CN213546785U

CN213546785U - High-integration multistage multi-double-pass optical fiber amplification structure

Info

Publication number: CN213546785U
Application number: CN202023063286.8U
Authority: CN
Inventors: 杨润兰; 钱勇; 路桥; 张媛媛; 丁建永
Original assignee: Nanjing Institute of Advanced Laser Technology
Current assignee: Nanjing Institute of Advanced Laser Technology
Priority date: 2020-12-18
Filing date: 2020-12-18
Publication date: 2021-06-25
Anticipated expiration: 2030-12-18

Abstract

The invention discloses a high-integration multistage multi-double-pass optical fiber amplification structure, which comprises: four fiber amplification modules, two fiber gratings and a four-port circulator. The invention can realize the effect of 6-pass amplification at most, and the used device is only a device with a 4-stage amplifier; meanwhile, each stage of amplifier module only comprises four devices, namely a pumping source, a pumping signal coupler, a gain optical fiber and a cladding pumping filter, and a band-pass filter and an isolator are omitted optimally, so that the whole system is low in cost, high in integration level and good in stability while high-gain and low-noise amplified laser signals are obtained.

Description

High-integration multistage multi-double-pass optical fiber amplification structure

Technical Field

The invention relates to the technical field of optical fiber amplification, in particular to a high-integration multistage multi-pass optical fiber amplification structure.

Background

The fiber laser has high beam quality, good stability, low cost and simple structure, and in recent years, the application of the fiber laser is continuously expanded, such as low-power marking and engraving, and cutting and welding of high-power heavy metals, and especially the application of the fiber laser with single frequency and low noise in the fields of coherent laser radar, atomic cooling, atomic clock, laser spectroscopy, fiber sensing and the like, so that the development of the fiber laser is faster and faster.

The traditional high-power optical fiber laser mainly adopts a Main Oscillation Power Amplification (MOPA) scheme, which is composed of an external seed source and multi-stage optical fiber amplification, wherein the optical fiber amplification generally adopts a one-way linear structure, the seed light is input into the laser output after the multi-stage amplification, in the linear structure, in order to reduce the noise of the whole amplifier, a band-pass filter is required to be added between stages to filter pump light and amplified spontaneous radiation light, meanwhile, an isolator is required to be added to prevent micro mirror surface reflection or nonlinear Brillouin (SBS) scattering caused by poor welding quality of the rear stage, the cost is high due to more types of devices, particularly, when the high-power laser is amplified, the noise introduced in the whole amplification process needs to be reduced, the gain of each stage of amplifier needs to be controlled, therefore, the one-way optical fiber amplification structure needs to be cascaded with more stages of optical fiber amplifiers, and the cost is further increased, the structure of the system is complex and the integration level is also reduced.

Disclosure of Invention

The technical problem to be solved by the present invention is to provide a highly integrated multi-stage multi-pass optical fiber amplifying structure, which obtains high-gain and low-noise amplified laser signals, and has the advantages of low cost, high integration level and good stability of the whole system.

In order to solve the above technical problem, the present invention provides a highly integrated multi-stage multi-pass optical fiber amplifying structure, including: the four-port ring-shaped optical fiber amplifier comprises four optical fiber amplification modules, two optical fiber gratings and a four-port ring-shaped device; the output end of the first optical fiber amplification module 10 is connected with the port 1 of the four-port circulator, the input end of the second optical fiber amplification module 20 is connected with the port 2 of the four-port circulator, the output end of the second optical fiber amplification module is connected with the first optical fiber grating 50, the input end of the third optical fiber amplification module 30 is connected with the port 3 of the four-port circulator, the output end of the third optical fiber amplification module is connected with the second optical fiber grating 60, the input end of the fourth optical fiber amplification module 40 is connected with the port 4 of the four-port circulator, and the output end of the fourth optical fiber amplification module is used as a final amplified laser signal to.

Preferably, the optical fiber amplification module is a single-mode core-pumped optical fiber amplifier or a multi-mode cladding-pumped optical fiber amplifier, or a combination of the two.

Preferably, the pumping direction of the fiber amplification module may be forward pumping, backward pumping, and bidirectional pumping.

