Optical fiber composite and optical fiber laser light source comprising same

Abstract

Provided is an optical fiber composite applicable to a high-power optical fiber laser and the like, the optical fiber composite comprising: a fibrous laser core; and at least one fibrous heating core adjacent to the laser core, wherein the heating core radiates heat having a temperature gradient, and the heat radiated from the heating core is applied to the laser core. In addition, provided is an optical fiber laser light source comprising the optical fiber composite, wherein, in forward light with respect to a laser output direction, the difference (I2-I1) between a laser peak intensity (I1) (unit: dBm) and a stimulated Brillouin scattering (SBS) peak intensity (I2) (unit: dBm) on an optical output spectrum is about -22.00 dB to about -50.00 dB.

Description

Fiber optic composite and fiber laser light source including the same

[0001] The present invention relates to a fiber laser light source having a single wavelength. The present invention relates to a fiber composite exhibiting a narrow linewidth and high output capable of functioning as a high-power, high-quality laser light source, and a fiber laser light source comprising the same. According to the present invention, a single wavelength fiber laser light source having excellent spectral characteristics, no noise, and stable output characteristics can be provided. The single wavelength laser light source technology according to the present invention can be used in fiber sensor systems, remote optical measurement systems, and the development of high-power laser light sources.

[0002] Single-wavelength fiber laser light sources with excellent and stable spectral characteristics can be widely utilized in fiber optic sensor systems, remote optical measurement systems, and the development of industrial high-power lasers. For example, a single-wavelength fiber laser light source can be used as a reference light source to analyze and correct the measurement characteristics of an optical signal analyzer in a fiber optic sensor system. In addition, in the case of a Distributed Acoustic Sensing (DAS) system, a laser light source with a very narrow linewidth of several to tens of kHz or less is required for coherent optical measurement. Furthermore, laser light sources with a narrow linewidth of several MHz or less are also used in Doppler lidar systems used to measure wind direction and speed.

[0003] Laser is an acronym for Light Amplification by Stimulated Emission of Radiation. Depending on the basic constituent materials, there are various types, including solid-state lasers, gas lasers, semiconductor lasers, dye lasers, fiber lasers, diode lasers, and chemical lasers. Laser technology has become an essential technology not only in scientific and technological fields such as electrical engineering, electronics, physics, chemistry, biology, and medicine, but also in industry and national defense. Stimulated emission refers to the process in which an atom in a high-energy state transitions to a lower-energy state due to external light, generating photons with identical frequency, phase, and polarization. To induce stimulated emission, a high-energy excitation state must first be created. To create this excitation state, energy must be supplied, a process known as pumping. There are various methods of pumping, including optical pumping, electrical pumping, and chemical pumping. Fiber lasers utilize a light source for pumping, and inventions regarding pump light sources are disclosed in Korean Registered Patent No. 10-1423987, among others. The advancement of fiber optic amplifiers and laser technology utilizing them has enabled the development of ultra-high-speed internet technology and is attracting significant attention beyond the field of optical communication to high-power lasers and their applications. Fiber lasers offer excellent cooling characteristics due to the high ratio of the gain medium volume to the external surface area resulting from the geometric properties of the fiber structure. Furthermore, they possess high stability and durability, allow for structural simplification and integration, and are advantageous for miniaturization and lightweighting, making them suitable for a wider range of applications compared to other types of lasers. For example, fiber-based MOPA lasers are used as LADAR (Laser Detection and Ranging) light sources capable of distance measurement and 3D image acquisition, and are high-power pulsed train lasers.A MOPA laser consists of a seed laser and a high-power optical amplifier. The seed laser is a laser that generates a continuous wave or pulse train, and multi-stage optical amplifiers are generally used to generate high-power lasers. Multi-stage amplification is required because the optical output of the seed laser is very small. However, in the case of fiber amplifiers, noise problems can arise not only from effective amplification for the laser but also from amplifier spontaneous emission and spontaneous Brillouin scattering (SBS).

[0004] To construct a fiber laser with a narrow linewidth, various factors must be considered, and the control of SBS is particularly essential. In silica glass optical fibers, SBS is generated by scattering resulting from interactions with the acoustic vibration modes of the glass medium. SBS causes distortion of the laser output spectrum and creates back-reflection in the opposite direction to the laser beam's output, which not only destabilizes the laser output but also causes damage to optical components. A characteristic of SBS generation is that it becomes stronger as the laser beam linewidth becomes narrower.

[0005] For example, since the duty cycle of a pulsed laser output by a seed light source is very small, approximately 1 / 10000, the intensity of the amplification noise after passing the seed light source through an amplifier can be higher than the average output of the seed light source. Generally, even if the amplification noise is filtered, it is difficult to completely eliminate it. Therefore, there is a need to develop technology for noise removal when applying fiber lasers as high-power laser light sources.

