A LiTaO3 microcrystalline-glass composite optical fiber, its preparation method and application

Abstract

The application belongs to the technical field of nonlinear optics, and particularly relates to a LiTaO3 microcrystal-glass composite optical fiber and a preparation method and application thereof. Different from a preparation method of a traditional microcrystal-glass composite optical fiber, heavy metal oxides are doped in a glass matrix, the refractive index of the glass matrix is adjusted to match a LiTaO3 microcrystal phase, then a frequency doubling crystal is directly doped into the glass matrix to prepare a fiber core, the fiber core is combined with a cladding to form a preform, and the composite optical fiber is prepared through a low-temperature heat drawing method, thereby avoiding a secondary crystallization problem existing in a preparation process of a traditional microcrystal-glass composite optical fiber. The composite optical fiber provided by the application can realize isotropic broadband tunable frequency doubling output under excitation of femtosecond laser, is not affected by an incident polarization state, effectively bypasses a traditional single crystal complex phase matching mechanism, and is suitable for being used in the field of nonlinear optics.

Description

Technical Field

[0001] This invention belongs to the field of nonlinear optics technology, specifically relating to a LiTaO3 microcrystalline-glass composite optical fiber, its preparation method, and its application. Background Technology

[0002] Second-order nonlinear optical processes are a common method for obtaining new laser frequency sources and have been widely applied in spectroscopy, bioimaging, ultrafast optics, and quantum optics, becoming a key aspect of recent photonics technology development. It is generally believed that highly ordered crystalline materials are required for second-order nonlinear optical processes. However, in ordered crystalline materials, effective three-wave mixing often relies on stringent phase-matching techniques, which have high requirements for incident polarization, wavelength, and ambient temperature. Therefore, these techniques typically limit the application of materials in broadband tunable applications. Simultaneously, driven by application demands, researchers are not only focusing on the performance of frequency-doubling materials but also increasingly on smaller, lower-power, and miniaturized frequency-doubling optical components. Therefore, nonlinear fibers with efficient SHG effects are of great significance in broadening the laser frequency range.

[0003] However, the fabrication of high-quality nonlinear single-crystal optical fibers and the control of their domain structures remain insurmountable challenges. Nonlinear microcrystalline glass composite fibers, due to their combination of frequency-doubling crystals and excellent optical waveguide structures, are considered an alternative to meet the requirements of high-efficiency SHG effect optical fibers.

[0004] Currently, the main method for preparing nonlinear glass-ceramics is in-situ crystallization heat treatment. In 2017, Bin Zhu et al. precipitated nanoscale Ba2TiSi2O8 nonlinear crystals in silicate glass through heat treatment, achieving broadband frequency doubling output of the three primary colors (red, blue, and green) in glass-ceramics (B. Zhu, B. Qian, Y. Liu, et al. A volumetric full-color display realized by frequency upconversion of a transparent composite incorporating dispersed nonlinear optical crystals [J]. NPG Asia materials, 2017, 9, e394.). However, this method for preparing nonlinear glass-ceramics suffers from secondary crystallization problems. Summary of the Invention

[0005] The purpose of this invention is to provide a LiTaO3 microcrystalline-glass composite optical fiber, its preparation method, and its application. The preparation method provided by this invention solves the problem of secondary crystallization.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing LiTaO3 microcrystalline-glass composite optical fiber, comprising the following steps:

[0008] (1) TeO2, Bi2O3 and BaCO3 are mixed and sintered for the first time to obtain homogeneous glass; the refractive index of the homogeneous glass is 2.130 and the density is 6.087 g / cm³. 3 ;

[0009] (2) After the homogeneous glass is sintered for the second time, it is cooled to 620-660°C to obtain molten glass liquid;

[0010] (3) The LiTaO3 microcrystals and the molten glass were mixed and shaped to obtain the fiber core; the particle size of the LiTaO3 microcrystals was 30-50 μm;

[0011] (4) The fiber core is inserted into the cladding and then heated for drawing to obtain LiTaO3 microcrystalline-glass composite optical fiber; the heating temperature is 600-700℃.

[0012] Preferably, the cladding is heavy flint ZF4 optical glass.

[0013] Preferably, the molar ratio of TeO2 to Bi2O3 is 70-85:5-15; and the molar ratio of Bi2O3 to BaCO3 is 5-15:5-15.

