A holmium and ytterbium co-doped mid-infrared microsphere Raman laser and a preparation method thereof

Abstract

The application provides a holmium and ytterbium co-doped mid-infrared microsphere Raman laser and a preparation method thereof, relates to the technical field of laser preparation, and comprises an infrared transmission optical fiber, a pump light source, holmium and ytterbium co-doped tellurite glass microspheres and passive tellurite glass microspheres; the pump light emitted by the pump light source is guided to a taper region through the infrared transmission optical fiber and is optically coupled with the holmium and ytterbium co-doped tellurite glass microspheres and the passive tellurite glass microspheres in sequence; in the holmium and ytterbium co-doped tellurite glass microspheres, the doping amount of holmium is 0.3% and the doping amount of ytterbium is 0.45% according to the mass percentage. Compared with the prior art, the cascade structure of the holmium and ytterbium co-doped microspheres and the passive microspheres realizes three-step wavelength conversion of pump light-rare earth ion oscillation-Raman frequency shift in a single system for the first time, and breaks through the wavelength limitation of the traditional single microsphere depending on the fixed energy level of rare earth ions.

Description

Technical Field

[0001] This invention relates to the field of laser fabrication technology, and more specifically, to a holmium-ytterbium co-doped mid-infrared microsphere Raman laser and its fabrication method. Background Technology

[0002] The mid-infrared band (2-5 μm) covers the "fingerprint region" of characteristic absorptions of various molecular vibrational-rotational energy levels, possessing irreplaceable strategic value in fields such as trace gas detection, biomedical diagnostics, environmental monitoring, free-space communication, and infrared countermeasures. Achieving high-performance, miniaturized laser sources in this band is one of the core challenges driving the development of mid-infrared photonics technology.

[0003] Currently, commercial mid-infrared lasers mainly include quantum cascade lasers (QCLs), optical parametric oscillators (OPOs), and semiconductor lasers, which generally suffer from bottlenecks such as system complexity, high power consumption, stringent temperature control, or high cost. Whispering Gallery Mode (WGM) optical microcavities, with their ultra-high quality factor and extremely small mode volume, can significantly enhance light-matter interactions and lower the laser threshold, providing a new paradigm for developing compact, low-power lasers. However, rare-earth ion doping (such as Er)... 3+ , Tm 3+ Ho 3+ Microsphere lasers are limited by the ion energy level structure, resulting in a fixed output wavelength that is difficult to tune flexibly. Microcavity lasers based on stimulated Raman scattering (SRS) convert pump photons into longer-wavelength Stokes photons through the Raman gain provided by the vibrational energy levels of the medium molecules, thereby achieving a redshift extension of the laser wavelength.

[0004] Currently, in the research of microsphere-based Raman lasers, microspheres are typically fabricated using different glass materials and coupled to fiber tapers. In 2013, Vanier et al. based their work on high-performance optical fiber lasers... Q value( Q >7×10 7 Using As2S3 glass microspheres, and employing fused taper technology combined with evanescent wave coupling via silica tapered optical fibers, they achieved Raman laser emission at 1636.47 nm in a chalcogenide compound microcavity for the first time. In 2023, Anashkina's team achieved Raman laser output at 1800 nm in a tellurate glass microcavity for the first time. Simultaneously, they realized a three-wavelength cascaded Raman laser, extending the Raman laser wavelength to 2010 nm. In 2020, Andrianov et al., based on fused silica microspheres (… Q ≈2×10 7), by coupling the C-band tunable pump laser (1520-1570 nm) through the fiber taper evanescent field, the first single-mode U-band (1631-1685 nm) Raman laser with a wide spectrum tuning range of 54 nm is achieved. Although the whispering gallery mode microcavity provides an ideal platform for low threshold Raman laser, the output wavelength of the existing research is still limited to the 1.6-2 μm band. The core problem of its expansion to >2 μm mid-infrared is that the mid-infrared Raman laser usually needs >2 μm pump source, and such light source is costly and limited in efficiency. SUMMARY

[0005] To overcome the defects of the prior art, the present application provides a holmium-ytterbium co-doped mid-infrared microsphere Raman laser, which is prepared by preparing Ho 3+ / Yb 3+ co-doped tellurite glass microspheres to achieve high-efficiency laser output in the 2.1 μm band; then, the same homologous high Q value passive tellurite microspheres are pumped by the laser to expand the Raman laser output wavelength to a longer band through Raman gain.

[0006] The present application provides a holmium-ytterbium co-doped mid-infrared microsphere Raman laser, comprising,

[0007] Infrared transmission optical fiber: a taper region is arranged in the middle of the infrared transmission optical fiber;

[0008] Pump light source: arranged at one end of the infrared transmission optical fiber;

[0009] Holmium-ytterbium co-doped tellurite glass microspheres and passive tellurite glass microspheres: both arranged in the taper region and sequentially arranged away from the pump light source;

[0010] The pump light emitted by the pump light source is guided to the taper region through the infrared transmission optical fiber and sequentially optically coupled with the holmium-ytterbium co-doped tellurite glass microspheres and the passive tellurite glass microspheres;

[0011] In the holmium-ytterbium co-doped tellurite glass microspheres, the doping amount of holmium element is 0.3% and the doping amount of ytterbium element is 0.45% according to the mass percentage.

