KR19990075817A - Optical Fiber for Attenuator Doped with Transition Element - Google Patents

Abstract

The present invention relates to a method for manufacturing an optical fiber for use in an optical attenuator. The present invention relates to an optical attenuator, which exhibits a high absorption rate and is formed by varying the type and amount of additives to produce an optical fiber having an even attenuation amount at 1310 nm and 1550 nm. It's about things. Conventional optical attenuator is manufactured by doping cobalt or aluminum to the core of the optical fiber to be used, but considering that it is difficult to use at the same time in the onion field because the difference between the attenuation at 1310 nm and the attenuation at 1550 nm is severe, at 1550 nm Using the properties of cobalt with large loss value and vanadium with large loss value at 1310 nm, the equipment is configured to manufacture an optical fiber that can be used for attenuator by modifying the optical fiber manufacturing process using MCVD equipment and partially fabricating the optical fiber core. After sintering to remove from the equipment and immersed in a solution in which vanadium and cobalt are dissolved together, the solution is subjected to about 1 hour to diffuse into the core, and then attached to the equipment and sintered again to obtain an optical fiber.

Description

Optical Fiber for Attenuator Doped with Transition Element

The present invention relates to a method for manufacturing an optical fiber for use in an optical attenuator. The present invention relates to an optical attenuator formed by varying the type and amount of additives to produce an optical fiber having a high absorption rate and an even attenuation amount at 1310 nm and 1550 nm. It's about things. Although the aluminum doped optical fiber manufactured by the conventional method satisfies the requirements of the loss value and the loss difference in the onion field, according to the experiment, it was difficult to manufacture by the solution doping method, and the optical fiber desired by the method of doping with the cobalt solution Although a loss value was obtained, the loss difference between 1310 nm and 1550 nm was large due to the characteristics of cobalt. For example, the 20dB attenuator showed more than 200dB / m difference.

In order to reduce the difference between the loss value of cobalt doped fiber and the loss value of vanadium doped fiber, cobalt and vanadium are simultaneously doped into the core to adjust the light absorption loss in the onion field to provide the required attenuator at both wavelengths with one attenuator. There is an object of the present invention.

As described above, the aluminum-doped optical fiber can satisfy the requirements at both wavelengths of the loss value and the difference in loss, but by the advanced experiments, a more convenient manufacturing method and a solution doping method which can reduce the production cost have been developed. Although realistically available solution doping has been prepared using MCVD equipment, the single doping of the cobalt alone has a loss of more than 10% between 1310 nm and 1550 nm and a higher loss value at 1550 nm. Since a single doping has a higher loss value at 1310 nm, a single doped attenuator with only cobalt or vanadium has a large loss difference and thus is limited to use at both wavelengths. Therefore, by simultaneously doping cobalt and vanadium solution into the core, one of the attenuators formed by trade-off between the high loss rate of cobalt and the high loss rate of vanadium can meet the specifications required at both wavelengths, and the difference in the loss of optical fibers manufactured as described above is 5 ± 1.5. The values of dB, 10 ± 1.5dB, 15 ± 1.5dB, 20 ± 1.5dB are preferred, and the fiber required for the attenuator is preferably 2.1 cm. The tube should be detachable during operation in the MCVD facility. In the core, vanadium and cobalt are simultaneously doped and the mode field has a wider area at 1550 nm than 1310 nm. Since it is concentrated inward, the core area of the doped region is preferably 1/3, and in view of the above, it is effective to compensate for the disadvantage of cobalt having a lower loss characteristic at 1310 nm. Enemy

Figure 1 A is a process of forming a partial sintered layer of the core in the optical fiber core.

Figure 1 B is a process of doping using a transition metal solution in the optical fiber core.

2 is a refractive index distribution of an optical fiber for an attenuator in which a transition element is doped in a core.

3A is a plot of higher loss values at a wavelength of 1550 nm.

3B is a plot of higher loss values at a wavelength of 1310 nm.

3C is a plot of the loss values that appear when A and B are mixed.

{Description of symbols for main parts of the drawing}

11 tube 12 cladding layer

13 core layer 14 solution in which vanadium and cobalt are dissolved

Hereinafter, with reference to the accompanying drawings and embodiments will be described in detail with respect to the present invention.

The invention consists of a tube 11 layer, a cladding layer 12 and a partially sintered core layer 13 from the outside, and a vanadium-cobalt solution is doped into the partially sintered core layer.

FIG. 1A illustrates a process of doping a transition metal having a high light absorption rate into a solution in a fiber core 13 with a solution as a manufacturing method for forming an optical fiber for attenuator. FIG. This is a state diagram in which the transition metal solution is removed from the tube and injected into the tube.

Figure 2 shows the refractive index distribution of the optical fiber manufactured by the above method, the overall refractive index distribution is the same as a general single-mode optical fiber, it is shown to see the region doped with cobalt and vanadium in the center of the core.

FIG. 3 shows a schematic curve of the spectra for a single doped cobalt, a single doped vanadium, and a mixed doped cobalt as a dopant in the core 13. Higher loss values are shown at a wavelength of 1550 nm when doped with cobalt, while B in FIG. 3 shows higher loss values at 1310 nm when doped with vanadium, as shown in C of FIG. 3. When mixed, the loss values are shown at both wavelengths.

Partially sintered the core 13 of the optical fiber using the MCVD facility in the shape as shown in A of FIG. 1 and again out of the facility and then impregnated in a solution in which vanadium and cobalt are dissolved together so that the solution is the core 13. It is impregnated for a sufficient time to diffuse into, and then attached to the equipment, sintered, and then edged to obtain an optical fiber for attenuator. For example, if the core layer 13 of the optical fiber is not partially sintered as shown in FIG. 1A, space formation is difficult in the core layer 13, and thus doping is not actively performed. After that, it is dried by applying heat from outside and then completely sintered to form a preform and then formed into an optical fiber.

The optical fiber for attenuator made with the present invention is different from the conventional attenuator by adjusting the light absorption loss at both wavelengths of 1310 nm and 1550 nm by adding vanadium having a higher loss at 1310 nm in contrast to cobalt. The attenuator can be used according to the specifications required at both wavelengths, and the simple structure can significantly reduce the fabrication cost of the attenuator. The manufactured attenuator has also demonstrated superior optical durability compared to the conventional filter type attenuator.

Claims (3)

In the manufacture of optical fiber for attenuator, the optical fiber formed from the tube 11, the clad layer 12, and the core layer 13 is externally doped using a transition metal as a dopant, and the attenuation loss is equalized to be required at both wavelengths. An optical fiber for attenuator doped with transition elements, characterized in that to obtain an amount of attenuation that satisfies simultaneously. 2. The optical fiber for attenuator according to claim 1, wherein the dopant in the core (13) is doped using cobalt and vanadium solution (14) when doping the optical fiber. The optical fiber for attenuator according to claim 1 or 2, wherein the doping method is formed to sinter a portion of the core (13) in the core (13) of the optical fiber to facilitate diffusion of the transition metal.