A saturable absorber based on ternary low-dimensional composites and its method and application

Abstract

The present invention discloses a saturable absorber based on ternary low-dimensional composites, its method and application in the technical field of passive mode-locked fiber lasers. The method includes the following steps: dispersing to obtain the pre-dispersion liquids of three materials respectively; mixing to obtain the mixed liquid of the three materials, namely the ternary low-dimensional material pre-mixed liquid; centrifuging to obtain the dispersion liquid of the ternary low-dimensional material composites; heating and stirring to prepare a polyvinyl alcohol solution; weighing the dispersion liquid of the ternary low-dimensional material composites and dropping it into the polyvinyl alcohol solution, stirring and mixing, and drying to obtain a ternary low-dimensional composite / polyvinyl alcohol film; cutting and transferring it to the end face of an optical fiber jumper, and connecting it with another optical fiber jumper using an optical fiber flange adapter to prepare a saturable absorber. The saturable absorber in the present invention obtains more excellent optical properties on the basis of the initial characteristics of individual materials, and can perform better mode-locking operations; the preparation method has a simple process, is easy to operate, has a short production cycle, and a low production cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of passively mode-locked fiber lasers, and specifically relates to a saturable absorber based on ternary low-dimensional composites, its method, and application. Background Technique

[0002] Ultrafast fiber lasers have the advantages of high output beam quality, strong stability, small volume, easy to carry, compact structure, easy to integrate, and convenient maintenance, and can generate picosecond and femtosecond ultra-short laser pulses, and have been widely used in many fields such as optical communication, fiber sensing, material processing, biomedicine, precision measurement, and scientific research. The saturable absorber is an important component of the ultrafast fiber laser and plays a crucial role in generating ultra-short pulses. The physical saturable absorber based on nanomaterials has the advantages of various types, compact structure, and self-starting.

[0003] Currently, semiconductor saturable absorber mirrors (SESAMs) are still widely used in mode-locked lasers in the commercial field. However, SESAMs have many problems. For example, in the preparation method, the production cost of SESAMs is high and the manufacturing process is complex; in terms of performance, the application band is narrow (about 800 - 1600 nm), the recovery time is long (about several nanoseconds), the structure is complex, the modulation depth is difficult to control, and the damage threshold is low.

[0004] Therefore, obtaining a saturable absorber with a simple preparation process, low production cost, good stability, and high nonlinear optical performance to meet the use requirements of passively mode-locked lasers, and building a fully fiber self-starting ultrafast fiber laser based on this device is an urgent topic to be studied and explored in this field. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a saturable absorber based on ternary low-dimensional composites, its method, and application, so as to solve the problems raised in the above background technique.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A preparation method of a saturable absorber based on ternary low-dimensional composites includes the following steps:

[0008] Step 1: Weigh three low-dimensional materials and place them in three containers respectively, then add their respective surfactants to them, add deionized water for dispersion, and finally use an ultrasonic device to ultrasonically vibrate the three for 12 h to obtain the pre-dispersion liquids of the three materials respectively;

[0009] Among them, the three low-dimensional materials are single-walled carbon nanotube powder, graphene powder, and molybdenum disulfide powder. The surfactant of the single-walled carbon nanotube powder is sodium dodecylbenzenesulfonate, the surfactant of the graphene powder is sodium deoxycholate, and the surfactant of the molybdenum disulfide powder is absolute ethanol;

[0010] Step 2: Mix the three kinds of predispersion liquids obtained in Step 1 according to the volume ratio, and then place them in an ultrasonic device for ultrasonic oscillation for 6 h to make the three solutions mix evenly, obtaining a mixed liquid of the three materials, that is, a ternary low-dimensional material premixed liquid;

[0011] Step 3: Centrifuge the ternary low-dimensional material premixed liquid obtained in Step 2 for 30 min. After centrifugation, take the supernatant to obtain a dispersion liquid of the ternary low-dimensional material composite;

[0012] Step 4: Weigh polyvinyl alcohol particles and place them in a container. Add deionized water and then heat and stir for 6 h to fully dissolve and obtain a polyvinyl alcohol solution;

