JPH05188414A - Optical fiber amplifying device - Google Patents

Abstract

PURPOSE:To decrease fusion splicing positions between optical fibers by decreasing optical fibers, to decrease optical components, to reduce the loss of light to shorten the assembly time and to reduce the cost. CONSTITUTION:Signal light is inputted from an input optical fiber 1 to an erbium-doped optical fiber 4 through an optical isolator 2. Light beams having orthogonal planes of polarization are emitted from semiconductor laser chips 17 and 18 for excitation and converted by lenses 19 and 20 into parallel light beams coupled by a polarizing filter 35. The coupled light is reflected by a dielectric filter 36 as it is and inputted to the erbium-doped filter 4 through a lens 42, and the signal light is optically amplified. The amplified light passes through a lens 42 and transmitted through the dielectric filter 36, then is transmitted through an optical isolator 41 as it is, and outputted from an output fiber 8 through a lens 43.

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 used in an optical communication device or the like.

[0002]

2. Description of the Related Art FIG. 2 is a schematic block diagram showing a conventional optical fiber amplifier, FIG. 3 is a schematic block diagram showing a semiconductor laser module used in the optical fiber amplifier, and FIG. 4 is an optical fiber amplifier used in the optical fiber amplifier. It is a schematic block diagram which shows a wave demultiplexer.

As shown in FIG. 2, the input optical fiber 1 transmits the signal light having a wavelength of 1.55 μm to the first optical isolator 2
Is input to the optical fiber 3 via the optical fiber 3 and the first optical isolator 2 prevents light from being reflected back to the input side.
One end of an optical fiber 4 doped with erbium is connected to the optical fiber 3 by a fusion splicing part 5. An optical fiber 6 is attached to the other end of the erbium-doped optical fiber 4 by a fusion portion 7
Connected by.

The output optical fiber 8 is connected to the optical fiber 10 through the second optical isolator 9 and prevents the optical components connected to the output side by the second optical isolator 9 from reflecting and returning light. ing. An optical fiber 11 is connected to the optical fiber 10 by a fusion splicing part 12,
Are opposed to the optical fiber 6.

The first and second semiconductor laser modules 13 and 14 for excitation have polarization planes of 1.48 μm orthogonal to each other.
Of light having a wavelength of
And 16 can be output. Specifically, as shown in FIG. 3, the first and second semiconductor laser modules 13 and 14 for excitation are composed of semiconductor laser chips 17 and 18 and lenses 19 and 20, respectively.
The light emitted from the lens is focused on the polarization maintaining optical fibers 15 and 16 by the lenses 19 and 20. The polarization-maintaining optical fiber 15 and the fusion-splicing part 2
The polarization maintaining optical fiber 16 is connected to the polarization maintaining optical fiber 23 by the fusion splicing part 24. The two orthogonal polarizations output from the polarization maintaining optical fibers 21 and 23 are combined by the polarization beam coupler 25 and output from the optical fiber 26. The optical fiber 26 is connected to the optical fiber 27 by a fusion splicing portion 28, and the optical fiber 27 is arranged so as to be perpendicular to the optical fibers 6 and 11.

An optical multiplexer / demultiplexer 29 is provided at the intersection of the optical fibers 6, 11, and 27. As shown in FIG. 4, in the optical multiplexer / demultiplexer 29, a dielectric filter 31 is vapor-deposited on an inclined surface perpendicular to the bisector of the optical fibers 6 and 27 in an optical glass 30 having a triangular prism shape. . The dielectric filter 31 reflects light having a wavelength of 1.48 μm,
It can transmit light with a wavelength of 1.55 μm. Lenses 32, 33, 34 are provided between the optical fibers 6, 11, 27 and the optical glass 30 and the dielectric filter 31, respectively.