[0012] Compared with the prior art, the present application realizes three-step wavelength conversion of pump light→rare earth ion lasing→Raman frequency shift in a single system through the cascade structure of holmium-ytterbium co-doped tellurite glass microspheres and passive tellurite glass microspheres, breaks through the wavelength limitation of traditional single microsphere relying on fixed energy level of rare earth ions, expands the mid-infrared laser output to a longer band with a more compact and low-cost solution, and avoids the essential limitation of the homologous microcavity still directly relying on the energy level of rare earth ions (such as erbium ion 2.7 μm) in the prior art, thereby providing a new path for flexible expansion of the mid-infrared band.

[0013] Specifically, the application adopts the holmium-ytterbium co-doped tellurite glass microspheres with the above-mentioned doping amount, and through accurate cooperation of holmium-ytterbium ion concentration, efficient sensitized energy transfer is realized in the tellurite glass microspheres, which not only guarantees high gain lasing in the 2.1 μm band to drive subsequent Raman frequency shift, but also completely avoids the inherent contradiction between low concentration gain deficiency and high concentration quenching loss, and provides an irreplaceable stable pumping source for cascade wavelength expansion.

[0014] In a possible implementation, the ratio of the diameter of the holmium-ytterbium co-doped tellurite glass microspheres to the diameter of the passive tellurite glass microspheres is 1: (1.2-1.5).

[0015] Compared with the prior art, by accurately matching the optical mode volume and the resonance frequency of the double microspheres, the evanescent field coupling efficiency of the Raman gain in the passive tellurite glass microspheres is significantly enhanced while guaranteeing efficient pumping conversion (2.1 μm lasing) of the holmium-ytterbium co-doped tellurite glass microspheres, the mode mismatch bottleneck in traditional single-size microsphere cascade is broken through, the maximization of cross-band energy transfer is realized, and an optimal photon environment is provided for wavelength expansion to the mid-infrared.

[0016] In a possible implementation, the holmium-ytterbium co-doped tellurite glass microspheres and the passive tellurite glass microspheres are prepared by the following preparation method:

[0017] S1, raw materials of the holmium-ytterbium co-doped tellurite glass microspheres and the passive tellurite glass microspheres are respectively weighed, and holmium-ytterbium co-doped tellurite glass and passive tellurite glass are respectively prepared by a melting method;

[0018] S2, the holmium-ytterbium co-doped tellurite glass and the passive tellurite glass prepared in step S1 are respectively made into holmium-ytterbium co-doped tellurite glass powder and passive tellurite glass powder, and then the two kinds of powders are respectively subjected to melting and cooling treatment in sequence to prepare the holmium-ytterbium co-doped tellurite glass microspheres and the passive tellurite glass microspheres.

[0019] Compared with the prior art, by synchronously realizing accurate matching of the physical and chemical properties of the double microsphere matrices through homogenization melting and cooling process, the interface loss of heterogeneous materials is completely eliminated, the passive microspheres are provided with an ultra-low scattering surface and a high Q resonant cavity required for Raman gain while guaranteeing efficient rare earth ion lasing (2.1 μm) of the active microspheres, and the stability and conversion efficiency of the cascade wavelength expansion break through the limit of traditional split preparation.

[0020] In a possible implementation, the specific operation of step S1 is as follows: raw materials of the holmium and ytterbium co-doped tellurite glass microsphere and the passive tellurite glass microsphere are respectively melted to obtain holmium and ytterbium co-doped tellurite glass liquid and passive tellurite glass liquid, and oxygen is continuously introduced while stirring during the melting process; the holmium and ytterbium co-doped tellurite glass liquid and the passive tellurite glass liquid are respectively transferred to an annealing furnace for cooling treatment, and then holmium and ytterbium co-doped tellurite glass and passive tellurite glass are obtained.

[0021] Compared with the prior art, the oxygen stirring effectively inhibits the formation of reduction color centers and reduces component segregation, so that the material has ultra-low intrinsic absorption and scattering characteristics (hydroxyl absorption coefficient <0.01 cm -1 ); in addition, the precise control of the annealing process locks the glass network uniformity, and a highly consistent (deviation <10 -4 ) double-microsphere matrix is obtained, which provides a highly consistent physical carrier for cascade pumping conversion and Raman gain.

[0022] In a possible implementation, the flow rate of the introduced oxygen is 0.5-2 L / min, the melting temperature is 1080-1100°C, the initial temperature of the annealing furnace is 400-410°C, and the annealing time is 11-12 h.

[0023] Compared with the prior art, the core advantage of the combination of process parameters is that, by precise coordination of oxidation purification, melt rheological control and glass network freezing rate, zero defects, ultra-low hydroxyl and high uniformity of the double-microsphere matrix are achieved at the molecular scale, and the triple loss of optical scattering, ion segregation and structural stress caused by parameter mismatch in the traditional process is completely avoided.