[0006] [Prior Art Literature]

[0007] [Patent Literature]

[0008] (Patent Document 1) Republic of Korea Registered Patent No. 10-1423987

[0009] One embodiment of the present invention enables the emission of a high-quality laser without noise such as stimulated Brillouin scattering (SBS) when applied to a high-power fiber laser, and provides a fiber composite with high utility as it is not limited by the application location.

[0010] Another embodiment of the present invention provides a fiber laser light source in which the function of emitting a high-power and high-quality laser is maximized by applying the fiber composite.

[0011] In one embodiment of the present invention, a fiber composite is provided comprising: a fibrous laser core; and at least one fibrous heating core adjacent to the laser core, wherein the heating core radiates heat having a temperature gradient and the heat radiated from the heating core is applied to the laser core.

[0012] The laser core may comprise silica (SiO2) and an additive component, wherein the additive component is one selected from the group consisting of germanium (Ge), phosphorus (P), boron (B), fluorine (F), aluminum (Al), lithium (Li), sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), bismuth (Bi), scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), preseodymium (Pr), neodymium (Nd), promedium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), ruthenium (Lu), and combinations thereof; Alternatively, it may include an oxide derived from one selected from the group consisting of germanium (Ge), phosphorus (P), boron (B), fluorine (F), aluminum (Al), lithium (Li), sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), bismuth (Bi), scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), preseodymium (Pr), neodymium (Nd), promedium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), ruthenium (Lu), and combinations thereof.

[0013] The above heating core may include a heating region, and the heating region may satisfy 1) or 2) below.

[0014] 1) The heating region is continuous in the longitudinal direction

[0015] 2) The heating region is discontinuous in the longitudinal direction

[0016] The heating core may include a heating region, and the heating region includes silica (SiO2) and a heating component, wherein the heating component is scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), zirconium (Zr), niobium (Nb), molybdenum (Mo), technedium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), indium (In), tin (Sn), tungsten (W), radium (Ir), platinum (Pt), gold (Au), lead (Pb), bismuth (Bi), ruthenium (Lu), lanthanum (La), cerium (Ce), preseodymium (Pr), neodymium (Nd), promedium (Pm), One selected from the group consisting of samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and combinations thereof; or Scandium (Sc), Titanium (Ti), Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu), Zinc (Zn), Gallium (Ga), Zirconium (Zr), Niobium (Nb), Molybdenum (Mo), Technedium (Tc), Ruthenium (Ru), Rhodium (Rh), Palladium (Pd), Silver (Ag), Cadmium (Cd), Indium (In), Tin (Sn), Tungsten (W), Iridium (Ir), Platinum (Pt), Gold (Au), Lead (Pb), Bismuth (Bi), Ruthenium (Lu), Lanthanum (La), Cerium (Ce), Preseodymium (Pr), Neodymium (Nd), Promedium (Pm), Samarium (Sm), Europium (Eu), Gadolinium (Gd), Terbium (Tb), It may include oxides derived from one selected from the group consisting of dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and combinations thereof.

[0017] The optical fiber composite may further include a first peripheral portion surrounding the laser core; and a second peripheral portion surrounding the heating core, and may include a heat transfer region that simultaneously surrounds the first peripheral portion and the second peripheral portion.

[0018] The above optical fiber composite may further include a third peripheral portion that simultaneously surrounds the laser core and the heating core.

[0019] The optical fiber composite may further include at least one fibrous stress imparting material adjacent to the laser core.

[0020] In another embodiment of the present invention, a fiber laser light source is provided that includes the fiber composite and, in the forward light with respect to the laser output direction, the difference (I2-I1) between the laser peak intensity (I1) (unit: dBm) and the stimulated Brillouin scattering (SBS) peak intensity (I2) (unit: dBm) in the light output spectrum is -22.00 dB to -50.00 dB.

[0021] The above fiber laser light source can emit light of a single wavelength having a linewidth of about 0 to about 100 GHz within a wavelength range of about 500 nm to about 2200 nm.

[0022] The above-described optical fiber composite is formed such that both the laser core and the heating core are arranged adjacent to each other in a fibrous form, enabling it to be applied to a high-power fiber laser to emit a high-quality laser without noise such as stimulated Brillouin scattering (SBS), and possesses the technical advantage of high utility as it is not restricted by the application location.

[0023] By applying the fiber composite to the optical path, the above fiber laser maximizes the ability to emit high-power and high-quality lasers, thereby effectively emitting a laser of a single wavelength while simultaneously achieving the effect of effectively eliminating noise such as stimulated Brillouin scattering (SBS).

[0024] FIG. 1 schematically illustrates a longitudinal cross-section of a portion of an optical fiber composite according to one embodiment.

[0025] FIG. 2 schematically illustrates a cross-section in the thickness direction of an optical fiber composite according to one embodiment.

[0026] FIGS. 3 and 4 schematically illustrate a cross-section in the thickness direction of an optical fiber composite according to a different embodiment.

[0027] FIG. 5 schematically illustrates a cross-section in the thickness direction of an optical fiber composite according to another embodiment.

