KR100879582B1 - Optical fiber with metal nano-particles and fabrication methods for the optical fiber - Google Patents

Abstract

The present invention relates to a functional optical fiber containing metal nano-particles and a method of manufacturing the same. The present invention comprises the steps of depositing and sintering the cladding layer in the glass tube in the optical fiber manufacturing method; Depositing and partially sintering a core layer in the glass tube; Adding a metal element to the core layer; Drying the core layer to which the metal element is added and then forming a reducing atmosphere; Performing a sintering, vitrification, compression, and sealing process while maintaining the formed reducing atmosphere; It provides a method for producing an optical fiber containing metal nanoparticles, comprising; forming a optical fiber by withdrawing the prepared optical fiber base material.

Metal element, nano particle, optical fiber, reduction method, solution addition method, MCVD method

Description

Optical fiber with metal nano-particles and fabrication methods for the optical fiber}

1 is a view for explaining a metal nanoparticle-containing optical fiber manufacturing process according to the present invention.

2 is a side view of an apparatus for performing a metal element addition process using a solution addition method.

3 is a view for explaining the metal element addition process (step ST3) shown in FIG. 1 using the apparatus shown in FIG.

Figures 4a to 4c is a view showing the light absorption coefficient of a functional optical fiber containing a common optical fiber and Ag-metal nanoparticles in the core.

5A and 5B are TEM photographs of a functional optical fiber base material containing a general optical fiber base material and Ag-metal nanoparticles in a core;

FIG. 6 is a view showing nonlinear optical coefficients of a functional optical fiber including a general optical fiber, Ag-metal nanoparticles, and Au-metal nanoparticles in a core; FIG.

The present invention relates to a functional optical fiber containing metal nano-particles and a method of manufacturing the same.

In general, an optical fiber manufacturing process is divided into an optical fiber preform manufacturing process and an optical fiber drawing process. Solution doping method (JE Townsend et al., Electron. Lett. Vol. 23, pp. 329-331 (1987)) and MCVD method (modified chemical vapor) deposition method; JB MacChesney and PB O'Connor, US Patent 4 217 027).

In the MCVD method for manufacturing the optical fiber base material, raw material gas is injected into a silica glass tube, and a glass tube is heated using an oxygen-hydrogen torch to induce a gas phase reaction between the raw material gas and oxygen in the tube. do. The soot produced as a result of the reaction is deposited on the inner wall of the glass tube to form a cladding and core layer that acts as an optical waveguide. Then, the glass substrate is sintered by heating to a temperature of 1800 ^° C. or more using an oxygen-hydrogen torch and then subjected to a collapsing and sealing process to prepare an optical fiber base material. The prepared fiber base material is manufactured by drawing an optical fiber at a temperature of 1900 ~ 2200 ^o C using a fiber drawer.

By classifying the optical fibers into functional groups, they can be divided into ordinary optical fibers, which are simply used as passive optical waveguides for transmitting light, and functional optical fibers with special performance such as switching, amplification, attenuation, and polarization retention characteristics. Among the functional optical fibers, nonlinear fiber which has increased optical nonlinearity has an all-optic effect, which is a phenomenon in which the refractive index is changed by optical pumping, and a phenomenon in which the refractive index is changed by application of an electric field. It has an electro-optic effect. Functional optical fibers having excellent nonlinear optical properties can be widely used in the manufacture of optical devices such as optical switching devices, optical modulators, wavelength variable filters, frequency modulators, and optical sensors.

In order to manufacture a functional optical fiber with special performance, elements such as rare earth elements are added to the optical fiber core during the optical fiber base material manufacturing process by the MCVD method. For this purpose, the soot for the fiber core is deposited on the glass tube, soaking in the solution containing the element to be added to the core without completely sintering, so that the ions penetrate between the soot and dry the soot so that the additional element is contained in the core . This method is called solution addition.

Various methods have been tried to date to manufacture functional optical fibers having excellent nonlinear optical properties.

A nonlinear optical fiber made of a chalcogenide glass composition with a fiber core and cladding may be manufactured. In the case of the chalcogenide glass optical fiber, the nonlinear optical coefficient is nonlinear compared to an optical fiber having a silica glass composition. The optical coefficient is more than 100 times larger. Despite these advantages, optical loss is very high and mechanical strength is remarkably decreased compared to silica glass.

