Small signal laser high gain amplification system and method based on co-band pump cavity

Abstract

The present invention discloses a small-signal laser high-gain, high-power amplification system and method based on a co-band pumping cavity, belonging to the field of fiber laser technology. The amplification system comprises a laser seed source, a co-band pumping wavelength fiber oscillator, and a signal laser main amplifier, connected in sequence. The laser seed source is used to output a signal laser of less than milliwatts; the co-band pumping wavelength fiber oscillator is used to generate a high-power co-band pumping laser and perform low-noise, high-gain pre-amplification on the signal laser; and the signal laser main amplifier is used to gain the signal laser through the co-band pumping effect of the fiber core, thereby further amplifying the pre-amplified signal laser to ultimately form a high-power signal laser. This high-gain, high-power amplification system adds a co-band pumping wavelength fiber oscillator to the MOPA structure. The preparation method is simple and low-cost, effectively avoiding the technical complexity associated with existing multi-stage MOPA cascade amplification methods. It is easy to implement and has high practical and promotional value.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber laser technology, and in particular to a small-signal laser high-gain and high-power amplification system and method based on a co-band pump cavity. Background Art

[0002] High-power single-frequency (or narrow linewidth) continuous fiber lasers and high-power pulsed fiber lasers are two important types of fiber lasers. They have important application value in industrial production, scientific research, and national defense science and technology due to their high conversion efficiency, good beam quality, compact structure, and easy heat dissipation. Continuous fiber lasers are widely used in radar communications and other fields, such as remote sensing ranging, space communications, gravitational wave detection, and high-power laser spectral beam combination; high-power pulsed fiber lasers are widely used in industrial processing fields, such as cutting and drilling, marking and cleaning. These two types of fiber lasers are generally designed based on the master oscillator power amplifier (MOPA) structure, which provides high-power laser output by combining a master oscillator and a power amplifier. The master oscillator is used to generate the required signal laser seed source, and then the power amplifier increases its power to the required output power value.

[0003] At present, single-frequency (or narrow linewidth) continuous signal laser seed sources are mainly generated by directly generating single-frequency (or narrow linewidth) continuous signal lasers through distributed feedback laser diodes (DFB-LD) or short-cavity fiber lasers; pulse signal laser seed sources are mainly generated by directly driving laser diodes (LDs) with pulse current or by generating pulse signal lasers with the required waveform through optical modulators (such as acousto-optic modulators, electro-optic modulators, etc.) from low-power continuous lasers. The (average) output power of the signal laser seed sources obtained by these methods is relatively small, usually only in the microwatt-milliwatt range. Therefore, how to safely and efficiently amplify these small signal lasers to high power levels (hundreds of watts or more), that is, small signal laser high-power amplification technology, is still one of the key core technologies in the field of high-power fiber lasers.

[0004] Currently, high-power amplification of small-signal lasers is primarily achieved using a multi-stage MOPA cascade approach. This involves first passing the small-signal laser through several pre-amplifier stages before being injected into the main amplifier for amplification. This existing cascade amplification technology has significant drawbacks: first, the system is too complex, resulting in high technical complexity and high cost; second, it presents significant safety risks. Under high-power operation, accidental failures in the small-signal laser seed source or any pre-amplifier stage can cause the main amplifier to burn out. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention provides a small-signal laser high-gain and high-power amplification system and method based on a co-band pump cavity, which can achieve safe and efficient amplification of small-signal laser.

[0006] The present invention is achieved through the following technical solutions:

[0007] A small-signal laser high-gain and high-power amplification system based on a co-band pump cavity includes a laser seed source and a signal laser amplification component. The signal laser amplification component includes a co-band pump wavelength fiber oscillator and a signal laser main amplifier.

[0008] The laser seed source, the fiber oscillator with the same pump wavelength, and the signal laser main amplifier are connected in sequence;

[0009] The laser seed source is used to output a signal laser less than the milliwatt level;

[0010] The same-band pump wavelength fiber oscillator is used to generate high-power same-band pump laser and perform low-noise and high-gain pre-amplification on the signal laser;

[0011] The signal laser main amplifier is used to obtain gain for the signal laser through the fiber core co-band pumping effect, thereby further amplifying the pre-amplified signal laser to form a high-power signal laser.

[0012] Preferably, the laser seed source is a continuous signal laser seed source or a pulse signal laser seed source.

