A saturable absorber based on tantalum arsenide quantum dots, its preparation method, and a mode-locked fiber laser.
By using tantalum arsenide quantum dots as saturable absorbers in fiber lasers, the problem of low performance of existing two-dimensional materials is solved, enabling rapid laser saturation and stable mode-locked signal output, thus improving the performance of fiber lasers.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GUANGDONG UNIV OF TECH
- Filing Date
- 2023-07-25
- Publication Date
- 2026-05-26
AI Technical Summary
The performance of existing two-dimensional saturable absorbers is low, which limits the application of fiber lasers and also causes problems such as complex preparation and poor stability.
Tantalum arsenide quantum dots were used as saturable absorbers. A saturable absorber based on tantalum arsenide quantum dots was prepared by dropping a tantalum arsenide quantum dot solution onto a tapered optical fiber and depositing it under the action of the optical gradient force of the evanescent field. The absorber was then combined with a mode-locked fiber laser to form a ring laser resonator.
This invention achieves ultrafast laser saturation with rapid output and high repetition rate, with stable laser mode-locking signal and superior performance compared to traditional two-dimensional materials. It solves the problem of low performance of saturable absorbers in existing technologies.
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Figure CN116706663B_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of saturable absorber technology, and particularly relates to a saturable absorber based on tantalum arsenide quantum dots, its preparation method, and a mode-locked fiber laser. Background Technology
[0002] Saturable absorbers are one of the key components in fiber lasers for generating laser pulses. Current saturable absorbers include artificial saturable absorbers such as nonlinear ring mirrors and nonlinear polarization evolution mirrors, as well as non-artificial "real" saturable absorbers such as semiconductor saturable absorber mirrors and low-dimensional materials.
[0003] The difficulty and cost of fabricating semiconductor saturable absorbers in saturable absorbers limit their widespread application in fiber lasers. Low-dimensional materials, on the other hand, are widely used in fiber lasers due to their excellent optoelectronic properties. Currently, existing two-dimensional saturable absorber materials are represented by graphene, molybdenum disulfide, and black phosphorus. However, graphene-based saturable absorbers suffer from low absorption efficiency. Molybdenum disulfide-based saturable absorbers have complex fabrication processes and large band gaps, making them difficult to replicate in large quantities. Black phosphorus-based saturable absorbers are sensitive to the surrounding environment, have poor stability, and cannot operate stably for long periods. They also cannot function properly in humid or other special environments. Therefore, the performance of saturable absorbers based on graphene and other two-dimensional materials is currently relatively low. Summary of the Invention
[0004] In view of this, this application provides a saturable absorber based on tantalum arsenide quantum dots, a preparation method thereof, and a mode-locked fiber laser, to solve the technical problem of low performance of saturable absorbers based on two-dimensional materials in the prior art.
[0005] The first aspect of this application provides a saturable absorber based on tantalum arsenide quantum dots, comprising: tantalum arsenide quantum dots and a tapered optical fiber;
[0006] The tapered optical fiber is loaded with tantalum arsenide quantum dots.
[0007] Preferably, the tantalum arsenide quantum dots have a particle size of 2.73 nm.
[0008] The second aspect of this application provides a method for preparing a saturable absorber based on tantalum arsenide quantum dots, comprising: dropping a tantalum arsenide quantum dot solution onto a tapered optical fiber, and obtaining a saturable absorber based on tantalum arsenide quantum dots after deposition.
[0009] Preferably, the step of dropping a tantalum arsenide quantum dot solution onto a tapered optical fiber and depositing it to obtain a saturable absorber based on tantalum arsenide quantum dots specifically includes:
[0010] Step S1: Place the tapered optical fiber on a constant temperature heating table for preheating to obtain a preheated tapered optical fiber;
[0011] Step S2: Drop a tantalum arsenide quantum dot solution onto the tapered region of a tapered optical fiber. Pass a 1550nm continuous wave laser through the other end of the tapered optical fiber. Under the action of the optical gradient force of the evanescent field, the tantalum arsenide quantum dots surround the tapered region of the tapered optical fiber, thus obtaining a saturable absorber based on tantalum arsenide quantum dots.
