KR100728919B1 - A multi-mode optical fiber for achieving an optical attenuation to a desired degree at specific working wavelengths or achieving a substantially uniform optical attenuation in specific range of wavelength - Google Patents

Abstract

The present invention relates to a multi-mode optical attenuation optical fiber for attenuating optical signals of various modes received in short-range communication, etc. requiring multiple access. According to the present invention, a core layer and a cladding layer are provided. A multimode type optical attenuation optical fiber for obtaining a substantially constant light attenuation at a desired degree or a specific working wavelength band at a specific working wavelength having a thickness ratio of 50 nm: 125 nm or 62.5 nm: 125 nm, wherein the core layer is Wherein the light absorption coefficient at the particular working wavelength is doped with at least one ion of the first metal having a negative slope, and preferably the at least one ion of the second metal having the positive working wavelength light absorption coefficient has a positive slope A multimode optically attenuated optical fiber is co-doped.

Fiber Optic, Light Attenuation, Multimode, Dopant

Description

Multimode optical fiber for achieving an optical attenuation to a desired degree at specific working wavelengths or achieving a substantially uniform optical attenuation in specific range of wavelength}

1 is a flow chart showing a multimode optical attenuated optical fiber manufacturing process for optical attenuation according to a first embodiment of the present invention.

2a to 2d are cross-sectional views showing the metal ion doping process shown in FIG.

The present invention relates to a multimode optical attenuated optical fiber for attenuating received optical signals of various modes in short-range communication or the like requiring multiple access.

Wavelength division multiplexing (WDM) has been developed in addition to time division multiplexing (TDM) due to explosive demand for data to be transmitted in optical communication. WDM can improve the signal transmission efficiency by transmitting optical signals with different wavelengths through one transmission line.

In such an optical communication system, since signal loss is generated in proportion to the length of the optical fiber, the reception side that is present at a long distance receives a weak signal, which makes it difficult to receive an accurate signal. In order to solve this problem of signal loss, an amplification means for amplifying the optical signal is disposed between the transmitting side and the receiving side, and the transmitting side transmits a signal of high output in consideration of such signal loss. However, when a receiving apparatus such as an optical fiber amplifier is installed near the transmitting side generating a high output signal, the receiving apparatus may not accurately detect such a signal. Therefore, a method for attenuating the optical signal received at the front end of the receiver is used.

Meanwhile, there are two types of optical fibers used in optical communication systems, single-mode optical fibers and multi-mode optical fibers.

First, single-mode fiber is mainly used for long-distance communication because it can transmit miles of high speed without a relay. This excellent transfer capability is made possible by a small core with a diameter of 9 mu m. The small core restricts the transmission of only one basic mode of light in the optical fiber, minimizes the distortion of the optical pulses, and extends the signal transmission distance.

Next, multimode fiber is used for data communication, such as local area networks (LANs) in campus and hospital businesses. Multimode optical fibers can transmit more than one optical mode because the core diameter is larger than the wavelength of the transmitted light. Because of this relatively large core, it is easy to connect and is used for short distance communication requiring multiple access. Recently, the demand for multi-mode (M / M) type is increasing worldwide due to the visualization of LAN and FTTH.

In a multimode optical fiber system, a conventional multimode optical attenuator for attenuating optical signals of various modes is used. The ferrules are shifted from each other, or a certain amount of light is counted at small intervals between the ferrules. Either to exit, to vary the size of the fiber core, or to insert a filter between the ferrules.

However, filter-type optical attenuators have too small attenuation zones to precisely control the degree of absorption.

In addition, conventional multimode type optical attenuators have not achieved a substantially constant optical attenuation at a desired degree or at a specific working wavelength band at certain working wavelengths.

SUMMARY OF THE INVENTION An object of the present invention is to provide a multimode optical attenuated optical fiber for obtaining a desired degree of optical attenuation in a specific working wavelength band of various modes of optical signals received in short distance communication or the like requiring multiple connections.

Another object of the present invention is to provide a multimode optical attenuation optical fiber for obtaining a substantially constant optical attenuation in a specific working wavelength band of various modes of optical signals received in short distance communication or the like requiring multiple access.

The configuration of the present invention for achieving the above object is as follows.