[0013] Step 5: Weigh the dispersion liquid of the ternary low-dimensional material composite obtained in Step 3 and drop it into the polyvinyl alcohol solution prepared in Step 4. Stir and mix evenly for 2 h to obtain a ternary low-dimensional composite / polyvinyl alcohol solution, and then transfer it to a petri dish for drying for 8 - 12 h, and finally obtain a ternary low-dimensional composite / polyvinyl alcohol film;

[0014] Step 6: Cut the ternary low-dimensional composite / polyvinyl alcohol film obtained in Step 5 into small pieces of appropriate size, and transfer it to the end face of an optical fiber jumper. Connect it with another optical fiber jumper using an optical fiber flange adapter to prepare a saturable absorber.

[0015] Preferably, the mass ratio of the single-walled carbon nanotube powder, sodium dodecylbenzenesulfonate, and deionized water in Step 1 is 1:15:2500, the mass ratio of the graphene powder, sodium deoxycholate, and deionized water is 1:5:2500, and the mass ratio of the molybdenum disulfide powder, absolute ethanol, and deionized water is 1:320:600.

[0016] Preferably, the three predispersion liquids in Step 2 are carbon nanotube predispersion liquid, graphene predispersion liquid, and molybdenum disulfide predispersion liquid, and the volume ratio is 8:1:1.

[0017] Preferably, the mass ratio of the polyvinyl alcohol powder and deionized water in Step 4 is 17:1000.

[0018] Preferably, the volume ratio of the ternary low-dimensional composite dispersion liquid and the polyvinyl alcohol solution in Step 5 is 4.5:5.

[0019] Preferably, the optical fiber jumper heads in Step 6 need to be connected with coaxial fitting.

[0020] A saturable absorber based on ternary low-dimensional composite, which is prepared by using the preparation method according to any one of claims 1 to 6.

[0021] Preferably, the saturable absorber based on ternary low-dimensional composite can be applied to a soliton laser.

[0022] Preferably, the soliton laser includes a laser pump source, a three-in-one device, an erbium-doped gain fiber, a saturable absorber based on ternary low-dimensional composite, and a single-mode fiber connected in sequence. The laser pump source provides pump light, and the light is coupled into the ring cavity through the three-in-one device. After being amplified by the erbium-doped gain fiber, it passes through the saturable absorber based on ternary low-dimensional composite and the single-mode fiber in sequence, and finally returns to the three-in-one device to realize the cyclic operation of light in the ring cavity. Finally, the laser outputs soliton pulse laser.

[0023] Preferably, the three-in-one device (102) is an integrated device of three devices: a wavelength division multiplexer, an optical isolator, and a splitter.

[0024] Advantages of the present invention:

[0025] 1. The saturable absorber in the present invention stacks and composites three low-dimensional nanomaterials to form a heterojunction, overcoming the disadvantages and limitations of single materials, obtaining more excellent optical properties based on the initial characteristics of single materials, and being able to perform better mode-locking operations.

[0026] 2. When the present invention is used, it only needs to transfer the ternary low-dimensional composite / polyvinyl alcohol composite film to the end face of the fiber optic jumper head for use, which is very convenient. Moreover, after being added to the optical path, a mode-locking signal can be generated without other operations, that is, self-mode-locking can be achieved. In addition, the entire laser optical path system operates inside the optical fiber and is not affected by the external environment, and the performance is very stable.

[0027] 3. The preparation method in the present invention has a simple process, is easy to operate, has a short production cycle, and a low production cost. The saturable absorber film has high film-forming quality, strong repeatability, high yield, is easy to store and package, and is conducive to commercialization. Description of the Drawings

[0028] 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 description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0029] Figure 1 It is the flowchart of the preparation method in the present invention;

[0030] Figure 2It is a schematic structural diagram of the soliton laser in the present invention;

[0031] Figure 3 It is a schematic diagram of the saturable absorber placed in the fixture in the present invention;

[0032] Figure 4 It is a port description diagram of the three-in-one device in the present invention;

[0033] Figure 5 It is a spectrogram of the saturable absorber soliton laser based on ternary low-dimensional composites measured in the experiment of the present invention;

[0034] Figure 6 It is a pulse sequence diagram of the saturable absorber soliton laser based on ternary low-dimensional composites measured in the experiment of the present invention;

[0035] Figure 7 It is a single-pulse morphology diagram of the saturable absorber soliton laser based on ternary low-dimensional composites measured in the experiment of the present invention;

[0036] Figure 8 It is a radio frequency spectrogram of the saturable absorber soliton laser based on ternary low-dimensional composites measured in the experiment of the present invention. Detailed implementation manners

[0037] 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 shall fall within the protection scope of the present invention.

