Sub-hundred femtosecond controllable fiber laser based on zirconium metal organic framework material

Abstract

The invention belongs to the technical field of passive mode-locking ultrafast fiber lasers, and discloses a sub-hundred femtosecond controllable fiber laser based on a zirconium metal organic framework material. The optical fiber laser comprises a laser pumping source, a wavelength division multiplexer, an erbium-doped gain optical fiber, a polarization independent isolator, a polarization controller, an output coupler and an amino-based zirconium metal organic framework mode locking device which are sequentially connected through single-mode optical fibers. According to the metal organic framework mode locking device, a saturable absorber of an amino zirconium metal organic framework nanosphere is prepared through a hydrothermal method. The ultrafast pulse is generated by the saturable absorber based on the metal organic framework in the laser cavity, the back-and-forth switching between the sub-hundred femtosecond magnitude broadening pulse and the bound state soliton is realized by controlling the polarization controller, and the laser has the advantages of simple structure, stability, reliability and easiness in integration.

Description

Technical Field

[0001] The present invention relates to the technical field of fiber lasers, and particularly to a sub-100-femtosecond controllable fiber laser based on zirconium metal-organic framework materials. Background Art

[0002] An ultrashort pulse mode-locked fiber laser is a laser that uses optical fiber as a gain medium to generate ultrashort optical pulses, and is widely used in fields such as medical imaging, lidar, and spectral analysis. Currently, mainstream saturable absorption materials (such as graphene oxide and carbon nanotubes) have excellent nonlinear optical properties, can effectively promote the formation and compression of optical pulses, absorb and modulate laser light in a relatively wide wavelength range, and provide favorable conditions for the formation of mode-locked pulses. However, in the field of ultrafast mode-locked pulses, mainstream saturable absorber materials are limited in terms of stability, controllability, and mode-locked pulse width. At the same time, their scattering and absorption effects may cause optical losses and reduce the conversion efficiency of the laser. Summary of the Invention

[0003] To solve the deficiencies and drawbacks of the above-mentioned prior art, the present invention provides a sub-100-femtosecond controllable fiber laser based on zirconium metal-organic framework materials.

[0004] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0005] A preparation method for an amino-based zirconium metal-organic framework mode-locking device, and the specific steps are as follows:

[0006] Step 1. Under an argon atmosphere, 2,5-dibromoaniline (1.03 g, 4.11 mmol), 4-(methoxycarbonyl)phenylboronic acid (2.22 g, 12.22 mmol), and potassium fluoride (2.36 g, 40.6 mmol) are dispersed in tetrahydrofuran (20 mL). Then, [Pd(dba)2] (270 mg, 0.294 mmol; dba = dibenzylideneacetone) and PBu3 solution (10 mol%, 820 μL, 0.820 mmol) are added. The mixture is stirred and reacted at 50 °C for 17 hours. It is cooled to room temperature.

[0007] Step 2. The reaction mixture is poured into water (25 mL), and the aqueous phase is extracted with CH2Cl2. The organic phase is concentrated under reduced pressure. The solid residue is dissolved in CH2Cl2, silica gel (4.5 g) is added, the solvent is removed under reduced pressure to obtain a powder with good fluidity, and it is transferred to the top of a silica gel column. It is eluted with CH2Cl2 / EtOH (50:1, volume ratio; Rf = 0.35) to obtain a light yellow solid, dimethyl-2'-amino-1',4”:1',4”-terphenyl-4,4”-dicarboxylate.

[0008] Step 3. The obtained solid (2.51 g, 5.59 mmol) was suspended in tetrahydrofuran (50 mL), and the temperature was raised to 40 °C. A methanol solution containing potassium hydroxide (5.5 mol / L; 250 mL, 13.8 mmol) was added, and the reaction mixture was stirred at 40 °C for 20 hours.