In the case of silica-based optical fibers, nonlinear optical fibers may be manufactured by adding transition metal oxides such as PbO, TiO ₂ , and Bi ₂ O ₃ to the optical fiber core. However, when the non-linear optical fiber is prepared by adding transition metal oxide, it is difficult to manufacture the optical fiber and the optical loss is also large because it requires the addition of a transition metal oxide of 10 mol% or more.

Until recently, many researches on glass containing nanoparticles have been conducted along with interest in nanotechnology. In particular, glass containing metal nanoparticles has high optical nonlinear optical properties and its response speed is also very fast, and thus it is widely applicable to the development of ultra-high-speed functional optical devices. In particular, in the case of an optical fiber type optical waveguide using glass containing metal nanoparticles, the optical fiber structure can have various advantages, and thus the utility as an optical device is very large. However, despite its effectiveness, there have been no reported cases of the development of functional optical fibers containing metal nanoparticles through process development.

The present invention relates to the production of functional optical fibers containing metal nanoparticles, and using Ag, Au, Cu, Pb, Sn, Pt, Al, Sc, Ti using MCVD method, solution addition method, reducing atmosphere composition and fiber drawing process , V, Cr, Mn, Fe, Co, Ni, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Cd, In, Hf, Ta, W, Re, Os, Ir, Tl, Bi It is an object of the present invention to provide a technical method for producing a functional optical fiber having a high nonlinear optical coefficient and low light loss by containing metal nanoparticles composed of such components in the optical fiber core.

In order to achieve the above object, the present invention comprises the steps of depositing and sintering the cladding layer inside the glass tube in the optical fiber manufacturing method; Depositing and partially sintering a core layer in the glass tube; Adding a metal element to the core layer; Drying the core layer to which the metal element is added and then forming a reducing atmosphere; Performing a sintering, vitrification, compression, and sealing process while maintaining the formed reducing atmosphere; It provides a method for producing an optical fiber containing metal nanoparticles, comprising; forming a optical fiber by withdrawing the prepared optical fiber base material.

Preferably, the metal element is Ag, Au, Cu, Pb, Sn, Pt, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Y, Zr as constituents of the metal nanoparticles. , Nb, Mo, Tc, Ru, Rh, Pd, Cd, In, Hf, Ta, W, Re, Os, Ir, Tl, Bi is one or more selected from, more preferably the metal element In order to add to the core layer, the solution containing the metal element is injected into the glass tube and then discharged so that the metal element-containing solution is adsorbed to the pores between the core layer.

Also preferably, in order to form the reducing atmosphere, the inflow of oxygen (O ₂ ) gas is prevented and instead helium (He), nitrogen (N ₂ ), argon (Ar), carbon monoxide (CO) and hydrogen (H ₂ ) Gas may be introduced into the glass tube.

In addition, the present invention is Ag, Au, Cu, Pb, Sn, Pt, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Metal nanoparticles of several nm to several hundred nm in size, consisting of one or more of metal elements of Pd, Cd, In, Hf, Ta, W, Re, Os, Ir, Tl, Bi It provides an optical fiber characterized by.

Referring to the accompanying drawings, a manufacturing method for manufacturing a functional optical fiber containing metal nanoparticles according to the present invention will be described according to each step.

Metal nanoparticles refer to particles formed of agglomerates having different metal atoms agglomerating with each other and having a size of several nm to several hundred nm. When the metal nanoparticles are contained in the glass which is a material of the functional optical fiber, the metal nanoparticles have very different physical properties from the glass containing metal atoms and metal ions due to the surface plasmon effect. In particular, glass containing metal nanoparticles has very excellent nonlinear optical properties.

1 shows a manufacturing process of an optical fiber base material and an optical fiber containing metal nanoparticles, and shows an MCVD method, a solution addition method, a reducing atmosphere composition process, and an optical fiber drawing process.

1) First, the cladding layer is completely sintered after deposition by using a mixture of SiCl ₄ , POCl _3, CF ₄ and oxygen mixed in an appropriate ratio inside the glass tube (step ST1), and mixed with an appropriate ratio with oxygen. The core layer is deposited using SiCl ₄ and GeCl ₄ , followed by partial sintering (step ST2).

2) Then, a metal element is added to the core layer using a solution addition method (step ST3).

3) Then, the core layer to which the metal element is added is dried (step ST4), and then a reducing atmosphere is formed (step ST5).

4) The vitrification and sintering process is performed while maintaining the formed reducing atmosphere (step ST6).

