JPH05211359A - Optical fiber amplifier - Google Patents

Abstract

PURPOSE:To provide a rare earth-doped optical fiber amplifier suitable for miniaturization. CONSTITUTION:An optical fiber amplifier is equipped with a pumping light source 2, an optical multiplexer 4 which multiplexes inputted signal light and pumping light emitted from the pumping light source 2 together, and a rare earth-doped fiber 6 where the multiplexed light composed of signal light and pumping light and outputted from the optical multiplexer 4 is inputted, where the rare earth-doped fiber 6 is arranged as wound around the periphery of the other component parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber amplifier using a rare earth doped fiber. An optical amplifier that directly amplifies an optical signal as it is without converting it into an electrical signal is virtually bit rate-free, and it is easy to increase the capacity, and it is possible to collectively amplify multiple channels. , Is being actively studied by each research institute as one of the key devices for future optical communication systems.

As one form of this kind of optical amplifier, an optical fiber whose main core is doped with rare earth elements or ions (Er, Nd, Yb, etc.) (referred to as "rare earth doped fiber" in the present specification) is used. There is an optical fiber amplifier.

The optical fiber amplifier has excellent features such as a large gain, no polarization dependence of the gain, low noise, and a small connection loss with the fiber for the transmission line, which is put to practical use. The optimization of the above configuration is being sought.

[0004]

2. Description of the Related Art FIG. 5 is a diagram showing a general configuration of a conventional optical fiber amplifier. This optical fiber amplifier includes a pumping light source 2, an optical multiplexer 4 that multiplexes the input signal light with the pumping light from the pumping light source 2, and a rare earth-doped fiber into which the signal light and the pumping light from the optical multiplexer 4 are input. 6 and 6. Reference numeral 8 is an input port for inputting the signal light, 10 and 12 are optical isolators respectively provided on the input side and the output side of the rare earth-doped fiber 6, 14 is an output port for outputting the amplified signal light, and 16 is a rare earth-doped fiber. 6 is a reel wound around.

[0005]

By the way, in the rare earth-doped fiber, if the doping concentration of the rare earth element is too high, the gain is lowered due to the concentration quenching phenomenon, so there is an optimum value of the doping concentration.

For example, the rare earth element is Er (erbium).
In this case, the optimum doping concentration is several hundred ppm or less. In this case, the length of the rare earth-doped fiber required to obtain a sufficient gain is as long as several tens of meters to several hundreds of meters, and when the optical fiber amplifier is constructed using this rare earth-doped fiber, the rare earth-doped fiber is large. There is a problem that the space is occupied and the optical fiber amplifier becomes large in size.

The loss of the rare earth-doped fiber increases if the curvature is made too small. Specifically, when the width of the reel is set to the height of other parts and set to about 20 mm,
The reel inner diameter is about 60 mm and the reel outer diameter is 100 mm to 200 mm.
Therefore, it is difficult to downsize the optical fiber amplifier.

The present invention was created in view of such circumstances, and an object thereof is to provide an optical fiber amplifier suitable for miniaturization.

[0009]

The optical fiber amplifier of the present invention created to solve the above-mentioned technical problems includes:
In an optical fiber amplifier including a pumping light source, an optical multiplexer that combines the input signal light with the pumping light from the pumping light source, and a rare earth-doped fiber into which the signal light and the pumping light from the optical multiplexer are input The wound rare-earth doped fiber is arranged on the outer circumference of other components.

[0010]

According to the structure of the present invention, the wound rare earth-doped fiber is arranged on the outer periphery of the other components,
The device volume can be effectively used, and the optical fiber amplifier can be downsized. Further, the increase in loss due to the small curvature curvature of the rare earth-doped fiber is unlikely to occur.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an optical fiber amplifier showing an embodiment of the present invention. Portions substantially the same as those in FIG. 5 showing the prior art are designated by the same reference numerals.

