Two-way polarization-maintaining amplification laser light source

Abstract

The utility model relates to a two-way polarization-maintaining amplification laser light source, which comprises a seed source, a first isolator, a polarization splitting prism, an optical path separation device, an optical filter, a double-optical-fiber collimator, a pumping source, a non-polarization-maintaining single-mode gain optical fiber, a single-optical-fiber collimator, a polarization rotator, a reflection device and a second isolator. The polarization-maintaining optical fiber amplifier can solve the problems of high cost and secondary pulse of a polarization-maintaining optical fiber amplifier in the prior art.

Description

Technical Field

[0001] The utility model relates to the technical field of lasers, in particular to a double-pass polarization-maintaining amplified laser light source. Background Art

[0002] At present, the application scope of fiber lasers is very wide, especially in the fields of laser radar, etc., but in some special applications, such as coherent communication and coherent sensor, a high-power linear polarization output laser light source is required. In this case, the general polarization-maintaining laser is difficult to meet the demand, so the polarization-maintaining fiber amplifier laser comes into being. Since the ordinary fiber amplifier laser changes the polarization state of the laser during its amplification process, the traditional high extinction ratio polarization-maintaining fiber amplifier usually adopts a full polarization-maintaining structure, that is, the components constituting the high extinction ratio polarization-maintaining fiber amplifier laser are all polarization-maintaining, so that the polarization signal always maintains the consistency of the polarization state during the transmission process. However, the high extinction ratio polarization-maintaining fiber amplifier laser using the full polarization-maintaining structure has the problem of high cost, especially the polarization-maintaining gain fiber used in the high extinction ratio polarization-maintaining fiber amplifier laser, whose production technology is only in the hands of a few companies, and the existing high extinction ratio polarization-maintaining fiber amplifier laser with the full polarization-maintaining structure has the problem of high cost. In addition, the fiber amplifier laser made with the ordinary structure also has the problem of sub-pulse. Summary of the invention

[0003] The main purpose of the utility model is to provide a double-pass polarization-maintaining amplified laser light source, which can solve the problems of high cost and sub-pulse of polarization-maintaining optical fiber amplifiers in the prior art.

[0004] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0005] A double-pass polarization-maintaining amplified laser light source, comprising: a seed source, a first isolator, a polarization beam splitter, an optical path separation device, a filter, a dual-fiber collimator, a pump source, a non-polarization-maintaining single-mode gain fiber, a single-fiber collimator, a polarization rotator, a reflection device and a second isolator;

[0006] The seed source is used to provide collimated horizontal or vertical polarized signal light;

[0007] The first isolator is used to transmit polarized signal light and isolate the backward transmitted signal light;

[0008] The polarization beam splitter prism is used to transmit the input polarized signal light and reflect the light perpendicular to the polarization direction of the input polarized signal light;

[0009] The optical path separation device is used to transmit the input polarized signal light and the backward transmitted signal light, and make the two beams of light have an angle;

[0010] The pump source is used to provide pump light;

[0011] The dual-fiber collimator is composed of a coupling lens and a dual-fiber head, one of the optical fibers in the dual-fiber head is connected to a pump source to transmit pump light, and the other optical fiber is used to transmit signal light;

[0012] The filter is used to transmit the signal light and reflect the pump light;

[0013] The non-polarization-maintaining single-mode gain optical fiber is used to amplify polarized signal light;

[0014] The single fiber collimator is used to collimate or couple the amplified polarized signal light;

[0015] The polarization rotator is used to non-reciprocally rotate the polarization direction of the amplified polarized signal light, and the polarization direction of the signal light passing through the polarization rotator once is rotated by 45 degrees;

[0016] The reflecting device is used to reflect the amplified polarized signal light;

[0017] The second isolator is used to output the signal light reflected from the polarization beam splitter prism and isolate the backward transmitted light.

[0018] Furthermore, the first isolator and the second isolator are single-stage isolators or multi-stage isolators.

[0019] Furthermore, the filter is a wedge-shaped piece, the flat end of which faces the dual-fiber collimator and is coated with a film layer for transmitting signal light and reflecting pump light.