[0014] Preferably, the temperature of the first sintering is 800-900℃, and the holding time is more than 10 minutes.

[0015] Preferably, the second sintering temperature is 750°C and the holding time is 5 to 20 minutes.

[0016] Preferably, the mass ratio of the LiTaO3 microcrystals to the molten glass is 1–4:96–99.

[0017] Preferably, the wire drawing rate is 0.3 to 0.5 m / s; the target wire diameter is 300 to 600 μm.

[0018] The present invention also provides a LiTaO3 microcrystalline-glass composite optical fiber obtained by the preparation method described above, comprising a core and a cladding covering the outer layer of the core; the core is LiTaO3 microcrystalline-glass; the LiTaO3 microcrystalline-glass comprises LiTaO3 microcrystals and a glass matrix; the refractive index difference between the LiTaO3 microcrystals and the glass matrix is ​​less than 0.05.

[0019] Preferably, the diameter of the fiber core is 100-200 μm; and the diameter of the LiTaO3 microcrystalline-glass composite optical fiber is 300-600 μm.

[0020] This invention also provides the application of the LiTaO3 microcrystalline-glass composite optical fiber described above in the field of nonlinear optics.

[0021] This invention provides a method for fabricating LiTaO3 microcrystalline-glass composite optical fiber. Traditional microcrystalline glass composite optical fibers typically have a tendency for crystallization in the core, requiring precise heat treatment to precipitate crystals in situ. However, during subsequent fiber drawing, secondary heating leads to undesirable secondary crystallization. Unlike traditional methods, this invention designs a thermally stable glass matrix—doping a heavy metal oxide into the glass matrix to match its refractive index with that of LiTaO3 microcrystals (the refractive index difference between LiTaO3 microcrystals and glass is less than 0.05). Then, a frequency-doubling crystal is directly doped into the glass matrix (direct doping method) to prepare the core. The core and cladding are then combined to form a preform, and the composite optical fiber is fabricated using a low-temperature hot drawing method. This method avoids the secondary crystallization problem present in traditional microcrystalline glass composite optical fiber fabrication.

[0022] This invention incorporates heavy metal oxides into a glass matrix, adjusting the refractive index of the glass matrix to match that of the LiTaO3 microcrystals. This also results in a glass matrix with high transparency and a low melting point, effectively preventing thermal corrosion of the thermally unstable LiTaO3 crystals. This invention combines a LiTaO3 crystal with a high nonlinear coefficient and a glass matrix with a high laser damage threshold and easy processing. Furthermore, this invention allows for control over the doping amount of the LiTaO3 microcrystals, providing a foundation for the fabrication and processing of high-performance composite optical fibers.

[0023] This invention achieves broadband frequency doubling output by rationally designing the doped crystal size of LiTaO3 microcrystals to create a glass fiber core. The preparation method provided by this invention is simple, widely applicable, and easy to apply on a large scale.

[0024] This invention also provides a LiTaO3 microcrystalline-glass composite optical fiber prepared by the method described above. The LiTaO3 microcrystalline-glass composite optical fiber prepared by this invention has LiTaO3 microcrystalline crystals that are uniformly and randomly oriented within the glass matrix, exhibiting isotropy. This allows the material to achieve isotropic, broadband, tunable frequency doubling output under femtosecond laser excitation, unaffected by the incident polarization state. This effectively bypasses the complex phase-matching mechanism of traditional single crystals, providing convenience for nonlinear frequency conversion and a feasible solution for miniaturized, integrated frequency doubling optical components.

[0025] This invention also provides the application of the LiTaO3 microcrystalline-glass composite fiber described above in the field of nonlinear optics. The LiTaO3 microcrystalline-glass composite fiber provided by this invention achieves isotropic broadband tunable frequency doubling output under femtosecond laser excitation, unaffected by the incident polarization state, effectively bypassing the complex phase-matching mechanism of traditional single crystals. It is suitable for use in the field of nonlinear optics, especially for nonlinear laser frequency conversion. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 The image shows the XRD pattern of the LiTaO3 microcrystalline glass prepared in Example 1.