[0012] It should be noted that, to ensure the deposition effect, a much larger amount of dispersion solution than is required to meet the requirements for cone deposition should be added. The optical power was monitored by the power meter and decreased as the deposition process continued. After adding an excessive amount of dispersion solution and waiting for a short period of time, it was found that the optical power remained basically unchanged, indicating that enough tantalum arsenide quantum dot material had been deposited in the tapered fiber and it was not advisable to add more dispersion solution. Therefore, the addition operation needs to be carried out by adjusting the appropriate volume of dispersion solution between 0.2 and 2 ml according to the concentration of quantum dots in the dispersion solution.
[0013] Preferably, in step S1, the heating temperature of the constant temperature heating table is 60°C.
[0014] Preferably, in step S2, the power of the continuous wave laser is 10 to 30 mW.
[0015] It should be noted that setting the heating temperature of the constant-temperature heating stage is beneficial for solvent evaporation. The incident light power during the tapered fiber deposition process will have a certain impact on the final deposition effect. When the input power is below 10mW, the output power remains basically unchanged, indicating that deposition has not occurred. Higher optical deposition power results in more material deposition and a greater modulation depth of the saturable absorber. When the incident light power exceeds approximately 30mW, excessive material deposition may occur, exceeding the tapered fiber's tolerance threshold, leading to a significant reduction in transmittance and a sharp drop in output light power to nanowatts. Therefore, the deposition operation requires adjusting the continuous-wave laser power between 10 and 30mW based on the quantum dot concentration in the tantalum arsenide quantum dots.
[0016] Preferably, the method for preparing the tantalum arsenide quantum dots includes the following steps:
[0017] Step S12: Mix tantalum arsenide and organic solvent, sonicate, and let stand to obtain an organic solution of tantalum arsenide;
[0018] Step S22: Take the upper layer of the organic solution of tantalum arsenide, mix it with the organic solvent, centrifuge, discard the upper layer of solution to obtain tantalum arsenide quantum dots.
[0019] Preferably, in step S12, the mass-to-volume ratio of tantalum arsenide to organic solvent is 1–3 g: 30–60 mL.
[0020] Preferably, in steps S12 and S22, the organic solvent is selected from ethanol.
[0021] Preferably, in step S12, the power of the ultrasound is 300-500W and the duration is 4-8h.
[0022] Preferably, in step S12, the settling time is 4 to 8 hours.
[0023] Preferably, in step S22, the centrifugation speed is 8000-12000 rpm and the time is 2-6 min.
[0024] A third aspect of this application provides a mode-locked fiber laser, including a laser pump source, a wavelength division multiplexer, an erbium-doped gain fiber, a polarization-independent isolator, a polarization controller, an output coupler, a saturable absorber based on tantalum arsenide quantum dots, and a single-mode fiber.
[0025] The wavelength division multiplexer includes a first input terminal and a second input terminal;
[0026] The laser pump source, the first input terminal of the wavelength division multiplexer, the erbium-doped gain fiber, the polarization-independent isolator, the polarization controller, the output coupler, the saturable absorber based on tantalum arsenide quantum dots, the single-mode fiber, and the second input terminal of the wavelength division multiplexer are sequentially connected to form a ring laser resonant cavity.