[0009] Step 4. After cooling to room temperature, the colorless solid was filtered and separated, suspended in tetrahydrofuran (200 mL) and trifluoroacetic acid (25 mL, 0.34 mol), stirred overnight at room temperature, the solid was filtered and separated, washed with cold water and dried to obtain the yellow powder of H2tpdc-NH2. The amino-based zirconium metal-organic framework saturable absorber film was cut into small pieces of appropriate size and placed on the fiber optic connector.

[0010] A sub-100-femtosecond controllable fiber laser based on zirconium metal-organic framework materials, characterized in that the system consists of a laser pump source, a wavelength division multiplexer, an erbium-doped gain fiber, a polarization-independent isolator, a polarization controller, an output coupler, and an amino-based zirconium metal-organic framework mode-locking device. These components are sequentially connected by a single-mode fiber to form a ring laser resonator.

[0011] Preferably, the laser pump source has good stability and adjustable power, which is an important prerequisite for the generation of the pulse mode-locking phenomenon. While ensuring the high absorption efficiency of erbium ions, it provides energy for the erbium-doped ion gain fiber.

[0012] Preferably, the wavelength division multiplexer inputs the optical signals of the pump source light wave (976 nm) and the gain light wave (1550 nm) into the resonator cavity together, and can realize the simultaneous transmission of signals of two wavelengths without mutual interference.

[0013] Preferably, the length of the erbium-doped gain fiber is 10 m, and due to its special material structure, the light wave in the resonator cavity is amplified to the 1550 nm band.

[0014] Preferably, the polarization controller is used to control the polarization state of the laser output, adjust the polarization direction of the light wave, thereby realizing the birefringence effect, and finally realizing the regulation of sub-100-femtosecond broadened pulses and bound-state solitons.

[0015] Preferably, the output coupler has two output ends with a ratio of 3:7 to ensure the continuous operation of the optical path in the resonator cavity and the signal output outside the resonator cavity.

[0016] Preferably, the polarization-independent isolator allows light to pass through in one direction while blocking the transmission of light from the opposite direction, so that the light beam cannot flow back, preventing the reflected light from interfering with the laser, and finally improving the stability and reliability of the system.

[0017] Preferably, the total length of the single-mode fiber is 17 m, which is used to appropriately adjust the negative dispersion in the resonant cavity, thereby obtaining more stable mode-locked laser pulses and simultaneously used to transmit C-band pulses.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention provides a method for preparing a metal-organic framework mode-locking device. The zirconium metal-organic framework thin film with amino groups prepared by the hydrothermal method is simple to prepare, has a high modulation depth and broadband spectral absorption, expands the selection range of saturable absorber materials, and provides a richer option for the selection of mode-locked fiber lasers in this field.

[0020] 2. The present invention provides a sub-100-femtosecond controllable fiber laser based on zirconium metal-organic framework materials. In terms of pulse output, the fiber mode-locked laser can achieve stretched pulses with a pulse width of 86 fs and a signal-to-noise ratio of 79 dB. The stretched pulses and bound-state solitons can be rapidly regulated by controlling the polarization controller. Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0022] Figure 1 It is a schematic diagram of the structure and result of a fiber laser with sub-100-femtosecond pulses provided by the present invention. It includes Figure 1 (a): Laser pump source 1, wavelength division multiplexer 2, erbium-doped gain fiber 3, polarization-independent isolator 4, polarization controller 5, output coupler 6, amino-based zirconium metal-organic framework mode-locking device 7; Figure 1 (b), Figure 1 (c): Autocorrelation schematic diagrams of stretched pulses and bound-state solitons; Figure 1 (d): Schematic diagram of spectral regulation of stretched pulses and bound-state solitons.

[0023] Figure 2 It is a schematic diagram of the output performance in a specific embodiment. Figure 2 (a), Figure 2 (b): Spectral schematic diagrams of stretched pulses and bound-state solitons; Figure 2 (c), Figure 2 (d): Pulse sequence diagram and radio frequency spectrum diagram of the sub-100-femtosecond controllable fiber laser.

