KR100341544B1 - Process for the preparation of metal ion-doped optical device - Google Patents

Abstract

The present invention relates to an improved solution doping method for doping rare earth ions and metal ions such as transition metal ions to an optical device such as an optical fiber, and to form a partially sintered microstructure on a substrate for optical device manufacturing, A method of manufacturing a metal ion-doped optical device comprising performing a soaking process of dipping the microstructure in a metal ion doping solution, wherein the metal ion is doped into the microstructure. According to the method of the present invention, characterized in that carried out at a temperature lower than the manufacturing temperature, an optical fiber or a flat plate type to overcome the limitation of the doping concentration, which is a disadvantage of the conventional solution doping method in an easy and economical process Optical devices such as glass can be doped with high concentrations of rare earth ions and (transition) metal ions.

Description

Method for manufacturing metal ion-doped optical device {PROCESS FOR THE PREPARATION OF METAL ION-DOPED OPTICAL DEVICE}

The present invention relates to a method for manufacturing an optical device in the form of an optical fiber or a flat glass. More specifically, the content of metal ions such as rare earth ions and (transition) metal ions added to an optical fiber core or the like can be increased, and the treatment is easy. It is about an inexpensive process.

If metal ions such as rare earth ions and aluminum ions are added to the cores of optical fiber and flat waveguides, which are the core materials of active devices for optical communication such as optical amplifiers and fiber lasers, gain flattening can be achieved even if the active devices for optical communication have the same size. There is an advantage to increase the output gain while maintaining.

To this end, various methods have been developed, and a conventional method of heating a raw material saturated with doped ions (Heated Frit) is as follows. After forming a partially sintered porous microparticle layer on the front inner wall of the MCVD glass tube used for the Modified Chemical Vapor Deposition (MCVD), the microparticle layer was dissolved in rare earth or (transition) metal chlorides. After soaking in an ethanol solution, a doped ion-saturated raw material layer was made and dried by heating to 900 ° C. Then, when it is heated to deposit the core layer of the optical fiber base material, rare earth ions and (transition) metal ions are doped into the core layer.

In addition, the chloride source (Heated Source) method of the doping ions is a method used in the MCVD process, the basic idea is that the doping ions are the same as the saturated raw material heating method, and instead directly heat the chloride. In order to prevent the grains of chloride from directly entering the core part, a jaw is made in front of the glass tube and the core layer is deposited. At the same time, the chloride layer is heated with a flame to dope the core layer with rare earth ions or (transition) metal ions.

Heated chloride injector (Heated Source Injector) is used in the MCVD process and is similar to the chloride heated (Heated Source) method of doping ions, but independent of chloride in order to prevent pre-reaction with chloride and the basic raw materials forming the core layer. The other way is to put it in and use it.

Aerosol Delivery is a method used for MCVD and Vapor-phase Axial Deposition (VAD), which supplies doping ions to the core layer through a carrier gas in the form of an aerosol. Doped as layer deposition. In addition, the doping method using a chelating compound (Chelate Delivery) is a method used in the MCVD and VAD processes to simultaneously doping ions during the core layer deposition using an organic material having a high vapor pressure as a raw material of the doping ions.

However, these methods require ancillary equipment in addition to conventional MCVD equipment. Not only is the cost low, but there is a problem that the use of expensive MCVD equipment is limited because the inside of the MCVD equipment is highly contaminated after the modification, and a solution addition method that does not require modification of the MCVD equipment is relatively widely used.

In the solution doping method, an MCVD process is used to build up a core layer with a large number of partially sintered voids inside a silica tube, and then gradually fill the core layer with a rare earth or chloride solution of a (transition) metal. Maintain the solution for about 1 hour to sufficiently infiltrate the core layer, and then flow out the solution, and dry the doped core layer by flowing a mixed gas of chlorine and oxygen using an MCVD process, and then sintered at a high temperature. Fiber optic base material is manufactured through sintering and collapsing process.