Preferably, the optical fiber amplification module comprises a pump source, a pump signal coupler, a gain fiber and a cladding pump filter; the pumping source is connected with the pumping end of the pumping signal coupler, the output end of the pumping signal coupler is connected with the gain fiber, the output end of the gain fiber is connected with the cladding pumping filter during cladding pumping, and the cladding pumping filter is not needed during fiber core pumping.

Preferably, the four-port circulator is a one-way light-transmitting device, that is, light entering the circulator from the 1 port is output from only the 2 port, light entering from the 2 port is output from only the 3 port, and light entering from the 3 port is output from only the 4 port.

The invention has the beneficial effects that: the invention can realize the effect of 6-pass amplification at most, and the used device is only a device with a 4-stage amplifier; meanwhile, each stage of amplifier module only comprises four devices, namely a pumping source, a pumping signal coupler, a gain fiber and a cladding pumping filter (a single-mode fiber core pumping structure does not need a cladding pumping filtering device), and a band-pass filter and an isolator are omitted optimally, so that the whole system is low in cost, high in integration level and good in stability while high-gain and low-noise amplified laser signals are obtained.

Drawings

Fig. 1 is a schematic view of the overall structure of the present invention.

Fig. 2 is a schematic diagram of a forward single-mode core pumping structure of the fiber amplifier module of the present invention.

Fig. 3 is a schematic diagram of an inverted multimode pumping structure of the fiber amplifier module of the present invention.

Fig. 4 is a schematic diagram of bidirectional pumping of the fiber amplifier module of the present invention.

10, a first optical fiber amplification module; 20. a second fiber amplification module; 30. a third fiber amplification module; 40. a fourth fiber amplification module; 50. a first fiber grating; 60. a second fiber grating; 00. a four-port circulator; 70. pump signal couplers in the first fiber amplification module 10 and the second fiber amplification module 20; 80. a pump source in the first fiber amplification module 10 and the second fiber amplification module 20; 90. gain fibers in the first fiber amplification module 10 and the second fiber amplification module 20; 101. a cladding-pumped filter in the third fiber amplification module 30; 901. a gain fiber in the third fiber amplification module 30; 801. a pump source in the third fiber amplification module 30; 701. a pump signal coupler in the third fiber amplification module 30; 102. 103, a cladding pumping filter in the fourth fiber amplifying module 40; 702. 703 pump signal coupler in the fourth optical fiber amplifying module 40; 802. 803, a pump source in the fourth fiber amplification module 40; 902. the gain fiber in the fourth fiber amplification module 40.

Detailed Description

As shown in fig. 1, a highly integrated multi-stage multi-double pass fiber amplifier structure includes: the four-port ring-shaped optical fiber amplifier comprises four optical fiber amplification modules, two optical fiber gratings and a four-port ring-shaped device; the output end of the first optical fiber amplification module 10 is connected with the port 1 of the four-port circulator, the input end of the second optical fiber amplification module 20 is connected with the port 2 of the four-port circulator, the output end of the second optical fiber amplification module is connected with the first optical fiber grating 50, the input end of the third optical fiber amplification module 30 is connected with the port 3 of the four-port circulator, the output end of the third optical fiber amplification module is connected with the second optical fiber grating 60, the input end of the fourth optical fiber amplification module 40 is connected with the port 4 of the four-port circulator, and the output end of the fourth optical fiber amplification module is used as a final amplified laser signal to.

The weak signal light enters the first optical fiber amplification module 10 for the first time, the first optical fiber amplification module 10 is generally a single-mode fiber core pump amplifier, and includes a single-mode pump laser, a pump signal coupling device and a single-mode single-clad gain fiber inside, and the single-mode single-clad gain fiber is on the right side of the pump signal coupler. As shown in fig. 2, a forward pumping structure is adopted, and a pump laser 80, a pump signal coupler 70, a gain fiber 90, and a 1-port of a four-port circulator 00 are connected in this order. By utilizing the one-way light guide characteristic of the circulator, after the signal light is subjected to primary amplification of the first optical fiber amplification module 10, the signal light enters the port 2 of the circulator for secondary two-way amplification; according to the intensity of the signal light, selecting the secondary amplification as a single-mode fiber core pump or a multi-mode cladding pump, as a specific implementation mode, assuming that the intensity of the signal light is not large enough after the primary amplification, the secondary amplification continues to adopt the single-mode fiber core pump, the structure and the device of the second fiber amplification module 20 are the same as those of the first fiber amplification module 10, the second fiber amplification module 20 is connected with the first fiber grating 50, the signal light is reflected by the fiber grating and enters the first fiber amplification module 20 again for the second-pass amplification, and simultaneously the residual pump light and the ASE light are transmitted, and similarly, the signal light after the two-pass amplification enters the 3 ports from the 2 ports of the four-port circulator for the third-pass amplification.