[0038] Embodiment 1:

[0039] The embodiment of the present application provides a preparation method of a saturable absorber based on ternary low-dimensional composites. Please refer to Figure 1 as shown, and it includes the following steps:

[0040] Step 1: Use an electronic microbalance to respectively weigh 8 mg of single-walled carbon nanotube powder, 120 mg of sodium dodecylbenzenesulfonate, and 20 ml of deionized water (the density of deionized water is 1 g / cm3) and place them in beaker 1; weigh 8 mg of graphene powder, 40 mg of sodium deoxycholate, and 20 ml of deionized water and place them in beaker 2; weigh 10 mg of molybdenum disulfide powder and 4 ml of absolute ethanol (the density of absolute ethanol is 0.8 g / cm

[0039] ,

[0038] , , Figure 1 , , 3 ,

[0040] ) and 6 ml of deionized water in beaker 3, place the three beakers in an ultrasonic cleaner for ultrasonic oscillation stripping, set the power of the ultrasonic cleaner to 400 W (60%), and set the ultrasonic oscillation time to 12 h to obtain the pre-dispersion liquids of the three materials respectively;

[0041] Step 2: Mix the pre-dispersion liquids of the three materials obtained in Step 1 according to the ratio of the volume of the carbon nanotube pre-dispersion liquid: the volume of the graphene pre-dispersion liquid: the volume of the molybdenum disulfide pre-dispersion liquid being equal to 8 ml: 1 ml: 1 ml. Place the obtained mixed liquid in a test tube and put it into an ultrasonic cleaner for ultrasonic oscillation to make the three solutions mix evenly, obtaining a mixed liquid of the three materials (carbon nanotube - graphene - molybdenum disulfide (CNT - Graphene - MoS2)), that is, a ternary low-dimensional material pre-mixed liquid.

[0042] Step 3: Centrifuge the pre-mixed liquid obtained in Step 2. Set the rotation speed of the centrifuge to 8000 rmp and the centrifugation time to 30 min. After centrifugation, take the supernatant to obtain a dispersion liquid of the ternary low-dimensional material composite.

[0043] Step 4: Use a balance to take 85 mg of polyvinyl alcohol (PVA) particles and place them in a beaker. Add 5 ml of deionized water, heat and stir to dissolve them fully. Set the rotation speed of the stirrer to 600 r / min, the heating temperature to 60 °C, and the stirring time to 6 h to obtain a polyvinyl alcohol solution (PVA solution).

[0044] Step 5: Drop 4.5 ml of the dispersion liquid of the ternary low-dimensional material composite obtained in Step 3 into the polyvinyl alcohol solution prepared in Step 4, and stir to mix them evenly. Set the rotation speed of the stirrer to 8,00 r / min and the stirring time to 2 h to obtain a ternary low-dimensional composite / polyvinyl alcohol (CNT - Graphene - MoS2 / PVA) solution, and transfer it to a petri dish and place it in an oven for drying. The drying temperature is 60 - 70 °C and the drying time is 8 - 12 h to obtain a ternary low-dimensional composite / polyvinyl alcohol film.

[0045] Step 6: Cut the ternary low-dimensional composite / polyvinyl alcohol film obtained in Step 5 into small pieces of appropriate size, transfer them to the end face of an optical fiber jumper, and connect them with another optical fiber jumper using an optical fiber flange adapter to manufacture a saturable absorber.