[0013] Preferably, the same-band pump wavelength fiber oscillator comprises a pump source, a pump coupler, a high-reflection grating, an output grating and a gain fiber;

[0014] The output end of the pump source is connected to the pump input end of the pump coupler, the output end of the pump coupler is connected to the input end of the high-reflection grating, the output end of the high-reflection grating is connected to the input end of the first gain fiber, and the output end of the first gain fiber is connected to the output grating.

[0015] Preferably, the signal laser main amplifier includes a gain fiber, the input end of the gain fiber is connected to the output end of the fiber oscillator with the same pump wavelength, and the output end of the gain fiber is connected to the output end cap.

[0016] Preferably, the input end of the gain fiber of the signal laser main amplifier is connected to the output end of the fiber oscillator with the same pump wavelength band through a pump coupler, and the pump input end of the pump coupler is connected to the pump source.

[0017] Preferably, an optical fiber isolator is provided between the laser seed source and the same-band pump wavelength optical fiber oscillator.

[0018] Preferably, an optical fiber isolator is provided between the same-band pump wavelength optical fiber oscillator and the signal laser main amplifier.

[0019] Preferably, there are multiple signal laser amplifying components, and the multiple signal laser amplifying components are cascaded, the input end of the first-stage signal laser amplifying component is connected to the laser seed source, and the output end of the last-stage signal laser amplifying component is connected to the output end cap.

[0020] An amplification method for a small-signal laser high-gain high-power amplification system based on a co-band pump cavity comprises the following steps:

[0021] Step 1: The signal laser generated by the laser seed source is injected into the high-reflection end of the oscillator with the same pump wavelength;

[0022] Step 2: The same-band pump wavelength fiber oscillator provides gain to the signal laser and realizes low-noise and high-gain pre-amplification. At the same time, the same-band pump wavelength fiber oscillator generates high-power same-band pump laser;

[0023] Step 3: The signal laser main amplifier absorbs the same-band pump laser and enables the pre-amplified signal laser to further gain gain, thereby forming a high-power signal laser.

[0024] A laser device is provided with the small-signal laser high-gain and high-power amplification system based on the same-band pump cavity according to any one of claims 1 to 8.

[0025] Compared with the prior art, the present invention has the following beneficial technical effects:

[0026] The present invention provides a small-signal laser high-gain and high-power amplification system based on a co-band pumping cavity. The co-band pumping wavelength fiber oscillator of the system has dual functions: first, it generates high-power co-band pumping laser light to provide pumping energy for subsequent amplification of the signal laser light based on the co-band pumping effect of the fiber core; second, amplifying the small-signal laser light in the co-band pumping cavity can effectively suppress amplified spontaneous emission noise, thereby achieving low-noise and high-gain pre-amplification of the injected small-signal laser light. The high-gain and high-power amplification system adds a co-band pumping wavelength fiber oscillator to the MOPA structure. The preparation method is simple and the preparation cost is low, effectively avoiding the technical complexity brought about by the existing multi-stage MOPA cascade amplification method, and is easy to implement in engineering. In addition, the amplification system has high safety. When the small-signal laser light suffers an accidental failure, the amplification system will automatically switch to the output system structure of the co-band pumping laser light, which will not cause the burning of the main amplifier of the signal laser light. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of a small-signal narrow-linewidth continuous laser high-power amplification system according to Example 1 of the present invention;

[0028] Figure 2 This is a correlation diagram between the total output power of the amplification system and the pump source power in Example 1 of the present invention;

[0029] Figure 3 is the output spectrum of the maximum total output power of the amplification system in Example 1 of the present invention;

[0030] Figure 4 This is a schematic diagram of a small-signal continuous single-frequency laser high-power amplification system according to embodiment 2 of the present invention;

[0031] Figure 5 This is a schematic diagram of a small-signal continuous single-frequency laser high-power cascade amplification system according to Example 3 of the present invention;

[0032] In the figure: 11-laser seed source, 12-fiber oscillator with the same pump wavelength, 13-signal laser main amplifier, 101-small signal laser seed source, 102-first pump source, 103-first pump coupler, 104-high reflection grating, 105-first gain fiber, 106-output grating, 107-second gain fiber, 108-output end cap, 109-second pump source, 110-second pump coupler, 32-first stage fiber oscillator with the same pump wavelength, 33-first stage signal laser main amplifier, 34-second stage fiber oscillator with the same pump wavelength, 35-second stage signal laser main amplifier. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below with reference to the accompanying drawings, which are intended to explain rather than limit the present invention.