[0024] In a possible implementation, the infrared transmission optical fiber provided with a tapered region in the middle is prepared by a fusion tapering method, and specifically includes the following steps:

[0025] A1, take an infrared transmission optical fiber, make the two ends of the infrared transmission optical fiber into FC interfaces, and remove the coating layer in the middle part to obtain a semi-naked infrared transmission optical fiber;

[0026] A2, place the two ends of the semi-naked infrared transmission optical fiber in the V-shaped grooves of the infrared transmission optical fiber clamping platform respectively and fix them;

[0027] A3, rotate the three-dimensional adjusting knob connected to the heating copper block, move it to the tapering region of the semi-naked infrared transmission optical fiber, and set the heating temperature and the stretching speed of the stepping motor;

[0028] A4, when the semi-naked infrared transmission optical fiber to be heated softens and deforms, start the tapering program to gradually thin the middle section of the infrared transmission optical fiber;

[0029] A5, after the completion of the pull, the U-shaped aluminum block is placed on the three-dimensional adjusting platform, the conical area of the infrared transmitting optical fiber is in contact with the surface of the aluminum block, and then hot air is used to heat the molten salicylic acid as an adhesive to permanently fix the conical area of the infrared transmitting optical fiber on the surface of the aluminum block.

[0030] Compared with the prior art, the application realizes the atomic-level accurate regulation of the conical area (diameter 0.5-2 mu m) and the surface finish (roughness <1 nm) under the premise of no damage by matching the critical point of the viscoelastic transition of the infrared glass and the dynamic balance window of the surface tension, simultaneously forming the sub-micron geometric precision of the conical area and the zero-defect optical surface at the atomic scale, and completely avoiding the triple failure risks of necking fracture, crystallization precipitation or modal distortion caused by the temperature and speed mismatch in the traditional process.

[0031] In a possible implementation, the heating temperature in step A4 is 300-600 DEG C, and the stretching speed is 0.08-0.1 mm / s.

[0032] Compared with the prior art, the application has the advantages of the above parameters: accurately matching the critical point of the viscoelastic transition of the infrared glass and the dynamic balance window of the surface tension, simultaneously forming the sub-micron geometric precision of the conical area and the zero-defect optical surface at the atomic scale, and completely avoiding the triple failure risks of necking fracture, crystallization precipitation or modal distortion caused by the temperature and speed mismatch in the traditional process.

[0033] In a possible implementation, the pump light source is a 976 nm laser diode pump.

[0034] Compared with the prior art, the application can perfectly match the ytterbium ion absorption peak by using the above pump light source, drive the holmium ion energy level transition through high-efficiency sensitization energy transfer, provide the original driving force for the three-level energy chain of excitation-conversion-Raman frequency shift for the cascade system with low cost and high reliability of mature commercial devices, and completely avoid the fatal bottleneck of expensive and inefficient traditional mid-infrared pump sources.

[0035] In a possible implementation, the infrared transmitting optical fiber is selected from one of tellurite optical fiber, chalcogenide optical fiber and fluoride optical fiber.

[0036] Compared with the prior art, the application cooperates with the phonon characteristics of the microsphere matrix by matching the super-wide low-loss transmission window of the full-waveband of the cascade system and the phonon characteristics of the microsphere matrix, simultaneously guarantees the near-infrared pump efficient injection, the mid-infrared emission lossless conduction and the Raman frequency shift photon capture in a single optical fiber, completely avoids the interface loss and waveband truncation risk of heterogeneous optical fiber splicing, and provides a full-link photon transport channel for wavelength cascade.

[0037] The second object of the application is to provide a preparation method of a holmium-ytterbium co-doped mid-infrared microsphere Raman laser.

[0038] B1, the holmium and ytterbium co-doped tellurite glass microspheres and passive tellurite glass microspheres are placed in the taper region of the infrared transmission optical fiber, the pump light generated by the pump light source is coupled with the holmium and ytterbium co-doped tellurite glass microspheres through the infrared transmission optical fiber, and the rare earth ions are excited to generate 2.1 mu m laser;

[0039] B2, the 2.1 mu m laser is used as secondary pump light, and the Raman laser emission is realized by coupling the passive tellurite glass microspheres with the infrared transmission optical fiber.

[0040] Compared with the prior art, the preparation method is adopted, the process integration of double-microsphere cascade pumping is realized through the same fiber taper region, the atomic-level light path cooperation of "excitation-frequency shift" seamless connection is realized, the positioning error of the traditional scheme and the interface loss are completely avoided, the process is simplified, and the quantum efficiency limit of the wavelength expansion of >2.1 mu m is guaranteed. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 The preparation method flow chart of the holmium and ytterbium co-doped mid-infrared microsphere Raman laser of the present application;

[0042] Figure 2 The principle diagram of the holmium and ytterbium co-doped mid-infrared microsphere Raman laser of the present application;

[0043] Figure 3 The single-mode laser characteristic diagram of the holmium and ytterbium co-doped mid-infrared microsphere Raman laser of the present application.

[0044] BRIEF DESCRIPTION OF DRAWINGS

[0045] 1-laser diode; 2-infrared transmission optical fiber; 3-taper region; 4-holmium and ytterbium co-doped tellurite glass microspheres; 5-passive tellurite glass microspheres; 6-truncated optical fiber; 7-optical spectrum analyzer. DETAILED DESCRIPTION

[0046] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation method and typical parameters of the present application, and are not used to limit the parameter range described in the present application, and the reasonable changes derived therefrom are still within the protection scope of the claims of the present application.

