Single-frequency pulse fiber laser based on sawtooth wave amplification

Abstract

The utility model relates to a single-frequency pulse fiber laser based on sawtooth wave amplification, which belongs to the technical field of lasers and comprises a single-frequency seed source, a signal source, an acoustic optical modulator, a first amplifier, a second amplifier and a first isolator. The single-frequency seed source, the acoustic optical modulator, the first amplifier, the second amplifier and the first isolator are connected in sequence; and the signal source is connected with the acousto-optic modulator. According to the single-frequency pulse fiber laser based on sawtooth wave amplification provided by the utility model, adverse effects caused by SBS, transient gain effect, SPM and the like can be suppressed by using proper signal light pulse waveforms, and narrow linewidth laser with higher output can be realized.

Description

Technical Field

[0001] The utility model relates to the technical field of lasers, in particular to a single-frequency pulse optical fiber laser based on sawtooth wave amplification. Background Art

[0002] Fiber lasers use rare earth ion-doped optical fibers as gain media, and have many advantages, such as low pump threshold, high coupling efficiency, good beam quality, convenient thermal management, compact structure, and wide tunable range. Among them, single-frequency laser amplification technology has become a hot topic of research at home and abroad. Its spectral line width is very narrow and has good coherence characteristics, which makes it have huge and strong demand in high-precision detection and long-distance detection, such as laser radar, coherent detection, nonlinear frequency conversion and other fields. Improving the output power of single-frequency fiber lasers can further expand their application range and fields, giving them a wider application prospect.

[0003] In order to obtain high output power, a master oscillator power amplifier structure is usually used to amplify the laser power. However, the extremely narrow linewidth, long pulse, and polarization-maintaining characteristics also bring many adverse effects, such as stimulated Brillouin scattering (SBS), transient gain effect, and self-phase modulation (SPM). Utility Model Content

[0004] In view of this, it is necessary to provide a single-frequency pulse fiber laser based on sawtooth wave amplification to solve the problem of suppressing SBS, transient gain effect, and SPM during power amplification.

[0005] In order to solve the above problems, the utility model provides a single-frequency pulse fiber laser based on sawtooth wave amplification, comprising:

[0006] A single frequency seed source, a signal source, an acousto-optic modulator, a first amplifier, a second amplifier and a first isolator;

[0007] The single-frequency seed source, the acousto-optic modulator, the first amplifier, the second amplifier and the first isolator are connected in sequence;

[0008] The signal source is connected to the acousto-optic modulator.

[0009] In a possible implementation manner, the first amplifier includes:

[0010] a second isolator, a first pump laser, a wavelength division multiplexer, a first gain fiber, and a narrowband filter;

[0011] The second isolator, the wavelength division multiplexer, the first gain optical fiber and the narrowband filter are connected in sequence;

[0012] The first pump laser is connected to the wavelength division multiplexer;

[0013] The second isolator is connected to the AOM.

[0014] In a possible implementation manner, the first gain fiber is a 6 / 125 erbium-doped fiber.

[0015] In a possible implementation manner, the wavelength of the pump light provided by the first pump laser is 976 nm.

[0016] In a possible implementation, the wavelength of the wavelength division multiplexer is 976nm / 1550nm.

[0017] In a possible implementation manner, the second amplifier includes:

[0018] a third isolator, a second pump laser, a beam combiner, and a second gain fiber;

[0019] The third isolator, the beam combiner and the second gain optical fiber are connected in sequence;

[0020] The second pump laser is connected to the beam combiner;

[0021] The third isolator is connected to the narrowband filter.

[0022] In a possible implementation, the second gain fiber is a 10 / 125 erbium-ytterbium co-doped fiber.

[0023] In a possible implementation manner, the wavelength of the pump light provided by the second pump laser is 940 nm.

[0024] In a possible implementation, the wavelength of the beam combiner is 940nm / 1550nm.

[0025] In a possible implementation manner, the central wavelengths of the first isolator, the second isolator, and the third isolator are 1550 nm.