[0034] The definitions of various terms in the embodiments of the present invention are as follows:

[0035] In the description of the following embodiments, it should be understood that the terms "single-ended," "double-ended," "forward," "reverse," "bidirectional," "between," "high-reverse end," "output end," "pump input end," "signal laser input end," and the like, indicating positions or location relationships, are based on the positions or location relationships in the accompanying drawings and are intended solely to facilitate the description of the present invention. They do not indicate or imply that the system or components of the present invention must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0036] In the description of the present invention, "plurality" means two or more.

[0037] In the description of the present invention, a "pump source" refers to a light source whose wavelength is at a point where the absorption cross section of the doped rare earth ions is large, and is generally composed of a combination of single-mode or multi-mode semiconductor laser diodes.

[0038] In the description of the present invention, a "pump coupler" includes three types of ports: a pump input port, a signal laser input port, and an output port. The pump input port is usually connected to a pump source, and the signal laser input port is used to input a signal laser.

[0039] In the description of the present invention, "co-band pump laser" refers to a fiber laser whose wavelength is in the same emission band of doped ions as that of the signal laser, and whose wavelength is smaller than that of the signal laser.

[0040] On the one hand, the present invention provides a small-signal laser high-gain and high-power amplification system based on a co-band pump cavity, comprising a laser seed source 11 and a signal laser amplification component connected in sequence, wherein the signal laser amplification component comprises a co-band pump wavelength fiber oscillator 12 and a signal laser main amplifier 13.

[0041] The laser seed source 11 is used to output a signal laser less than the milliwatt level, and inject the small signal laser into the high-reflection end of the same-band pump wavelength oscillator 12; after the small signal laser passes through the same-band pump wavelength oscillator 12, low-noise and high-gain pre-amplification can be achieved. At the same time, the same-band pump wavelength oscillator 12 will also generate high-power same-band pump laser in the fiber core. The pre-amplified signal laser and the same-band pump laser in the fiber core are injected into the gain fiber of the main amplifier 13 together. At this time, the gain fiber will efficiently absorb the same-band pump laser and enable the signal laser to obtain gain, thereby achieving high-power amplification of the signal laser.

[0042] In some embodiments, the laser seed source 11 can be a single-frequency or narrow-linewidth continuous signal laser directly generated by a distributed feedback laser diode or a short-cavity fiber laser, or a pulse signal laser prepared by directly driving a semiconductor laser diode by pulse current. The pulse signal laser seed source includes femtosecond, picosecond, nanosecond and microsecond pulse signal lasers; it can also be a pulse signal laser prepared by an external modulation method of a continuous laser (including electro-optical modulation and acousto-optic modulation), or a signal laser with a lower average power obtained by any other method, such as a weak laser signal received by a space laser communication receiver. The signal laser with a lower average power is a signal laser in the order of microwatts to milliwatts or lower than the microwatt level.

[0043] The in-band pump wavelength fiber oscillator 12 has two main functions: on the one hand, it is used to generate high-power in-band pump laser; on the other hand, it is used for low-noise and high-gain pre-amplification of signal laser.

[0044] In some embodiments, the co-band pump wavelength fiber oscillator 12 can be single-ended pumped or double-ended pumped. Single-ended pumping refers to the coupling of pump light from either the high-reflection end or the output end of the fiber oscillator into the gain fiber through a pump coupler; double-ended pumping refers to the coupling of pump light from both ends of the fiber oscillator into the gain fiber through pump couplers. The pumping structure can adopt intracavity or extracavity pumping. Intracavity pumping involves placing the pump coupler inside the co-band pump cavity formed by the high-reflection grating and the output grating. Extracavity pumping involves placing the pump coupler outside the co-band pump cavity.

[0045] In some embodiments, the same-band pump wavelength fiber oscillator 12 includes a pump source, a pump coupler, a high-reflection grating, an output grating, and a gain fiber.

[0046] The pump source of the same-band pump wavelength fiber oscillator 12 can be a pump source system composed of one or more multi-mode or single-mode semiconductor lasers, and the pump light energy can be coupled into the gain fiber through a pump coupler.

[0047] The pump couplers of the same-band pump wavelength fiber oscillator 12 include: a fused-taper (N+1)×1 type end-pump coupler (N≤20), a side-pump coupler based on side fusion affinity, and a wavelength division multiplexer for single-mode pump light coupling.

[0048] The central wavelength of the high-reflectivity grating with the same pump wavelength band is within the same pump wavelength range of the signal laser, and the reflectivity is ≥99%.