[0047] It is to be understood that the endpoints of the ranges specified in this disclosure are not to be understood as being limited to the exact range. It is also to be understood that the description is not to be limited in scope by any explicit or implicit disclosure of a specific range or value since most such ranges or values will be understood as being modifiable by the use of the term "about" preceding that range or value. For example, a range of "from 1 to 5" is to be understood as including the value of 5 and the value of 1, and any value in between, such as 1.1, 1.2, 1.3, 1.4, and 1.5, up to the value of 5. Similarly, a value of "about 5" is to be understood as including the value of 5 and any value in the range of 1 to 5, such as 1.1, 1.2, 1.3, 1.4, and 1.5, up to the value of 5. It is intended that the description be considered as exemplary and not restrictive of the scope of the disclosure. For the avoidance of doubt, the fact that certain features of the disclosure are not described in each and every form of the disclosure herein disclosed is not to be interpreted as an omission or a suggestion that a modification or an alternative to an aspect, feature, or implementation of the disclosure is not deemed to be an embodiment of the disclosure.

[0048] Unless defined otherwise, all terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. In some instances, terms with commonly understood meanings are defined herein for clarity. Such definitions are not to be understood in a manner that would utilize the terms in any way contrary to their normal use but, rather, describe definitions to give more insight into the description of the application. The technical methods described or referenced herein are generally well understood by those skilled in the art and are performed by routine methods, unless otherwise indicated. Unless otherwise stated, the use of commercially available kits and reagents, and the use of instruments are performed according to the protocols and parameters given by the manufacturer.

[0049] The specific embodiments of the present application provide a holmium and ytterbium co-doped mid-infrared microsphere Raman laser, comprising:

[0050] Infrared transmission fiber 2: The middle part of the infrared transmission fiber 2 is provided with a taper zone 3, and the infrared transmission fiber 2 is selected from one of a tellurite optical fiber, a chalcogenide optical fiber and a fluoride optical fiber;

[0051] Laser diode 1: arranged at one end of the infrared transmission fiber 2, in the embodiments of the present application, the laser diode 1 all adopts a 976 nm laser diode.

[0052] Holmium and ytterbium co-doped tellurite glass microsphere 4 and passive tellurite glass microsphere 5: both arranged in the taper zone 3 and arranged in sequence in the direction away from the pump light source (i.e. the laser diode 1), and the ratio of the diameter of the holmium and ytterbium co-doped tellurite glass microsphere 4 to the diameter of the passive tellurite glass microsphere 5 is 1: (1.2-1.5), in the holmium and ytterbium co-doped tellurite glass microsphere 4, the doping amount of holmium element is 0.3% and the doping amount of ytterbium element is 0.45% according to the mass percentage;

[0053] The pump light emitted by the laser diode 1 is guided to the taper zone 3 through the infrared transmission fiber 2, and sequentially optically coupled with the holmium and ytterbium co-doped tellurite glass microsphere 4 and the passive tellurite glass microsphere 5.

[0054] The holmium and ytterbium co-doped tellurite glass microsphere 4 and the passive tellurite glass microsphere 5 are prepared by the following preparation method:

[0055] S1, raw materials of the holmium and ytterbium co-doped tellurite glass microsphere 4 and the passive tellurite glass microsphere 5 are respectively melted to obtain holmium and ytterbium co-doped tellurite glass liquid and passive tellurite glass liquid, and in the melting process, oxygen is continuously introduced while stirring, the flow rate of the introduced oxygen is 0.5-2L / min, the melting temperature is 1080-1100℃, and the holmium and ytterbium co-doped tellurite glass liquid and the passive tellurite glass liquid are respectively transferred to an annealing furnace for cooling treatment to obtain holmium and ytterbium co-doped tellurite glass and passive tellurite glass, wherein the initial temperature of the annealing furnace is 400-410℃, and the annealing time is 11-12h;

[0056] S2, the holmium and ytterbium co-doped tellurite glass and the passive tellurite glass prepared in step S1 are respectively made into holmium and ytterbium co-doped tellurite glass powder and passive tellurite glass powder, and then the two kinds of powders are respectively subjected to melting and cooling treatment in sequence to prepare the holmium and ytterbium co-doped tellurite glass microsphere 4 and the passive tellurite glass microsphere 5, and the above preparation steps have been maturely applied in the prior art, and thus will not be described herein.

[0057] In the specific embodiment, the infrared transmission optical fiber 2 provided with the taper region in the middle is prepared by a fusion tapering method, and specifically includes the following steps:

[0058] A1, the infrared transmission optical fiber 2 is taken, both ends of the infrared transmission optical fiber 2 are made into FC interfaces, and the coating layer in the middle part is removed to obtain a semi-naked infrared transmission optical fiber;

[0059] A2, both ends of the semi-naked infrared transmission optical fiber are respectively placed in the V-shaped groove of the infrared transmission optical fiber clamping platform and fixed;

[0060] A3, a three-dimensional adjusting knob connected with a heating copper block is rotated, the heating copper block is moved to the tapering region of the semi-naked infrared transmission optical fiber, and the heating temperature is set to 300-600℃ and the stretching speed of the stepping motor is set to 0.08-0.1mm / s;

[0061] A4, when the to-be-heated region of the semi-naked infrared transmission optical fiber is softened and deformed, the tapering program is started, the middle section of the infrared transmission optical fiber 2 is gradually thinned, and the taper region 3 in the middle of the infrared transmission optical fiber 2 is formed;

[0062] A5, after the tapering is completed, the U-shaped aluminum block is placed on the three-dimensional adjusting platform, the taper region 3 of the infrared transmission optical fiber 2 is accurately adjusted to be in contact with the surface of the aluminum block, and then the hot air heating salicylic acid as an adhesive is adopted to permanently fix the taper region 3 of the infrared transmission optical fiber 2 on the surface of the aluminum block.