5) Also maintaining a reducing atmosphere, and through the compression (coallapsing) and sealing (sealing) process to produce an optical fiber base material (step ST7).

6) Finally, the optical fiber base material is manufactured into the optical fiber by using the optical fiber extractor (step ST8).

Partial sintering (step ST2) without core sintering after depositing the core layer creates a large amount of pores between the glass particles so that the solution containing the metal element can easily penetrate and adsorb into the core layer when using the solution addition method (step ST3). To do this. In addition, if the sintering is not performed at all, the core layer collapse may occur when the solution addition method is used.

Here, the method of adding the metal element to the core layer is as shown in FIG. 2 and described with reference to FIG. 3.

After partially sintering the core layer (step ST2), as shown in FIG. 3A, the glass tube 1 is completely clad with the cladding layer 2 and the silica particles on which the glass particles (soot) 3 to be the core layer are deposited. The tube is made. As shown in FIG. 2, the glass tube 1 having the glass particles deposited thereon is connected to the hose 5 using the connector 4 and installed to be perpendicular to the ground 6.

Subsequently, when the solution 7 containing the metal element to be contained in the core layer is injected using the hose 5, the solution is passed through the connector 4 to fill the inside of the glass tube 8 and as shown in FIG. 3B. .

In this state, the solution 7 is discharged out of the glass tube 1 through the hose 5 after a predetermined time so that the solution 7 penetrates between the soot. Most of the solution is discharged out of the tube via the hose 5, but even after the solution has been discharged, a portion of the solution 9 remains adsorbed to the soot 3 in the voids between the soot 3 as shown in FIG. 3C. Through this, the desired metal element is contained in the core layer.

After the drying process (step ST4), a reducing atmosphere is formed (step ST5). He, N ₂ , Ar, CO, and H ₂ are blocked for the inflow of oxygen (O ₂ ) gas, which is generally used during the MCVD process. Gas is introduced into the tube for a certain time to remove oxygen remaining inside the glass tube. Thereafter, even during the sintering and vitrification process (step ST6) and compression and sealing (step ST7), oxygen gas is not used, and only gas that is prevented from oxidation, such as He, N ₂ , Ar, CO, and H ₂ , is used for reducing and reducing. Through this, anti-oxidation and reducing atmospheres are formed during the sintering, vitrification, compression, and sealing processes of about 1800 ^° C. or higher, thereby preventing metal nanoparticles from being inhibited by ionizing metal elements.

The solution 7 contains Ag, Au, Cu, Pb, Sn, Pt, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Y, Zr, and Nb as constituents of the metal nanoparticles. One or more metal components such as Mo, Tc, Ru, Rh, Pd, Cd, In, Hf, Ta, W, Re, Os, Ir, Tl, Bi are contained in appropriate concentrations.

Hereinafter, the light absorption coefficient, the TEM image, and the nonlinear optical properties of the functional optical fiber containing Ag-metal nanoparticles prepared according to the method of the present invention in the core will be described with reference to FIGS. 4 to 6. In order to make an optical fiber containing Ag-metal nanoparticles, 0.48 M (mol) of Ag was dissolved to prepare a solution, and a metal element addition process was performed using the solution addition method. In the vitrification and sintering process, only 3000 sccm (standard cubic centimeter per minute) He gas was used instead of O ₂ as an inlet gas to prevent oxidation. Subsequently, only 3000-50 sccm He gas was used in the compression and sealing process to prevent the oxidation atmosphere.

4a, 4b and 4c show optical absorption coefficients of a common germanosilicate optical fiber, an Ag-metal nanoparticle-containing optical fiber and an Au-metal nanoparticle-containing optical fiber prepared according to the manufacturing method of the present invention, respectively. It is a graph.

Figure 4a shows the light absorption coefficient according to the wavelength of a general optical fiber shows a light absorption distribution characteristics without a particular peak except for the light absorption band by UV transition below 500 nm.

Compared with this, in the case of the light absorption coefficient of the Ag-metal nanoparticle-containing optical fiber shown in FIG. 4B, a very large light absorption band exists around 425 nm, which is included in the Ag metal nano contained in the optical fiber core layer. By particles. 4b shows very low light absorption characteristics of about 3x10 ^-5 cm ^-1 in the entire wavelength range of 800 nm or more except for light absorption around 1380 nm by the OH group.