[0020] Furthermore, the optical path separation device is a polarization separation device based on a birefringent crystal, including a Wollaston prism, an yttrium vanadate crystal, a lithium niobate crystal, a lithium tantalate crystal or a quartz crystal.

[0021] Furthermore, the optical fiber used for transmitting signal light in the dual-fiber head of the dual-fiber collimator is a non-gain optical fiber or a gain optical fiber; and the optical fiber of the single-fiber collimator is a non-gain optical fiber or a gain optical fiber.

[0022] Furthermore, the reflecting device is a plane reflecting mirror or a reflecting prism or a reflecting film layer coated on the output end face of the polarization rotator.

[0023] Furthermore, the positions of the dual-fiber collimator, the filter, the pump source and the single-fiber collimator can be interchanged, that is, the dual-fiber collimator, the filter, and the pump source are located on the right side of the non-polarization-maintaining single-mode gain fiber, and the single-fiber collimator is located on the left side of the non-polarization-maintaining single-mode gain fiber.

[0024] Furthermore, the polarization rotator is a Faraday rotator.

[0025] Furthermore, the non-polarization-maintaining single-mode gain optical fiber is a single-clad or double-clad optical fiber.

[0026] Furthermore, an output fiber collimator is additionally provided at the output end of the second isolator to realize the output of signal light through the fiber.

[0027] The utility model adopts the above technical solution, and has the beneficial effects of: by setting a polarization rotator and a reflection device, the polarization-maintaining double-pass fiber amplification laser system can achieve polarization-maintaining amplification effect by using a non-polarization-maintaining single-mode gain fiber, so that there is no need to use a special polarization-maintaining gain fiber, which can effectively reduce the cost of a high extinction ratio polarization-maintaining double-pass fiber amplification laser. And by setting an optical path separation device, the amplified signal light after the second pass through the non-polarization-maintaining single-mode gain fiber is deviated from the optical path of the original signal light, and by setting a first isolator and a second isolator, the problem of secondary pulses caused by end face reflection is greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention is further described in detail below with reference to the accompanying drawings and specific implementations:

[0029] Figure 1 This is a schematic diagram of Embodiment 1 of the present utility model;

[0030] Figure 2 It is a light path schematic diagram of the light path separation device of this utility model;

[0031] Figure 3 This is a schematic diagram of Example 2 of the utility model. DETAILED DESCRIPTION Example

[0032] Figure 1 This is a schematic diagram of the structure of the polarization-maintaining double-pass fiber-amplified laser light source of the utility model, which structure includes: a seed source 101, a first isolator 102, a polarization splitter prism 103, an optical path separation device 104, a filter 105, a dual-fiber collimator 106, a pump source 107, a non-polarization-maintaining single-mode gain fiber 108, a single-fiber collimator 109, a polarization rotator 110, a reflection device 111, and a second isolator 112.

[0033] The seed source 101 is used to provide collimated horizontal or vertical polarized signal light; the first isolator 102 is used to transmit the polarized signal light and isolate the backward transmitted signal light; the polarization splitter prism 103 is used to transmit the input polarized signal light and reflect the light perpendicular to the polarization direction of the input polarized signal light; the optical path separation device 104 is used to transmit the input polarized signal light and the backward transmitted signal light, and make the two beams of light have an angle; the optical path separation device is a polarization separation device based on a birefringent crystal, including but not limited to a Wollaston prism, a yttrium vanadate crystal, a lithium niobate crystal, a lithium tantalate crystal or a quartz crystal; the pump source 107 is used to provide pump light; the dual-fiber collimator 106 is composed of a coupling lens and a dual-fiber head, one optical fiber in the dual-fiber head is connected to the pump source 107 to transmit the pump light, and the other optical fiber is used to transmit the signal light; the filter The optical sheet 105 is used to transmit the signal light and reflect the pump light; the non-polarization-maintaining single-mode gain fiber 108 is used to amplify the polarized signal light, and the gain ions in the non-polarization-maintaining single-mode gain fiber 108 include any one or more of neodymium ions, erbium ions, germanium ions, praseodymium ions, holmium ions, europium ions, ytterbium ions, dysprosium ions, and thulium ions. The non-polarization-maintaining single-mode gain fiber can be a single-clad or double-clad fiber; the single-fiber collimator 109 is used to collimate or couple the amplified polarized signal light; the polarization rotator 110 is used to non-reciprocally rotate the polarization direction of the amplified polarized signal light, and the polarization direction of the signal light passing through the polarization rotator once is rotated by 45 degrees; the reflecting device 111 is used to reflect the amplified polarized signal light; the second isolator 112 is used to output the signal light reflected from the polarization beam splitter prism and isolate the backward transmitted light.

