Gold nanomaterial saturable absorber device based on TEC technology

Abstract

The utility model discloses a gold nanomaterial saturable absorber device based on TEC technology, comprising a housing, an all-fiber saturable absorber formed by connecting two fibers through a fiber connector, and a semiconductor cooler, and a cavity is formed in the housing; the all-fiber saturable absorber is arranged in the cavity; and the semiconductor cooler is embedded in the cavity wall of the shell. According to the technical scheme of the utility model, the semiconductor cooler is embedded on the shell, so that the photothermal effect of the all-fiber saturable absorber is weakened, the stability of the device is improved, the operation of ultrashort pulses with high peak power can be borne, and shorter pulse (femtosecond) laser output is expected to be obtained.

Description

Technical Field

[0001] The utility model relates to the technical field of ultrashort pulse laser devices, in particular to a gold nano material saturable absorber device based on TEC technology. Background Art

[0002] Saturable absorber (SA): a device whose transmittance is related to the intensity of incident light. When the intensity of incident light is low, it will absorb the incident light strongly; when the intensity of incident light is high, it will produce bleaching effect, become transparent, and have almost no absorption effect on light, that is, produce saturated absorption effect. By using this modulation feature, pulsed laser output can be achieved in the field of fiber laser.

[0003] Lasers were once regarded as mysterious lights and have been widely used by humans. Pulsed lasers in the near-infrared band (1100-2500nm) have very important applications in research fields such as laser micromachining, biomedical imaging, laser medicine, laser radar, and optical coherence tomography.

[0004] The saturable absorber is the core device of the passive mode-locked laser. Currently, the saturable absorber of semiconductor materials is commonly used, but it will introduce a reflector, making the structure of the laser complicated and not easy to achieve an all-fiber structure. Recently, researchers have focused their efforts on saturable absorbers for passive mode locking based on carbon nanomaterials (single-walled carbon nanotubes, graphene), but the production process of the above two nanomaterials is complex and costly, and it is difficult to independently build a saturable absorber mode-locked laser under general conditions to obtain ultrashort pulses. Therefore, exploring new saturable absorber materials and devices to achieve femtosecond pulse laser output has become a hot research topic worldwide.

[0005] With the in-depth development of nanotechnology, gold nanomaterials have attracted extensive attention from researchers due to their unique localized surface plasmon resonance characteristics and their broad application prospects in biochemical sensing, surface-enhanced Raman spectroscopy, biomedicine, imaging technology, optical information storage, and nanophotonics. In addition, gold nanomaterials also have high third-order nonlinear coefficients, fast recovery time, simple preparation, easy integration with optical fibers, and special absorption spectrum characteristics, and have the potential to become a new type of saturable absorber.

[0006] In 2012, Qin Guanshi's research group at Jilin University used thin-film gold nanomaterials to achieve Q-switched pulsed laser output for the first time. However, due to the strong photothermal effect when light interacts with gold nanomaterials, the damage threshold of the thin-film saturable absorber is low, which is not conducive to ultrashort pulse operation with high peak power. The obtained pulse width is only in the microsecond range. In addition, the surface plasmon resonance absorption peak of gold nanomaterials is usually located in the visible light band (530nm). Although surface plasmon resonance absorption in the near-infrared band can be achieved by adjusting the size of the material, its unsaturated loss is large. The photothermal effect generated when light interacts with the material greatly limits the improvement of laser performance. Finding a saturable absorber material or device with good photothermal effect stability is extremely important for achieving stable pulsed laser output.

[0007] Existing technology 1: At present, the performance of gold nanomaterials is mainly restricted by the photothermal effect. In order to reduce the influence of the photothermal effect, researchers have proposed to use the evanescent field effect to solve this problem. At present, research on gold nanomaterials as saturable absorbers to achieve femtosecond pulse laser output has been reported.