The solution doping method is an optical fiber base material such as Modified Chemical Vapor Deposition (MCVD), Vapor-phase Axial Deposition (VAD) and Outside Vapor Deposition (OVD). Semi-finished products) are used as a method of doping rare earth ions or (transition) metal ions in the fiber core irrespective of the manufacturing method, as well as in the manufacture of flat glass optical devices using flame hydrolysis deposition (FHD). It is used as a doping method for all rare earth ions and (transition) metal ions that are ready in form.

However, the conventional solution addition method has an advantage of easy processing and low cost process, but it is difficult to dope the metal ions to the optical device above the concentration that can be prepared as a doped metal solution. That is, the conventional solution addition method has a disadvantage of low doping effect.

Accordingly, it is an object of the present invention to provide a new method capable of doping rare earth ions and (transition) metal ions at high concentrations in optical devices such as optical fibers or planar optical devices.

1 is a schematic diagram of a device for a doping process using a solution addition method, with temperature control means, according to the present invention.

FIG. 2 shows the glass-based composition of the doped optical fibers (Holmium, Ho) and aluminum (Al) doped at various soaking temperatures (the ion-doped optical fiber core portion is near the 1150 nm wavelength of SiO ₂ -GeO ₂ ). It shows the light absorption spectrum of.

3 shows an optical fiber (ion-doped optical fiber core) doped with holmium (Ho) and aluminum (Al) (■, λ = 1150 nm) or erbium (Er) and aluminum (Al) (□, λ = 1550 nm). The glass base composition of is a graph showing the tendency to change the light absorption coefficient of SiO ₂ -GeO ₂ ) at various impregnation temperatures.

4 is a graph showing the results of quantitative analysis of the average concentrations of holmium ions (■) and aluminum ions (□) of the optical fiber base material core part by electron probe micro analysis (EPMA) with respect to the impregnation temperature.

FIG. 5 is a graph showing the results of quantitative analysis of the average concentrations of erbium ions (■) and aluminum ions (□) in the optical fiber base material core part by electron probe microanalysis (EPMA) with respect to impregnation temperature.

According to the above object of the present invention, forming a partially sintered microstructure on the substrate for optical device manufacturing, and performing a soaking process of immersing the microstructure in a metal ion doping solution to dope the metal ion into the microstructure In the method of manufacturing a metal ion-doped optical device comprising a, the impregnation process is provided at a temperature lower than the temperature of the doping solution is provided.

Optical devices that can be processed in the present invention include optical fibers and planar optical devices that can be used in optical fibers and planar optical amplifiers, optical communication lasers, optical fibers and planar optical switching devices, medical optical fiber lasers, and the like.

In addition, the optical device of the present invention is a silicon dioxide or silicon oxide (SiO ₂ ) germanium oxide (GeO ₂ ), boron oxide (B ₂ O ₃ ), phosphate (P ₂ O ₅ ), titanium oxide (TiO ₂ ) and the like The composition is based on a mixture of oxides of. Specific examples thereof include silica (SiO ₂ ), germanosilicate (SiO ₂ -GeO ₂ ), phosphorosilicate (SiO ₂ -P ₂ O ₅ ), phosphorogermanosilicate (SiO ₂ -GeO ₂ -P ₂ O ₅ ), borosilicate (SiO ₂ -B ₂ O ₃ ), borophosphosilicate (SiO ₂ -P ₂ O ₅ -B ₂ O ₃ ), borogeranosilicate (SiO ₂ -GeO ₂ -B ₂ O ₃ ) , Titanosilicate (SiO ₂ -TiO ₂ ), phosphoro titanosilicate (SiO ₂ -TiO ₂ -P ₂ O ₅ ), boro titanosilicate (SiO ₂ -TiO ₂ -B ₂ O ₃ ), and the like.

As the doped metal used in the present invention, metal elements including rare earth elements (eg, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, etc.) and transition metals (Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Hf, Ta , W, Re, Os, Ir, Pt, Au, Tl, Pb, Bi and the like).

