Gain flattening filter device for multi-core optical fiber light amplification device

Abstract

The utility model provides a gain flattening filter device for a multi-core optical fiber light amplification device, which comprises an input multi-core optical fiber, an input lens, an optical isolation system, a gain flattening filter plate, an output lens and an output multi-core optical fiber which are sequentially arranged along the direction of an optical path, the light passes through an optical isolation system, a gain flattening filter and an output lens in sequence and then is input to a second fiber core; each beam of light passing through the gain flattening filter and the optical axis form an emergent included angle theta, and the optical isolation system is used for isolating return light of the gain flattening filter. A light beam enters the gain flattening filter plate at an angle to ensure that interface reflected light can deviate from an inlet end collimator, so that return loss is ensured, pre-stage amplification is prevented from being influenced, meanwhile, the interface reflected light of the gain flattening filter plate is isolated by using an optical isolation system in a matched manner, normal operation of a pre-stage amplification system is ensured, and the integration of the devices is utilized. And miniaturization packaging can be facilitated.

Description

TECHNICAL FIELD

[0001] The utility model relates to optical communication technical field especially relates to a gain flat filter device for multi -core optical fiber optical amplification device. BACKGROUND

[0002] In current optical fiber communication system, erbium-doped optical fiber amplifer (EDFA for short) is the key component for long distance communication, can carry out power amplification to C band 1550nm, S band 1480nm and L band 1610nm, and is widely used in long distance optical fiber communication, high speed communication and optical fiber access cable television and the like field.

[0003] In the single core EDFA system of current large scale operation, gain flat filter device is generally used for gain, but gain flat filter device needs to solve the problem of return loss, otherwise it is difficult to ensure that the interface reflected light can deviate from the input end collimator to ensure return loss, and further affect the front stage amplification. UTILITY MODEL CONTENTS

[0004] The utility model aims at providing a gain flat filter device for multi -core optical fiber optical amplification device.

[0005] In order to realize the utility model purposes, the utility model provides a gain flat filter device for multi -core optical fiber optical amplification device, including input multi -core optical fiber, input lens, optical isolation system, gain flat filter piece, output lens and output multi -core optical fiber that are arranged in sequence along the light path direction, and the input lens and the output lens are aspherical lenses;The input multi -core optical fiber includes first cladding and multiple first fiber cores, and the first cladding is arranged as a cylinder along the optical axis, and the multiple first fiber cores are arranged in the first cladding parallel to the optical axis, and the multiple first fiber cores are arranged rotationally symmetric around the optical axis, and the output end of the input multi -core optical fiber is opposite the input end inclined surface of the input lens;The output multi -core optical fiber includes second cladding and multiple second fiber cores, and the second cladding is arranged as a cylinder along the optical axis, and the multiple second fiber cores are arranged in the second cladding parallel to the optical axis, and the multiple second fiber cores are arranged rotationally symmetric around the optical axis, and the output end of the output lens is opposite the input end inclined surface of the output multi -core optical fiber;The light of a first fiber core is output from the input lens, and is input to a second fiber core after passing through the optical isolation system, gain flat filter piece and output lens in turn;Each beam of light passing through the gain flat filter piece is arranged with an exit angle θ with the optical axis, and the exit angle θ of each beam of light is equal, and 0 ° < θ ≤ 3 °, and the optical isolation system is used for isolating the return light of the gain flat filter piece.

[0006] Further, the input lens is a C lens or a self-focusing lens.

[0007] Further, the output lens is a C lens or a self-focusing lens.

[0008] Further, the number of the first cores and the number of the second cores are equal.

[0009] Further, the number of the first cores and the number of the second cores are four.

[0010] Further, the optical isolation system is a wedge-type optical isolator, which includes a first wedge angle piece, an optical rotator and a second wedge angle piece arranged in sequence along an optical path.

[0011] Further, the optical isolation system is a Displacer-type optical isolator, which includes a first birefringent crystal, an optical rotator, a half-wave plate and a second birefringent crystal arranged in sequence along an optical path.