[0008] One of the related technologies is that Xu Wencheng's research group at South China Normal University (Microfiber-based gold nanorods as saturable absorber for femtosecond pulse generation in a fiber laser, Appl. Phys. Lett. 105 (16), 116107, (2014).) deposited gold nanorods onto micro-nano optical fibers to produce micro-nano optical fibers-gold nanorod saturable absorbers, and obtained mode-locked pulses with a central wavelength of 1552nm and a pulse width of 887fs in an erbium-doped fiber laser. In this study, the evanescent field in the micro-nano optical fiber interacted with the gold nanorods to increase the damage threshold of the gold nanorod-based saturable absorber, effectively improving the performance of the saturable absorber. Using the same method, Qin Guanshi et al. from Jilin University (Microfiber coated with gold nanorods as saturable absorber for 2μm Opt. Mater. Express 12(8), 3841-3850, (2018)) obtained a mode-locked pulse laser output with a central wavelength of 1943.5nm and a pulse width of 404fs in a thulium-doped fiber laser.

[0009] Implementation scheme of prior art 1: By adopting the method of melt-tapering, ordinary single-mode optical fiber (a) is drawn into a micro-nano optical fiber structure (b), and a gold nanorod solution is deposited onto the surface of the micro-nano optical fiber to prepare a micro-nano optical fiber-gold nanorod saturable absorber.

[0010] The prepared microfiber based GNRs-SA was integrated into the ring cavity laser to achieve femtosecond pulse laser output.

[0011] Disadvantages of prior art 1: (1) The micro-nano optical fiber is prepared by melting and taper-drawing bare optical fibers, and the optical fiber core diameter is several microns, which is easy to break during actual use, making the operation of the device inflexible and difficult to integrate;

[0012] (2) The uniform deposition process of gold nanorods on micro-nano optical fibers is cumbersome and difficult to achieve precise control;

[0013] (3) The prepared saturable absorber is not easy to preserve and is not easy to use in practice.

[0014] Prior art 2: Xu Wencheng's research group at South China Normal University ("Wavelength-switchable femtosecond pulse fiber laser mode-locked by silica-encased gold nanorods", Laser. Phys. Lett. 13, 045101, (2016)) prepared a saturable absorber of a gold nanorod-silicon dioxide core-shell structure by silica coating, and placed it in an erbium-doped fiber laser to obtain a tunable mode-locked laser output with a central wavelength of 1535.6 to 1560.5 nm, and the narrowest pulse width was 403 fs.

[0015] Implementation of prior art 2: A silica-coated gold nanorod sample is prepared by coating, and PVA is further used as a film-forming agent to prepare a gold nanorod thin film saturable absorber device. The prepared silica-gold nanorod saturable absorber (GNRs@SiO2 SA) is integrated into a ring cavity laser to achieve femtosecond pulse laser output.

[0016] Disadvantages of prior art 2: The main problem with devices of this structure is that the material preparation process is very complicated, the size is difficult to control, the sample uniformity is poor, and the unsaturated loss increases, making it difficult for the laser to operate stably and difficult to apply in practice.

[0017] In summary, since light has a strong photothermal effect when interacting with gold nanomaterials, how to design a saturable absorber device with good photothermal effect stability is an urgent problem to be solved by technicians in this field. Utility Model Content

[0018] The main purpose of the embodiment of the utility model is to propose a gold nanomaterial saturable absorber device based on TEC technology, aiming to design a gold nanomaterial saturable absorber device based on TEC technology that utilizes semiconductor refrigerator (TEC) technology to regulate the influence of photothermal effect.

[0019] The utility model solves the above technical problems by providing a gold nanomaterial saturable absorber device based on TEC technology, comprising a shell, an all-fiber saturable absorber formed by two optical fibers connected together by an optical fiber connector, and a semiconductor refrigerator, wherein a cavity is formed in the shell; the all-fiber saturable absorber is arranged in the cavity; and the semiconductor refrigerator is embedded in the cavity wall of the shell.