[0028] FIGS. 6 (a) to (c) schematically illustrates examples of possible cross-sectional structures in the longitudinal direction of the heating core in the optical fiber composite according to one embodiment.

[0029] FIG. 7 schematically illustrates the circuit structure of a fiber laser light source with the MOPA structure applied according to one embodiment.

[0030] Figure 8 shows a graph of the optical intensity by wavelength of forward and reverse light with respect to the laser output direction for the fiber laser light sources of Example 1 and Comparative Example 1.

[0031] The present invention relates to a fiber optic composite comprising: a fibrous laser core; and at least one fibrous heating core adjacent to the laser core, wherein the heating core radiates heat having a temperature gradient and the heat radiated from the heating core is applied to the laser core.

[0032] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments or examples described below. However, the present invention is not limited to the embodiments or examples disclosed below but may be implemented in various different forms. The embodiments or examples specified below are provided merely to ensure that the disclosure of the present invention is complete and to inform those skilled in the art of the scope of the invention, and the scope of the rights of the present invention is defined by the scope of the claims.

[0033] In the drawings, the thickness or size of some components has been enlarged as necessary to clearly represent layers or regions. Additionally, in the drawings, the thickness of some layers and regions has been exaggerated for convenience of explanation. Throughout the specification, the same reference numerals refer to the same components.

[0034] When one component is described as being 'adjacent' to another component in this specification, this should be interpreted to include not only cases where there is no other component between one component and another, but also cases where there is another component between one component and another, even if they exist in close proximity to each other.

[0035] When one configuration is described in this specification as 'comprising' another configuration, this should be interpreted as not excluding the inclusion of additional configurations other than the other configuration.

[0036] When one configuration is described in this specification as being 'composed' of another configuration, this should be interpreted as defining a case where one configuration does not substantially include any configuration other than the other configuration. More specifically, when a first configuration is described as being 'composed' of a second configuration, the first configuration should be interpreted as defining a case where the second configuration includes more than about 99% by volume, weight, or mole.

[0037] In this specification, 'diameter' may be understood as a value obtained by measuring the outer diameter of the corresponding configuration in a cross-section or projected image.

[0038] Hereinafter, embodiments according to the present invention will be described in detail.

[0039] In one embodiment of the present invention, a fiber composite is provided comprising: a fibrous laser core; and at least one fibrous heating core adjacent to the laser core, wherein the heating core radiates heat having a temperature gradient and the heat radiated from the heating core is applied to the laser core.

[0040] FIG. 1 schematically illustrates a longitudinal cross-section of a portion of an optical fiber composite (100) according to one embodiment. The optical fiber composite may be used, for example, as an optical fiber laser light source. Here, the term 'composite' may be understood as a term indicating the use of at least two or more different types of optical fibers combined. Referring to FIG. 1, the optical fiber composite (100) may be characterized by including a fibrous laser core (10) and a fibrous heating core (20) adjacent to the laser core (10), wherein the heating core (20) radiates heat (H) having a temperature (T) gradient in the longitudinal direction (L), and the heat (H) radiated from the heating core (20) is applied to the laser core (10) (the direction in which heat is applied is indicated by the arrow in FIG. 1).

[0041] Recently, there has been an increasing demand for high-power, high-quality laser light sources in various fields, including fiber optic sensors, advanced processing industries, medical applications, and defense. Consequently, there is growing interest in high-power optical fiber composites, which offer excellent spectral characteristics, high oscillation efficiency, and advantages in terms of miniaturization and maintenance. However, noise generation, such as stimulated Brillouin scattering (SBS), can be a problem for optical fiber composites during high-power oscillation. The threshold value (P) of stimulated Brillouin scattering (SBS) th ) is as shown in [Equation 1] below, and the threshold value (P th ) is the effect on the degree of polarization (1 <k<2), 브릴루앙 이득계수(g B ), effective area (A eff ), effective length (L eff ), signal light source linewidth (Δv s ) and Brillouin gain linewidth (Δv p It is affected by ).

[0042] [Equation 1]

[0043]

[0044] Techniques for suppressing stimulated Brillouin scattering (SBS) include increasing the linewidth of the signal light source and phase modulation techniques. The present invention relates to a technique for effectively suppressing stimulated Brillouin scattering (SBS) by inducing a change in the Brillouin gain linewidth through a temperature gradient applied to an optical fiber. When heat radiated from the heating core (20) is applied to the laser core (10), a temperature gradient is applied in the longitudinal direction to cause a change in the refractive index of the laser core (10). As a result, a Brillouin frequency shift phenomenon occurs, and as the Brillouin gain spectrum is dispersed, the effect of increasing the linewidth and decreasing the gain can be obtained. In particular, one embodiment according to the present invention forms both the laser core (10) and the heating core (20) into fibers and arranges them adjacent to each other, thereby enabling the formation of a temperature gradient in the laser core (10) without the need for a separate cylindrical or similar mechanism in which an optical fiber is wound to create a temperature gradient, thus enabling the realization of a technical advantage in that the volume does not significantly increase or become exposed externally even when applied to the output end of a fiber laser device.

