratio of 7:3.

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