[0020] Furthermore, the shell is a rectangular parallelepiped, and the gold nanomaterial saturable absorber device based on TEC technology includes three semiconductor refrigerators, which are respectively embedded in three cavity walls of the shell, and the three semiconductor refrigerators are respectively located on three sides of the shell.

[0021] Furthermore, the gold nanomaterial saturable absorber device based on TEC technology also includes a fiber adapter, which is fixed on the cavity wall of the shell and located in the cavity, and the all-fiber saturable absorber is fixed on the fiber adapter.

[0022] Furthermore, the optical fiber adapter is thermally insulated and fixed to the cavity wall of the shell through a polyimide thermal insulation pad and titanium alloy screws.

[0023] Furthermore, the gold nanomaterial saturable absorber device based on TEC technology further includes: a thermistor, and the thermistor is arranged on the optical fiber adapter.

[0024] Furthermore, the gold nanomaterial saturable absorber device based on TEC technology further includes a fan, and the fan is arranged on a side of the housing where the semiconductor refrigerator is arranged.

[0025] The technical solution of the utility model embeds a semiconductor cooler on the shell to weaken the photothermal effect of the all-fiber saturated absorber (SA) (SA is based on gold nanomaterials, and gold nanomaterials have a strong photothermal effect when interacting with light), thereby improving the stability of the device, so that it can withstand ultrashort pulse operation with high peak power, and is expected to obtain shorter pulse (femtosecond) laser output. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0027] Figure 1 It is a schematic diagram of the cross-sectional structure of the gold nanomaterial saturable absorber device based on TEC technology described in the utility model;

[0028] Figure 2 This is a schematic diagram of the structure of the gold nanomaterial saturable absorber device based on TEC technology described in the utility model;

[0029] Figure 3 This is a schematic diagram of the structure of a mode-locked fiber laser of a gold nano-saturable absorber device based on TEC technology described in the utility model;

[0030] Figure 4 The utility model discloses an output spectrum and a pulse train of the saturable absorber device used in a 1560 nm mode-locked laser.

[0031] Description of Figure Numbers:

[0032]

[0033] DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the utility model specification 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 of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0035] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back...) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0036] In addition, in the present invention, the descriptions of "first", "second", etc. are only used 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 features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "several" or "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0037] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0039] The utility model proposes a gold nanomaterial saturable absorber device based on TEC technology, aiming to design a gold nanomaterial saturable absorber device based on TEC technology which utilizes semiconductor refrigerator technology to adjust the influence of photothermal effect.

[0040] The gold nanomaterial saturable absorber device based on TEC technology proposed in the present invention will be described in the following specific embodiments:

[0041] In the technical solution of this embodiment, Figure 1 , Figure 2As shown, a gold nanomaterial saturable absorber device based on TEC technology includes a shell 10, an all-fiber saturable absorber 20 formed by two optical fibers connected together through an optical fiber connector, and a semiconductor refrigerator 30. A cavity 11 is formed in the shell 10; the all-fiber saturable absorber 20 is arranged in the cavity 11; and the semiconductor refrigerator 30 is embedded in the cavity wall of the shell 10.

[0042] It can be understood that by embedding the semiconductor refrigerator 30 on the housing 10, the photothermal effect of the all-fiber saturated absorber 20 (SA) (SA is based on gold nanomaterials, and gold nanomaterials have a strong photothermal effect when interacting with light) is weakened, the stability of the device is improved, and it can withstand ultra-short pulse operation with high peak power, and it is expected to obtain shorter pulse (femtosecond) laser output. (Femtosecond fiber lasers have important potential applications in material preparation, fiber sensing, medicine, military and basic research fields, so our utility model has high practical value).

[0043] Specifically, the shell 10 is connected to the semiconductor refrigerator 30 through a polyimide thermal insulation pad 50, and the body 11 is a sealed cavity.