[0045] FIG. 2 schematically illustrates a cross-section in the thickness direction of an optical fiber composite (100) according to one embodiment. Referring to FIG. 2, the optical fiber composite (100) may include a fibrous laser core (10) and a first peripheral portion (11) surrounding the laser core (10), and may include a fibrous heating core (20) and a second peripheral portion (21) surrounding the heating core (20). Additionally, the optical fiber composite (100) may include a heat transfer region (30) that simultaneously surrounds the first peripheral portion (11) and the second peripheral portion (21). By having a structure in which the heat transfer region (30) simultaneously surrounds the first peripheral portion (11) and the second peripheral portion (21), it can function as a medium for transferring heat radiated from the heating core (20) to the laser core (10) (the flow of heat is indicated by an arrow in FIG. 2).

[0046] FIGS. 3 and 4 schematically illustrate cross-sections in the thickness direction of optical fiber composites (200, 300, 400) according to different embodiments.

[0047] Referring to FIG. 3, the optical fiber composite (200) comprises a fibrous laser core (10) and at least one fibrous heating core (20) adjacent to the laser core (10), wherein the heating core (20) radiates heat (H) having a temperature gradient (the flow of radiated heat is shown by the arrow in FIG. 3), and the heat radiated from the heating core (20) can be applied to the laser core (10). Additionally, the optical fiber composite (200) may further comprise a third peripheral portion (31) that simultaneously surrounds the laser core (10) and the heating core (20).

[0048] Referring to FIG. 4, the optical fiber composite (300) comprises a fibrous laser core (10) and two or more fibrous heating cores (20) adjacent to the laser core (10), wherein the heating cores (20) radiate heat (H) having a temperature gradient (the flow of radiated heat is shown by the arrows in FIG. 4), and the heat radiated from the heating cores (20) can be applied to the laser core (10). Additionally, the optical fiber composite (300) may further comprise a third peripheral portion (31) that simultaneously surrounds the laser core (10) and the heating cores (20).

[0049] In one embodiment, the optical fiber composite (300) may include two or more, for example, two to four, fibrous heating cores (20).

[0050] FIG. 5 schematically illustrates a cross-section in the thickness direction of an optical fiber composite (400) according to another embodiment.

[0051] Referring to FIG. 5, the optical fiber composite (400) comprises a fibrous laser core (10) and at least one fibrous heating core (20) adjacent to the laser core (10), wherein the heating core (20) radiates heat (H) having a temperature gradient (the flow of heat is shown by an arrow in FIG. 5), and the heat radiated from the heating core (20) is applied to the laser core (10), and may comprise at least one fibrous stress imparting material (40) adjacent to the laser core (10). The optical fiber composite (400) can reduce induced Brillouin scattering (SBS) through the adjacent arrangement of the heating core (20) and the laser core (10), and at the same time function as a polarization maintaining fiber (PMF). By making the structure of the cross-section of the optical fiber composite (400) in the x and y directions different through the stress-applying material (40), the effective refractive index in the corresponding directions can be made different, thereby preserving the polarization plane of the transmitted light.

[0052] In one embodiment, the laser core (10) on the fiber may be a core of an optical fiber for a gain medium or a core of an optical fiber for transmission.

[0053] In one embodiment, the laser core (10) may comprise silica (SiO2) and an additive component. For example, the additive component may be one selected from the group consisting of germanium (Ge), phosphorus (P), boron (B), fluorine (F), aluminum (Al), lithium (Li), sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), bismuth (Bi), scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), preseodymium (Pr), neodymium (Nd), promedium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), ruthenium (Lu), and combinations thereof; Alternatively, it may include an oxide derived from one selected from the group consisting of germanium (Ge), phosphorus (P), boron (B), fluorine (F), aluminum (Al), lithium (Li), sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), bismuth (Bi), scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), preseodymium (Pr), neodymium (Nd), promedium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), ruthenium (Lu), and combinations thereof.

[0054] In one embodiment, the additive component may include one selected from the group consisting of germanium oxide (GeO2), phosphorus oxide (P2O5), boron oxide (B2O3), aluminum oxide (Al2O3), lithium oxide (Li2O), sodium oxide (Na2O), potassium oxide (K2O), calcium oxide (CaO), magnesium oxide (MgO), fluorine (F), and combinations thereof.

[0055] The laser core (10) may contain the silica in an amount of about 80 mol% or more, for example, about 81 mol% or more, for example, about 82 mol% or more, for example, about 83 mol% or more, for example, about 84 mol% or more, for example, about 85 mol% or more, for example, less than about 100 mol%, for example, about 99 mol% or less.

[0056] Additionally, the laser core (10) may contain the additive component in an amount of about 20 mol% or less, for example, about 19 mol% or less, for example, about 18 mol% or less, for example, about 17 mol% or less, for example, about 16 mol% or less, for example, about 15 mol% or less, for example, about 14 mol% or less, for example, about 13 mol% or less, for example, about 12 mol% or less, for example, more than about 0 mol%, for example, about 1 mol% or more.