[0027] In summary, this application provides a saturable absorber based on tantalum arsenide quantum dots, its preparation method, and a mode-locked fiber laser. The saturable absorber based on tantalum arsenide quantum dots includes tantalum arsenide quantum dots and a tapered fiber loaded with tantalum arsenide quantum dots. The tantalum arsenide quantum dots in the saturable absorber have excellent nonlinear optical properties and saturation intensity, so that when the laser passes through the tantalum arsenide quantum dots on the saturable absorber, the laser reaches saturation quickly, enabling the output of ultrafast laser with a repetition frequency and stable laser mode-locked signal. This solves the technical problem of low performance of saturable absorbers based on two-dimensional materials in the prior art. Attached Figure Description
[0028] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0029] Figure 1 The image shows the morphology of tantalum arsenide quantum dots prepared by the method described in Example 2 of this application.
[0030] Figure 2 The diagram shows the nonlinear optical properties of tantalum arsenide quantum dots prepared by the method described in Example 2 of this application.
[0031] Figure 3 This is a schematic diagram of the mode-locked fiber laser structure described in Embodiment 3 of this application;
[0032] Figure 4 This is a pulse sequence diagram of the mode-locked fiber laser described in Embodiment 3 of this application;
[0033] Figure 5 This is a broadband spectrum diagram of the mode-locked fiber laser described in Embodiment 3 of this application;
[0034] Figure 6 This is the fundamental frequency diagram of the mode-locked fiber laser described in Embodiment 3 of this application;
[0035] Figure 7 This is the spectrum of the mode-locked fiber laser described in Embodiment 3 of this application;
[0036] Figure 8 This is a graph showing the spectrum of the mode-locked fiber laser described in Embodiment 3 of this application as a function of time.
[0037] Figure 9 This is a graph showing the relationship between the optical path output power and the pump power of the mode-locked fiber laser described in Embodiment 3 of this application.
[0038] Figure 10 The pulse width diagram of a single pulse of the mode-locked fiber laser described in Embodiment 3 of this application;
[0039] Figure 11 for Figure 1 Black and white comparison chart;
[0040] Figure 1 Image a is a high-resolution transmission electron microscope image of tantalum arsenide quantum dots. Figure 1 b is a transmission electron microscope image of tantalum arsenide quantum dots. Figure 1 c is an atomic force microscope image of tantalum arsenide quantum dots. Figure 1 d is the height profile image of the tantalum arsenide quantum dots;
[0041] Figure 2 a is a schematic diagram of a dual-arm balanced detector used to test the nonlinear optical properties of tantalum arsenide quantum dots. Figure 2 b is the saturable absorption curve of tantalum arsenide quantum dots obtained by testing with a dual-arm balanced detector. Detailed Implementation
[0042] This application provides a saturable absorber based on tantalum arsenide quantum dots, its preparation method, and a mode-locked fiber laser, which solves the technical problem of low performance of saturable absorbers based on two-dimensional materials in the prior art.
[0043] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0044] Example 1
[0045] Given the low performance of existing saturable absorbers based on two-dimensional materials, Embodiment 1 of this application provides a saturable absorber based on tantalum arsenide quantum dots, comprising a tapered optical fiber and tantalum arsenide quantum dots loaded thereon. Nonlinear optical property testing of the tantalum arsenide quantum dots using a dual-arm balanced detector revealed that the tantalum arsenide quantum dots in the saturable absorber have a low saturation intensity. This allows the laser to reach saturation quickly when passing through the tantalum arsenide quantum dots on the saturable absorber, enabling the output of ultrafast lasers with a repetition frequency and stable laser mode-locking signal, thus overcoming the low performance of traditional saturable absorbers based on two-dimensional materials.
[0046] For tapered optical fibers, tapered optical fibers are obtained using a tapering method commonly used in this field. During tapering, the outer film of the portion of the single-mode optical fiber that needs to be tapered is first stripped off, and then the fiber is placed on a tapering machine of a forward fusion tapering system for tapering preparation.
[0047] Example 2
[0048] Example 2 of this application provides a method for preparing a saturable absorber based on tantalum arsenide quantum dots as described in Example 1. The preparation method includes first preparing tantalum arsenide quantum dots and then preparing a saturable absorber based on tantalum arsenide quantum dots.