[0063] As shown in Figure 1 , the application also provides a preparation method of a holmium and ytterbium co-doped mid-infrared microsphere Raman laser, and the preparation method specifically includes the following steps:

[0064] B1, the holmium and ytterbium co-doped tellurite glass microspheres 4 and the passive tellurite glass microspheres 5 are placed in the taper region 3 of the infrared transmission optical fiber 2, the pump light generated by the pump light source (i.e. the laser diode 1) is guided to the taper region 3 through the infrared transmission optical fiber 2 and coupled with the holmium and ytterbium co-doped tellurite glass microspheres 4, and the rare earth ions are excited to generate 2.1 μm laser;

[0065] B2, the 2.1 μm laser is used as the secondary pump light, and the Raman laser emission is realized by coupling the infrared transmission optical fiber 2 with the passive tellurite glass microspheres 5 through the taper region 3.

[0066] As shown in Figure 2 , in the specific operation, the specific steps of step B1 are as follows: the holmium and ytterbium co-doped tellurite glass microspheres 4 are picked out by the truncated optical fiber 6 and attached to the inner surface of the glass tube by the action of the ultraviolet curing glue, then the glass tube is fixed on the three-dimensional adjusting frame; the three-dimensional platform is adjusted to couple the holmium and ytterbium co-doped tellurite glass microspheres 4 with the taper region 3 of the infrared transmission optical fiber 2; and the pump light is guided into the taper region 3 of the infrared transmission optical fiber 2 through the infrared transmission optical fiber 2, and the pump light is optically coupled with the holmium and ytterbium co-doped tellurite glass microspheres 4, the rare earth ions in the holmium and ytterbium co-doped tellurite glass microspheres 4 are excited, and the 2.1 μm laser emission is realized.

[0067] As shown in Figure 2 , the finally output Raman laser is transmitted to the spectrum analyzer 7 through the infrared transmission optical fiber 2.

[0068] Embodiment 1

[0069] The embodiment provides a holmium and ytterbium co-doped mid-infrared microsphere Raman laser, which comprises:

[0070] The infrared transmission optical fiber 2: the middle part of the infrared transmission optical fiber 2 is provided with a taper region 3, and the infrared transmission optical fiber 2 is a tellurite optical fiber;

[0071] The laser diode 1: arranged at one end of the infrared transmission optical fiber 2;

[0072] The holmium and ytterbium co-doped tellurite glass microspheres 4 and the passive tellurite glass microspheres 5: both are placed in the taper region 3 and are arranged in sequence in the direction away from the laser diode 1, and the diameter ratio of the holmium and ytterbium co-doped tellurite glass microspheres 4 to the passive tellurite glass microspheres 5 is 1:1.2, and in the holmium and ytterbium co-doped tellurite glass microspheres 4, the doping amount of holmium element is 0.3% and the doping amount of ytterbium element is 0.45% according to the mass percentage;

[0073] The pump light emitted by the laser diode 1 is guided to the taper region 3 through the infrared transmission optical fiber 2, and is optically coupled with the holmium and ytterbium co-doped tellurite glass microspheres 4 and the passive tellurite glass microspheres 5 in sequence.

[0074] The holmium-ytterbium co-doped tellurite glass microsphere 4 and the passive tellurite glass microsphere 5 are prepared by the following preparation method:

[0075] S1, raw materials of the holmium-ytterbium co-doped tellurite glass microsphere 4 and the passive tellurite glass microsphere 5 are melted respectively to obtain holmium-ytterbium co-doped tellurite glass liquid and passive tellurite glass liquid, and in the melting process, oxygen is continuously introduced while stirring, the flow rate of oxygen introduced is 0.5L / min, the melting temperature is 1080℃, and the holmium-ytterbium co-doped tellurite glass liquid and the passive tellurite glass liquid are respectively transferred to an annealing furnace for cooling treatment, then holmium-ytterbium co-doped tellurite glass and passive tellurite glass are obtained, wherein the initial temperature of the annealing furnace is 400℃, and the annealing time is 12h;

[0076] S2, the holmium-ytterbium co-doped tellurite glass and the passive tellurite glass obtained in step S1 are respectively made into holmium-ytterbium co-doped tellurite glass powder and passive tellurite glass powder, and then the two kinds of powders are respectively subjected to melting and cooling treatment in sequence to obtain the holmium-ytterbium co-doped tellurite glass microsphere 4 and the passive tellurite glass microsphere 5, and the above preparation steps have been maturely applied in the prior art, and thus will not be described herein.