[0049] The central wavelength of the output grating with the same pump wavelength is consistent with the central wavelength of the high-reflection grating with the same pump wavelength, and the reflectivity is between 2% and 40%.

[0050] The gain fiber of the co-band pump wavelength fiber oscillator 12 includes a double-clad gain fiber and a single-clad gain fiber. The core of the gain fiber contains a rare earth element, such as ytterbium, erbium, thulium, holmium, or neodymium. The length of the gain fiber can be determined by the rare earth doping concentration.

[0051] The signal laser main amplifier 13 is used to further amplify the pre-amplified signal laser through the fiber core in-band pumping effect, thereby forming a high-power signal laser. In some embodiments, the signal laser main amplifier 13 can be of two types:

[0052] In the first type, the signal laser main amplifier 13 includes a gain fiber and an output end cap, and only the core in-band pumping process is implemented in the signal laser main amplifier 13 .

[0053] The second type, the signal laser main amplifier 13 includes a pump source, a pump coupler, a gain fiber and an output end cap. It can adopt forward pumping or backward pumping, or bidirectional pumping. The only difference is that a mixed pumping process of the fiber core co-band pump laser and the pump source can be realized in the signal laser main amplifier 13 to obtain a higher gain signal laser output.

[0054] The pump source of the signal laser main amplifier 13 can be a pump source system composed of one or more multi-mode or single-mode semiconductor lasers, and the pump light energy can be coupled into the gain fiber through a pump coupler; the pumping method of the signal laser main amplifier can adopt co-directional pumping, reverse pumping or bidirectional pumping.

[0055] The pump couplers of the signal laser main amplifier 13 include: a fused taper (N+1)×1 type end-pump coupler (N≤20), a side-pump coupler based on side fusion affinity, and a single-mode pump optical coupler prepared based on wavelength division multiplexing technology.

[0056] The gain fiber of the signal laser main amplifier 13 includes a double-clad gain fiber and a single-clad gain fiber. The core of each gain fiber contains a rare earth element, such as ytterbium, erbium, thulium, holmium, or neodymium. The length of the gain fiber can be determined based on the rare earth doping concentration. The core size of the gain fiber is no smaller than that of the gain fiber of the fiber oscillator 12 with the same pump wavelength.

[0057] The output end cap of the signal laser main amplifier 13 is a quartz output end cap.

[0058] In other embodiments, a fiber isolator is provided between the laser seed source 11 and the same-band pump wavelength fiber oscillator 12 to prevent the echo from adversely affecting the signal laser.

[0059] In other embodiments, a fiber isolator may be provided between the same-band pump wavelength fiber oscillator 12 and the signal laser main amplifier to prevent the echo from adversely affecting the same-band pump wavelength fiber oscillator.

[0060] The specific process of high-gain, high-power amplification of small-signal laser light is as follows: first, the small-signal laser light is injected into the high-reflection terminal of a fiber oscillator with the same pump wavelength as the laser. After passing through the fiber oscillator, the small-signal laser light acquires some of the gain of the oscillator, achieving low-noise, high-gain pre-amplification. Simultaneously, the fiber oscillator with the same pump wavelength as the laser light generates high-power, same-band pump laser light in the fiber core. The pre-amplified signal laser light and the same-band pump laser light are then injected together into the main amplifier of the signal laser light. Through the amplifier's core-co-band pumping or hybrid pumping process, the small-signal laser light is ultimately amplified to high power. Furthermore, when the output power of the small-signal laser light is as low as picowatts to nanowatts, the proposed small-signal high-gain, high-power amplification system can be cascaded. Compared with existing technologies, the present invention offers the advantages of simple structure, low cost, safety, and effectiveness.

[0061] In a second aspect, the present invention further provides a method for high-gain and high-power amplification of a small-signal laser based on a co-band pump cavity, comprising the following steps:

[0062] Step 1: Inject a small signal laser into the high-reflection end of the oscillator with the same pump wavelength;

[0063] Step 2: After the small signal laser passes through the same-band pump wavelength oscillator, it can achieve low-noise and high-gain pre-amplification. At the same time, the same-band pump wavelength oscillator will also generate high-power same-band pump laser in the fiber core.

[0064] Step 3: The pre-amplified signal laser is injected into the gain fiber of the main amplifier together with the same-band pump laser in the fiber core. At this time, the gain fiber will efficiently absorb the same-band pump laser and enable the signal laser to obtain further gain, thereby achieving high-power amplification of the signal laser.