[0049] The steps for preparing tantalum arsenide quantum dots include: first, placing 2g of tantalum arsenide (TaAs) powder in 45ml of ethanol solvent, then placing the ethanol solvent containing tantalum arsenide in an ultrasonic machine for a period of time and then removing it and letting it stand; wherein, the ultrasonic machine power is 400W, the ultrasonic duration is 6 hours, and the standing time is 12 hours.
[0050] After standing, 15 ml of the supernatant was mixed with 15 ml of ethanol solvent and centrifuged at 10,000 rpm for 3 min. The supernatant was then removed to obtain the tantalum arsenide quantum dot solution. The morphological characteristics of the saturable absorber tantalum arsenide quantum dot solution are as follows: Figure 1 As shown, the nonlinear optical properties are as follows Figure 2 As shown.
[0051] The steps for preparing a saturable absorber based on tantalum arsenide quantum dots include: dropping 2 mL of tantalum arsenide quantum dot solution onto a tapered optical fiber, and depositing the saturable absorber based on tantalum arsenide quantum dots; wherein, the tantalum arsenide quantum dot solution is dropped onto the tapered optical fiber, and a 1550 nm continuous wave laser is introduced on one side. Under the action of the optical gradient force of the evanescent field, the tantalum arsenide quantum dots surround the tapered region of the tapered optical fiber. After the dispersion is completely dried, the tantalum arsenide quantum dots are deposited on the tapered optical fiber to obtain a saturable absorber based on tantalum arsenide quantum dots. During the preparation process, in order to ensure that the anhydrous ethanol in the tantalum arsenide quantum dot solution evaporates as soon as possible, the tapered optical fiber should be preheated, and the entire deposition operation should be carried out on a constant temperature heating stage at 60°C, and the continuous wave laser should be controlled between 10 and 30 mW.
[0052] Example 3
[0053] Embodiment 3 of this application provides a mode-locked fiber laser, the structure of which is as follows: Figure 3 As shown, the system comprises a laser pump source 1, a wavelength division multiplexer 2, an erbium-doped gain fiber 3, a polarization-independent isolator 4, a polarization controller 5, an output coupler 6, a saturable absorber based on tantalum arsenide quantum dots 7, and a single-mode fiber 8; wherein, the wavelength division multiplexer 2 includes a first input terminal and a second input terminal; the output coupler 6 includes a 75% output terminal and a 25% output terminal; the saturable absorber based on tantalum arsenide quantum dots 7 is the saturable absorber based on tantalum arsenide quantum dots described in Example 1 or 2.
[0054] The structure consists of a laser pump source 1, the first input of a wavelength division multiplexer 2, an erbium-doped gain fiber 3, a polarization-independent isolator 4, a polarization controller 5, the 75% output of an output coupler 6, a saturable absorber based on tantalum arsenide quantum dots 7, and a single-mode fiber 8 connected in sequence. The single-mode fiber 8 is connected to the second input of the wavelength division multiplexer 2 to form a ring resonant cavity. The ring resonant cavity is mainly composed of single-mode fibers connected by fiber fusion splicing. In the ring resonant cavity, the laser pump source provides energy to the resonant cavity in a pulsed or continuous manner. The erbium-doped gain fiber serves as the gain medium. The wavelength division multiplexer is used to couple the pump light (980nm) and the excitation light (1550nm) from the erbium-doped fiber. The output coupler allows 75% of the laser energy to continue operating within the cavity, while 25% of the energy is output outside the cavity for detection. The polarization controller is used to adjust the polarization state and loss of the entire optical path. The polarization-independent isolator ensures that the entire laser operates unidirectionally within the cavity.
[0055] Experimental Example 1
[0056] The experimental examples in this application tested the morphology and nonlinear optical properties of the tantalum arsenide quantum dots obtained in Example 2. The results are as follows: Figure 1-2As shown, the mode-locked fiber laser characteristics of the described Example 3 were tested. The saturable absorber was obtained by depositing tantalum arsenide quantum dots described in Example 2 onto a tapered optical fiber. The results are as follows. Figure 4-10 As shown.