[0012] Further, the optical isolation system is a PBS-type optical isolator, which includes a first PBS crystal, an optical rotator, a half-wave plate and a second PBS crystal arranged in sequence along an optical path.

[0013] The beneficial effect of the utility model is that the same gain flat effect is obtained by the same incident angle of four-core exit light beams to the same gain flat filter piece, the exit light beams are symmetrically distributed relative to the optical axis of the gain flat filter piece, the interface reflected light can deviate from the entrance collimator to ensure the return loss by the beam angle incident to the gain flat filter piece, the front-stage amplification is avoided, the optical isolation system is used to isolate the interface return light of the gain flat filter piece, the return loss is ensured to be more than 45dB, the front-stage amplification system is ensured to operate normally, the integration of the above-mentioned device is used, and the miniaturized packaging is facilitated. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is the optical path schematic view of the gain flat filter device embodiment of the utility model.

[0015] Figure 2 is the optical path schematic view of the gain flat filter piece in the gain flat filter device embodiment of the utility model.

[0016] Figure 3 is the schematic view of the light angle in the gain flat filter device embodiment of the utility model.

[0017] Figure 4 is the schematic view of the wedge-type optical isolator in the gain flat filter device embodiment of the utility model.

[0018] Figure 5is a schematic diagram of the Displacer type optical isolator in the gain-flattened filter device embodiment of the utility model.

[0019] Figure 6 is a schematic diagram of the PBS light-splitting type optical isolator in the gain-flattened filter device embodiment of the utility model.

[0020] The utility model will be further described below in combination with the drawings and embodiments. DETAILED DESCRIPTION

[0021] Referring to Figures 1 to 3 The gain-flattened filter device comprises an input multi-core optical fiber 11, an input lens 13, an optical isolation system 2, a gain-flattened filter 15, an output lens 14 and an output multi-core optical fiber 12 arranged in sequence along the light path direction, the input lens 13 and the output lens 14 are aspherical lenses, the input lens 13 adopts a C lens or a self-focusing lens, and the output lens 14 adopts a C lens or a self-focusing lens.

[0022] The input multi-core optical fiber 11 adopts a four-core optical fiber, the input multi-core optical fiber 11 comprises a first cladding 111 and four first cores 112, the first cladding 111 is arranged in a column along an optical axis L0, the four first cores 112 are arranged in the first cladding 111 in parallel to the optical axis L0, and the four first cores 112 are arranged in rotational symmetry around the optical axis L0; the output end of the input multi-core optical fiber 11 is opposite the input end inclined surface of the input lens 13.

[0023] The output multi-core optical fiber 12 adopts a four-core optical fiber, the output multi-core optical fiber 12 comprises a second cladding 121 and four second cores 122, the second cladding 121 is arranged in a column along an optical axis L0, the four second cores 122 are arranged in the second cladding 121 in parallel to the optical axis L0, and the four second cores 122 are arranged in rotational symmetry around the optical axis L0; the output end of the output lens 14 is opposite the input end inclined surface of the output multi-core optical fiber 12.

[0024] The light of one first core 112 is output from the input lens 13, sequentially passes through the optical isolation system 2, the gain-flattened filter 15 and the output lens 14 and is input to one second core 122, each beam of light L1 passing through the gain-flattened filter 15 is arranged at an exit angle θ with the optical axis L0, the exit angle θ of each beam of light L1 is equal, 0° < θ ≤ 3°, preferably, 1° ≤ θ ≤ 2°, and the four beams of light are arranged in rotational symmetry around the optical axis L0.

[0025] The optical isolation system 2 is used for isolating the return light of the gain-flattened filter 15, and the optical isolation system 2 has various arrangement modes.

[0026] Referring to Figure 4The optical isolation system 2 can adopt a wedge-type optical isolator, which includes a first wedge angle sheet 211, an optical rotator 212 and a second wedge angle sheet 213 arranged in sequence along the light path.