[0028] Figure 2 Transmittance diagram of the glass matrix prepared in Example 1 and the LiTaO3 microcrystalline glass;

[0029] Figure 3 Optical microscope and scanning electron microscope images of the LiTaO3 microcrystalline glass prepared in Example 1;

[0030] Figure 4 An optical microscope image of the LiTaO3 microcrystalline glass prepared in Example 2;

[0031] Figure 5 An optical microscope image of the LiTaO3 microcrystalline glass prepared in Example 3;

[0032] Figure 6 An optical microscope image of the LiTaO3 microcrystalline glass prepared in Example 4;

[0033] Figure 7 The blue light frequency doubling output of the LiTaO3 microcrystalline-glass composite optical fiber prepared in Example 1 under 884nm pump light is shown.

[0034] Figure 8 The green light frequency doubling output diagram of the LiTaO3 microcrystalline-glass composite optical fiber prepared in Example 1 under 1064nm pump light;

[0035] Figure 9 The frequency doubling output intensity-pump polarization relationship diagram of the LiTaO3 microcrystalline-glass composite optical fiber prepared in Example 1;

[0036] Figure 10The frequency doubling output polarization state diagram of the LiTaO3 microcrystalline-glass composite optical fiber prepared in Example 1;

[0037] Figure 11 This is a process flow diagram of the preparation method of LiTaO3 microcrystalline-glass composite optical fiber of the present invention. Detailed Implementation

[0038] This invention provides a method for preparing LiTaO3 microcrystalline-glass composite optical fiber, comprising the following steps:

[0039] (1) TeO2, Bi2O3 and BaCO3 are mixed and sintered for the first time to obtain homogeneous glass;

[0040] (2) After the homogeneous glass is sintered for the second time, it is cooled to 620-660°C to obtain molten glass liquid;

[0041] (3) The LiTaO3 microcrystals and the molten glass liquid are mixed and shaped to obtain the fiber core;

[0042] (4) After inserting the fiber core into the cladding, heat it to draw it into a fiber to obtain a LiTaO3 microcrystalline-glass composite optical fiber.

[0043] The present invention mixes TeO2, Bi2O3 and BaCO3 (referred to as the first mixture) and then performs a first sintering and shaping (referred to as the first shaping) to obtain homogeneous glass.

[0044] In this invention, the refractive index of the homogeneous glass is preferably 2.130, and the density is preferably 6.087 g / cm³. 3 .

[0045] In this invention, the first mixing is preferably carried out by weighing TeO2, Bi2O3 and BaCO3 and placing them in an agate mortar and mixing and grinding them thoroughly.

[0046] In this invention, the molar ratio of TeO2 to Bi2O3 is preferably 70-85:5-15, more preferably 75-80:10-15, and even more preferably 80:10.

[0047] In this invention, the molar ratio of Bi2O3 to BaCO3 is preferably 5-15:5-15, more preferably 10-15:10-15, and even more preferably 10:10.

[0048] In this invention, the first sintering is preferably performed by placing the mixed raw materials into a corundum crucible, without covering the crucible, and sintering it in a high-temperature furnace. Through this first sintering, the present invention obtains a uniform, bubble-free glass melt.

[0049] In this invention, the temperature of the first sintering is preferably 800-900°C, more preferably 830-870°C, and even more preferably 850°C. The holding time is preferably 10 minutes or more, more preferably 20 minutes or more, and even more preferably 30 minutes or more.

[0050] In this invention, the temperature of the first forming is preferably room temperature; the first forming is preferably: pouring the product obtained from the first sintering onto a steel plate; and the first forming process preferably further includes quenching the obtained product.

[0051] After obtaining homogeneous glass, the present invention performs a second sintering of the homogeneous glass and then cools it to 620-660°C to obtain molten glass. In the present invention, the second sintering temperature is preferably 750°C, the holding time is preferably 5-20 min, more preferably 8-16 min, and even more preferably 10 min; the equipment for the second sintering is preferably a high-temperature furnace.

[0052] In this invention, the final cooling temperature is preferably 635–645°C, more preferably 640°C. This invention involves placing homogeneous glass in a high-temperature furnace for low-temperature sintering followed by cooling to achieve the optimal temperature for doping LiTaO3 crystals.