[0057] Among them, the morphology characterization of tantalum arsenide quantum dots obtained by transmission electron microscopy and atomic force microscopy is as follows: Figure 1 As shown, from Figure 1 As can be seen, the tantalum arsenide quantum dots exhibit clear lattice fringes with an inner plane distance of 0.21 nm. Figure 1 As can be seen from b, the lateral dimension of the tantalum arsenide quantum dots is approximately 2.73 nm, while Figure 1 The AFM images and their height profiles shown in c and d also show similar results. The preparation method provided in Example 2 of this application can prepare tantalum arsenide quantum dots.
[0058] The nonlinear optical properties of tantalum arsenide quantum dots were tested using a dual-arm balanced detector, such as... Figure 2 As shown in Figure a, the system consists of a light source, attenuator, coupler, and two identical power meters a and b. The laser beam is split into two beams by the coupler. One beam passes through a tantalum arsenide quantum dot loss before entering power meter a for measurement, while the other beam directly enters power meter b for measurement. The saturable absorption curve of the material can be obtained by processing and analyzing the data measured by the two power meters. Specifically, the data processing steps are as follows: a 50:50 coupler is used to build a dual-arm balanced detector for convenient data processing; T = P1 / P2 (T is the transmittance, P1 and P2 are the power values measured by power meters a and b, respectively); each transmittance corresponds to a light field intensity, I = P2 / S (I is the light field intensity, S is the fiber core area); processing the above data yields a scatter plot, which can be fitted with formula 1 to obtain the saturable absorption curve (T is the transmittance, α is the attenuator, α is the attenuator). NS The loss is nonlinear and saturable, ΔT is the modulation depth, and I is the optical field intensity. sat (Saturated light intensity).
[0059]
[0060] The nonlinear optical properties of tantalum arsenide quantum dots, such as Figure 2 As shown in b, the basic parameters of saturable absorber tantalum arsenide quantum dots, including saturation intensity, modulation depth and unsaturation loss, can be obtained. By comparison with other two-dimensional materials, it is found that tantalum arsenide quantum dots have a lower saturation intensity and are a saturable absorber material with superior performance.
[0061] The mode-locked laser characteristics of a mode-locked fiber laser at a pump power of 100mW are as follows: Figure 4-10 As shown, Figure 4The diagram shows the pulse sequence of a mode-locked fiber laser, indicating that the mode-locked pulses operate very stably with a pulse interval of approximately 47.2 ns. Figure 5 The broadband spectrum of the mode-locked fiber laser in the 600MHz range shows a relatively flat sequence, further illustrating the stability of the mode-locked signal. Figure 6 Based on the fundamental frequency spectrum of the mode-locked fiber laser, the signal-to-noise ratio of the laser is approximately 58.12 dB. Figure 7 The image shows the spectrum of the mode-locked signal of a mode-locked fiber laser. The center wavelength is approximately 1559.41 nm, and the full width at half maximum (FWHM) is approximately 6.41 nm. Figure 8 The spectrum of the mode-locked fiber laser changes over time. It can be clearly seen that the shape and intensity of the spectrum do not change significantly within 0-80 minutes, which further illustrates the stability of the mode-locked signal. Figure 9 The relationship between the optical output power and pump power of a mode-locked fiber laser is shown. When the pump power increases from 50mW to 300mW, the output power also changes from 0.5mW to 5mW, with a corresponding slope efficiency of 1.66%. Figure 10 The autocorrelation curve of the autocorrelation unit of the mode-locked fiber laser shows that the pulse width of the output single pulse is 1.54 × 621 fs.