[0057] In one embodiment, the laser core (10) may have a structure in which the additive component is contained within a cylindrical fibrous interior containing silica (SiO2).

[0058] In one embodiment, the diameter of the cross-section in the thickness direction of the laser core (10) may be about 2 μm or more, for example, about 3 μm or more, for example, about 4 μm or more, for example, about 5 μm or more, for example, about 250 μm or less, for example, about 200 μm or less, for example, about 180 μm or less, for example, about 160 μm or less, for example, about 150 μm or less, for example, about 140 μm or less, for example, about 130 μm or less, for example, about 120 μm or less, for example, about 110 μm or less, for example, about 100 μm or less, for example, about 90 μm or less, for example, about 80 μm or less, for example, about 70 μm or less, for example, about 60 μm or less, for example, about 50 μm or less, for example, about 40 μm or less, for example, about 30 μm or less.

[0059] In one embodiment, the heating core (20) includes a heating region, and the heating region may include silica (SiO2) and a heating component.

[0060] FIGS. 6(a) to (c) schematically illustrates examples of possible cross-sectional structures in the longitudinal direction of the heating core (20) in the optical fiber composite (100, 200, 300, 400) according to one embodiment. Referring to FIGS. 6(a) to (c), the heating core (20) according to one embodiment includes the heating region (201), wherein the heating region (201) may satisfy 1) or 2) below.

[0061] 1) The heating region (201) is continuous in the longitudinal direction.

[0062] 2) The heating region (201) is discontinuous in the longitudinal direction.

[0063] More specifically, FIG. 6(a) illustrates a case where the heating region (201) in the heating core (20) is continuous in the longitudinal direction, and FIG. 6(b) and (c) illustrate a case where the heating region (201) is discontinuous in the longitudinal direction. FIG. 6(a) is an example in which the heating component is included in a substantially uniform concentration / content along the fibrous longitudinal direction of the heating core (20), and a graph showing a temperature (T) gradient along the length (L) when pump light is irradiated from left to right in the drawing is also shown. FIG. 6(b) and (c) are examples in which the heating region (201) containing the heating component and the non-heating region (202) not containing the heating component are arranged alternately, and a graph showing a temperature (T) gradient along the length (L) corresponding to this arrangement structure is also shown. Referring to FIG. 6(b), the non-heating region (202) may include, for example, an optical fiber that does not contain the heating component. Referring to FIG. 6(c), the non-heating region (202) may be, for example, a spaced-out region. The spaced-out region may be understood as an empty space. By placing such a non-heating region (202) between two adjacent heating regions (201), a multi-stage temperature gradient can be formed.

[0064] The above-mentioned exothermic component is, for example, scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), zirconium (Zr), niobium (Nb), molybdenum (Mo), technedium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), indium (In), tin (Sn), tungsten (W), radium (Ir), platinum (Pt), gold (Au), lead (Pb), bismuth (Bi), ruthenium (Lu), lanthanum (La), cerium (Ce), preseodymium (Pr), neodymium (Nd), promedium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), One selected from the group consisting of terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and combinations thereof; or Scandium (Sc), Titanium (Ti), Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu), Zinc (Zn), Gallium (Ga), Zirconium (Zr), Niobium (Nb), Molybdenum (Mo), Technedium (Tc), Ruthenium (Ru), Rhodium (Rh), Palladium (Pd), Silver (Ag), Cadmium (Cd), Indium (In), Tin (Sn), Tungsten (W), Iridium (Ir), Platinum (Pt), Gold (Au), Lead (Pb), Bismuth (Bi), Ruthenium (Lu), Lanthanum (La), Cerium (Ce), Preseodymium (Pr), Neodymium (Nd), Promedium (Pm), Samarium (Sm), Europium (Eu), Gadolinium (Gd), Terbium (Tb), It may include oxides derived from one selected from the group consisting of dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and combinations thereof.

[0065] In one embodiment, the exothermic component may include one selected from the group consisting of iron oxide (Fe2O3), cobalt oxide (Co2O3), and combinations thereof.

[0066] In one embodiment, the heating core may further include an additive component in addition to the heating component. The additive component of the heating core is a component for securing the refractive index of the heating core within an appropriate range or for ensuring that the heating component is uniformly dispersed, and is, for example, one selected from the group consisting of germanium (Ge), phosphorus (P), boron (B), fluorine (F), aluminum (Al), lithium (Li), sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), bismuth (Bi), scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), preseodymium (Pr), neodymium (Nd), promedium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), ruthenium (Lu), and combinations thereof; Or it may further include an oxide derived from one selected from the group consisting of germanium (Ge), phosphorus (P), boron (B), fluorine (F), aluminum (Al), lithium (Li), sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), bismuth (Bi), scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), preseodymium (Pr), neodymium (Nd), promedium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), ruthenium (Lu), and combinations thereof.