[0053] After obtaining the molten glass, the present invention mixes the LiTaO3 microcrystals with the molten glass (referred to as the second mixing) and then shapes it (referred to as the second shaping) to obtain the fiber core. In the present invention, the particle size of the LiTaO3 microcrystals is preferably 30-50 μm. The present invention has found that the particle size distribution range of the LiTaO3 microcrystals should be greater than the coherence length L corresponding to the tunable band. c Twice that, for frequency harmonic output in the 400–800 nm band, its coherence length L c All are less than 10μm, so the particle size of LiTaO3 microcrystals is within the above range, which can ensure the output intensity of different wavebands.

[0054] In this invention, the mass ratio of LiTaO3 microcrystals to molten glass is preferably 1-4:96-99, more preferably 1-3:97-99, and even more preferably 2-3:97-98.

[0055] In this invention, the second mixing is preferably stirring; the stirring time is preferably 1 to 5 minutes, more preferably 3 minutes; the second mixing is preferably: LiTaO3 microcrystals and the molten glass liquid are continuously stirred with a quartz rod.

[0056] In this invention, the second molding process is preferably carried out by pouring the product obtained from the second mixture into a graphite mold and keeping it at 340°C, and then cooling it to room temperature.

[0057] In this invention, the graphite abrasive is preferably a cylindrical graphite abrasive; the heat preservation time is preferably 6 hours; and the cooling rate is preferably 0.1℃ / min. This invention eliminates the internal stress of the material through a second forming process.

[0058] In this invention, the second molding process preferably includes post-processing; the post-processing is preferably: grinding and polishing the material obtained from the second molding process in sequence.

[0059] After obtaining the fiber core, the present invention inserts the fiber core into the cladding and then heats and draws it to obtain a LiTaO3 microcrystalline-glass composite optical fiber. In the present invention, the cladding is preferably heavy flint ZF4 optical glass.

[0060] In this invention, the heating temperature is preferably 600-700°C, more preferably 620-680°C, and even more preferably 640-660°C; the heating and drawing equipment is preferably a low-temperature graphite furnace.

[0061] In this invention, the wire drawing rate is preferably 0.3 to 0.5 m / s, more preferably 0.35 to 0.45 m / s, and even more preferably 0.40 m / s; the target diameter of the wire drawing is preferably 300 to 600 μm, more preferably 400 to 500 μm, and even more preferably 450 to 480 μm.

[0062] The preparation method provided by this invention successfully prepared LiTaO3 microcrystalline-glass composite optical fiber. The main process flow is as follows: Figure 11 As shown: In this invention, a precursor glass is obtained by melting a glass matrix at high temperature. The precursor glass is then cooled and melted at low temperature. LiTaO3 microcrystals are directly doped into the molten glass at low temperature to prepare a fiber core. The fiber core is then inserted into the glass cladding and drawn to obtain a LiTaO3 microcrystal-glass composite optical fiber.

[0063] The present invention also provides a LiTaO3 microcrystalline-glass composite optical fiber obtained by the preparation method described above, comprising a core and a cladding covering the outer layer of the core; the core is LiTaO3 microcrystalline-glass; the LiTaO3 microcrystalline-glass comprises LiTaO3 microcrystals and a glass matrix; the refractive index difference between the LiTaO3 microcrystals and the glass matrix is ​​less than 0.05.

[0064] In this invention, the LiTaO3 microcrystalline-glass composite optical fiber is preferably core-clad coaxial.

[0065] In this invention, the diameter of the fiber core is preferably 100-200 μm, more preferably 120-180 μm, and even more preferably 140-160 μm.

[0066] In this invention, the diameter of the LiTaO3 microcrystalline-glass composite optical fiber is preferably 300-600 μm, more preferably 350-550 μm, and even more preferably 400-500 μm.

[0067] This invention also provides the application of the LiTaO3 microcrystalline-glass composite optical fiber described above in the field of nonlinear optics.

[0068] The LiTaO3 microcrystalline-glass composite fiber provided by this invention achieves isotropic broadband tunable frequency doubling output under femtosecond laser excitation, unaffected by the incident polarization state, effectively bypassing the complex phase matching mechanism of traditional single crystals, making it suitable for nonlinear optics, especially for nonlinear laser frequency conversion.