[0065] When the signal laser main amplifier adopts the second type, that is, the signal laser main amplifier is provided with a pump source and a pump coupler, then when the signal laser and the same-band pump laser are injected into the gain fiber of the main amplifier together, the gain fiber is pumped by the pump source and the same-band pump laser at the same time (i.e., hybrid pumping is realized), thereby enabling the signal laser to obtain higher gain and achieve higher gain amplification.

[0066] Example 1

[0067] like Figure 1 As shown, this embodiment is a small-signal narrow-linewidth continuous laser high-gain, high-power amplification system, comprising a laser seed source 11 and a signal laser amplification component, which includes a co-band pump wavelength fiber oscillator 12 and a signal laser main amplifier 13. The small-signal laser seed source 101 is a narrow-linewidth continuous laser signal source with a central wavelength of 1070nm, a spectral width of 0.09nm, and an output power of 50μW.

[0068] The same-band pump wavelength fiber oscillator 12 includes a first pump source 102 , a first pump coupler 103 , a high-reflection grating 104 , a first gain fiber 105 and an output grating 106 .

[0069] The output end of the small signal laser seed source 101 is connected to the signal laser input end of the first pump coupler 103, the output ends of the two first pump sources 102 are connected to the pump input end of the first pump coupler 103, the output end of the first pump coupler 103 is connected to the input end of the high reflection grating 104, the output end of the high reflection grating is connected to the input end of the first gain fiber 105, and the output end of the first gain fiber 105 is connected to the output grating 106.

[0070] The first pump source 102 comprises two high-power wavelength-locked multimode semiconductor lasers with a central wavelength of 976 nm, with a maximum total power of 236 W. The first pump coupler 103 is a (6+1)×1 pump coupler. The high-reflectivity grating 104 has a central wavelength of 1028 nm and a reflectivity of 99.6%. The output grating 106 has a central wavelength of 1028 nm and a reflectivity of 15%.

[0071] The first gain fiber 105 is a double-clad ytterbium-doped fiber with a core diameter of 14 μm, a cladding diameter of 250 μm, and a pump absorption coefficient of 2 dB / m.

[0072] The signal laser main amplifier 13 includes a second gain fiber 107 and an output end cap 108 . The input end of the second gain fiber 107 is connected to the output end of the output grating 106 , and the output end of the second gain fiber 107 is connected to the output end cap 108 .

[0073] The first gain fiber 105 and the second gain fiber 107 are double-clad ytterbium-doped fibers, and the parameters of the two gain fibers are the same. The output end cap 108 is a quartz output end cap with a 1070 nm high transmittance film coated on the end face.

[0074] The connections between the various components in the high-gain and high-power amplification system are all made by low-loss welding.

[0075] In this high-gain, high-power amplification system, a highly reflective grating 104, a first gain fiber 105, and an output grating 106 form a co-band pump cavity. The first pump source 102 couples pump light into the first gain fiber 105 via the first pump coupler 103, providing gain for the co-band pump cavity and generating a high-power co-band pump laser. Simultaneously, a small-signal laser seed source 101 injects a narrow-linewidth continuous laser signal into the co-band pump cavity via the pump coupler. After passing through the co-band pump cavity, the small-signal laser gains a small portion of the energy from the co-band pump oscillator, achieving high-gain, low-noise pre-amplification of the signal laser. The signal laser output from the co-band pump cavity and the high-power co-band pump laser are then injected into the second gain fiber 107 of the signal laser main amplifier 13. The co-band pumping effect within the core of the second gain fiber 107 further amplifies the signal laser, generating a high-power signal laser. This amplification system makes full use of the low-noise characteristics of the co-band pumping cavity and the fiber core co-band pumping technology to achieve signal laser amplification from microwatt level to high power while maintaining the narrow linewidth characteristics of the signal laser.

[0076] In this high-gain, high-power amplification system, when the laser seed source 11 fails, the subsequent same-band pump wavelength fiber oscillator 12 and the signal laser main amplifier 13 will automatically adjust to the same-band pump laser output system structure, which will not cause the signal laser main amplifier to burn out, thereby improving the safety and stability of the entire system.

[0077] Through experimental testing, the correlation between the total output power of the small signal amplification system and the power of the first pump source 102 is as follows: Figure 2 As shown in Figure 2, the total output power now includes both the 1070nm signal laser and the 1028nm co-band pump laser. When the power of the first pump source 102 reaches 236W, the total output power is a maximum of 156.6W. The output spectrum is as follows: Figure 3 As shown in the figure, spectral integration calculation shows that the power of the 1070nm signal laser accounts for 82.1%, corresponding to a signal laser power of 128.5W. This shows that the small-signal amplification system can directly amplify a 50μW small-signal laser to 128.5W, with a total gain of up to 64dB.