[0067] In one embodiment, the additive component of the heating core may further include one selected from the group consisting of germanium oxide (GeO2), phosphorus oxide (P2O5), boron oxide (B2O3), aluminum oxide (Al2O3), lithium oxide (Li2O), sodium oxide (Na2O), potassium oxide (K2O), calcium oxide (CaO), magnesium oxide (MgO), fluorine (F), and combinations thereof.

[0068] The above-mentioned heating region may contain the silica in an amount of about 70 mol% or more, for example, about 75 mol% or more, for example, about 80 mol% or more, for example, about 85 mol% or more, for example, about 90 mol% or more, for example, less than about 100 mol%, for example, about 99 mol% or less, for example, about 98 mol% or less, for example, about 97 mol% or less, for example, about 96 mol% or less.

[0069] In addition, the heat-generating region may contain the heat-generating component in an amount of about 30 mol% or less, for example, about 25 mol% or less, for example, about 20 mol% or less, for example, about 10 mol% or less, for example, more than about 0 mol%, for example, about 0.1 mol% or more, for example, about 0.5 mol% or more, for example, about 1.0 mol% or more.

[0070] In one embodiment, the heating region may have a structure in which the heating component is contained within a cylindrical fibrous structure containing silica (SiO2).

[0071] In one embodiment, the diameter of the cross-section in the thickness direction of the heating core (20) is about 2 μm or more, for example, about 3 μm or more, for example, about 4 μm or more, for example, about 5 μm or more, for example, about 800 μm or less, for example, about 750 μm or less, for example, about 700 μm or less, for example, about 650 μm or less, for example, about 600 μm or less, for example, about 550 μm or less, for example, about 500 μm or less, for example, about 450 μm or less, for example, about 400 μm or less, for example, about 350 μm or less, for example, about 300 μm or less, for example, about 250 μm or less, for example, about 200 μm or less, for example, about 180 μm or less, for example, about 160 μm or less, for example, about 150 μm or less, for example, about 140 μm or less, for example, about It may be 130㎛ or less, for example, about 120㎛ or less, for example, about 110㎛ or less, for example, about 100㎛ or less, for example, about 90㎛ or less, for example, about 80㎛ or less, for example, about 70㎛ or less, for example, about 60㎛ or less, for example, about 50㎛ or less, for example, about 40㎛ or less.

[0072] Referring to FIG. 2, in one embodiment, the first peripheral portion (11) may include a first cladding (111) and a first jacket (112). In this specification, the term "cladding" is understood to mean a configuration that covers the core to enable total internal reflection of the core. Additionally, in this specification, the term "jacket" is understood to mean a configuration that is coated or covered on the outer surface of the core and the cladding to serve the roles of protection, cushioning, and / or heat transfer.

[0073] In one embodiment, the first cladding (111) may be made of a component with a lower refractive index than the laser core (10). For example, the numerical aperture (NA) of the laser core (10) may be about 0.01 to about 1.00, for example, about 0.05 to about 0.50, for example, about 0.10 to about 0.30. The numerical aperture (NA) is a value determined by the difference in refractive index between the laser core (10) and the first cladding (111), and can be defined by the following [Equation 2].

[0074] [Equation 2]

[0075]

[0076] In the above Equation 2, n1 is the refractive index of the core, and n2 is the refractive index of the cladding.

[0077] The numerical aperture (NA) is a value indicating how much light the laser core (10) can receive from a light source while satisfying internal total reflection conditions. By designing the difference in refractive index between the first cladding (111) and the laser core (10) to correspond to the range of the numerical aperture, it is advantageous for efficient transmission of light through the laser core (10) and efficient thermal interaction with the heating core (20).

[0078] In one embodiment, the first cladding (111) may include one selected from the group consisting of silica (SiO2), phosphate (P2O5), boron oxide (B2O3), fluorine (F), aluminum oxide (Al2O3), polyacrylate (PA), and combinations thereof.

[0079] In one embodiment, the first cladding (111) may have a double cladding structure. Specifically, the first cladding (111) may include an inner cladding and an outer cladding. More specifically, the inner cladding, which is the primary cladding, may include one selected from the group consisting of silica (SiO2), phosphate (P2O5), boron oxide (B2O3), fluorine (F), aluminum oxide (Al2O3), and combinations thereof, and the outer cladding, which is the secondary cladding, may include polyacrylate (PA).