[0069] To further illustrate the present invention, the following detailed description of the invention's solutions, in conjunction with the accompanying drawings and embodiments, is provided, but should not be construed as limiting the scope of protection of the present invention.

[0070] Example 1

[0071] A LiTaO3 microcrystalline-glass composite optical fiber is disclosed, wherein the glass matrix of the fiber core is tellurate glass (Molar ratio of TeO2:Bi2O3:BaO is 80:10:10), and the nonlinear crystal doped in the fiber core is LiTaO3 microcrystalline with a LiTaO3 microcrystalline content of 4wt%. The preparation steps are as follows:

[0072] (1) Preparation of LiTaO3 microcrystalline glass

[0073] TeO2, Bi2O3 and BaCO3 were thoroughly mixed and ground in an agate mortar, then heated to 850℃ and held for 30 minutes in an alumina crucible, and then poured onto a steel plate for quenching to obtain a dense precursor glass.

[0074] The obtained precursor glass was kept at 750℃ for 10 min, then slowly cooled to 640℃ at a rate of 5℃ / min and kept at that temperature for 5 min. LiTaO3 powder was then added to the precursor glass and stirred continuously with a quartz rod for 3 min to obtain a uniformly stirred glass liquid. The glass liquid was poured into a cylindrical graphite mold and slowly cooled to room temperature at a rate of 0.1 K / min. The resulting material was then ground and polished to obtain a transparent rod-shaped LiTaO3 microcrystalline glass.

[0075] (2) Preparation of LiTaO3 microcrystalline-glass composite optical fiber: ZF4 glass is processed into a preform cladding, and the LiTaO3 microcrystalline-glass rod obtained in step (1) is inserted into the cladding to obtain an optical fiber preform. The obtained optical fiber preform is then placed in a low-temperature graphite furnace at 600-700℃ for drawing to obtain LiTaO3 microcrystalline-glass composite optical fiber.

[0076] Example 2

[0077] A LiTaO3 microcrystalline-glass composite optical fiber is disclosed, wherein the glass matrix of the fiber core is tellurate glass (Molar ratio of TeO2:Bi2O3:BaO is 70:15:15), and the nonlinear crystal doped in the fiber core is LiTaO3 microcrystalline with a LiTaO3 microcrystalline content of 1 wt%. The preparation steps are as follows:

[0078] (1) Preparation of LiTaO3 microcrystalline glass

[0079] TeO2, Bi2O3 and BaCO3 were thoroughly mixed and ground in an agate mortar, then heated to 900℃ and held for 30 minutes in an alumina crucible, and then poured onto a steel plate for quenching to obtain a dense precursor glass.

[0080] The obtained precursor glass was kept at 750℃ for 10 min, then slowly cooled to 640℃ at a rate of 5℃ / min and kept at that temperature for 5 min. LiTaO3 powder was then added to the precursor glass and stirred continuously with a quartz rod for 3 min to obtain a uniformly stirred glass liquid. The glass liquid was poured into a cylindrical graphite mold and slowly cooled to room temperature at a rate of 0.1 K / min. The resulting material was then ground and polished to obtain a transparent rod-shaped LiTaO3 microcrystalline glass.

[0081] (2) Preparation of LiTaO3 microcrystalline-glass composite optical fiber: ZF4 glass is processed into a preform cladding, and the LiTaO3 microcrystalline-glass rod obtained in step (1) is inserted into the cladding to obtain an optical fiber preform. The obtained optical fiber preform is then placed in a low-temperature graphite furnace at 600-700℃ for drawing to obtain LiTaO3 microcrystalline-glass composite optical fiber.

[0082] Example 3

[0083] A LiTaO3 microcrystalline-glass composite optical fiber is disclosed, wherein the glass matrix of the fiber core is tellurate glass (Molar ratio of TeO2:Bi2O3:BaO is 85:5:10), and the nonlinear crystal doped in the fiber core is LiTaO3 microcrystalline with a LiTaO3 microcrystalline content of 2wt%. The preparation steps are as follows:

[0084] (1) Preparation of LiTaO3 microcrystalline glass

[0085] TeO2, Bi2O3 and BaCO3 were thoroughly mixed and ground in an agate mortar, then heated to 800℃ and held for 30 minutes in an alumina crucible, and then poured onto a steel plate for quenching to obtain a dense precursor glass.