 According to one aspect of the present invention, a multimode fluorescence attenuated optical fiber for obtaining a desired degree of optical attenuation at a specific working wavelength includes a core layer and a cladding layer, and a thickness ratio of the core layer and the cladding layer is 50 μm: 125 μm. Or 62.5 μm: 125 μm, wherein the core layer is doped with ions of at least one of the first metals whose light absorption coefficient has a negative slope in a predetermined wavelength band. Here, the specific working wavelength means 850 nm used for the multimode optical fiber.

Also preferably, in a particular wavelength band, the light absorption coefficient is co-doped with at least one ion of the second metal having a positive slope.

Also preferably, the first metal is iron (Fe), chromium (Cr), manganese (Mn) and vanadium (V), and the second metal is cobalt (Co) and nickel (Ni).

In addition, the core layer is preferably co-doped with aluminum.

According to another aspect of the invention, a multi-mode optical attenuation optical fiber for obtaining a substantially constant light attenuation in a particular working wavelength band comprises a core layer and a cladding layer, the thickness ratio of the core layer and the cladding layer 50㎛: 125 [mu] m or 62.5 [mu] m: 125 [mu] m, the core layer is doped with ions of at least one of the first metals whose light absorption coefficient has a negative slope in a predetermined wavelength band. Here, the specific working wavelength band is 1200 nm to 1650 nm, and preferably 1310 nm or 1550 nm of the wavelength band is mainly used.

Also preferably, in a particular wavelength band, the light absorption coefficient is co-doped with at least one ion of the second metal having a positive slope.

Also preferably, the first metal is iron (Fe), chromium (Cr), manganese (Mn) and vanadium (V), and the second metal is cobalt (Co) and nickel (Ni).

In addition, the core layer is preferably co-doped with aluminum.

1 is a multimode type of optical attenuation to obtain a substantially constant light attenuation at a desired degree or at a specific working wavelength band at certain working wavelengths in accordance with a first embodiment of the present invention using improved chemical vapor deposition (MCVD). It is a flowchart which shows the manufacturing process of an optical fiber.

First, the cladding layer is deposited inside the tube using SiCl ₄ , POCl _3, and CF ₄ (ST1), and the core layer is deposited using SiCl ₄ and GeCl ₄ (ST2).

Here, the coating process of the core is repeated several times so that the ratio of the core layer and the cladding layer is 50: 125, or 62.5: 125.

Thereafter, the core layer is partially sintered and doped with a predetermined metal ion (ST3). The core layer is dried, sintered and oxidized (ST4).

Then, an optical fiber preform is obtained through a collapsing and sealing step (ST5, ST6), and finally, an optical fiber containing metal ions is produced through a drawing process (ST7).

Hereinafter, a process of doping the core layer with metal ions will be described with reference to FIGS. 2A to 2D.

First, as shown in FIGS. 2A to 2D, the cladding layer 12 and the core layer 13 are deposited inside the tube 11 (FIG. 2A), and then partially sintered to form a porous layer (FIG. 2B). .

Subsequently, after impregnating the solution 14 containing a predetermined amount of metal ions into the porous layer, the state is maintained for about 1 hour (Fig. 2C).

Thereafter, the solution 14 is discharged from the tube 11. At this time, some of the metal ions dissolved in the solution 14 remain in the porous core layer. That is, the core layer 13 is doped with metal ions (FIG. 2D).

In this case, the metal ion dissolved in the solution 14 includes at least one ion of a first metal such as iron, chromium, vanadium and manganese, at least one ion of a second metal such as cobalt and nickel, aluminum The first metal has a negative slope of the light absorption coefficient in the optical signal wavelength band, and the second metal has a positive slope of the light absorption coefficient in the optical signal wavelength band. Aluminum is used to prevent evaporation of metal ions during high temperature collapsing steps.

In this case, the molar ratio of the first metal ion, the second metal ion, and the aluminum is 1 to 3: 4 to 6: 1 to 3. Since the final molar ratio value may vary depending on the temperature and gas pressure of the process, the molar ratio should be determined within the highest and lowest limits.