In addition, in the case of the light absorption coefficient of the Au-metal nanoparticle-containing optical fiber shown in FIG. 4c, it can be seen that a very large light absorption band exists around 500 nm, which is caused by the Au metal nanoparticles contained in the optical fiber core layer. will be. Also, except for the absorption of light around 1380 nm by OH group, it shows very low light absorption characteristics of about 5x10 ^-5 cm ^-1 in the entire wavelength range of 800 nm or more.

5A and 5B are TEM photographs of a general optical fiber base material and an Ag-metal nanoparticle-containing optical fiber base material, respectively.

Figure 5a shows a TEM picture of a general optical fiber base material shows that there is no particular form. On the other hand, in the TEM photograph shown in FIG. 5B, a spot shape having a size of about 4-8 nm is distinguished from the background, which is caused by Ag-metal nanoparticles formed in the core layer.

6 shows a comparison of the nonlinear optical coefficients of a general optical fiber having a germanosilicate (GeO ₂ -SiO ₂ ) -based optical fiber and an Ag-metal nanoparticle-containing optical fiber and Au-metal nanoparticle-containing optical fiber according to the method of the present invention. Long period grating pair method for nonlinear optical coefficient measurement [YHKim et al., Opt. Lett. Vol. 27, p. 580-582 (2002). As shown in the figure, in the case of the functional optical fiber containing Ag or Au-metal nanoparticles in the core, it can be seen that it has a large nonlinear optical index (nonlinear refractive index, n ₂ ) of about 10 ⁴ times that of the general optical fiber.

As described above, according to the present invention, in the optical fiber core, Ag, Au, Cu, Pb, Sn, Pt, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Y, Zr, Nb Metal nanoparticles composed of components such as Mo, Tc, Ru, Rh, Pd, Cd, In, Hf, Ta, W, Re, Os, Ir, Tl, Bi can provide a functional optical fiber contained in the optical fiber core. Will be.

The functional optical fiber containing the metal nanoparticles prepared in the present invention in the core is expected to be widely applied to optical devices such as optical switching devices, optical modulators, wavelength tunable filters, and frequency modulators. In particular, the high nonlinear optical characteristics and fast response speed of optical fibers containing metal nanoparticles are expected to be suitable for the production of ultra-high speed all-optical switches, which are essential for ultra-high speed optical communication and optical logic circuits.

The functional optical fiber in which the metal nanoparticles are contained in the core can be applied not only to an optical device but also as a sensor device for measuring various physical quantities using light intensity, phase, polarization, and the like.

In the case of the optical fiber type sensor using optical fiber as a light transmission means, there is no problem caused by disturbance and leakage caused by electromagnetic wave which is a problem in general copper wire and electronic device using semiconductor chip. Compared with 100 ~ 1,000 times more communication, it can bring big ripple effect.

Claims (7)

In the optical fiber manufacturing method, Depositing and completely sintering the cladding layer inside the glass tube; Depositing and partially sintering a core layer in the glass tube; Connecting the glass tube to a hose through a connector and then installing the glass tube vertically on the ground, and filling the inside of the glass tube with a solution containing a metal element through the hose; Adding a metal element to the core layer by discharging the solution filled in the glass tube through the hose after a predetermined time so that a portion of the solution containing the metal element is adsorbed into the pores of the core layer; Forming a reducing atmosphere for removing oxygen remaining in the glass tube by introducing a reducing gas into the glass tube after drying the core layer to which the metal element is added; Performing a sintering, vitrification, compression, and sealing process while maintaining the formed reducing atmosphere; And And extracting the prepared optical fiber base material to form an optical fiber. The method of claim 1, wherein the metal element is Pb, Sn, Pt, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Y, Zr, Nb, Method for manufacturing an optical fiber containing metal nanoparticles, characterized in that one or more selected from Mo, Tc, Ru, Rh, Pd, Cd, In, Hf, Ta, W, Re, Os, Ir, Tl, Bi . delete The method of claim 1, wherein in order to form the reducing atmosphere, inflow of oxygen (O ₂ ) gas is prevented and helium (He), nitrogen (N ₂ ), argon (Ar), carbon monoxide (CO) and hydrogen (H) ₂ ) A method for manufacturing an optical fiber containing metal nanoparticles, wherein gas is introduced into the glass tube. The optical fiber manufactured by the manufacturing method of any one of Claims 1, 2, and 4. delete delete

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