[0086] The obtained precursor glass was kept at 750℃ for 10 min, then slowly cooled to 660℃ at a rate of 5℃ / min and kept at that temperature for 20 min. LiTaO3 powder was then added to the precursor glass and stirred continuously with a quartz rod for 3 min to obtain a uniformly stirred glass liquid. The glass liquid was poured into a cylindrical graphite mold and slowly cooled to room temperature at a rate of 0.1 K / min. The resulting material was then ground and polished to obtain a transparent rod-shaped LiTaO3 microcrystalline glass.

[0087] (2) Preparation of LiTaO3 microcrystalline-glass composite optical fiber: ZF4 glass is processed into a preform cladding, and the LiTaO3 microcrystalline-glass rod obtained in step (1) is inserted into the cladding to obtain an optical fiber preform. The obtained optical fiber preform is then placed in a low-temperature graphite furnace at 600-700℃ for drawing to obtain LiTaO3 microcrystalline-glass composite optical fiber.

[0088] Example 4

[0089] A LiTaO3 microcrystalline-glass composite optical fiber is disclosed. The glass matrix of the fiber core is tellurate glass (Molar ratio of TeO2:Bi2O3:BaO is 85:10:5), and the nonlinear crystal doped in the fiber core is LiTaO3 microcrystalline with a content of 3wt%. The preparation steps are as follows:

[0090] (1) Preparation of LiTaO3 microcrystalline glass

[0091] TeO2, Bi2O3 and BaCO3 were thoroughly mixed and ground in an agate mortar, then heated to 800℃ and held for 30 minutes in an alumina crucible, and then poured onto a steel plate for quenching to obtain a dense precursor glass.

[0092] The obtained precursor glass was kept at 750℃ for 10 min, then slowly cooled to 620℃ at a rate of 5℃ / min and kept at that temperature for 5 min. LiTaO3 powder was then added to the precursor glass and stirred continuously with a quartz rod for 3 min to obtain a uniformly stirred glass liquid. The glass liquid was poured into a cylindrical graphite mold and slowly cooled to room temperature at a rate of 0.1 K / min. The resulting material was then ground and polished to obtain a transparent rod-shaped LiTaO3 microcrystalline glass.

[0093] (2) Preparation of LiTaO3 microcrystalline-glass composite optical fiber: ZF4 glass is processed into a preform cladding, and the LiTaO3 microcrystalline-glass rod obtained in step (1) is inserted into the cladding to obtain an optical fiber preform. The obtained optical fiber preform is then placed in a low-temperature graphite furnace at 600-700℃ for drawing to obtain LiTaO3 microcrystalline-glass composite optical fiber.

[0094] X-ray diffraction analysis was performed on the crystal phase of the LiTaO3 microcrystalline glass prepared in Example 1, and the results are as follows: Figure 1 As shown. According to Figure 1 It can be confirmed that the doped LiTaO3 microcrystals exist in the glass matrix and have not undergone thermal corrosion.

[0095] The transmittance of the LiTaO3 microcrystalline glass prepared in Example 1 was measured, and the results are as follows: Figure 2 As shown. According to Figure 2 As can be seen, the transmittance of LiTaO3 microcrystalline glass is greater than 65%, and the transmittance decreases by less than 10% compared to the glass matrix.

[0096] The uniformity of the LiTaO3 microcrystalline glass prepared in Example 1 was detected using optical microscopy and scanning electron microscopy. The results are as follows: Figure 3 As shown. According to Figure 3 It can be seen that the LiTaO3 microcrystals are uniformly distributed within the glass matrix, and the microcrystal particles have not agglomerated.

[0097] The uniformity of the LiTaO3 microcrystalline glass prepared in Example 2 was detected using an optical microscope, and the results are as follows: Figure 4 As shown. According to Figure 4 It can be seen that the LiTaO3 microcrystals are uniformly distributed within the glass matrix, and the microcrystal particles have not agglomerated.

[0098] The uniformity of the LiTaO3 microcrystalline glass prepared in Example 3 was detected using an optical microscope, and the results are as follows: Figure 5 As shown. According to Figure 5 It can be seen that the LiTaO3 microcrystals are uniformly distributed within the glass matrix, and the microcrystal particles have not agglomerated.