[0046] It can be understood that the above Steps 1 - 6 only exemplarily show the method of manufacturing a saturable absorber based on ternary low-dimensional composite in a specific embodiment of the present invention. This embodiment can be understood as Figure 1 One implementation manner of the manufacturing method of the saturable absorber based on ternary low-dimensional composite shown. The specific operation details in the above Steps 1 - 6 can be adjusted correspondingly according to the actual experimental scenario. For example, the number of operation steps can be increased or decreased or the order can be adjusted according to the specific situation, or multiple steps can be carried out simultaneously. The present invention is not limited to the above-listed Steps 1 - 6.

[0047] Embodiment 2:

[0048] Based on the saturable absorber of the ternary low-dimensional composite of the present invention proposed in Embodiment 1 above, an embodiment of the present application provides a soliton laser.

[0049] Please refer to Figures 2 to 4 As shown, the soliton laser includes a laser pump source Pump101, a three-in-one device WTI102, an erbium-doped gain fiber EDF103, a saturable absorber SA104 based on ternary low-dimensional composite, and a single-mode fiber SMF105 connected in sequence.

[0050] Among them, the three-in-one device WTI102 in the soliton laser has a total of four ports, namely the first port "Pump port", the second port "Common port", the third port "Signal port", and the fourth port "Tap port". The splitting ratio of the three-in-one device used is 90% / 10%, that is, 90% of the light remains in the ring cavity for circulation, and 10% of the light is used for output.

[0051] In addition, the length of the erbium-doped fiber EDF used in the laser cavity of the soliton laser is about 3m, and the length of the single-mode fiber SMF is about 7m. Adding fiber jumpers and various devices and their tail fibers, the total cavity length of the laser cavity is about 12m.

[0052] Embodiment 3:

[0053] An embodiment of the present application provides a method for building a soliton laser, including the following:

[0054] The output end of the 980nm pump light source is connected to the first port "Pump port" of the three-in-one device; the second port "Common port" is connected to one end of the erbium-doped fiber; the other end of the erbium-doped fiber is connected to one end of the saturable absorber based on ternary low-dimensional composite; the other end of the saturable absorber is connected to one end of the single-mode fiber; the other end of the single-mode fiber is connected to the third port "Signal port" of the three-in-one device to form a ring laser resonator; the fourth port "Tap port" of the three-in-one device is used to output signals and is connected to the corresponding detection instrument.

[0055] The test results of the examples of the present invention are as follows:

[0056] First, when the saturable absorber based on ternary low-dimensional composite is not inserted into the cavity, by adjusting the pump power, no mode-locking operation occurs, indicating that the fiber laser in Embodiment 2 cannot be mode-locked without the saturable absorber. Then, when the saturable absorber based on ternary low-dimensional composite is inserted into the cavity, under the condition that the pump power is adjusted to 19.3mW, stable mode-locked pulses are obtained. At a cavity length of about 12m and a pump power of 19.3mV, the properties of the pulsed laser recorded are as follows:

[0057] It can be seen from Figure 5 that the 3dB bandwidth of the spectrum is 5.1nm and the central wavelength is 1531nm; it can be seen from Figure 6 that the pulse interval is 74.59ns, and the corresponding pulse repetition frequency is 13.41MHz, and the laser operates in a relatively stable state; it can be seen from Figure 7 that the hyperbolic secant (Sech 2 ) function is used to fit the data, and the full width at half maximum (FWHM) of the pulse is obtained as 1.9ps, and the corresponding pulse width is 1.22ps; it can be seen from Figure 8 that the central frequency of the signal is 13.41MHz, and the signal-to-noise ratio of the pulse is 50dB, indicating that the pulse signal is very stable. In summary, the pulse repetition frequency of the soliton laser provided by the present invention is 13.41MHz, the pulse width is 1.22ps, the signal-to-noise ratio of the pulse can reach 50dB, and the stability of the pulse is good.