The doping solution used in the present invention is prepared by dissolving a water-soluble salt of a doped metal, generally a water-soluble chloride, in ethanol or water. Generally, the preparation temperature of the solution is from 15 to 25 ° C. and is mostly prepared at room temperature. The concentration of metal in the solution prepared at this time maintains the ratio between the metal elements in accordance with the characteristic requirements of the optical device, making the solution as saturated as possible. For example, when holmium and aluminum are made to have a doping concentration ratio (molar ratio) of about 1 to 10 in an optical fiber, a saturated solution having a molar concentration of about 1 to 10 is prepared when the solution is prepared. For example, when the ethanol solution is prepared at about 15 ° C., the concentration of the saturated solution is about 0.05 M of holmium and about 0.5 M of aluminum, respectively.

In the practice of the present invention, partially sintered porous microstructures can be prepared by conventional methods (see MacChesney et. Al., "Optical fiber fabrication andresulting product", US Patent, 1997). For example, the liquid SiCl ₄ and GeCl ₄ raw material is passed through purified O ₂ and flows into the inside of the MCVD silica tube, and the tube ambient temperature is maintained at about 1600 ℃, SiCl ₄ and GeCl ₄ is O ₂ and The particles are then deposited on the inner wall of the silica tube to form a microstructure that will be the core of the optical fiber. On the other hand, in order to create a partially sintered porous microstructure on the flat glass, using a flame hydrolysis deposition (FHD) process (M. Kawachi et. Al., "Fabrication of SiO ₂ -TiO ₂ glass planar optical waveguides by flame hydrolysis deposition ", Electron. Lett., vol. 19, No. 15, 1983). This process is similar to the improved chemical vapor deposition process, except that the raw material is transported using an inert gas (Ar or N ₂ ) and meets directly with a spark of hydrogen and oxygen, which causes the particles to be deposited on the flat glass through hydrolysis. It is deposited to form a microstructured layer that will be the core of the planar device. The size of the microstructure is designed to be able to form the core portion. For example, in general, the core diameter of the rare earth-doped optical fiber or flat panel device has a 3 to 4 탆 (final diameter after the device is manufactured), thereby forming a microstructure to form such a core.

The microstructures prepared as above are immersed in the doping solution so that the solution is retained in the pores of the microstructures. At this time, by keeping the temperature lower than the temperature at the time of solution preparation, the solubility difference causes the doping of the solute metal ions to the pores of the microstructure. You can see the effect of doping. Preferably the impregnation process is carried out for about 1 to 1.5 hours at a temperature that differs by at least about 30 ° C. from the solution preparation temperature.

For example, the method of the present invention can be performed using an apparatus as in FIG. The porous microstructure was partially sintered by improved chemical vapor deposition in a silica tube having an inner diameter of 19 mm and an outer diameter of 25 mm, and a doping solution prepared at 15 to 25 ° C. was injected into a silica tube having a porous microstructure. The microstructures are submerged in the doping solution. At this time, the temperature of the soaking process is maintained at a temperature lower than the solution preparation temperature, preferably at least about 30 ℃ using a temperature controller, for example, a cold refrigerator temperature control device attached. After about 1 hour, the doping solution was removed from the silicon tube, dried at 100 to 300 ° C. while flowing chlorine and oxygen gas, and sparked at about 1,980 to 2,020 ° C. to sinter the porous fine particles to each other (MF Yan, et. al., "Sintering of optical wave-guide glasses", J. of Mater. Sci., pp1371-1378, 1980). Then, the silica glass tube was recessed using hydrogen / oxygen flame at about 2200 ° C. (JB MacChesney, et. Al., “Optical fiber fabrication and resulting product”, US Patent, 1997) to prepare a metal base doped optical fiber base material This uses an optical fiber extractor to produce an optical fiber doped with metal ions. The sintering and depression process may be appropriately repeated as necessary.