[0080] In one embodiment, the diameter of the cross-section in the thickness direction of the first cladding (111) is about 10 μm or more, for example, about 20 μm or more, for example, about 30 μm or more, for example, about 40 μm or more, for example, about 50 μm or more, for example, about 60 μm or more, for example, about 70 μm or more, for example, about 80 μm or more, for example, about 90 μm or more, for example, about 100 μm or more, for example, about 110 μm or more, for example, about 120 μm or more, for example, about 130 μm or more, for example, about 140 μm or more, for example, about 150 μm or more, for example, about 160 μm or more, for example, about 170 μm or more, for example, about 180 μm or more, for example, about 190 μm or more, for example, about 200 μm or more, for example, about 210 μm or more, for example, about It may be 220㎛ or more, for example, about 230㎛ or more, for example, about 240㎛ or more, for example, about 250㎛ or more, for example, 1000㎛ or less, for example, about 900㎛ or less, for example, about 800㎛ or less, for example, about 700㎛ or less, for example, about 600㎛ or less, for example, about 500㎛ or less, for example, about 480㎛ or less, for example, about 460㎛ or less, for example, about 450㎛ or less, for example, about 440㎛ or less, for example, about 430㎛ or less, for example, about 420㎛ or less, for example, about 410㎛ or less, for example, about 400㎛ or less.

[0081] In one embodiment, the first jacket (112) serves as a buffer and protector and may include, for example, one selected from the group consisting of polyacrylate (PA), polyimide (PI), nylon, polycarbonate (PC), polyvinyl chloride (PVC) and combinations thereof.

[0082] In one embodiment, the first jacket (112) may include a metal coating layer. For example, the metal coating layer of the first jacket (112) is lithium (Li), beryllium (Be), boron (B), sodium (Na), magnesium (Mg), aluminum (Al), potassium (K), calcium (Ca), scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), arsenic (As), rubinium (Rb), strontium (Sr), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), technedium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), indium (In), tin (Sn), antimony (Sb), tellurium (Te), cesium (Cs), barium (Ba), It may include one selected from the group consisting of lanthanum (La), cerium (Ce), ruthenium (Lu), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), radium (Ir), platinum (Pt), gold (Au), mercury (Hg), thallium (Tl), lead (Pb), bismuth (Bi), and combinations thereof.

[0083] In one embodiment, the diameter of the cross-section in the thickness direction of the first jacket (112) is about 20 μm or more, for example, about 30 μm or more, for example, about 40 μm or more, for example, about 50 μm or more, for example, about 60 μm or more, for example, about 70 μm or more, for example, about 80 μm or more, for example, about 90 μm or more, for example, about 100 μm or more, for example, about 200 μm or more, for example, about 300 μm or more, for example, about 350 μm or more, for example, about 400 μm or more, for example, about 1500 μm or less, for example, about 1400 μm or less, for example, about 1300 μm or less, for example, about 1200 μm or less, for example, about 1100 μm or less, for example, about 1000 μm or less, for example, about 900 μm or less, for example, about 800 μm It may be less than, for example, about 700㎛ or less, for example, about 600㎛ or less, for example, about 550㎛ or less, for example, about 500㎛ or less.

[0084] Referring to FIG. 2, in one embodiment, the second peripheral portion (21) may include a second cladding (211) and a second jacket (212).

[0085] In one embodiment, the second cladding (211) may be made of a component with a lower refractive index than the heating core (20). For example, the numerical aperture (NA) of the heating core (20) may be about 0.01 to about 2.50, for example, about 0.05 to about 1.50, for example, about 0.10 to about 1.00. The numerical aperture (NA) is a value determined by the difference in refractive index between the heating core (20) and the second cladding (211), and may be defined by [Equation 2]. In Equation 2, n1 is the refractive index of the core, and n2 is the refractive index of the cladding.

[0086] This is a value indicating how much light the heating core (20) can receive from a light source while satisfying internal total reflection conditions. By designing the difference in refractive index between the second cladding (211) and the heating core (20) to correspond to the range of the numerical aperture, the transmission of light through the heating core (20) is efficiently carried out, and at the same time, the process of applying heat generated from the heating core (20) to the laser core (10) can be advantageously carried out efficiently.

[0087] In one embodiment, the second cladding (211) may include one selected from the group consisting of silica (SiO2), phosphate (P2O5), boron oxide (B2O3), fluorine (F), aluminum oxide (Al2O3) and combinations thereof.

[0088] In one embodiment, the diameter of the cross-section in the thickness direction of the second cladding (211) is about 10 μm or more, for example, about 20 μm or more, for example, about 30 μm or more, for example, about 40 μm or more, for example, about 50 μm or more, for example, about 60 μm or more, for example, about 70 μm or more, for example, about 80 μm or more, for example, about 90 μm or more, for example, about 100 μm or more, for example, about 110 μm or more, for example, about 120 μm or more, for example, about 130 μm or more, for example, about 140 μm or more, for example, about 150 μm or more, for example, about 160 μm or more, for example, about 170 μm or more, for example, about 180 μm or more, for example, about 190 μm or more, for example, about 200 μm or more, for example, about 210 μm or more, for example, about It may be 220㎛ or more, for example, about 230㎛ or more, for example, about 240㎛ or more, for example, about 250㎛ or more, for example, about 1000㎛ or less, for example, about 900㎛ or less, for example, about 800㎛ or less, for example, about 700㎛ or less, for example, about 600㎛ or less, for example, about 500㎛ or less, for example, about 480㎛ or less, for example, about 460㎛ or less, for example, about 450㎛ or less, for example, about 440㎛ or less, for example, about 430㎛ or less, for example, about 420㎛ or less, for example, about 410㎛ or less, for example, about 400㎛ or less.