[0034] The first isolator 102 and the second isolator 112 may be single-stage isolators or multi-stage isolators.

[0035] The optical fiber used to transmit the signal light in the dual optical fiber head of the dual optical fiber collimator 106 can be a non-gain optical fiber or a gain optical fiber. Similarly, the optical fiber of the single optical fiber collimator 109 can also be a non-gain optical fiber or a gain optical fiber.

[0036] The reflecting device 111 may be a plane reflecting mirror or a reflecting prism or a reflecting film layer coated on the output end face of the polarization rotator.

[0037] The non-polarization-maintaining single-mode gain fiber can be a single-clad fiber or a double-clad fiber. If cost is not considered, the non-polarization-maintaining single-mode gain fiber 108 can also be replaced by a polarization-maintaining single-mode gain fiber.

[0038] In addition, an output fiber collimator may be further provided at the output end of the second isolator 112 to realize the output of the signal light through the fiber.

[0039] In this embodiment, the optical path separation device 104 is a Wollaston prism 104; the filter 105 is a wedge-shaped piece 105, whose flat end faces the dual-fiber collimator 106 and is coated with a film layer for signal light transmission and pump light reflection; the optical fiber used for transmitting the signal light and the non-polarization-maintaining single-mode gain fiber 108 in the dual-fiber collimator 106 are both double-clad optical fibers; the polarization rotator 110 is a Faraday rotator 110; and the reflecting device 111 is a plane mirror 111.

[0040] The seed source 101 emits collimated horizontal polarized signal light, which is incident on the polarization beam splitter prism 103 after passing through the first isolator 102. The horizontal polarized signal light is incident on the Wollaston prism 104 after passing through the polarization beam splitter prism 103. Figure 2 As shown, the horizontally polarized signal light (indicated by the vertical line on the light in the figure) is incident from the left side of the Wollaston prism 104, emitted from the right side of the Wollaston prism 104, then passes through the wedge 105, and is coupled into the core of the optical fiber used for transmitting the signal light in the dual-fiber collimator 106.

[0041] The pump light emitted by the pump source 107 is incident on the core of the optical fiber used to transmit the pump light in the dual-fiber collimator 106, is incident on the plane of the wedge 105 after being collimated, returns to the dual-fiber collimator 106 after being reflected, and is coupled to the inner cladding of the optical fiber used to transmit the signal light in the dual-fiber collimator 106.

[0042] The horizontally polarized signal light is amplified by the pump light in the non-polarization-maintaining single-mode gain fiber 108. The amplified horizontally polarized signal light passes through the single-fiber collimator 109 and is incident on the Faraday rotator 110. Its polarization direction is rotated 45 degrees clockwise (or counterclockwise). Then, it is incident on the plane reflector 111. After being reflected, it passes through the Faraday rotator 110 again. Due to the non-reciprocity of the Faraday rotator 110, its polarization direction is rotated 45 degrees clockwise (or counterclockwise), that is, it is changed from the initial horizontally polarized signal light to a vertically polarized signal light. The vertically polarized signal light passes through the single-fiber collimator 109 and the non-polarization-maintaining single-mode gain fiber 108 in sequence and is amplified again. Then, it passes through the optical fiber and the filter 105 used for transmitting the signal light in the dual-fiber collimator 106 in sequence and is incident on the Wollaston prism 104. Figure 2As shown (indicated by the black dots on the light in the figure), the vertically polarized signal light is incident from the left side of the Wollaston prism 104 and emerges from the right side of the Wollaston prism 104, forming a certain angle with the original horizontally polarized signal light. There will be no light incident on the non-polarization-maintaining single-mode gain fiber 108 at the end face of the polarization beam splitter prism 103, thereby avoiding the problem of secondary pulses. Then, the vertically polarized signal light is incident on the polarization beam splitter prism 103, and is reflected and then output through the second isolator 112. In addition, since the vertically polarized signal light will inevitably have a very small part of the horizontally polarized signal light after passing through the non-polarization-maintaining single-mode gain fiber 108, this part of the light will return to the first isolator 102 along the original optical path, but will be isolated by the first isolator 102, thereby avoiding the formation of secondary pulses. Example