Thus, the core portion is co-doped with a first metal ion and a second metal ion having a light absorption coefficient having a negative slope and a positive slope, respectively, in the optical signal wavelength band, so that the improved optical fiber is substantially constant in the input optical signal. It can be done.

 According to the present invention, a core layer is formed of one ion of a first metal having a negative slope with a light absorption coefficient and one ion of a second metal having a positive slope with a light absorption coefficient in a predetermined optical signal wavelength band. By co-doping a constant multimode type of optically attenuated optical fiber can be provided. In particular, the co-dopant pairs described above include iron and cobalt ions, chromium ions and cobalt ions, manganese and cobalt ions, iron and nickel ions, vanadium and nickel ions, chromium and nickel ions, manganese and nickel ions. And the like.

While it has been shown and described that it is to be considered a preferred embodiment of the invention, it is to be understood that the invention is not limited to the specific embodiments and that various changes, modifications and equivalents may be substituted without departing from the scope of the invention. Those skilled in the art will understand.

For example, the core layer may be co-doped with a mixture of at least two of the first metals including iron ions, vanadium ions, chromium ions, and manganese ions in a predetermined ratio, and a mixture of cobalt and nickel in a predetermined ratio. It is possible to manufacture a constant multimode optical attenuation optical fiber.

In addition, the optical attenuator can be configured using the multi-mode optical attenuated optical fiber according to the embodiment.

As described above, according to the present invention, in a short range communication requiring multiple access, a specific working wavelength of the received various modes of optical signals, that is, a desired degree or a specific working wavelength band of 850 nm, that is, 1200 nm to 1650 nm, mainly 1310 It is possible to obtain a multimode optical attenuated optical fiber for obtaining a substantially constant light attenuation at nm and 1550 nm. That is, a multimode optical attenuation optical fiber is provided in which a light absorption coefficient is doped with at least one or more ions of a first metal having a negative slope in a predetermined optical signal wavelength band. Further, a multimode type optical attenuation optical fiber is provided by the core by co-doping the core layer with at least one ion of the second metal whose light absorption coefficient is positive in the predetermined optical signal wavelength band. In particular, the first metals are iron, chromium, manganese and vanadium and the second metals are nickel and cobalt.

Claims (11)

A multimode optical attenuation optical fiber having a core layer and a cladding layer, to obtain a desired degree of optical attenuation at a specific working wavelength in which the thickness ratio of the core layer and the cladding layer is 50 μm: 125 μm or 62.5 μm: 125 μm. , The core layer is doped with a first metal having a negative slope of light absorption coefficient at the specific working wavelength and a second metal ion having a positive slope of light absorption coefficient at the specific working wavelength. Multimode optically attenuated fiber optics to achieve the desired degree of optical attenuation in the band. delete The method according to claim 1, wherein the first metal is any one or more of iron, chromium, manganese and vanadium, and the second metal is any one or more of cobalt and nickel. Multimode optical attenuation fiber to obtain. 2. The multimode optical attenuation optical fiber of claim 1, wherein the core layer is configured to obtain a desired degree of optical attenuation at a particular working wavelength co-doped with aluminum. 2. The multimode optical attenuation optical fiber of claim 1, wherein the specific working wavelength is 850 nm. A multimode optical attenuation optical fiber having a core layer and a cladding layer, for obtaining a substantially constant light attenuation in a specific working wavelength band in which the thickness ratio of the core layer and the cladding layer is 50 μm: 125 μm or 62.5 μm: 125 μm. as, Wherein said core layer is doped with a first metal having a negative slope of light absorption coefficient in said specific working wavelength band and a second metal ion having a positive slope of light absorption coefficient in said specific working wavelength band. Multimode optically attenuated optical fiber to achieve a substantially constant optical attenuation in the working wavelength band. delete 7. The multimode optical attenuation optical fiber of claim 6, wherein the core layer is to achieve a substantially constant light attenuation in a particular working wavelength band co-doped with aluminum. delete 7. The multimode optical attenuation optical fiber of claim 6, wherein the specific working wavelength band is 1200 nm to 1650 nm. 7. The method of claim 6, wherein the first metal is at least one of iron, chromium, manganese and vanadium, and the second metal is at least one of cobalt and nickel. Multimode optical attenuation fiber to obtain.

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