[0078] Example 2

[0079] like Figure 4 As shown, this embodiment is a small-signal continuous single-frequency laser high-power amplification system, including a laser seed source 11 and a signal laser amplification component. The signal laser amplification component includes a same-band pump wavelength fiber oscillator 12 and a signal laser main amplifier 13.

[0080] The small signal laser seed source 101 is a continuous single-frequency laser signal source with a central wavelength of 1550 nm, a line width of 50 kHz, and an output power of only 1 μW.

[0081] The structure of the same-band pump wavelength fiber oscillator 12 in this embodiment 2 is the same as that of the same-band pump wavelength fiber oscillator 12 in embodiment 1. The difference lies in the types and parameters of the components, which are specifically as follows:

[0082] The same-band pump wavelength fiber oscillator 12 includes a first pump source 102 , a first pump coupler 103 , a high-reflection grating 104 , a first gain fiber 105 and an output grating 106 .

[0083] The first pump source 102 consists of two high-power, wavelength-locked, multimode semiconductor lasers with a central wavelength of 976 nm and a total power of 30 W. The first pump coupler 103 is a (6+1)×1 pump coupler. The high-reflectivity grating 104 has a central wavelength of 1480 nm and a reflectivity of 99.6%. The output grating 106 has a central wavelength of 1480 nm and a reflectivity of 20%. The first gain fiber 105 is a double-clad erbium-ytterbium co-doped fiber with a core diameter of 12 μm, a cladding diameter of 125 μm, and a pump absorption coefficient of 9.3 dB / m.

[0084] The signal laser main amplifier 13 includes a second gain fiber 107 , an output end cap 108 , a second pump source 109 and a second pump coupler 110 .

[0085] The output end of the output grating 106 is connected to the signal laser input end of the second pump coupler 110 . The output end of the pump coupler 110 is connected to the input end of the second gain fiber 107 . The output end of the second gain fiber 107 is connected to the output end cap 108 .

[0086] The first gain fiber 105 and the second gain fiber 107 are both double-clad erbium-ytterbium co-doped fibers with a core diameter of 12 μm, a cladding diameter of 125 μm, and a pump absorption coefficient of 9.3 dB / m.

[0087] The output end cap 108 is a quartz output end cap with a 1550nm high-transmittance film on the end face. The second pump source 109 is a high-power wavelength-locked multimode semiconductor laser with a wavelength of 976nm and a power of 80W. The second pump coupler 110 is a (6+1)×1 pump coupler.

[0088] The connections between the various components in the high-gain and high-power amplification system are all made by low-loss welding.

[0089] The functions of the co-band pump wavelength fiber oscillator 12 in this high-gain, high-power amplifier system are substantially similar to those of Example 1. It primarily generates a co-band pump laser with a wavelength of 1480 nm and pre-amplifies a continuous single-frequency signal laser with a wavelength of 1550 nm. The 1480 nm co-band pump laser output from the co-band pump wavelength fiber oscillator 12 and the pre-amplified 1550 nm signal laser are injected into the second gain fiber 107 via a second pump coupler 110. Simultaneously, a second pump source 109 is injected into the gain fiber via the pump input of the second pump coupler 110. The second gain fiber 107 is then simultaneously pumped by both the co-band pump laser and the pump source (i.e., a hybrid pumping process is implemented), thereby providing higher gain for the signal laser and generating a high-power signal laser.

[0090] In this high-gain, high-power amplification system, when the laser seed source 11 fails, the subsequent fiber oscillator 12 with the same pump wavelength and the signal laser main amplifier 13 will automatically adjust to a MOPA amplification structure with the same pump laser, which will not cause the signal laser main amplifier to burn out, thereby improving the safety and stability of the entire system.

[0091] Example 3

[0092] like Figure 5 As shown, this embodiment is a weak signal continuous single-frequency laser high-power cascade amplification system, comprising a laser seed source 11, a first-stage signal laser amplification assembly, and a second-stage signal laser amplification assembly. The first-stage signal laser amplification assembly includes a fiber oscillator with the same pump wavelength 32 and a signal laser main amplifier 33, while the second-stage signal laser amplification assembly includes a fiber oscillator with the same pump wavelength 34 and a signal laser main amplifier 35. The first-stage fiber oscillator with the same pump wavelength 32 and the second-stage fiber oscillator with the same pump wavelength 34 have the same structure. The first-stage signal laser main amplifier 33 and the second-stage signal laser main amplifier 35 have the same structure. The output end of the second-stage signal laser main amplifier 35 is connected to the output end cap 108.