[0024] Figure 3(a) is the saturable absorption curve of the amino-functionalized zirconium metal-organic framework mode-locking device provided by the present invention. Figure 3 (b) is the pulse output power diagram of the sub-100-femtosecond controllable fiber laser. Specific implementation method

[0026] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention. Embodiment

[0027] The object of the present invention is to prepare an amino-functionalized zirconium metal-organic framework mode-locking device, and utilize the characteristics of high modulation depth and broadband spectral absorption of the amino-functionalized zirconium metal-organic framework saturable absorber to achieve controllable sub-100-femtosecond broadened pulses and bound-state soliton mode-locking in a fiber laser, improve the anti-interference ability of the output pulses, and have the characteristics of stable performance, controllability, and easy operation.

[0028] Figure 1 It is a schematic diagram of the structure and results of a sub-100-femtosecond controllable fiber laser based on a zirconium metal-organic framework material provided by the present invention. The laser structure is as Figure 1 (a) shows a fiber laser with sub-100-femtosecond pulses provided by the present invention. The laser pump source 1, the 21-port of the wavelength division multiplexer 2, the 10-m erbium-doped gain fiber 3, the polarization-independent isolator 4, the polarization controller 5, the 61-port of the output coupler 6, and the amino-functionalized zirconium metal-organic framework mode-locking device 7. The 22-port of the wavelength division multiplexer is connected to a 17-m single-mode fiber in sequence to form a ring resonator.

[0029] The laser pump 1 mentioned above uses a 976-nm band laser, which has good stability and adjustable power. This is an important prerequisite for the generation of the pulse mode-locking phenomenon. While ensuring the high absorption efficiency of erbium ions, it provides energy for the erbium-doped ion gain fiber.

[0030] The wavelength division multiplexer 2 is divided into port 21 and port 22, which jointly input the optical signals of the pump source light wave (976 nm) and the gain light wave (1550 nm) into the resonator, and can realize the simultaneous transmission of two-wavelength signals without mutual interference.

[0031] The erbium-doped gain fiber 3 has a length of 10 m, and its special material structure amplifies the light wave in the resonator to the 1550-nm band.

[0032] The polarization-independent isolator 4 allows light to pass through in one direction while blocking the transmission of light from the opposite direction, thereby preventing the light beam from flowing back and interfering with the laser, ultimately improving the stability and reliability of the system.

[0033] The polarization controller 5 is used to control the polarization state of the laser output and adjust the polarization direction of the light wave, thereby achieving the birefringence effect and ultimately realizing the regulation of sub-100-femtosecond broadened pulses and bound-state solitons.

[0034] The output coupler 6 has a 30% port 61 and a 70% port 62 to ensure the continuous operation of the optical path in the resonator and the signal output outside the resonator.

[0035] The amino-based zirconium metal-organic framework mode-locking device 7 is used to narrow the pulse. The amino-based zirconium metal-organic framework saturable absorber can withstand higher energy and output broadened pulses and bound-state solitons due to its high modulation depth and broadband spectral absorption.

[0036] The total length of the single-mode fiber is 17 m, which is used to appropriately adjust the dispersion in the resonator to obtain more stable mode-locked laser pulses and is also used to transmit C-band pulses.

[0037] As a specific embodiment, Figure 1 (b)- Figure 1 (d) shows the schematic diagram of the laser for sub-100-femtosecond mode-locked pulses. When a specific pump power is input, mode locking is achieved by adjusting the polarization controller 5, where Figure 1 (b) is the autocorrelation trace of the broadened pulse, and its pulse width is 1.414 * 86 fs, Figure 1 (c) is the autocorrelation trace of the bound-state soliton, and the distance between its two peaks is 1.54 * 840 fs, Figure 1 (d) is the mutual switching between the broadened pulse and the bound-state soliton under the condition of adjusting the angle of the polarization controller. Sub-100-femtosecond broadened pulses are achieved at 15° of the polarization controller. Continuing to adjust the polarization controller, bound-state soliton mode locking is achieved at 75°, and finally the broadened pulse is restored at 135°.