[0026] The beneficial effects of the utility model are as follows: the single-frequency pulse fiber laser based on sawtooth wave amplification provided by the utility model can output high-quality, high-signal-to-noise ratio continuous single-frequency seed light through a single-frequency seed source, the signal source provides a waveform signal, the acousto-optic modulator modulates the single-frequency seed light and the waveform signal to obtain a sawtooth wave light signal, high-quality small signal amplification can be achieved through the first amplifier, and main amplification can be achieved through the second amplifier, the waveform of the amplified signal light is approximately rectangular and is output through the first isolator, and the adverse effects caused by SBS, transient gain effect, SPM, etc. can be suppressed by using a suitable signal light pulse waveform, thereby achieving a higher output narrow linewidth laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 This is one of the structural schematic diagrams of an embodiment of a single-frequency pulse fiber laser based on sawtooth wave amplification provided by the utility model;

[0029] Figure 2 A schematic structural diagram of an embodiment of a first amplifier provided by the utility model;

[0030] Figure 3 A schematic structural diagram of an embodiment of a second amplifier provided by the utility model;

[0031] Figure 4 The second structural schematic diagram of an embodiment of a single-frequency pulse fiber laser based on sawtooth wave amplification provided by the utility model;

[0032] Figure 5 This is a waveform diagram of a sawtooth wave and a square wave provided by the utility model. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the utility model.

[0034] In the description of the embodiments of the present utility model, unless otherwise specified, "multiple" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" may mean: A exists alone, A and B exist at the same time, and B exists alone.

[0035] The descriptions of "first", "second", etc. involved in the embodiments of the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the technical features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0036] Figure 1 This is a schematic diagram of a structure of an embodiment of a single-frequency pulse fiber laser based on sawtooth wave amplification provided by the utility model, as shown in FIG. Figure 1 As shown, the single-frequency pulse fiber laser based on sawtooth wave amplification includes:

[0037] A single frequency seed source 110, a signal source 120, an acousto-optic modulator 130, a first amplifier 140, a second amplifier 150 and a first isolator 160;

[0038] The single-frequency seed source 110, the acousto-optic modulator 130, the first amplifier 140, the second amplifier 150 and the first isolator 160 are connected in sequence;

[0039] The signal source 120 is connected to the AOM 130 .

[0040] In the specific implementation, the single-frequency seed source is used to output high-quality, high-signal-to-noise ratio continuous single-frequency seed light, the signal source is used to provide a waveform signal, and the acousto-optic modulator is used to modulate the single-frequency seed light and the waveform signal to obtain a sawtooth wave optical signal. The sawtooth wave has a front edge with a gentle slope, which can suppress the transient gain effect and obtain a higher single pulse energy. Compared with the Gaussian wave, it has the advantage of suppressing self-phase modulation. Then, high-quality small signal amplification can be achieved through the first amplifier and main amplification can be achieved through the second amplifier. The waveform of the amplified signal light is approximately rectangular and is output through the first isolator. By using a suitable signal light pulse waveform, the adverse effects of SBS, transient gain effect, SPM, etc. can be suppressed to achieve a higher output narrow linewidth laser.

[0041] Compared with the prior art, the single-frequency pulse fiber laser based on sawtooth wave amplification provided by the embodiment of the utility model can output high-quality, high-signal-to-noise ratio continuous single-frequency seed light through a single-frequency seed source, the signal source provides a waveform signal, the acousto-optic modulator modulates the single-frequency seed light and the waveform signal to obtain a sawtooth wave light signal, high-quality small signal amplification can be achieved through the first amplifier, and main amplification can be achieved through the second amplifier, the waveform of the amplified signal light is approximately rectangular and is output through the first isolator, and the adverse effects brought by SBS, transient gain effect, SPM, etc. can be suppressed by using a suitable signal light pulse waveform, thereby achieving a higher output narrow linewidth laser.