[0044] Furthermore, the shell 10 is a rectangular parallelepiped, and the gold nanomaterial saturable absorber device based on TEC technology includes three semiconductor refrigerators 30, which are respectively embedded in three cavity walls of the shell 10, and the three semiconductor refrigerators 30 are respectively located on three sides of the shell 10.

[0045] It can be understood that by arranging a semiconductor refrigerator 30 on each of the three cavity walls of the housing 10, the temperature of the all-fiber saturated absorber 20 is reduced from different directions to improve the stability of the all-fiber saturated absorber 20. The cold end of the semiconductor refrigerator 30 is arranged toward the all-fiber saturated absorber 20, and the hot end of the semiconductor refrigerator 30 is arranged outward relative to the cavity.

[0046] Furthermore, the gold nanomaterial saturable absorber device based on TEC technology also includes a fiber adapter 40 , which is fixed on the cavity wall of the shell 10 and located in the cavity 11 , and the all-fiber saturable absorber 20 is fixed on the fiber adapter 40 .

[0047] It can be understood that the optical fiber adapter 40 is disposed on the cavity wall of the housing 10 and is located on the other side surface of the housing 10 (relative to the three sides of the housing 10 where the semiconductor refrigerator 30 is disposed).

[0048] Furthermore, the optical fiber adapter 40 is fixed on the cavity wall of the housing 10 by means of a polyimide thermal insulation pad 50 and titanium alloy screws for thermal insulation.

[0049] Furthermore, the gold nanomaterial saturable absorber device based on TEC technology further includes a thermistor 60 , and the thermistor 60 is disposed on the optical fiber adapter 40 .

[0050] It can be understood that the thermistor 60 is arranged on the optical fiber adapter 40, and is used to monitor the temperature of the all-optical fiber saturated absorber 20 and transmit the temperature to the temperature control system. The temperature control system adjusts the power of the semiconductor refrigerator 30 according to the temperature monitored by the thermistor 60, cools the cavity 11 of the shell 10, and then adjusts the temperature of the all-optical fiber saturated absorber 20, so that the all-optical fiber saturated absorber 20 can be stable, thereby improving the stability of the device.

[0051] Furthermore, if Figure 2 As shown, the gold nanomaterial saturable absorber device based on TEC technology further includes a fan 70 , and the fan 70 is arranged on a side of the housing 10 where the semiconductor refrigerator 30 is arranged.

[0052] It can be understood that a fan 70 is arranged at the heat dissipation surface of the hot end of the semiconductor refrigerator 30 to use air cooling to remove heat. The heat dissipation method currently uses air cooling technology, and water cooling can also be used. The advantage of this technology is that the cooling temperature of the semiconductor refrigerator 30 can be controlled by the circuit. Compared with other refrigeration technologies, the temperature control is more precise.

[0053] Specifically, the film former material and the gold nanomaterial are combined together to obtain a saturable absorber material.

[0054] Gold nanomaterials can be spherical, rod-shaped, butterfly-shaped, triangular, etc., and different longitudinal surface plasmon resonance absorption peaks can be obtained by changing the size and morphology of the nanospheres.

[0055] The film-forming material includes polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), sodium carboxymethyl cellulose (NaCMC), polymethyl methacrylate (PMMA), SU8 polymer or styrene dimethyl methacrylate copolymer (SMMA), and the film-forming material used can be one or more of the materials mentioned above. After optimization and selection, the film-forming materials used are sodium carboxymethyl cellulose (NaCMC), polyvinyl alcohol (PVA), and polyvinyl pyrrolidone (PVP). The above-mentioned film-forming materials can be combined with the precious metal material by mixing, physical or chemical doping.

[0056] The metal fixture is designed according to the optical fiber FC / PC structure and can be made of iron or steel.

[0057] The prepared saturated absorber is placed in a sealed cavity, and the temperature of the saturated absorber is precisely controlled by utilizing TEC technology to further control the photothermal effect generated by the interaction between gold nanomaterials and light.