In addition to the MCVD process, the method of the present invention can also be used to dope rare earth ions and (transition) metal ions in a matrix prepared by the VAD, OVD, FHD process. In addition, the present invention may be applied in the fabrication of an optical communication device or a medical device using the characteristics of the doped ions by doping rare earth ions or (transition) metal ions to the optical fiber or flat glass. Specific applications include optical fibers doped with rare earth ions and (transition) metal ions, optical fiber lasers doped with planar optical amplifiers, rare earth ions and (transition) metal ions, optical fibers doped with rare earth ions and (transition) metal ions And medical optical fibers doped with planar optical switching elements, rare earth ions, and (transition) metal ions.

Although the present invention will be described in detail with reference to the following examples, the present invention is not limited to the following examples.

Example 1

Holmium salt (HoCl ₃ · 6H ₂ O) and aluminum salt (AlCl ₃ · 6H ₂ O) were dissolved in ethanol at a concentration of 0.05 M and 0.5 M, respectively, at about 15 ° C., so that rare earth ions Ho ³⁺ and metal ions Al A doping solution comprising ³⁺ was prepared.

In the apparatus as shown in FIG. 1, a porous microstructure was formed by MCVD method with a glass base composition of SiO ₂ -GeO ₂ in the inner wall of the silica glass tube having an inner diameter of 19 mm and an outer diameter of 25 mm so that the core of the optical fiber was a core. The doping solution prepared above was injected therein, and the temperature was kept at -10 ° C for 1 hour. Then, it was dried while flowing oxygen and chlorine.

The sintering and depression processes were repeated three times and seven times, respectively, to prepare an optical fiber doped with metal ions.

2 and 3 show light absorption spectra and light absorption coefficients of the optical fiber manufactured as described above. In addition, the average concentrations of the doping ions in the optical fiber base material analyzed using Electron Probe Micro Analysis (EPMA) are shown in Table 1 and FIG. 4.

Comparative Example 1

The same procedure as in Example 1 was repeated except that the impregnation temperature was 15 ° C., to thereby prepare an optical fiber doped with metal ions.

2 and 3 show light absorption spectra and light absorption coefficients of the optical fiber manufactured as described above. In addition, the average concentrations of the doping ions in the optical fiber base material analyzed using Electron Probe Micro Analysis (EPMA) are shown in Table 1 and FIG. 4.

Comparative Example 2

The same procedure as in Example 1 was repeated except that the impregnation temperature was 70 ° C., to thereby prepare an optical fiber doped with metal ions.

2 and 3 show light absorption spectra and light absorption coefficients of the optical fiber manufactured as described above. In addition, the average concentrations of the doping ions in the optical fiber base material analyzed using Electron Probe Micro Analysis (EPMA) are shown in Table 1 and FIG. 4.

Example 2

At about 15 ° C., erbium salt (ErCl ₃ · 6H ₂ O) and aluminum salt (AlCl ₃ · 6H ₂ O) were dissolved in ethanol at concentrations of 0.06M and 0.6M, respectively, and rare earth ions Er ³⁺ and metal ions Al A doping solution comprising ³⁺ was prepared.

In the apparatus as shown in FIG. 1, a porous microstructure was formed by MCVD method with a glass base composition of SiO ₂ -GeO ₂ in the inner wall of the silica glass tube having an inner diameter of 19 mm and an outer diameter of 25 mm so that the core of the optical fiber was a core. The doping solution prepared above was injected therein, and the temperature was kept at -20 ° C for 1 hour. Then, it was dried while flowing oxygen and chlorine.

The sintering and depression processes were repeated three times and seven times, respectively, to prepare an optical fiber doped with metal ions.

The optical absorption coefficient of the optical fiber thus manufactured is shown in FIG. 3. In addition, the average concentrations of the doping ions in the optical fiber base material analyzed using Electron Probe Micro Analysis (EPMA) are shown in Table 1 and FIG. 5.

Comparative Example 3

The same procedure as in Example 3 was repeated except that the soaking temperature was 13 ° C., to thereby prepare an optical fiber doped with metal ions.

