Miniaturized optical amplifier and fiber laser
By designing a miniaturized optical amplifier, using the combination of a circulator, gain crystal and pump input collimator, the existing fiber laser structure complex and large size are solved, and the miniaturization of fiber lasers and the improvement of optical amplification efficiency is achieved.
Patent Information
- Application Number
- CN202411892703.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-20
- Publication Date
- 2025-04-11
AI Technical Summary
The structure of existing fiber lasers is complex, resulting in large equipment size and complex connection of passive devices, which increases manufacturing difficulty and cost.
A miniaturized optical amplifier is designed, including a circulator, a gain crystal and a pump input collimator. Through the wavelength transmissive setting of the inverted film, the spot overlap between the pump light and the signal light inside the gain crystal is improved, and the optical amplification efficiency is improved.
The miniaturization of fiber lasers is achieved, the equipment structure is simplified, the connection complexity of passive devices is reduced, the optical amplification efficiency is improved, and the optical nonlinear effect is suppressed.
Smart Images
Figure CN119812925A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of optical fiber lasers, and in particular to a miniaturized optical amplifier and an optical fiber laser. Background Art
[0002] Conventional master oscillator amplifier (MOPA) fiber lasers achieve seed laser amplification by cascading seed lasers with single-stage or multi-stage fiber amplifiers, such as Figure 1 As shown, in addition to the seed source needing to be matched with the isolator ISO1, the cascaded fiber amplifier also needs to be connected with fiber passive devices such as the pump combiner, isolator ISO2, and cladding pump stripper, and its overall structure is relatively complex. Summary of the invention
[0003] A first object of the present invention is to provide a miniaturized optical amplifier.
[0004] A second object of the present invention is to provide a fiber laser having the above optical amplifier.
[0005] In order to achieve the first purpose of the present invention, the present invention provides a miniaturized optical amplifier, including a circulator, a gain crystal and a pump input collimator; the gain crystal extends along the optical path direction and is respectively provided with a first working end face and a second working end face at both ends of the optical path direction, the first working end face is plated with a first transflective film, the second working end face is plated with a second transflective film, the first transflective film is highly transparent to the working wavelength, the first transflective film is highly reflective to the pump wavelength, the second transflective film is highly reflective to the working wavelength, and the second transflective film is highly transparent to the pump wavelength; the pump input collimator is used to output pump light toward the second transflective film, the circulator is provided with a first port, a second port and a third port, signal light is input from the first port and output from the second port, the second port is used to output signal light toward the first transflective film, the second port is used to receive the amplified signal light output by the first transflective film, the amplified signal light is input from the second port and output from the third port.
[0006] A further solution is that the first working end face is arranged at an acute angle to the normal plane in the direction of the optical path.
[0007] A further solution is that the acute angle is between 1° and 13°.
[0008] A further solution is that the second working end face is perpendicular to the direction of the light path.
[0009] A further solution is that the first transflective film is highly transparent to light with a wavelength of 1550nm, and the first transflective film is highly reflective to light with a wavelength of 980nm; the second transflective film is highly reflective to light with a wavelength of 1550nm, and the second transflective film is highly transparent to light with a wavelength of 980nm.
[0010] A further solution is that the circulator includes a first fiber collimator, a third fiber collimator, a first birefringent crystal, a Faraday rotator, a half-wave plate, a second birefringent crystal, a polarization beam splitter and a reflector; the first fiber collimator is located at the first port, and the third fiber collimator is located at the third port; the signal light output by the first fiber collimator passes through the first birefringent crystal, the Faraday rotator, the half-wave plate, and the second birefringent crystal in sequence, and then is output from the second port and incident on the first transflective film; the amplified signal light output from the first transflective film is input from the second port, the first polarization split light of the amplified signal light passes through the second birefringent crystal, the half-wave plate, the Faraday rotator, the first birefringent crystal, and the polarization beam splitter in sequence, and then is incident on the third fiber collimator, and the second polarization split light of the amplified signal light passes through the second birefringent crystal, the half-wave plate, the Faraday rotator, the first birefringent crystal, the reflector, and the polarization beam splitter in sequence, and then is incident on the third fiber collimator.
[0011] In order to achieve the second object of the present invention, the present invention provides a fiber laser, comprising the optical amplifier as described above.
[0012] A further solution is that the fiber laser includes a seed source and a pump source, the seed source is connected to the first port and outputs signal light to the first port, and the pump source is connected to the pump input collimator and outputs pump light to the pump input collimator.