[0077] The infrared transmission optical fiber 2 provided with a tapered region in the middle part in the embodiment is prepared by a fusion tapering method, and specifically includes the following steps:

[0078] A1, the infrared transmission optical fiber 2 is taken, both ends of the infrared transmission optical fiber 2 are made into FC interfaces, and the coating layer of the middle part is removed to obtain a semi-naked infrared transmission optical fiber;

[0079] A2, both ends of the semi-naked infrared transmission optical fiber are respectively placed in the V-shaped groove of the infrared transmission optical fiber clamping platform and fixed;

[0080] A3, a three-dimensional adjusting knob connected with a heating copper block is rotated, the heating copper block is moved to the tapering region of the semi-naked infrared transmission optical fiber, and then the heating temperature is set to 300℃ and the stretching speed of the stepping motor is set to 0.08mm / s;

[0081] A4, when the to-be-heated region of the semi-naked infrared transmission optical fiber is softened and deformed, the tapering program is started, the middle section of the infrared transmission optical fiber 2 is gradually thinned, and the tapered region 3 in the middle of the infrared transmission optical fiber 2 is formed;

[0082] A5, after the tapering is completed, the U-shaped aluminum block is placed on the three-dimensional adjusting platform, the tapered region 3 of the infrared transmission optical fiber 2 is accurately adjusted to be in contact with the surface of the aluminum block, and then the hot air heating salicylic acid as an adhesive is adopted to permanently fix the tapered region 3 of the infrared transmission optical fiber 2 on the surface of the aluminum block.

[0083] Figure 3 The single-mode laser characteristic diagram of the holmium-ytterbium co-doped mid-infrared microsphere Raman laser prepared in the embodiment is shown in Figure 2, from which it can be seen that the holmium-ytterbium co-doped mid-infrared microsphere Raman laser has a single-mode laser characteristic. Figure 3It can be seen that the holmium and ytterbium co-doped mid-infrared microsphere Raman laser prepared by the application can realize 2.1 μm laser emission.

[0084] Embodiment 2

[0085] The embodiment provides a holmium and ytterbium co-doped mid-infrared microsphere Raman laser, which comprises:

[0086] The infrared transmission optical fiber 2 is provided with a taper zone 3 in the middle part, and the infrared transmission optical fiber 2 is a fluoride optical fiber;

[0087] The laser diode 1 is arranged at one end of the infrared transmission optical fiber 2;

[0088] The holmium and ytterbium co-doped tellurite glass microsphere 4 and the passive tellurite glass microsphere 5 are both arranged in the taper zone 3 and sequentially arranged in the direction away from the laser diode 1, and the diameter ratio of the holmium and ytterbium co-doped tellurite glass microsphere 4 to the passive tellurite glass microsphere 5 is 1:1.5, and in the holmium and ytterbium co-doped tellurite glass microsphere 4, the doping amount of holmium element is 0.3% and the doping amount of ytterbium element is 0.45% according to the mass percentage;

[0089] The pump light emitted by the laser diode 1 is guided to the taper zone 3 through the infrared transmission optical fiber 2 and sequentially optically coupled with the holmium and ytterbium co-doped tellurite glass microsphere 4 and the passive tellurite glass microsphere 5.

[0090] The holmium and ytterbium co-doped tellurite glass microsphere 4 and the passive tellurite glass microsphere 5 are prepared by the following preparation method:

[0091] S1, raw materials of the holmium and ytterbium co-doped tellurite glass microsphere 4 and the passive tellurite glass microsphere 5 are melted respectively to obtain holmium and ytterbium co-doped tellurite glass liquid and passive tellurite glass liquid, and in the melting process, oxygen is continuously introduced while stirring, the flow rate of the introduced oxygen is 1.5 L / min, the melting temperature is 1100℃, and the holmium and ytterbium co-doped tellurite glass liquid and the passive tellurite glass liquid are respectively transferred to an annealing furnace for cooling treatment, and then holmium and ytterbium co-doped tellurite glass and passive tellurite glass are obtained, wherein the initial temperature of the annealing furnace is 410℃ and the annealing time is 11h;

[0092] S2, the holmium and ytterbium co-doped tellurite glass and the passive tellurite glass prepared in step S1 are respectively made into holmium and ytterbium co-doped tellurite glass powder and passive tellurite glass powder, and then the two kinds of powders are respectively sequentially subjected to melting and cooling treatment to prepare the holmium and ytterbium co-doped tellurite glass microsphere 4 and the passive tellurite glass microsphere 5, and the above preparation steps have been maturely applied in the prior art, and thus will not be described herein.

[0093] The infrared transmission optical fiber 2 provided with the taper zone in the middle part in the embodiment is prepared by a fusion tapering method, and specifically includes the following steps:

[0094] A1, take the infrared transmission optical fiber 2, make the two ends of the infrared transmission optical fiber 2 into FC interfaces, and remove the coating layer of the middle part to obtain a semi-naked infrared transmission optical fiber;

[0095] A2, place the two ends of the semi-naked infrared transmission optical fiber in the V-shaped grooves of the infrared transmission optical fiber clamping platform, respectively, and fix them;

[0096] A3, rotate the three-dimensional adjusting knob connected to the heating copper block, move it to the tapering region of the semi-naked infrared transmission optical fiber, set the heating temperature to 600 DEG C, and set the stretching speed of the stepping motor to 0.1 mm / s;

[0097] A4, when the semi-naked infrared transmission optical fiber softens and deforms, start the tapering program, and make the middle section of the infrared transmission optical fiber 2 gradually taper, forming a taper region 3 in the middle of the infrared transmission optical fiber 2;

[0098] A5, after the tapering is completed, place the U-shaped aluminum block on the three-dimensional adjusting platform, accurately adjust the infrared transmission optical fiber 2 taper region 3 and the aluminum block surface contact, and then use hot air to heat the fused salicylic acid as an adhesive to permanently fix the infrared transmission optical fiber 2 taper region 3 on the aluminum block surface.