The operation of the above arrangement will be described below. Signal light having a wavelength of 1.55 μm is input from the input optical fiber 1 to the erbium-doped optical fiber 4 via the first optical isolator 2 and the optical fiber 3. On the other hand, the first and second semiconductor laser chips 17 and 1 for excitation
Light having a wavelength of 1.48 μm, which is emitted from 8 and whose polarization planes are orthogonal to each other, is condensed on the polarization-maintaining optical fibers 15 and 16 by the lenses 19 and 20, and is output from the polarization-maintaining optical fibers 15, 21 and 16, 23. Output. The two orthogonal polarized lights are combined by the polarization beam coupler 25 and output to the optical fiber 26. The light having a wavelength of 1.48 μm output from the optical fiber 26 is converted into parallel light by the lens 34 in the optical multiplexer / demultiplexer 29, and then reflected by the dielectric filter 31. This reflected light is reflected by the lens 32. The light is focused on the optical fiber 6 and input. The light having a wavelength of 1.48 μm from the first and second semiconductor laser chips 17 and 18 for pumping inputted to the optical fiber 6 is inputted to the erbium-doped optical fiber 4,
The erbium atoms in the erbium-doped optical fiber 4 are excited. At this time, since signal light having a wavelength of 1.55 μm is input to the erbium-doped optical fiber 4, stimulated emission occurs, and signal light having a wavelength of 1.55 μm is optically amplified. The amplified light having a wavelength of 1.55 μm is output from the optical fiber 6, converted into parallel light by the lens 32 in the optical multiplexer / demultiplexer 29, and then transmitted through the dielectric filter 31 and the optical glass 30, and the lens 33. Optical fiber 11
It is focused on and input. The amplified light input to the optical fiber 11 is output from the output optical fiber 8 via the optical fiber 10 and the second optical isolator 9.

As described above, the above-mentioned conventional optical fiber amplifier can also amplify the input light to obtain a constant output light.

[0009]

However, in the above-mentioned conventional optical fiber amplifier, many optical components such as the optical multiplexer / demultiplexer 29, the polarization beam coupler 25, the optical isolators 2 and 9, and the semiconductor laser modules 13 and 14 are used. Optical fiber is used, and the number of fusion points between optical fibers that connect each optical component increases, resulting in large optical loss, poor amplification efficiency, and long assembly time. There was a problem such as becoming expensive.

The present invention solves the above-mentioned conventional problems, and reduces the number of optical fibers to reduce the number of fused portions and the number of optical components, thus reducing the loss of light. It is an object of the present invention to provide an optical fiber amplifying device capable of reducing the assembly time and reducing the cost.

[0011]

In order to achieve the above object, the present invention provides an input optical fiber for inputting signal light and a first optical isolator for preventing the signal light from being reflected back to the input side. An erbium-doped optical fiber for optically amplifying the input signal light, an output optical fiber for outputting the light amplified by the erbium-doped optical fiber, and a second optical fiber for preventing the amplified light from being reflected and returned. An optical isolator, first and second pumping semiconductor laser modules that output light whose polarization planes are orthogonal to each other, a polarization filter that couples the light output from each pumping semiconductor laser module, and the coupled light Is input as is to the erbium-doped optical fiber for optical amplification of the signal light, and the light amplified by the erbium-doped optical fiber is transmitted. Is input to the second optical isolator is obtained by a dielectric filter.

[0012]

Therefore, according to the present invention, the signal light is input from the input optical fiber to the erbium-doped optical fiber through the first optical isolator and is output from the first and second semiconductor laser modules for pumping. Light having orthogonal wavefronts is combined by a polarization filter. The coupled light is reflected by the dielectric filter as it is, and is input to the erbium-doped optical fiber to which the signal light is input to excite the erbium atom to cause stimulated emission and optically amplify the signal light. The amplified light is transmitted through the dielectric filter, input to the second optical isolator as it is, and output from the output optical fiber. Since the polarization filter, the dielectric filter, and the second optical isolator are not connected by the optical fiber as described above, the number of fusion points of the optical fiber can be reduced and the number of optical fibers and optical parts can be reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing an optical fiber amplifier according to an embodiment of the present invention.