[0013] The beneficial effect of the present invention is that, through the passage characteristic of the circulator with an isolation function, that is, the characteristic that the third port cannot return to the first port, the first port is used as the input end of the optical amplifier, the third port is used as the output end, and the second port is used to face the gain crystal. Since the two ends of the gain crystal are respectively coated with a first transflective film and a second transflective film, the wavelength transflective setting of the transflective film is used to make the pump light input to the gain crystal, and the signal light is transmitted through the first transflective film and reflected by the second transflective film, thereby improving the overlap of the pump light and the signal light in the gain crystal, thereby achieving the improvement of the light amplification efficiency. Finally, the amplified signal light is output from the third port, and is arranged with an acute angle to prevent additional end face Fresnel reflection, and is combined with the structural arrangement of the circulator, so that it can stably achieve the predetermined optical path direction. Therefore, this case integrates the circulator, the gain crystal and the pump input collimator, thereby bringing the advantages of miniaturization to the fiber laser, and reducing the additional action length caused by the pigtail length required for the passive device fusion, which can suppress the optical nonlinear effect to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 It is a schematic diagram of the structure of a fiber laser in the prior art.
[0015] Figure 2 It is a schematic structural diagram of an embodiment of a fiber laser of the present invention.
[0016] Figure 3 It is a schematic diagram of the structure of an optical amplifier embodiment of the present invention.
[0017] Figure 4 1 is a light path diagram of P1-P2 of the circulator in the optical amplifier embodiment of the present invention.
[0018] Figure 5 1 is a light path diagram of P2-P3 of the circulator in the optical amplifier embodiment of the present invention.
[0019] The present invention is further described below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION
[0020] Reference Figures 2 to 5 The fiber laser includes a seed source Seed, a pump source LD1, an optical amplifier 10 and a main amplifier module. The main amplifier module includes a mode field adapter MFA, a cladding light filter CPS, an active fiber Activefiber, a coupler Combiner, a pump source LD2 and an isolator ISO3 which are connected and arranged in sequence.
[0021] The optical amplifier 10 includes a package 101, a circulator 1, a gain crystal 2 and a pump input collimator 23. The gain crystal 2 is preferably an erbium-doped (Er) crystal. The gain crystal 2 extends along the optical path direction X and is provided with a first working end face 21 and a second working end face 22 at both ends of the optical path direction X. The gain crystal 2 is arranged in a cylindrical shape. The optical path direction X is parallel to the geometric axis of the gain crystal 2. The first working end face 21 is arranged at an acute angle to the normal plane of the optical path direction X. The acute angle is between 1° and 13°, the second working end face 22 is perpendicular to the optical path direction X, the first working end face 21 is plated with a first transflective film 210, and the second working end face 22 is plated with a second transflective film 220. The first transflective film 210 is highly transparent to a working wavelength of 1550nm, and the first transflective film 210 is highly reflective to a pump wavelength of 980nm. The second transflective film 220 is highly reflective to a working wavelength of 1550nm, and the second transflective film 220 is highly transparent to a pump wavelength of 980nm.
[0022] The pump input collimator 23 is used to output pump light toward the second transflective film 220. The circulator 1 is provided with a first port P1, a second port P2 and a third port P3. The signal light is input from the first port P1 and output from the second port P2. The second port P2 is used to output the signal light toward the first transflective film 210. The second port P2 is used to receive the amplified signal light output by the first transflective film 210. The amplified signal light is input from the second port P2 and output from the third port P3.
[0023] Specifically, the circulator 1 includes a first fiber collimator 17, a third fiber collimator 18, a first birefringent crystal 11, a Faraday rotator 12, a half-wave plate 13, a second birefringent crystal 14, a polarization beam splitter 15 and a reflector 16. The first fiber collimator 17 is located at the first port P1, and the third fiber collimator 18 is located at the third port P3.
[0024] The seed source Seed is connected to the first fiber collimator 17 at the first port P1 and outputs signal light to the first fiber collimator 17. The signal light output by the first fiber collimator 17 is polarized and split by the first birefringent crystal 11. After the polarization splitting of the two signal lights passes through the first birefringent crystal 11, the Faraday rotator 12, the half-wave plate 13, and the second birefringent crystal 14 in sequence, the combined signal light is output from the second port P2 and incident on the first reflective film 210.
[0025] The signal light is transmitted through the first reflective film 210 and input into the gain crystal 2. Then, the signal light is reflected by the second reflective film 220 and then transmitted from the first reflective film 210 to the second port P2. At the same time, the pump source Seed is connected to the pump input collimator 23 and outputs the pump light to the pump input collimator 23. The pump input collimator 23 outputs the pump light toward the second reflective film 220. The pump light is transmitted through the second reflective film 220 and input into the gain crystal 2. The pump light is reflected by the first reflective film 210. Then, the optical axes of the pump light and the signal light inside the gain crystal coincide, which can realize the amplification of the optical power. Then, the amplified signal light after the signal amplification is input from the second port P2.