[0027] Referring to Figure 5 The optical isolation system 2 can also adopt a Displacer-type optical isolator, which includes a first birefringent crystal 221, an optical rotator 222, a half-wave plate 223 and a second birefringent crystal 224 arranged in sequence along the light path, and the outer periphery of the optical rotator 222 is provided with a magnet.

[0028] Referring to Figure 6 The optical isolation system 2 can also adopt a PBS-type optical isolator, which includes a first PBS crystal 231, an optical rotator 232, a half-wave plate 233 and a second PBS crystal 234 arranged in sequence along the light path, and the outer periphery of the optical rotator 232 is provided with a magnet.

[0029] Of course, the above embodiments are only preferred embodiments of the present application, and in specific applications, the number of fiber cores can be selected correspondingly, and the number can be two or more, and the number can be equal or unequal.

[0030] As can be seen from the above, the same incidence angle of the four-core exit light beams incident on the same gain flattening filter is obtained to achieve the same gain flattening effect, and the exit light beams are spatially symmetrically distributed relative to the optical axis of the gain flattening filter, the gain flattening filter is incident by the beam angle to ensure that the interface reflected light deviates from the entrance collimator to ensure the return loss, avoid affecting the front-stage amplification, and at the same time, the optical isolation system is used to isolate the interface return light of the gain flattening filter, so as to ensure that the return loss is more than 45 dB, ensure the normal operation of the front-stage amplification system, and the integration of the above-mentioned devices can be beneficial to miniaturization packaging.

Claims

1. A gain flattening filter device for a multi-core fiber optical amplifying apparatus, characterized by, The input multi-core optical fiber, the input lens, the optical isolation system, the gain flattening filter, the output lens and the output multi-core optical fiber are arranged in sequence along the light path direction, and the input lens and the output lens are aspherical lenses. The input multi-core optical fiber comprises a first cladding and a plurality of first cores, the first cladding is arranged in a column along an optical axis, and the plurality of first cores are arranged in the first cladding in parallel to the optical axis, and the plurality of first cores are arranged in rotational symmetry around the optical axis, and the output end of the input multi-core optical fiber is opposite to the input end of the input lens. The output multi-core optical fiber comprises a second cladding and a plurality of second cores, the second cladding is arranged in a column along an optical axis, and the plurality of second cores are arranged in the second cladding in parallel to the optical axis, and the plurality of second cores are arranged in rotational symmetry around the optical axis, and the output end of the output lens is opposite to the input end of the output multi-core optical fiber. The light of one of the first cores is output from the input lens, and then input to one of the second cores after passing through the optical isolation system, the gain flattening filter and the output lens in sequence. Each beam of light passing through the gain flattening filter is arranged at an exit angle θ with the optical axis, and the exit angle θ of each beam of light is equal, and 0° < θ ≤ 3°, and the optical isolation system is used to isolate the return light of the gain flattening filter.

2. The gain flattening filter device according to claim 1, wherein: The input lens is a C lens or a self-focusing lens.

3. The gain flattening filter device according to claim 1, wherein: The output lens is a C lens or a self-focusing lens.

4. The gain flattening filter device according to claim 1, wherein: The number of the first cores is equal to the number of the second cores.

5. The gain flattening filter device according to claim 4, wherein: The number of the first cores and the number of the second cores are four.

6. The gain flattening filter device according to any one of claims 1 to 5, wherein: The optical isolation system is a wedge-type optical isolator, and the wedge-type optical isolator comprises a first wedge angle piece, a rotatory piece and a second wedge angle piece arranged in sequence along the light path direction.

7. The gain flattening filter device according to any one of claims 1 to 5, wherein: The optical isolation system is a Displacer-type optical isolator, and the Displacer-type optical isolator comprises a first birefringent crystal, a rotatory piece, a half-wave plate and a second birefringent crystal arranged in sequence along the light path direction.

8. The gain flattening filter device according to any one of claims 1 to 5, wherein: The optical isolation system is a PBS-type optical isolator, and the PBS-type optical isolator comprises a first PBS crystal, a rotatory piece, a half-wave plate and a second PBS crystal arranged in sequence along the light path direction.

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