A portion surrounded by a dotted line in FIG. 1 corresponds to a portion surrounded by a dotted frame of the above-mentioned conventional example shown in FIG. 2, and the same portions will be denoted by the same reference numerals. As shown in FIG. 1, the input optical fiber 1 inputs the signal light having a wavelength of 1.55 μm into the optical fiber 3 via the first optical isolator 2, and the light is reflected by the first optical isolator 2 to the input side. And then prevent them from returning. One end of an optical fiber 4 doped with erbium is connected to the optical fiber 3 by a fusion splicing part 5. An optical fiber 6 is connected to the other end of the erbium-doped optical fiber 4 by a fusion splicing part 7. The output optical fiber 8 faces the optical fiber 6.

The semiconductor laser chips 17 and 18 in the first and second semiconductor modules for excitation have polarization planes that are parallel to and perpendicular to the plane of the paper, and are perpendicular to each other at 1.48 μm.
The light of the wavelength is emitted. The light emitted from the first and second semiconductor laser chips 17 and 18 is converted into parallel light by the lenses 19 and 20. The first and second semiconductor laser chips 17 and 18 and the lenses 19 and 20 are arranged so that their output directions are orthogonal to each other, and the output direction of the lens 19 is perpendicular to the optical fibers 6 and 8. It is located in.

A polarization filter 35, a dielectric filter 36, a second optical isolator 41 and the like are provided at the intersections of the output directions of the optical fibers 6 and 8 and the lens 19.
The polarization filter 35 is capable of transmitting light whose polarization plane is parallel to the paper surface and reflecting light whose polarization plane is perpendicular to the paper surface, and is a surface that is the hypotenuse of the pair of triangular prism-shaped optical glasses 37 and 38. It is glued so as to be sandwiched between. The dielectric filter 36 reflects light having a wavelength of 1.48 μm and is 1.5
Light having a wavelength of 5 μm can be transmitted, and it is arranged so as to be sandwiched between the sides of the pair of triangular prism-shaped optical glasses 39 and 40 which are the oblique sides, and vapor-deposited on either one side. The polarization filter 35 and the dielectric filter 36 are arranged at right angles, and the polarization filter 35 transmits the light from the lens 19 and reflects the light from the lens 20, and the dielectric filter 36 converts the light into the optical fiber 6 It is arranged so that it can be reflected. Optical glass 3
A second optical isolator 41 that causes the light that has passed through the dielectric filter 36 to enter the output optical fiber 8 is provided on the back side of the ninth optical isolator 41. The second optical isolator 41 is an optical component connected to the output side. It prevents reflections and returns. A lens 42 is provided between the optical fiber 6 and the dielectric filter 36, and the output optical fiber 8 and the second optical isolator 4 are provided.
A lens 43 is provided between the lens 43 and the lens 1.