[0042] In some embodiments of the present invention, the first amplifier 140 includes:

[0043] A second isolator 141, a first pump laser 142, a wavelength division multiplexer 143, a first gain fiber 144 and a narrowband filter 145;

[0044] The second isolator 141, the wavelength division multiplexer 143, the first gain optical fiber 144 and the narrowband filter 145 are connected in sequence;

[0045] The first pump laser 142 is connected to the wavelength division multiplexer 143;

[0046] The second isolator 141 is connected to the AOM 130 .

[0047] The single-frequency pulse fiber laser based on sawtooth wave amplification provided by the embodiment of the utility model comprises a first amplifier including a second isolator, a first pump laser, a wavelength division multiplexer, a first gain fiber and a narrowband filter. The reverse light is isolated by the second isolator. The first pump laser provides a 976nm pump light. The wavelength division multiplexer introduces the 976nm pump light and the 1550nm signal light into the gain fiber. The first gain fiber provides gain for signal amplification and the narrowband filter filters out the ASE signal entering the next stage, thereby realizing high-quality small signal amplification of the sawtooth wave optical signal.

[0048] For example, Figure 2 This is a structural schematic diagram of an embodiment of the first amplifier provided by the utility model.

[0049] In some embodiments of the present invention, the first gain fiber 144 is a 6 / 125 erbium-doped fiber.

[0050] The first gain fiber is a high absorption 6 / 125 erbium-doped fiber, which is used to provide gain for signal amplification.

[0051] In some embodiments of the present invention, the wavelength of the pump light provided by the first pump laser 142 is 976 nm.

[0052] The first pump laser is a 976 nm pump laser, which is used to provide 976 nm pump light.

[0053] In some embodiments of the present invention, the wavelength of the wavelength division multiplexer 143 is 976nm / 1550nm.

[0054] The wavelength of the wavelength division multiplexer (WDM) is 976nm / 1550nm, which is used to introduce the 976nm pump light and the 1550nm signal light into the gain fiber. WDM can realize the multiplexing and separation of two different wavelength optical signals, making the laser system more efficient and flexible.

[0055] Narrowband filters are used to filter out the amplified spontaneous emission (ASE) signal entering the next stage. ASE is the noise caused by unstimulated radiation in the optical amplifier, which will reduce the performance and stability of the laser system. By introducing narrowband filters in the laser system, the efficiency and performance of the laser system can be improved, the impact of ASE can be reduced, and a purer and more stable optical pulse can be generated.

[0056] The single-frequency pulse fiber laser based on sawtooth wave amplification provided by the embodiment of the utility model isolates the reverse light through the second isolator, the first pump laser provides 976nm pump light, the wavelength division multiplexer introduces the 976nm pump light and 1550nm signal light into the gain fiber, the first gain fiber provides gain for signal amplification and the narrowband filter filters out the ASE signal entering the next stage, thereby realizing high-quality small signal amplification of the sawtooth wave optical signal.

[0057] In some embodiments of the present invention, the second amplifier 150 includes:

[0058] A third isolator 151, a second pump laser 152, a beam combiner 153 and a second gain fiber 154;

[0059] The third isolator 151, the beam combiner 153 and the second gain optical fiber 154 are connected in sequence;

[0060] The second pump laser 152 is connected to the beam combiner 153;

[0061] The third isolator 151 is connected to the narrowband filter 145 .

[0062] For example, Figure 3 This is a schematic structural diagram of an embodiment of the second amplifier provided by the utility model.

[0063] In some embodiments of the present invention, the second gain fiber 154 is a 10 / 125 Erbium-Ytterbium co-doped fiber.

[0064] The second gain fiber is a high absorption 10 / 125 Erbium-Ytterbium co-doped fiber, which is used to provide gain for signal amplification.

[0065] In some embodiments of the present invention, the wavelength of the pump light provided by the second pump laser 152 is 940 nm.

[0066] The second pump laser is a pump laser with a wavelength of 940 nm, and is used to provide pump light of 940 nm.