[0093] The small signal laser seed source 101 is a continuous single-frequency laser signal source with a central wavelength of 1064 nm and an output power of only 100 pW.

[0094] In the first-stage signal laser amplification assembly, the high-reflectivity grating 104 has a central wavelength of 1018 nm and a reflectivity of 99.6%. The first gain fiber 105 is a single-clad, single-mode ytterbium-doped fiber with a core diameter of 7 μm, a cladding diameter of 125 μm, and a pump absorption coefficient of 250 dB / m. The output grating 106 has a central wavelength of 1018 nm and a reflectivity of 13%. The first pump coupler 103 is a wavelength division multiplexer. The first pump source 102 is a single-mode semiconductor laser with a wavelength of 976 nm and a power of 100 mW.

[0095] In the first-stage signal laser amplification assembly, the second gain fiber 107 is a single-clad single-mode ytterbium-doped fiber, and its parameters are consistent with those of the first gain fiber 105 .

[0096] In the second-stage signal laser amplification assembly, the first pump source 102 is a high-power, wavelength-locked, multimode semiconductor laser with a wavelength of 976 nm and a total power of 300 W. The first pump coupler 103 is a (6+1)×1 pump coupler. The high-reflectivity grating 104 has a central wavelength of 1018 nm and a reflectivity of 99.6%. The first gain fiber 105 is a double-clad ytterbium-doped fiber with a core diameter of 14 μm, a cladding diameter of 250 μm, and a pump absorption coefficient of 2 dB / m. The output grating 106 has a central wavelength of 1018 nm and a reflectivity of 15%.

[0097] In the second-stage signal laser amplification assembly, the second gain fiber 107 is a double-clad ytterbium-doped fiber with parameters identical to those of the first gain fiber 105. All components or assemblies in this amplification system are spliced with low-loss fusion. The output end cap 108 is a quartz output end cap coated with a 1064nm high-transmittance coating.

[0098] Because a weak, continuous, single-frequency laser signal source at the picowatt level is difficult to obtain a high-power signal laser through a single-stage signal laser amplification assembly, a two-stage signal laser amplification assembly is provided in this embodiment. In this high-gain, high-power amplification system, a first-stage, co-in-band pump wavelength fiber oscillator 32 and a first-stage signal laser main amplifier 33 form the first-stage signal amplification assembly; a second-stage, co-in-band pump wavelength fiber oscillator 34 and a second-stage signal laser main amplifier 35 form the second-stage signal amplification assembly. The structure and function of the first-stage signal laser amplification assembly are identical to those of the second-stage signal laser amplification assembly, differing only in the type and parameters of the various components. A weak, continuous, single-frequency laser signal source at the picowatt level can be obtained through the first-stage signal amplification assembly to produce a microwatt-level signal laser output. Further through the second-stage signal amplification assembly, a high-power laser signal of hundreds of watts can be obtained, meeting the requirements of high-power laser applications.

[0099] In this weak signal continuous single-frequency laser high-power cascade amplification system, when the laser seed source 11 and any stage of signal amplification components fail, the subsequent amplification components will automatically adjust to the same stage of pump laser output system structure, which will not cause the signal laser main amplifier to burn out, thereby improving the safety and stability of the entire system.

[0100] Example 4

[0101] The third aspect of the present invention further provides a laser device, in which the above-mentioned small-signal laser high-gain and high-power amplification system based on the same-band pump cavity is provided.

[0102] The laser device can be applied to laser industrial production devices, optical measurement devices, laser communication devices, optical monitoring devices, 3D printing devices, and laser medical equipment.

[0103] Laser industrial production equipment includes laser cutting equipment, laser drilling equipment, laser marking equipment, laser cleaning equipment, and laser welding equipment.

[0104] The high-power lasers generated by laser cutting devices and laser drilling devices can be used to process a variety of materials such as metals and non-metals.

[0105] The high-power laser generated by the laser marking device can burn a fixed pattern or text on the target object.

[0106] Laser cleaning device, which cleans the target object through the laser cleaning device.

[0107] Optical measuring devices include laser spectrometers, laser calibrators, etc.