[0038] The present technical solution provides the following detailed and clear performance test results of the fiber laser Figures 2 to 3 :

[0039] Figure 2 (a) is the spectrum of the broadened pulse, with a spectral width of 10.9 nm and a central wavelength of 1551 nm, Figure 2 (b) is the spectrum of the bound-state soliton, with a distance of 9.5 nm between the two peaks and a central wavelength of 1551 nm, Figure 2 (c), Figure 2(d) are the pulse sequence and radio frequency spectrum of the mode-locked pulses of the fiber laser, corresponding to a basic period of 129.37 ns and a basic frequency of 7.73 MHz respectively, and its signal-to-noise ratio is as high as 79 dB, fully demonstrating its high signal anti-interference ability. Figure 2 (d) The wide-range radio frequency spectrum indicates the long-term stability of the mode-locked pulses.

[0040] In this embodiment Figure 3 (a) shows the saturable absorption curve of the zirconium metal-organic framework device of the amino group, and the modulation depth (a s ), saturation intensity (I sat ), and non-saturation loss (a ns ) are 4.06%, 11.99 MW / cm 2 and 58.24% respectively. The higher modulation depth helps to achieve more stable mode-locked pulses. At the same time, through Figure 3 (b) the power curve of the fiber laser under the pump power range of 65 mW to 177.83 mW, it can be seen that the fiber laser has a high optical-to-optical conversion efficiency, which can reach 8.6%.

[0041] The key mode-locking device used in the sub-100 femtosecond pulse laser in this embodiment is composed of two fiber connectors and a thin film of zirconium metal-organic framework material with amino group in the middle. The specific preparation steps are as follows:

[0042] Step 1. Under an argon atmosphere, 2,5-dibromoaniline (1.03 g, 4.11 mmol), 4-(methoxycarbonyl)phenylboronic acid (2.22 g, 12.22 mmol), and potassium fluoride (2.36 g, 40.6 mmol) are dispersed in tetrahydrofuran (20 mL). Then [Pd(dba)2] (270 mg, 0.294 mmol; dba = dibenzylideneacetone) and PBu3 solution (10 mol%, 820 μL, 0.820 mmol) are added. Stir and react at 50 °C for 17 hours. Cool to room temperature.

[0043] Step 2. Pour the reaction mixture into water (25 mL), and extract the aqueous phase with CH2Cl2. Concentrate the organic phase under reduced pressure. Dissolve the solid residue in CH2Cl2, add silica gel (4.5 g), remove the solvent under reduced pressure to obtain a powder with good fluidity, and transfer it to the top of the silica gel column. Elute with CH2Cl2 / EtOH (50:1, volume ratio; Rf = 0.35) to obtain light yellow solid dimethyl-2'-amino-1',4”:1',4”-terphenyl-4,4”-dicarboxylate.

[0044] Step 3. The obtained solid (2.51 g, 5.59 mmol) was suspended in tetrahydrofuran (50 mL), and the temperature was raised to 40 °C. A methanol solution containing potassium hydroxide (5.5 mol / L; 250 mL, 13.8 mmol) was added, and the reaction mixture was stirred at 40 °C for 20 hours.

[0045] Step 4. After cooling to room temperature, the colorless solid was filtered and separated, suspended in tetrahydrofuran (200 mL) and trifluoroacetic acid (25 mL, 0.34 mol), stirred overnight at room temperature, the solid was filtered and separated, washed with cold water and dried to obtain the yellow powder of H2tpdc-NH2. The amino-based zirconium metal-organic framework saturable absorber film was cut into small pieces of appropriate size and placed on the fiber optic connector.

[0046] In this article, specific examples are used to elaborate on the principles and implementation modes of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation modes and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A zirconium metal organic framework-based locking device, characterized in that: The mode locking device comprises an amino zirconium metal organic framework film and two optical fiber jumpers, wherein the amino zirconium metal organic framework film is arranged between the two optical fiber jumpers to form a sandwich structure.