[0043] Figure 3 Another structural schematic diagram of a double-pass polarization-maintaining amplified laser light source of the utility model, the structure of which includes: a seed source 201, a first isolator 202, a polarization beam splitter 203, an optical path separation device 204, a single fiber collimator 205, a non-polarization-maintaining single-mode gain fiber 206, a pump source 207, a dual-fiber collimator 208, a filter 209, a polarization rotator 210, a reflecting device 211, and a second isolator 212. In the embodiment, the optical path separation device 204 is a Wollaston prism 204; the filter 209 is a wedge 209, the flat end of which faces the dual-fiber collimator 208 and is coated with a film layer for signal light transmission and pump light reflection; the optical fiber used for transmitting signal light and the non-polarization-maintaining single-mode gain fiber 206 in the dual-fiber collimator 208 are double-clad optical fibers; the polarization rotator 210 is a Faraday rotator 210; and the reflecting device 211 is a plane reflecting mirror 211.

[0044] The seed source 201 emits collimated horizontally polarized signal light, which is incident on the polarization beam splitter prism 203 after passing through the first isolator 202. The horizontally polarized signal light is incident on the Wollaston prism 204 after passing through the polarization beam splitter prism 203, and is then coupled to the single fiber collimator 205, and then enters the core of the non-polarization-maintaining single-mode gain fiber 206.

[0045] The pump light emitted by the pump source 207 is incident on the core of the optical fiber used to transmit the pump light in the dual-fiber collimator 208, is incident on the plane of the wedge 209 after being collimated, and then returns to the dual-fiber collimator 208 after being reflected, is coupled to the inner cladding of the optical fiber used to transmit the signal light in the dual-fiber collimator 208, and then enters the inner cladding of the non-polarization-maintaining single-mode gain fiber 206.

[0046] The horizontally polarized signal light is amplified by the pump light in the non-polarization-maintaining single-mode gain fiber 206. The amplified horizontally polarized signal light passes through the dual-fiber collimator 208, is incident on the wedge 209, is transmitted, and then is incident on the Faraday rotator 210. Its polarization direction is rotated 45 degrees clockwise (or counterclockwise). Then, it is incident on the plane reflector 211, and then is reflected and passes through the Faraday rotator 210 again. Due to the non-reciprocity of the Faraday rotator 210, its polarization direction is rotated 45 degrees clockwise (or counterclockwise), that is, the initial horizontally polarized signal light is changed to vertically polarized. The signal light, the vertically polarized signal light, is amplified again after passing through the wedge 209, the optical fiber used for transmitting the signal light in the dual-fiber collimator 208, and the non-polarization-maintaining single-mode gain fiber 206 in sequence, and then enters the Wollaston prism 204 after passing through the single-fiber collimator 205. The vertically polarized signal light forms a small angle with the original horizontally polarized signal light, and there will be no light incident on the non-polarization-maintaining single-mode gain fiber 2206 at the end face of other devices, thereby avoiding the problem of secondary pulses. Then, the vertically polarized signal light enters the polarization beam splitter prism 203, is reflected, and then is output after passing through the second isolator 212. In addition, since the vertically polarized signal light will inevitably have a very small part of the horizontally polarized signal light after passing through the non-polarization-maintaining single-mode gain fiber 206, this part of the light will return to the first isolator 202 along the original optical path, but will be isolated by the first isolator 202, thereby avoiding the formation of secondary pulses.