[0026] The amplified signal light output from the first transflective film 210 is input from the second port P2, the amplified signal light is polarized and split in the second birefringent crystal 14, the amplified signal light is combined at the polarization beam splitter 15, the polarization beam splitter 15 adopts PBS, the first polarization split light of the amplified signal light passes through the second birefringent crystal 14, the half-wave plate 13, the Faraday rotator 12, the first birefringent crystal 11, and the polarization beam splitter 15 in sequence, and then enters the third fiber collimator 18, the second polarization split light of the amplified signal light passes through the second birefringent crystal 14, the half-wave plate 13, the Faraday rotator 12, the first birefringent crystal 11, the reflector 16, and the polarization beam splitter 15 in sequence, and then enters the third fiber collimator 18, the amplified signal light is then output from the third port P3, the third fiber collimator 18 is connected to the mode field adapter MFA of the main amplifier module, and is output for use after amplification and transmission of the main amplifier module.
[0027] From the above, it can be seen that this case is Figure 1The prior art in the optical amplifier 10 can omit the isolator ISO1, the active fiber Active fiber, the coupler Combiner and the isolator ISO2 through the integrated design of the optical amplifier 10, which is conducive to the integration and miniaturization of the equipment. In addition, the circulator has the passing characteristic of the isolation function, that is, the characteristic that the third port cannot return to the first port, and then the first port is used as the input end of the optical amplifier, the third port is used as the output end, and the second port is used to face the gain crystal. Since the two ends of the gain crystal are respectively coated with the first transflective film and the second transflective film, the wavelength transflective setting of the transflective film is used to make the pump light input to the gain crystal, and the signal light is transmitted through the first transflective film and reflected by the second transflective film, and then the light spot overlap degree of the pump light and the signal light inside the gain crystal is improved, so as to achieve the improvement of the optical amplification efficiency.
Claims
1. A miniaturized optical amplifier, characterized in that: Includes circulator, gain crystal and pump input collimator; The gain crystal extends along the optical path and is provided with a first working end face and a second working end face at both ends of the optical path, the first working end face is plated with a first transflective film, the second working end face is plated with a second transflective film, the first transflective film is highly transparent to the working wavelength, the first transflective film is highly reflective to the pumping wavelength, the second transflective film is highly reflective to the working wavelength, and the second transflective film is highly transparent to the pumping wavelength; The pump input collimator is used to output pump light toward the second transflective film. The circulator is provided with a first port, a second port and a third port. Signal light is input from the first port and output from the second port. The second port is used to output the signal light toward the first transflective film. The second port is used to receive amplified signal light output by the first transflective film. The amplified signal light is input from the second port and output from the third port.
2. The optical amplifier according to claim 1, characterized in that: The first working end face is arranged at an acute angle to the normal plane of the optical path direction.
3. The optical amplifier according to claim 2, characterized in that: The acute angle is between 1° and 13°.
4. The optical amplifier according to claim 1, characterized in that: The second working end surface is perpendicular to the direction of the optical path.
5. The optical amplifier according to claim 1, characterized in that: The first transflective film is highly transparent to light with a wavelength of 1550nm, and the first transflective film is highly reflective to light with a wavelength of 980nm; The second transflective film is highly reflective to light with a wavelength of 1550 nm, and the second transflective film is highly transparent to light with a wavelength of 980 nm.
6. The optical amplifier according to any one of claims 1 to 5, characterized in that: The circulator includes a first fiber collimator, a third fiber collimator, a first birefringent crystal, a Faraday rotator, a half-wave plate, a second birefringent crystal, a polarization beam splitter and a reflector; The first optical fiber collimator is located at the first port, and the third optical fiber collimator is located at the third port; The signal light outputted by the first optical fiber collimator passes through the first birefringent crystal, the Faraday rotator, the half-wave plate, and the second birefringent crystal in sequence, and then is outputted from the second port and incident on the first transflective film; The amplified signal light output from the first reflective film is input from the second port, the first polarization split light of the amplified signal light passes through the second birefringent crystal, the half-wave plate, the Faraday rotator, the first birefringent crystal, and the polarization beam splitter in sequence, and then is incident on the third fiber collimator, and the second polarization split light of the amplified signal light passes through the second birefringent crystal, the half-wave plate, the Faraday rotator, the first birefringent crystal, the reflector, and the polarization beam splitter in sequence, and then is incident on the third fiber collimator.
7. A fiber laser, characterized in that: Comprising the optical amplifier as claimed in any one of claims 1 to 6 above.
8. The optical fiber laser according to claim 7, characterized in that: The fiber laser comprises a seed source and a pump source. The seed source is connected to the first port and outputs signal light to the first port. The pump source is connected to the pump input collimator and outputs pump light to the pump input collimator.