[0108] Laser communication device is a laser communication device. Laser communication has the advantages of anti-electromagnetic interference and good confidentiality, and is suitable for complex battlefield environments.

[0109] The optical monitoring device is a lidar: lidar plays an important role in target detection, tracking and identification, and high-power fiber laser is one of its key components.

[0110] Laser medical equipment, such as ophthalmic OCT for treating eye diseases, all-femtosecond laser, ophthalmic surgical microscope, and all-in-one phaco-vitrectomy machine, etc.

[0111] The above embodiments only illustrate three representative small-signal laser high-gain, high-power amplification systems for narrow-linewidth small-signal continuous lasers, single-frequency small-signal continuous lasers, and weak-signal single-frequency continuous lasers. This does not describe all possible applications. In fact, any fiber amplification system equipped with a co-band pump wavelength fiber oscillator that simultaneously performs the dual functions of low-noise pre-amplification of the injected small signal and generation of the co-band pump laser required for subsequent co-band pumping amplification is within the scope of the present invention.

[0112] The above content is only for explaining the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A small-signal laser high-gain and high-power amplification system based on a co-band pump cavity, characterized in that: It includes a laser seed source and a signal laser amplification component, wherein the signal laser amplification component includes a fiber oscillator with the same pump wavelength as the signal laser and a signal laser main amplifier; The laser seed source, the fiber oscillator with the same pump wavelength, and the signal laser main amplifier are connected in sequence; The laser seed source is used to output a signal laser less than the milliwatt level; The same-band pump wavelength fiber oscillator is used to generate high-power same-band pump laser and perform low-noise and high-gain pre-amplification on the signal laser; The same-band pump wavelength fiber oscillator includes a pump source, a pump coupler, a high-reflection grating, an output grating and a gain fiber; The output end of the pump source is connected to the pump input end of the pump coupler, the output end of the pump coupler is connected to the input end of the high-reflection grating, the output end of the high-reflection grating is connected to the input end of the first gain fiber, and the output end of the first gain fiber is connected to the output grating; The signal laser main amplifier is used to obtain gain for the signal laser through the fiber core co-band pumping effect, thereby further amplifying the pre-amplified signal laser to form a high-power signal laser; The input end of the gain fiber of the signal laser main amplifier is connected to the output end of the fiber oscillator with the same pump wavelength through a pump coupler, and the pump input end of the pump coupler is connected to the pump source; There are multiple signal laser amplifying components, and the multiple signal laser amplifying components are cascaded, the input end of the first-stage signal laser amplifying component is connected to the laser seed source, and the output end of the last-stage signal laser amplifying component is connected to the output end cap; When the laser seed source and any stage of signal amplification components fail, the subsequent amplification components will automatically adjust to the same-band pump laser output system structure.

2. The small-signal laser high-gain high-power amplification system based on a co-band pump cavity according to claim 1, characterized in that: The laser seed source is a continuous signal laser seed source or a pulse signal laser seed source.

3. The small-signal laser high-gain high-power amplification system based on a co-band pump cavity according to claim 1, characterized in that: The signal laser main amplifier comprises a gain optical fiber, the input end of the gain optical fiber is connected to the output end of the optical fiber oscillator with the same pump wavelength, and the output end of the gain optical fiber is connected to the output end cap.

4. The small-signal laser high-gain high-power amplification system based on a co-band pump cavity according to claim 1, characterized in that: An optical fiber isolator is provided between the laser seed source and the same-band pump wavelength optical fiber oscillator.

5. The small-signal laser high-gain high-power amplification system based on a co-band pump cavity according to claim 1, characterized in that: An optical fiber isolator is provided between the same-band pump wavelength optical fiber oscillator and the signal laser main amplifier.

6. An amplification method for a small-signal laser high-gain high-power amplification system based on a co-in-band pump cavity according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: The signal laser generated by the laser seed source is injected into the high-reflection end of the oscillator with the same pump wavelength; Step 2: The same-band pump wavelength fiber oscillator provides gain to the signal laser and realizes low-noise and high-gain pre-amplification. At the same time, the same-band pump wavelength fiber oscillator generates high-power same-band pump laser; Step 3: The signal laser main amplifier absorbs the same-band pump laser and enables the pre-amplified signal laser to further gain gain, thereby forming a high-power signal laser.

7. A laser device, characterized in that: The laser device is provided with the small-signal laser high-gain high-power amplification system based on the same-band pump cavity as described in any one of claims 1 to 5.

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