The optical absorption coefficient of the optical fiber thus manufactured is shown in FIG. 3. In addition, the average concentrations of the doping ions in the optical fiber base material analyzed using Electron Probe Micro Analysis (EPMA) are shown in Table 1 and FIG. 5.

Comparative Example 4

The same procedure as in Example 3 was repeated except that the soaking temperature was 65 ° C., to thereby prepare an optical fiber doped with metal ions.

The optical absorption coefficient of the optical fiber thus manufactured is shown in FIG. 3. In addition, the average concentrations of the doping ions in the optical fiber base material analyzed using Electron Probe Micro Analysis (EPMA) are shown in Table 1 and FIG. 5.

Impregnation temperature (℃) Average Doping Concentration by Weight of Ho or Er Average Doping Concentration of Al (wt%) Example 1 -10 0.424 0.706 Comparative Example 1 15 0.201 0.278 Comparative Example 2 70 0.136 0.147 Example 2 -20 0.577 0.778 Comparative Example 3 13 0.342 0.399 Comparative Example 4 65 0.327 0.315

As can be seen from the above results, as the impregnation temperature decreases, the doping concentration of both the rare earth ions and the metal ions increased in the optical fiber. As a result of the change, the impregnation temperature was lowered by about 25 ° C. from room temperature, and the doping concentration of the holmium and aluminum ions was increased by about 2 times. In addition, as a result of lowering the impregnation temperature by about 35 ° C. from the room temperature, the erbium, which is a rare earth ion, increased about 1.7 times, and about 2 times that of Al ³⁺ , which is a metal ion.

According to the method of the present invention, doping the rare earth ions and (transition) metal ions to a high concentration in a glass material such as an optical fiber or a planar optical device by overcoming the limitation of the doping concentration, which is a disadvantage of the conventional solution addition method, in a simple and economical manner. You can.

Claims (6)

Forming a partially sintered microstructure on a substrate for fabricating an optical device, and performing a soaking process of dipping the microstructure in a metal ion doping solution to dope the metal ion into the microstructure. An optical device manufacturing method, characterized in that the impregnation step is performed at a temperature lower than the doping solution preparation temperature. The method of claim 1, And wherein said impregnation process is carried out at a temperature that is at least about 30 [deg.] C. different from the temperature at which said doping solution is prepared. The method of claim 1, Metal ions contained in the doping solution are Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Sc, Ti, V, Cr, Mn, Fe , Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Hf, Ta, W, Re, Os, Ir, Pt, Au, Tl , Pb, Bi, and mixtures thereof The method of claim 1, Chemical Vapor Deposition (MCVD), Vapor-Phase Axial Deposition (VAD), Outside Vapor Deposition (OVD) ) Or Flame Hydrolysis Deposition (FHD) The method of claim 1, The optical device includes at least one selected from silicon oxide (SiO ₂ ), or germanium oxide (GeO ₂ ), boron oxide (B ₂ O ₃ ), phosphate (P ₂ O ₅ ), and titanium oxide (TiO ₂ ) Characterized in that the oxide-based base composition as a base composition. The method of claim 5, The optical device comprises silica (SiO ₂ ), germanosilicate (SiO ₂ -GeO ₂ ), phosphorosilicate (SiO ₂ -P ₂ O ₅ ), phosphorogermanosilicate (SiO ₂ -GeO ₂ -P ₂ O ₅ ) , Borosilicate (SiO ₂ -B ₂ O ₃ ), borophosphosilicate (SiO ₂ -P ₂ O ₅ -B ₂ O ₃ ), borogermanosilicate (SiO ₂ -GeO ₂ -B ₂ O ₃ ), titano Silicate (SiO ₂ -TiO ₂ ), phosphoro titanosilicate (SiO ₂ -TiO ₂ -P ₂ O ₅ ) or boro titanosilicate (SiO ₂ -TiO ₂ -B ₂ O ₃ ) characterized in that the basic composition Way.