[0099] The uniformity of the LiTaO3 microcrystalline glass prepared in Example 5 was detected using an optical microscope, and the results are as follows: Figure 6 As shown. According to Figure 6 It can be seen that the LiTaO3 microcrystals are uniformly distributed within the glass matrix, and the microcrystal particles have not agglomerated.

[0100] The frequency doubling output performance of the LiTaO3 microcrystalline-glass composite fiber prepared in Example 1 under pump light of 884 nm and 1064 nm was tested, and the results are as follows: Figure 7 and Figure 8 As shown. According to Figure 7 and Figure 8 It can be seen that the LiTaO3 microcrystalline-glass composite fiber achieved frequency doubling output of blue and green light under pump light of 884nm and 1064nm, proving that it has achieved broadband tunable frequency doubling output.

[0101] To verify that the LiTaO3 microcrystalline-glass composite fiber is independent of the pump light polarization state, the frequency doubling output intensity of the LiTaO3 microcrystalline-glass composite fiber under different pump polarization states was tested. The results are as follows: Figure 9 As shown. According to Figure 9 It can be seen that the frequency doubling output intensity of the optical fiber does not change significantly under different polarization states, proving that the LiTaO3 microcrystalline-glass composite optical fiber of this invention does not depend on pump polarization and effectively bypasses the cumbersome phase matching process of single crystal.

[0102] With the horizontal polarization state of the pump light remaining constant, the frequency doubling output intensity of the LiTaO3 microcrystalline-glass composite fiber under different polarization states was tested, and the results are as follows: Figure 10 As shown. According to Figure 10 It can be seen that the frequency-doubled signal output by the optical fiber is circularly polarized and has isotropic properties.

[0103] As can be seen from the above embodiments, the preparation method provided by the present invention effectively avoids secondary crystallization, and the LiTaO3 microcrystalline-glass composite optical fiber achieves isotropic broadband tunable frequency doubling output.

[0104] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing LiTaO3 microcrystalline-glass composite optical fiber, characterized in that, Includes the following steps: (1) TeO2, Bi2O3 and BaCO3 are mixed and sintered for the first time to obtain homogeneous glass; the refractive index of the homogeneous glass is 2.130 and the density is 6.087 g / cm³. 3 The molar ratio of TeO2 to Bi2O3 is 70~85:5~15; the molar ratio of Bi2O3 to BaCO3 is 5~15:5~15. (2) After the homogeneous glass is sintered for the second time, it is cooled to 620~660℃ to obtain molten glass liquid; (3) The LiTaO3 microcrystals and the molten glass liquid are mixed and shaped to obtain the fiber core; the particle size of the LiTaO3 microcrystals is 30~50μm; the mass ratio of the LiTaO3 microcrystals to the molten glass liquid is 1~4:96~99; (4) The fiber core is inserted into the cladding and then heated for drawing to obtain LiTaO3 microcrystalline-glass composite optical fiber; the heating temperature is 600~700℃.

2. The preparation method according to claim 1, characterized in that, The cladding is heavy flint ZF4 optical glass.

3. The preparation method according to claim 1, characterized in that, The first sintering temperature is 800~900℃, and the holding time is more than 10 minutes.

4. The preparation method according to claim 1, characterized in that, The second sintering temperature is 750℃, and the holding time is 5~20min.

5. The preparation method according to claim 1, characterized in that, The wire drawing speed is 0.3~0.5m / s; the target diameter of the wire drawing is 300~600μm.

6. The LiTaO3 microcrystalline-glass composite optical fiber obtained by the preparation method according to any one of claims 1 to 5 includes a core and a cladding covering the outer layer of the core; the core is LiTaO3 microcrystalline-glass; the LiTaO3 microcrystalline-glass includes LiTaO3 microcrystals and a glass matrix; the refractive index difference between the LiTaO3 microcrystals and the glass matrix is ​​less than 0.

05.

7. The LiTaO3 microcrystalline-glass composite optical fiber according to claim 6, characterized in that, The diameter of the fiber core is 100~200μm; the diameter of the LiTaO3 microcrystalline-glass composite optical fiber is 300~600μm.

8. The application of the LiTaO3 microcrystalline-glass composite optical fiber according to any one of claims 6 to 7 in the field of nonlinear optics.

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