[0062] The above experiments confirm that when laser light passes through a saturable absorber based on tantalum arsenide quantum dots in a mode-locked fiber laser, the portion of the pulse with low intensity is lost more, while the portion with high intensity is lost less, effectively achieving side-mode suppression and thus compressing the pulse. At the same time, tantalum arsenide quantum dots have low saturation intensity, and the laser light in the resonant cavity can saturate them, thereby outputting an ultrafast laser with a high repetition rate. The laser mode-locked signal is stable, and its performance is superior to other saturable absorbers based on two-dimensional materials.
[0063] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.
Claims
1. A mode-locked fiber laser, characterized in that, include: The system comprises a laser pump source, a wavelength division multiplexer, an erbium-doped gain fiber, a polarization-independent isolator, a polarization controller, an output coupler, a saturable absorber based on tantalum arsenide quantum dots, and a single-mode fiber; wherein the wavelength division multiplexer includes a first input terminal and a second input terminal; and the output coupler includes a 75% output terminal and a 25% output terminal. A laser pump source, a first input terminal of a wavelength division multiplexer, an erbium-doped gain fiber, a polarization-independent isolator, a polarization controller, a 75% output terminal of an output coupler, a saturable absorber based on tantalum arsenide quantum dots, and a single-mode fiber are connected in sequence. The single-mode fiber is connected to the second input terminal of the wavelength division multiplexer to form a ring resonant cavity. The saturable absorber based on tantalum arsenide quantum dots includes: tantalum arsenide quantum dots and a tapered optical fiber; The tapered optical fiber is loaded with tantalum arsenide quantum dots.
2. A mode-locked fiber laser according to claim 1, characterized in that, The method for preparing a saturable absorber based on tantalum arsenide quantum dots includes the following steps: dropping a tantalum arsenide quantum dot solution onto a tapered optical fiber, and obtaining a saturable absorber based on tantalum arsenide quantum dots after deposition.
3. A mode-locked fiber laser according to claim 2, characterized in that, The process of dropping a tantalum arsenide quantum dot solution onto a tapered optical fiber and depositing it to obtain a saturable absorber based on tantalum arsenide quantum dots specifically includes: Step S1: Place the tapered optical fiber on a constant temperature heating table for preheating to obtain a preheated tapered optical fiber; Step S2: Drop a tantalum arsenide quantum dot solution onto the tapered region of a tapered optical fiber. Pass a 1550nm continuous wave laser through the other end of the tapered optical fiber. Under the action of the optical gradient force of the evanescent field, the tantalum arsenide quantum dots surround the tapered region of the tapered optical fiber, thus obtaining a saturable absorber based on tantalum arsenide quantum dots.
4. A mode-locked fiber laser according to claim 3, characterized in that, In step S1, the heating temperature of the constant temperature heating table is 60°C; In step S2, the power of the continuous wave laser is 10~30 mW.
5. A mode-locked fiber laser according to claim 2, characterized in that, The method for preparing the tantalum arsenide quantum dots includes the following steps: Step S12: Mix tantalum arsenide and organic solvent, sonicate, and let stand to obtain an organic solution of tantalum arsenide; Step S22: Take the upper layer of the organic solution of tantalum arsenide, mix it with the organic solvent, centrifuge, discard the upper layer of solution to obtain tantalum arsenide quantum dots.
6. A mode-locked fiber laser according to claim 5, characterized in that, In step S12, the mass-to-volume ratio of tantalum arsenide to organic solvent is 1~3g:30~60mL.
7. A mode-locked fiber laser according to claim 5, characterized in that, In step S12, the power of the ultrasound is 300~500W, and the duration is 4~8h; The settling time is 4 to 8 hours.
8. A mode-locked fiber laser according to claim 5, characterized in that, In step S22, the centrifugation speed is 8000~12000 rpm and the time is 2~6 min.
9. A mode-locked fiber laser according to claim 5, characterized in that, In steps S12 and S22, the organic solvent is selected from ethanol.