[0067] In some embodiments of the present invention, the wavelength of the beam combiner 153 is 940nm / 1550nm.

[0068] The wavelength of the combiner is 940nm / 1550nm, which is used to couple the 940nm pump light into the gain fiber.

[0069] In some embodiments of the present invention, the central wavelength of the first isolator 160 , the second isolator 141 , and the third isolator 151 is 1550 nm.

[0070] The central wavelength of the first isolator, the second isolator and the third isolator is 1550 nm, and is used to isolate the reverse light.

[0071] The utility model provides a single-frequency pulse fiber laser based on sawtooth wave amplification, in which the reverse light is isolated by a third isolator, the second pump laser provides a 940nm pump light, the beam combiner couples the 940nm pump light into a gain fiber, and the second gain fiber provides gain for signal amplification, thereby realizing the main amplification of the signal.

[0072] Figure 4 The second structural diagram of an embodiment of a single-frequency pulse fiber laser based on sawtooth wave amplification provided by the utility model is as follows: Figure 4 As shown, the optical fiber amplifier device comprises:

[0073] The single-frequency seed source 110 is used to provide continuous single-frequency seed light with high quality and high signal-to-noise ratio;

[0074] an acousto-optic modulator 130, for performing pulse and waveform modulation on the continuous signal light;

[0075] A signal source 120, used for providing a waveform signal;

[0076] The second isolator 141 has a central wavelength of 1550 nm and is used to isolate the reverse light;

[0077] A first pump laser 142, a pump laser (976LD) with a wavelength of 976 nm, provides a pump light of 976 nm;

[0078] A wavelength division multiplexer 143, with a wavelength of 976nm / 1550nm, is used to introduce 976nm pump light and 1550nm signal light into the gain optical fiber;

[0079] The first gain fiber 144 is a high absorption 6 / 125 erbium-doped fiber, used to provide gain for signal amplification;

[0080] The narrowband filter 145 is used to filter out the ASE entering the next stage.

[0081] The third isolator 151 has a central wavelength of 1550 nm and is used to isolate the reverse light;

[0082] The second pump laser 152 has a wavelength of 940 nm pump laser (940LD), and is used to provide a pump light of 940 nm;

[0083] A beam combiner 153, with a wavelength of 940nm / 1550nm, is used to couple the 940nm pump light into the gain fiber;

[0084] The second gain fiber 154 is a high absorption 10 / 125 Erbium-Ytterbium co-doped fiber, used to provide gain for signal amplification;

[0085] The first isolator 160 has a central wavelength of 1550 nm and is used to isolate reverse light.

[0086] When a light pulse passes through a gain fiber, the leading edge of the pulse will affect its trailing edge, resulting in different gains between the leading and trailing edges, and the transient gain effect of the optical amplifier. The leading edge of the signal pulse first consumes most of the upper inversion particle population. If the upper energy level particle population cannot be replenished in time, the trailing edge of the pulse cannot be fully amplified. As time goes by, the trailing edge signal is not amplified, causing a change in the output pulse waveform. This change makes the optical signal with the same single pulse energy have an extremely high peak power, which is very prone to SBS phenomenon.

[0087] Narrow linewidth is an important parameter of single-frequency lasers, but the self-phase modulation caused by the optical Kerr effect leads to spectrum broadening.

[0088] The utility model adopts sawtooth wave optical signal for amplification, such as Figure 5 As shown, Figure 5 The waveform diagram of the sawtooth wave and square wave provided by the utility model shows that compared with the square wave, the sawtooth wave has a leading edge with a gentler slope, which can suppress the transient gain effect and obtain a higher single pulse energy. Compared with the Gaussian wave, it has the advantage of suppressing self-phase modulation.