The operation of the above arrangement will be described below. Signal light having a wavelength of 1.55 μm is input from the input optical fiber 1 to the erbium-doped optical fiber 4 via the first optical isolator 2 and the optical fiber 3. On the other hand, the first and second semiconductor laser chips 17 and 1 for excitation
From 8, the planes of polarization are parallel to and perpendicular to the plane of the paper, and the lights having wavelengths of 1.48 μm orthogonal to each other are emitted. Light having a wavelength of 1.48 μm, which has a plane of polarization output from the semiconductor laser chip 17 for the first pumping and is parallel to the paper surface, is reflected by the lens 1
After being converted into parallel light at 9, the light passes through the optical glass 37 and the polarization filter 35. The plane of polarization output from the second semiconductor laser chip 18 for excitation is perpendicular to the plane of the paper 1.
The light having a wavelength of 48 μm is converted into parallel light by the lens 20, then passes through the optical glass 38, and is reflected by the polarization filter 35. Thus, the light transmitted through the polarization filter 35, reflected by the polarization filter 35, and combined is the optical glass 3
8 and 40, and is reflected by the dielectric filter 36.
This reflected light passes through the optical glass 40, is condensed by the lens 42 on the optical fiber 6, and is input. First and second semiconductor laser chips 1 for excitation inputted to the optical fiber 6.
Light having a wavelength of 1.48 μm from 7, 18 enters the erbium-doped optical fiber 4 and excites erbium atoms in the erbium-doped optical fiber 4. At this time, since signal light having a wavelength of 1.55 μm is input to the erbium-doped optical fiber 4, stimulated emission occurs and
Signal light having a wavelength of μm is optically amplified. Amplified light with a wavelength of 1.55 μm is output from the optical fiber 6 and the lens 42
After being converted into parallel light by, the light passes through the optical glass 40, the dielectric filter 36, and the optical glass 39, and is input to the second optical isolator 41. Second optical isolator 41
The amplified light that has passed through is focused on the output optical fiber 8 by the lens 43 and output from the output optical fiber 8.

As described above, according to the above-mentioned embodiment, the polarization beam coupler 25 and the optical multiplexer / demultiplexer 2 in the above-mentioned conventional example are used.
9, the second optical isolator 9 and the functional portions of the first and second semiconductor laser modules 13 and 14 are integrated and combined to reduce the number of input / output optical fibers to reduce the number of fused portions, The number of optical parts is reduced. Therefore, the loss of light can be reduced to improve the amplification efficiency, the assembly time can be shortened, and the cost can be reduced.

[0020]

As described above, according to the present invention, the signal light is input from the input optical fiber to the erbium-doped optical fiber through the first optical isolator, and the first and second semiconductor lasers for pumping are input. Light output from the module and having orthogonal polarization planes is combined by a polarization filter. The coupled light is reflected by the dielectric filter as it is, and is input to the erbium-doped optical fiber to which the signal light is input to excite the erbium atom to cause stimulated emission and optically amplify the signal light. The amplified light is transmitted through the dielectric filter, input to the second optical isolator as it is, and output from the output optical fiber. Since the polarization filter, the dielectric filter, and the second optical isolator are not connected by the optical fiber in this way, the number of fusion points of the optical fiber can be reduced,
Moreover, the number of optical fibers and optical components can be reduced.
Therefore, the loss of light can be reduced, and
Assembling time can be shortened and cost reduction can be achieved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an optical fiber amplifier according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a conventional optical fiber amplifier.

FIG. 3 is a schematic configuration diagram showing a semiconductor laser module used in the optical fiber amplifier.

FIG. 4 is a schematic configuration diagram showing an optical multiplexer / demultiplexer used in the optical fiber amplifier.

[Explanation of symbols]

 1 Input Optical Fiber 2 First Optical Isolator 4 Erbium Doped Optical Fiber 8 Output Optical Fiber 17 First Excitation Semiconductor Laser Chip 18 Second Excitation Semiconductor Laser Chip 35 Polarizing Filter 36 Dielectric Filter 41 Second Optical isolator

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H04B 10/16

Claims (1)

[Claims] 1. An input optical fiber for inputting signal light, a first optical isolator for preventing the signal light from reflecting back to the input side, and an erbium-doped optical fiber for optically amplifying the input signal light. An output optical fiber for outputting the light amplified by the erbium-doped optical fiber, a second optical isolator for preventing the amplified light from reflecting and returning, and a first and a second for outputting light whose polarization planes are orthogonal to each other. A second pumping semiconductor laser module, a polarization filter that couples the light output from each pumping semiconductor laser module, the coupled light is reflected as it is, and the erbium-doped optical fiber optically amplifies the signal light. And a dielectric filter for transmitting the light amplified by the erbium-doped optical fiber and inputting it to the second optical isolator as it is. Optical fiber amplifier equipped.