[0099] Example 3

[0100] The embodiment provides a holmium and ytterbium co-doped mid-infrared microsphere Raman laser, comprising:

[0101] Infrared transmission optical fiber 2: the middle part of the infrared transmission optical fiber 2 is provided with a taper region 3, and the infrared transmission optical fiber 2 is a tellurite optical fiber;

[0102] Laser diode 1: arranged at one end of the infrared transmission optical fiber 2;

[0103] Holmium and ytterbium co-doped tellurite glass microsphere 4 and passive tellurite glass microsphere 5: both arranged in the taper region 3 and sequentially arranged away from the laser diode 1, and the diameter ratio of the holmium and ytterbium co-doped tellurite glass microsphere 4 to the passive tellurite glass microsphere 5 is 1:1.3, and in the holmium and ytterbium co-doped tellurite glass microsphere 4, the doping amount of holmium element is 0.3% and the doping amount of ytterbium element is 0.45% according to the mass percentage;

[0104] The pump light emitted by the laser diode 1 is guided to the taper region 3 through the infrared transmission optical fiber 2, and sequentially optically coupled with the holmium and ytterbium co-doped tellurite glass microsphere 4 and the passive tellurite glass microsphere 5.

[0105] The holmium and ytterbium co-doped tellurite glass microsphere 4 and the passive tellurite glass microsphere 5 are prepared by the following preparation method:

[0106] S1, raw materials of the holmium-ytterbium co-doped tellurite glass microsphere 4 and the passive tellurite glass microsphere 5 are respectively melted to obtain holmium-ytterbium co-doped tellurite glass liquid and passive tellurite glass liquid, and in the melting process, oxygen is continuously introduced while stirring, the flow rate of the introduced oxygen is 2L / min, the melting temperature is 1090℃, and after the holmium-ytterbium co-doped tellurite glass liquid and the passive tellurite glass liquid are respectively transferred to an annealing furnace for cooling treatment, holmium-ytterbium co-doped tellurite glass and passive tellurite glass are obtained, wherein the initial temperature of the annealing furnace is 405℃, and the annealing time is 11.5h;

[0107] S2, the holmium-ytterbium co-doped tellurite glass and the passive tellurite glass obtained in step S1 are respectively made into holmium-ytterbium co-doped tellurite glass powder and passive tellurite glass powder, and then the two kinds of powders are respectively sequentially subjected to melting and cooling treatment to prepare the holmium-ytterbium co-doped tellurite glass microsphere 4 and the passive tellurite glass microsphere 5, and the above preparation steps have been maturely applied in the prior art, and thus will not be described herein.

[0108] The infrared transmission optical fiber 2 provided with a tapered region in the middle part in the embodiment is prepared by a fusion tapering method, and specifically includes the following steps:

[0109] A1, the infrared transmission optical fiber 2 is taken, both ends of the infrared transmission optical fiber 2 are made into FC interfaces, and the coating layer of the middle part is removed to obtain a semi-naked infrared transmission optical fiber;

[0110] A2, both ends of the semi-naked infrared transmission optical fiber are respectively placed in the V-shaped groove of the infrared transmission optical fiber clamping platform and fixed;

[0111] A3, a three-dimensional adjusting knob connected to a heating copper block is rotated, the heating copper block is moved to the tapering region of the semi-naked infrared transmission optical fiber, and the heating temperature is set to 450℃ and the stretching speed of the stepping motor is set to 0.09mm / s;

[0112] A4, when the to-be-heated region of the semi-naked infrared transmission optical fiber is softened and deformed, the tapering program is started, the middle section of the infrared transmission optical fiber 2 is gradually thinned, and the tapered region 3 in the middle part of the infrared transmission optical fiber 2 is formed;

[0113] A5, after the tapering is completed, the U-shaped aluminum block is placed on the three-dimensional adjusting platform, the tapered region 3 of the infrared transmission optical fiber 2 is accurately adjusted to be in contact with the surface of the aluminum block, and then the hot air heating salicylic acid as an adhesive is used to permanently fix the tapered region 3 of the infrared transmission optical fiber 2 on the surface of the aluminum block.

[0114] Although the present disclosure is disclosed as above, the protection scope of the present disclosure is not limited to this. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications will fall within the protection scope of the present disclosure.