[0058] TEC can be composed of one or more TECs, and the shape of TEC can be rectangular, square or circular;

[0059] The heat dissipation method can be air cooling or water cooling (water pipes are required) to facilitate the heat dissipation of TEC.

[0060] This application selects a ring cavity mode-locked fiber laser operating in the 1560 nm band, uses gold nanomaterials based on TEC technology as saturable absorber materials, and when the saturable absorber device prepared based on this technology is used for this laser, stable femtosecond pulse laser output is achieved.

[0061] Gold nanomaterial saturable absorber device based on TEC technology is used for 1560 nm mode-locked laser output:

[0062] 1. Sample Preparation Process

[0063] Nano palladium particles were prepared by reduction method, and the obtained nano palladium aqueous solution was mixed with 1.5 wt% sodium carboxymethyl cellulose (NaCMC) aqueous solution in a volume ratio of 1:1 and ultrasonically dispersed for 2 h. The mixed solution after ultrasonic dispersion was spin-coated on the flat surface of silicon wafer and dried naturally in a vacuum-sealed container until film formation. A 1mm*1mm film was placed in a fiber clamp to form an all-fiber saturable absorber device. Further, it was placed in a sealed cavity, which was connected to TEC through a polyimide insulation pad for better thermal control management. The upper, left and right sides of the sealed cavity were all fitted with TEC cooling sheets for better temperature control management. Accurate temperature control was achieved through circuit control. In addition, in order to facilitate heat dissipation, air cooling or water cooling was used and placed around the sealed cavity for heat dissipation.

[0064] 2. Perform a fiber laser mode locking test. Select a ring cavity fiber laser pumped by a semiconductor laser and operating at 1560nm. Place the saturable absorber device in the fiber laser. Figure 3 As shown in the figure, the pump power of the semiconductor laser is gradually increased, and the polarization of the fiber laser is adjusted. When the mode-locked laser threshold is reached, pulsed laser output is achieved. By adjusting the TEC temperature control sensor setting, when the cooling temperature is -30°C, pulsed laser output with a pulse width of 200 femtoseconds is achieved. The experimental results are shown in Figure 4 Since the device can effectively control the influence caused by the photothermal effect of gold nanomaterials, it is expected to achieve shorter pulse laser output.

[0065] The above is only a preferred specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the utility model should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. A gold nanomaterial saturable absorber device based on TEC technology, characterized in that: include: a housing, wherein a cavity is formed in the housing; An all-fiber saturated absorber formed by connecting two optical fibers together through an optical fiber connector, wherein the all-fiber saturated absorber is arranged in the cavity; and A semiconductor refrigerator is embedded in the cavity wall of the shell.

2. The gold nanomaterial saturable absorber device based on TEC technology according to claim 1, characterized in that: The shell is a rectangular parallelepiped, and the gold nanomaterial saturable absorber device based on TEC technology includes three semiconductor refrigerators, which are respectively embedded in three cavity walls of the shell and located on three side surfaces of the shell.

3. The gold nanomaterial saturable absorber device based on TEC technology according to claim 1, characterized in that: Also includes: The optical fiber adapter is fixed on the cavity wall of the shell and is located in the cavity. The all-fiber saturated absorber is fixed on the optical fiber adapter.

4. The gold nanomaterial saturable absorber device based on TEC technology according to claim 3, characterized in that: The optical fiber adapter is fixed on the cavity wall of the shell through a polyimide heat insulation pad and a titanium alloy screw.

5. The gold nanomaterial saturable absorber device based on TEC technology according to claim 3, characterized in that: Also includes: Thermistor, wherein the thermistor is arranged on the optical fiber adapter.

6. The gold nanomaterial saturable absorber device based on TEC technology according to claim 2, characterized in that: Also includes: A fan is arranged on a side of the shell where the semiconductor refrigerator is arranged.

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