2. The metal organic framework-based locking device according to claim 1, characterized in that: A method for preparing an amino zirconium metal organic framework as a locking device, the specific steps are: Step 1. Under argon atmosphere, 2,5-dibromoaniline (1.03 g, 4.11 mmol), 4-(methoxycarbonyl)-phenylboronic acid (2.22 g, 12.22 mmol), potassium fluoride (2.36 g, 40.6 mmol) were dispersed in tetrahydrofuran (20 mL). Then [Pd(dba)2] (270 mg, 0.294 mmol; dba = dibenzylideneacetone) and PBu3 solution (10 mol%, 820 μL, 0.820 mmol) were added. The reaction was stirred at 50°C for 17 hours. Cooled to room temperature. Step 2. The reaction mixture was poured into water (25 mL) and the aqueous phase was extracted with CH2Cl2. The organic phase was concentrated under reduced pressure. The solid residue was dissolved in CH2Cl2, silica gel (4.5 g) was added, and the solvent was removed under reduced pressure to obtain a powder with good fluidity, which was transferred to the top of the silica gel column. It was eluted with CH2Cl2 / EtOH (50:1, volume ratio; Rf=0.35) to obtain a light yellow solid dimethyl-2'-amino-1',4":1',4"-terphenyl-4,4"-dicarboxylate. Step 3. The obtained solid (2.51 g, 5.59 mmol) was suspended in tetrahydrofuran (50 mL) and the temperature was raised to 40° C. A methanol solution containing potassium hydroxide (5.5 mol / L; 250 mL, 13.8 mmol) was added, and the reaction mixture was stirred at 40° C. for 20 hours. Step 4. After cooling to room temperature, filter and separate the colorless solid, suspend it in tetrahydrofuran (200 mL) and trifluoroacetic acid (25 mL, 0.34 mol), stir overnight at room temperature, filter and separate the solid, wash with cold water and dry to obtain H2tpdc-NH2 yellow powder. Cut the amino-based zirconium metal organic framework saturable absorber film into small pieces of appropriate size and place them on the optical fiber connector.

3. Sub-hundred-femtosecond controllable fiber laser based on zirconium metal organic framework material, characterized by: The system consists of a laser pump source, a wavelength division multiplexer, an erbium-doped gain fiber, a polarization-independent isolator, a polarization controller, an output coupler, and an amino-based zirconium metal organic framework mode-locking device. These components are connected in sequence through a single-mode optical fiber to form a ring laser resonator.

4. The sub-hundred-femtosecond controllable fiber laser based on zirconium metal organic framework material according to claim 3 is characterized in that the laser pump source operates in the 976nm band; the length of the erbium-doped gain fiber is 10m; the length of the overall single-mode fiber is 17m. The amino-based zirconium metal organic framework mode-locking device is composed of two optical fiber connectors and a thin film of an amino-based zirconium metal organic framework saturable absorber in the middle.

5. The sub-hundred-femtosecond controllable fiber laser based on zirconium metal organic framework material according to claim 3, characterized in that: The laser pump mentioned has good stability and adjustable power, which is an important prerequisite for the pulse mode locking phenomenon to occur; The polarization-independent isolator allows light to pass in one direction while blocking light transmission from the opposite direction, thereby preventing the light beam from flowing back and preventing the reflected light from interfering with the laser, ultimately improving the stability and reliability of the system; The wavelength division multiplexer inputs the optical signals of the pump source light wave (976nm) and the gain light wave (1550nm) into the resonant cavity, thereby realizing the simultaneous transmission of signals of the two wavelengths without mutual interference. The polarization controller is used to control the polarization state of the laser output, adjust the polarization direction of the light wave, change the competition state between the self-phase modulation effect and the dispersion effect in the cavity, and finally realize the regulation of sub-hundred-femtosecond broadened pulses and bound-state solitons.

6. The sub-hundred-femtosecond controllable fiber laser based on zirconium metal organic framework material according to claim 3, characterized in that: The output coupler is used to disperse the optical path into two pulses in a ratio of 3:

7. One laser beam continues to pass into the optical path to form a closed-loop resonant cavity, and the other beam is output outside the cavity to observe the output characteristics of the laser pulse.

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