Reference numeral 2 denotes an excitation light source composed of a semiconductor laser, and this excitation light source 2 outputs excitation light having a wavelength of 1.48 μm. The signal light having a wavelength of 1.55 μm input from the input port 8 using an optical connector or the like is input to the optical multiplexer 4 together with the pumping light from the pumping light source 2, where the signal light and the pumping light are combined. It

The signal light and the pumping light from the optical multiplexer 4 are input to the Er-doped rare earth element-doped fiber 6 via the optical isolator 10, and the signal is generated by the action of the rare earth element and the pumping light doped here. The light is amplified.

The amplified signal light is passed through the optical isolator 12
Is output from the output port 14 via. Each component is placed on a suitable substrate 18 and the optical connections between each component are made by optical fibers.

The rare earth-doped fiber 6 is wound around a reel 20 provided along the outer circumference of a substrate 18 having a rectangular component arrangement surface. The excitation light source 2, the optical multiplexer 4, and the optical isolators 10 and 12 are arranged inside the reel 20.

FIG. 2 is a plan view of the reel 20, and FIG. 3 is a sectional view of the reel 20 taken along the line AA. Reel 2
0 has a substantially rectangular shape along the outer periphery of the rectangular substrate 18, and its four corners have an appropriate curvature so that the bending loss of the wound rare earth-doped fiber does not increase. Given the curvature of.

In the cross section of the reel 20, reference numeral 22 is a groove around which the rare earth-doped fiber 6 is wound. By forming such a groove, the operation of winding the rare earth-doped fiber 6 around the reel 20 is easy. As a result, the wound rare earth-doped fiber is less likely to fall off.

By arranging the rare earth-doped fiber along the outer circumference of the substrate using such a reel, it is possible to arrange the components such as the pumping light source 2 inside the fiber, thereby reducing the size of the optical fiber amplifier. It will be possible.

By the way, when the reel is mounted on a rectangular substrate, it is advantageous that the reel has a substantially rectangular shape as described above, but the reel is a ring when the rare earth-doped fiber is wound around the reel. The shape is preferable.

Therefore, in another preferred embodiment of the present invention, a reel as shown in FIG. 4 is used. That is,
As shown in FIG. 4A, a reel 26 in which a plurality of cuts 24 at equal intervals in the circumferential direction are formed on the outer circumference of a ring member made of plastically deformable resin or the like is used, and the reel 26 is formed in this form. After winding the rare earth-doped fiber on
As shown in FIG. 4B, the reel 26 and the wound rare earth-doped fiber are transformed into a substantially rectangular shape.

According to this embodiment, the mountability of the reel on the substrate and the workability of winding the rare earth-doped fiber around the reel can be compatible with each other.

[0022]

As described above, according to the present invention,
It is possible to provide an optical fiber amplifier suitable for miniaturization.

[Brief description of drawings]

FIG. 1 is a block diagram of an optical fiber amplifier showing a preferred embodiment of the present invention.

2 is a plan view of the reel shown in FIG. 1. FIG.

3 is a sectional view taken along the line AA of the reel shown in FIG.

FIG. 4 is an explanatory diagram of a reel according to another preferred embodiment of the present invention.

FIG. 5 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 2 pumping light source 4 optical multiplexer 6 rare earth-doped fiber 20, 26 reel

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location H04B 10/16 8426-5K H04B 9/00 J (72) Inventor Osamu Oyama Nakahara-ku, Kawasaki-shi, Kanagawa 1015 Kamiodanaka, Fujitsu Limited (72) Inventor, Kiyoji Terai, 1015 Kamikodanaka, Nakahara-ku, Kawasaki, Kanagawa Within Fujitsu Limited

Claims (1)

[Claims] 1. A pumping light source (2), an optical multiplexer (4) for multiplexing the input signal light with the pumping light from the pumping light source, and a signal light and a pumping light from the optical multiplexer (4). An optical fiber amplifier comprising: a rare-earth-doped fiber (6) to be input by the above, wherein the wound rare-earth-doped fiber (6) is arranged on the outer circumference of another component.