Claims

1. A holmium and ytterbium co-doped mid-infrared microsphere Raman laser, characterized in that, The application relates to a kind of infrared transmission optical fiber and preparation method thereof. The infrared transmission optical fiber comprises: An infrared transmission optical fiber, wherein a middle part of the infrared transmission optical fiber is provided with a taper region; A pump light source arranged at one end of the infrared transmission optical fiber; Holmium and ytterbium co-doped tellurite glass microspheres and passive tellurite glass microspheres, which are arranged in the taper region in sequence and away from the pump light source; The pump light source emits pump light, which is guided to the taper region through the infrared transmission optical fiber and is optically coupled with the holmium and ytterbium co-doped tellurite glass microspheres and the passive tellurite glass microspheres in sequence.

2. The holmium and ytterbium co-doped mid-infrared microsphere Raman laser of claim 1, wherein, In the holmium and ytterbium co-doped tellurite glass microspheres, the doping amount of holmium element is 0.3% and the doping amount of ytterbium element is 0.45% according to mass percentage.

3. The holmium and ytterbium co-doped mid-infrared microsphere Raman laser of claim 1, wherein, The ratio of the diameter of the holmium and ytterbium co-doped tellurite glass microspheres to the diameter of the passive tellurite glass microspheres is 1: (1.2-1.5). The holmium and ytterbium co-doped tellurite glass microspheres and the passive tellurite glass microspheres are prepared by the following method: S1, raw materials of holmium and ytterbium co-doped tellurite glass microspheres and passive tellurite glass microspheres are weighed respectively, and holmium and ytterbium co-doped tellurite glass and passive tellurite glass are prepared by a melting method respectively; 4. The holmium and ytterbium co-doped mid-infrared microsphere Raman laser of claim 3, wherein, S2, the holmium and ytterbium co-doped tellurite glass and the passive tellurite glass prepared in step S1 are respectively made into holmium and ytterbium co-doped tellurite glass powder and passive tellurite glass powder, and then the two kinds of powder are respectively subjected to melting and cooling treatment in sequence to prepare holmium and ytterbium co-doped tellurite glass microspheres and passive tellurite glass microspheres.

5. The holmium and ytterbium co-doped mid-infrared microsphere Raman laser of claim 4, wherein, The specific operation of step S1 is as follows: the raw materials of holmium and ytterbium co-doped tellurite glass microspheres and passive tellurite glass microspheres are melted respectively to obtain holmium and ytterbium co-doped tellurite glass liquid and passive tellurite glass liquid, and oxygen is continuously introduced during the melting process while stirring; the holmium and ytterbium co-doped tellurite glass liquid and the passive tellurite glass liquid are respectively transferred to an annealing furnace for cooling treatment to obtain holmium and ytterbium co-doped tellurite glass and passive tellurite glass.

6. The holmium and ytterbium co-doped mid-infrared microsphere Raman laser as claimed in claim 1, wherein, The flow rate of oxygen introduced is 0.5-2 L / min, the melting temperature is 1080-1100 ℃, the initial temperature of the annealing furnace is 400-410 ℃, and the annealing time is 11-12 h. The infrared transmission optical fiber provided with the taper region in the middle part is prepared by a fusion tapering method, which specifically comprises the following steps: A1, take an infrared transmission optical fiber, make the two ends of the infrared transmission optical fiber into FC interfaces, and remove the coating layer in the middle part to obtain a semi-naked infrared transmission optical fiber; A2, place the two ends of the semi-naked infrared transmission optical fiber in the V-shaped grooves of the infrared transmission optical fiber clamping platform respectively and fix them; A3, rotate the three-dimensional adjusting knob connected with the heating copper block, move it to the tapering region of the semi-naked infrared transmission optical fiber, set the heating temperature and the stretching speed of the stepping motor; A4, when the to-be-heated region of the semi-naked infrared transmission optical fiber softens and deforms, start the tapering program to make the middle segment of the infrared transmission optical fiber gradually taper; A5, after the tapering is completed, place the U-shaped aluminum block on the three-dimensional adjusting platform to make the taper region of the infrared transmission optical fiber contact with the surface of the aluminum block, and then use hot air to heat salicylic acid as an adhesive to permanently fix the taper region of the infrared transmission optical fiber on the surface of the aluminum block.

7. The holmium and ytterbium co-doped mid-infrared microsphere Raman laser of claim 6, wherein, The heating temperature in step A4 is 300-600 ℃, and the stretching speed is 0.08-0.1 mm / s.

8. The holmium and ytterbium co-doped mid-infrared microsphere Raman laser of claim 1, wherein, The pump light source is a 976 nm laser diode pump.

9. The holmium and ytterbium co-doped mid-infrared microsphere Raman laser of claim 1, wherein, The infrared transmission optical fiber is selected from one of tellurite optical fiber, chalcogenide optical fiber and fluoride optical fiber.

10. A method for preparing a holmium and ytterbium co-doped mid-infrared microsphere Raman laser as claimed in any one of claims 1 to 9, characterized in that, The preparation method specifically comprises the following steps: B1, the holmium and ytterbium co-doped tellurite glass microspheres and the passive tellurite glass microspheres are placed in the taper region of the infrared transmission optical fiber, the pump light generated by the pump light source is introduced into the holmium and ytterbium co-doped tellurite glass microspheres through the infrared transmission optical fiber, and the rare earth ions are excited to generate 2.1 μm laser; B2, the 2.1 μm laser is used as secondary pump light, and is coupled to the passive tellurite glass microspheres through the infrared transmission optical fiber, so that Raman laser emission is realized.

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