[0058] In the description of this specification, the descriptions referring to the terms "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0059] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and the above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A method for preparing a saturable absorber based on a ternary low-dimensional composite, characterized in that: The following steps are involved: Step 1: Weigh three low-dimensional materials separately and place them in three containers. Then, add their respective surfactants and deionized water to disperse them. Finally, ultrasonically vibrate the three materials for 12 hours to obtain pre-dispersed solutions of the three materials. The three low-dimensional materials are single-walled carbon nanotube powder, graphene powder, and molybdenum disulfide powder. The surfactant of the single-walled carbon nanotube powder is sodium dodecylbenzenesulfonate, the surfactant of the graphene powder is sodium deoxycholate, and the surfactant of the molybdenum disulfide powder is anhydrous ethanol. Step 2: The three pre-dispersed solutions obtained in step 1 are mixed according to a volume ratio, and then placed in an ultrasonic device for ultrasonic oscillation for 6 hours to mix the three solutions evenly to obtain a mixture of the three materials, i.e., a ternary low-dimensional material pre-mixed solution; Step 3: Centrifuge the premixed solution of the ternary low-dimensional material obtained in step 2 for 30 minutes. After the centrifugation is completed, take the supernatant to obtain a dispersion of the ternary low-dimensional material composite; Step 4: Weigh polyvinyl alcohol particles and place them in a container. Add deionized water and heat and stir for 6 hours to fully dissolve the particles to obtain a polyvinyl alcohol solution. Step 5: Weigh the dispersion of the ternary low-dimensional material composite obtained in step 3 and drop it into the polyvinyl alcohol solution prepared in step 4. After stirring and mixing for 2 hours, a ternary low-dimensional composite / polyvinyl alcohol solution is obtained, which is then transferred to a culture dish and dried for 8 to 12 hours to obtain a ternary low-dimensional composite / polyvinyl alcohol film. Step 6: Cut the ternary low-dimensional composite / polyvinyl alcohol film obtained in step 5 into small pieces of appropriate size, transfer them to the end face of the optical fiber jumper, and connect them to another optical fiber jumper using an optical fiber flange adapter to prepare a saturable absorber.

2. The method for preparing a saturable absorber based on a ternary low-dimensional composite according to claim 1, characterized in that: The mass ratio of single-walled carbon nanotube powder, sodium dodecylbenzenesulfonate and deionized water in step 1 is 1:15:2500, the mass ratio of graphene powder, sodium deoxycholate and deionized water is 1:5:2500, and the mass ratio of molybdenum disulfide powder, anhydrous ethanol and deionized water is 1:320:

600.

3. The method for preparing a saturable absorber based on a ternary low-dimensional composite according to claim 1, characterized in that: The three pre-dispersions in step 2 are carbon nanotube pre-dispersion, graphene pre-dispersion and molybdenum disulfide pre-dispersion, with a volume ratio of 8:1:

1.

4. The method for preparing a saturable absorber based on a ternary low-dimensional composite according to claim 1, characterized in that: The mass ratio of the polyvinyl alcohol particles to deionized water in step 4 is 17:1000.

5. The method for preparing a saturable absorber based on a ternary low-dimensional composite according to claim 1, characterized in that: In step 5, the volume ratio of the ternary low-dimensional composite dispersion to the polyvinyl alcohol solution is 4.5:

5.

6. The method for preparing a saturable absorber based on a ternary low-dimensional composite according to claim 1, characterized in that: The optical fiber jumper heads in step 6 need to be coaxially connected.

7. A saturable absorber based on a ternary low-dimensional composite, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 6.

8. An application of the ternary low-dimensional composite saturable absorber according to claim 7, characterized in that: The ternary low-dimensional composite saturable absorber is used in the construction of a soliton laser.

9. The soliton laser according to claim 8, characterized in that The soliton laser comprises a laser pump source (101), a three-in-one device (102), an erbium-doped gain fiber (103), a saturable absorber (104) based on a ternary low-dimensional composite, and a single-mode fiber (105) connected in sequence. The laser pump source (101) provides pump light, which is coupled into a ring cavity through the three-in-one device (102). After being amplified by the erbium-doped gain fiber (103), the light sequentially passes through the saturable absorber (104) based on the ternary low-dimensional composite and the single-mode fiber (105), and finally returns to the three-in-one device (102), thereby realizing a cyclic reciprocating operation of light in the ring cavity. Finally, the laser outputs a soliton pulse laser.

10. The soliton laser according to claim 9, characterized in that The three-in-one device (102) is an integrated device of three devices: a wavelength division multiplexer, an optical isolator and a splitter.

Images