[0047] The above describes the specific implementation of the present invention, but those skilled in the art should understand that this is only an example. Those skilled in the art can make various changes or modifications to this implementation without departing from the principle and essence of the present invention, but these changes and modifications are all within the scope of protection of the present invention.

Claims

1. A double-pass polarization-maintaining amplified laser light source, characterized in that: include: A seed source, a first isolator, a polarization beam splitter, an optical path separation device, an optical filter, a dual-fiber collimator, a pump source, a non-polarization-maintaining single-mode gain fiber, a single-fiber collimator, a polarization rotator, a reflection device, and a second isolator; The seed source is used to provide collimated horizontal or vertical polarized signal light; The first isolator is used to transmit polarized signal light and isolate the backward transmitted signal light; The polarization beam splitter prism is used to transmit the input polarized signal light and reflect the light perpendicular to the polarization direction of the input polarized signal light; The optical path separation device is used to transmit the input polarized signal light and the backward transmitted signal light, and make the two beams of light have an angle; The pump source is used to provide pump light; The dual-fiber collimator is composed of a coupling lens and a dual-fiber head, one of the optical fibers in the dual-fiber head is connected to a pump source to transmit pump light, and the other optical fiber is used to transmit signal light; The filter is used to transmit the signal light and reflect the pump light; The non-polarization-maintaining single-mode gain optical fiber is used to amplify polarized signal light; The single fiber collimator is used to collimate or couple the amplified polarized signal light; The polarization rotator is used to non-reciprocally rotate the polarization direction of the amplified polarized signal light, and the polarization direction of the signal light passing through the polarization rotator once is rotated by 45 degrees; The reflecting device is used to reflect the amplified polarized signal light; The second isolator is used to output the signal light reflected from the polarization beam splitter prism and isolate the backward transmitted light.

2. A double-pass polarization-maintaining amplified laser light source according to claim 1, characterized in that: The first isolator and the second isolator are single-stage isolators or multi-stage isolators.

3. A double-pass polarization-maintaining amplified laser light source according to claim 1, characterized in that: The filter is a wedge-shaped piece, the plane end of which faces the dual-fiber collimator and is coated with a film layer for signal light transmission and pump light reflection.

4. A double-pass polarization-maintaining amplified laser light source according to claim 1, characterized in that: The optical path separation device is a polarization separation device based on a birefringent crystal, including a Wollaston prism, an yttrium vanadate crystal, a lithium niobate crystal, a lithium tantalate crystal or a quartz crystal.

5. A double-pass polarization-maintaining amplified laser light source according to claim 1, characterized in that: The optical fiber used for transmitting signal light in the dual optical fiber head of the dual optical fiber collimator is a non-gain optical fiber or a gain optical fiber; the optical fiber of the single optical fiber collimator is a non-gain optical fiber or a gain optical fiber.

6. A double-pass polarization-maintaining amplified laser light source according to claim 1, characterized in that: The reflecting device is a plane reflecting mirror or a reflecting prism or a reflecting film layer coated on the output end face of the polarization rotator.

7. A double-pass polarization-maintaining amplified laser light source according to claim 1, characterized in that: The positions of the dual-fiber collimator, filter, pump source and single-fiber collimator can be interchanged, that is, the dual-fiber collimator, filter and pump source are located on the right side of the non-polarization-maintaining single-mode gain fiber, and the single-fiber collimator is located on the left side of the non-polarization-maintaining single-mode gain fiber.

8. The double-pass polarization-maintaining amplified laser light source according to claim 1, characterized in that: The polarization rotator is a Faraday rotator.

9. The double-pass polarization-maintaining amplified laser light source according to claim 1, characterized in that: The non-polarization-maintaining single-mode gain optical fiber is a single-clad or double-clad optical fiber.

10. The double-pass polarization-maintaining amplified laser light source according to claim 1, characterized in that: An output fiber collimator is additionally provided at the output end of the second isolator to realize the output of signal light by the fiber.

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