[0089] like Figure 4 As shown in the figure, the single-frequency seed source outputs low-power, high-quality single-frequency laser, which is modulated into a sawtooth wave by the AOM and then enters the first-stage amplification structure (i.e., the first amplifier). The 976nm pump light enters the 6 / 125 erbium-doped fiber together with the signal light through the WDM to achieve high-quality small signal amplification. The first-stage amplification structure includes the second isolator, WDM, 976LD, 6 / 125 erbium-doped fiber, and narrowband filter.

[0090] The amplified signal light enters the secondary amplification structure (i.e., the second amplifier), and the signal light is mainly amplified in the 10 / 125 erbium-ytterbium co-doped fiber. The secondary amplification structure includes the second isolator, 10 / 125 erbium-ytterbium co-doped fiber, a beam combiner, and a 940LD.

[0091] Finally, the amplified signal light waveform is approximately rectangular and is output through the first isolator.

[0092] The utility model utilizes a suitable signal light pulse waveform to suppress the adverse effects of SBS, transient gain effect, SPM, etc., to achieve a narrow linewidth laser with higher output, and to achieve pulse output with high single pulse energy. The waveform is simple and easy to implement, and compared with the use of an electro-optic phase modulator for pre-phase compensation, the utility model can reduce costs, has a simple design, a compact structure, a small size, and is easy to integrate.

[0093] The single-frequency pulse fiber laser based on sawtooth wave amplification provided by the utility model is introduced in detail above. The principle and implementation mode of the utility model are explained in this article by using specific examples. The description of the above embodiments is only used to help understand the core idea of ​​the utility model. At the same time, for technicians in this field, according to the idea of ​​the utility model, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as a limitation on the utility model.

Claims

1. A single-frequency pulse fiber laser based on sawtooth wave amplification, characterized in that: include: A single frequency seed source, a signal source, an acousto-optic modulator, a first amplifier, a second amplifier and a first isolator; The single-frequency seed source, the acousto-optic modulator, the first amplifier, the second amplifier and the first isolator are connected in sequence; The signal source is connected to the acousto-optic modulator.

2. The single-frequency pulse fiber laser based on sawtooth wave amplification according to claim 1, characterized in that: The first amplifier comprises: a second isolator, a first pump laser, a wavelength division multiplexer, a first gain fiber, and a narrowband filter; The second isolator, the wavelength division multiplexer, the first gain optical fiber and the narrowband filter are connected in sequence; The first pump laser is connected to the wavelength division multiplexer; The second isolator is connected to the AOM.

3. The single-frequency pulse fiber laser based on sawtooth wave amplification according to claim 2, characterized in that: The first gain optical fiber is a 6 / 125 erbium-doped optical fiber.

4. The single-frequency pulse fiber laser based on sawtooth wave amplification according to claim 2, characterized in that: The wavelength of the pump light provided by the first pump laser is 976 nm.

5. The single-frequency pulse fiber laser based on sawtooth wave amplification according to claim 2, characterized in that: The wavelength of the wavelength division multiplexer is 976nm / 1550nm.

6. The single-frequency pulse fiber laser based on sawtooth wave amplification according to claim 2, characterized in that: The second amplifier comprises: a third isolator, a second pump laser, a beam combiner, and a second gain fiber; The third isolator, the beam combiner and the second gain optical fiber are connected in sequence; The second pump laser is connected to the beam combiner; The third isolator is connected to the narrowband filter.

7. The single-frequency pulse fiber laser based on sawtooth wave amplification according to claim 6, characterized in that: The second gain fiber is a 10 / 125 erbium-ytterbium co-doped fiber.

8. The single-frequency pulse fiber laser based on sawtooth wave amplification according to claim 6, characterized in that: The wavelength of the pump light provided by the second pump laser is 940 nm.

9. The single-frequency pulse fiber laser based on sawtooth wave amplification according to claim 6, characterized in that: The wavelength of the beam combiner is 940nm / 1550nm.

10. The single-frequency pulse fiber laser based on sawtooth wave amplification according to claim 6, characterized in that: The central wavelengths of the first isolator, the second isolator and the third isolator are 1550 nm.

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