As a specific implementation, the third fiber amplification module 30 is a backward multimode pump, as shown in fig. 1 and 3, the four-port circulator 3 has a port connected to a cladding pump filter 101, so as to ensure the purity of the signal light returned to the 3 ports, and improve the stability of the circulator. Then, the gain fiber 901, the pump signal combiner 701, and the multimode pump source 801 are sequentially connected to form a third fiber amplification module 30, and finally, the third fiber amplification module is connected to the second fiber grating 60, and the fiber grating reflects the signal light to be amplified again while transmitting the pump light and the ASE light. And the signal light after the secondary two-way amplification enters the 4 ports of the four-port circulator through the 3 ports of the four-port circulator to carry out the next-stage amplification.

The fourth fiber amplification module 40 is also a multi-mode cladding pumped amplifier, and optionally, the pumping structure of the fourth fiber amplification module 40 may be forward pumping, backward pumping, or bidirectional pumping. As a specific implementation manner, the fourth fiber amplification module 40 is a bidirectional pump structure, as shown in fig. 1 and 4, a four-port circulator 4 is connected to a cladding pump filter 102 to filter cladding pump light returned by the amplifier 40, improve crosstalk of the circulator, and ensure stable operation of the circulator. Then, the pumping signal combiner 702, the pumping source 802, the gain fiber 902, the pumping signal combiner 703, the pumping source 803 and the cladding pumping filter 103 are sequentially connected to form a fourth fiber amplification module 40, and the amplified signal light is output after being filtered by the cladding pumping filter, so that the purity of the output signal light is ensured; optionally, in order to prevent the damage of the return light to the whole system, a high-power isolator may be connected after the fourth fiber amplification module 40; the final output light can be output by a customized oblique octave end cap or output after collimation.

Claims

1. A highly integrated multi-stage multi-double pass fiber amplifier structure comprising: the four-port ring-shaped optical fiber amplifier comprises four optical fiber amplification modules, two optical fiber gratings and a four-port ring-shaped device; the output end of the first optical fiber amplification module (10) is connected with the port 1 of the four-port circulator, the input end of the second optical fiber amplification module (20) is connected with the port 2 of the four-port circulator, the output end of the second optical fiber amplification module is connected with the first optical fiber grating (50), the input end of the third optical fiber amplification module (30) is connected with the port 3 of the four-port circulator, the output end of the third optical fiber amplification module is connected with the second optical fiber grating (60), the input end of the fourth optical fiber amplification module (40) is connected with the port 4 of the four-port circulator, and the output end of the fourth optical fiber amplification module serves as the final amplified laser signal to be output.

2. The highly integrated multi-stage multi-double pass fiber amplification structure of claim 1, wherein the fiber amplification module is a single mode core pumped fiber amplifier or a multi-mode cladding pumped fiber amplifier, or a combination thereof.

3. The highly integrated multi-stage multi-double pass fiber amplification structure of claim 1, wherein the pumping direction of the fiber amplification module can be forward pumping, backward pumping, and bidirectional pumping.

4. The highly integrated multi-stage multi-double pass fiber amplification structure of claim 1, wherein the fiber amplification module comprises at most a pump source, a pump signal coupler, a gain fiber, and a cladding pump filter; the pumping source is connected with the pumping end of the pumping signal coupler, the output end of the pumping signal coupler is connected with the gain fiber, the output end of the gain fiber is connected with the cladding pumping filter during cladding pumping, and the cladding pumping filter is not needed during fiber core pumping.

5. The highly integrated multi-stage multi-double pass optical fiber amplifying structure according to claim 1, wherein the four-port circulator is a one-way light-passing device, i.e. light entering the circulator from the 1 port is output from only the 2 port, light entering from the 2 port is output from only the 3 port, and light entering from the 3 port is output from only the 4 port.