[0089] In one embodiment, the second jacket (212) serves as a buffer, protector, and heat transfer agent and may include, for example, one selected from the group consisting of polyacrylate (PA), polyimide (PI), nylon, polycarbonate (PC), polyvinyl chloride (PVC), silicone resin, urethane resin, fluorinated resin, ester resin, and combinations thereof.

[0090] In one embodiment, the second jacket (212) may include a metal coating layer. For example, the metal coating layer of the second jacket (212) may include one selected from the group consisting of titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), zirconium (Zr), palladium (Pd), silver (Ag), indium (In), tin (Sn), platinum (Pt), gold (Au), lead (Pb), bismuth (Bi), and combinations thereof.

[0091] In one embodiment, the diameter of the cross-section in the thickness direction of the second jacket (212) is about 20 μm or more, for example, about 30 μm or more, for example, about 40 μm or more, for example, about 50 μm or more, for example, about 60 μm or more, for example, about 70 μm or more, for example, about 80 μm or more, for example, about 90 μm or more, for example, about 100 μm or more, for example, about 200 μm or more, for example, about 300 μm or more, for example, about 350 μm or more, for example, about 400 μm or more, for example, about 1500 μm or less, for example, about 1400 μm or less, for example, about 1300 μm or less, for example, about 1200 μm or less, for example, about 1100 μm or less, for example, about 1000 μm or less, for example, about 900 μm or less, for example, about 800 μm It may be less than, for example, about 700㎛ or less, for example, about 600㎛ or less, for example, about 550㎛ or less, for example, about 500㎛ or less.

[0092] The heat transfer region (30) can serve as a medium to apply heat radiated from the heating core (20) with a temperature gradient to the laser core (10). The heat transfer region (30) may include, for example, an adhesive resin selected from the group consisting of epoxy resin, silicone resin, urethane resin, acrylic resin, and combinations thereof.

[0093] The heat transfer region (30) may further include, for example, a metal component. The metal component in the heat transfer region (30) may include, for example, one selected from the group consisting of titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), zirconium (Zr), palladium (Pd), silver (Ag), indium (In), tin (Sn), platinum (Pt), gold (Au), lead (Pb), bismuth (Bi), and combinations thereof.

[0094] In one embodiment, the heat transfer coefficient of the heat transfer region (30) is Btu in / (h·ft 2 ·°F) The value in units may be about 10 or more, for example, about 11 or more, for example, about 12 or more, for example, about 13 or more, for example, about 14 or more, for example, about 15 or more, for example, about 16 or more, for example, about 17 or more, for example, about 100 or less, for example, about 80 or less, for example, about 50 or less, for example, about 45 or less, for example, about 40 or less, for example, about 35 or less.

[0095] Referring to FIGS. 3 and FIGS. 4, in one embodiment, the third peripheral portion (31) may include a third cladding (311) and a third jacket (312).

[0096] In one embodiment, the third cladding (311) may be composed of a component having a lower refractive index than the laser core (10) and simultaneously having a lower refractive index than the heating core (20). For example, the numerical aperture (NA) of the laser core (10) may be about 0.01 to about 1.00, for example, about 0.05 to about 0.50, for example, about 0.10 to about 0.30. For example, the numerical aperture (NA) of the heating core (20) may be about 0.01 to about 2.50, for example, about 0.05 to about 1.50, for example, about 0.10 to about 1.00. The numerical aperture of the laser core (10) is a value determined by the relationship between the refractive index of the third cladding (311) and the refractive index of the laser core (10), and may be defined by [Equation 2]. In the above Equation 2, n1 is the refractive index of the core and n2 is the refractive index of the cladding. Likewise, the numerical aperture of the heating core (20) can be defined by the above Equation 2, which is a value determined by the relationship between the refractive index of the third cladding (311) and the refractive index of the heating core (20). In the above Equation 2, n1 is the refractive index of the core and n2 is the refractive index of the cladding. By designing the refractive index of the third cladding (311) to have a difference in refractive index corresponding to the aforementioned numerical aperture (NA) for each of the laser core (10) and the heating core (20), a high-power laser can be emitted while satisfying internal total reflection for both cores in a structure in which the laser core (10) and the heating core (20) are simultaneously surrounded by a single cladding, and the thermal interaction between the laser core (10) and the heating core (20) can be more advantageous.

[0097] In one embodiment, the third cladding (311) may include one selected from the group consisting of silica (SiO2), phosphate (P2O5), boron oxide (B2O3), fluorine (F), aluminum oxide (Al2O3), polyacrylate (PA), and combinations thereof.

[0098] In one embodiment, the third cladding (311) may have a double cladding structure. Specifically, the third cladding (311) may include an inner cladding and an outer cladding. More specifically, the inner cladding, which is the primary cladding, may include one selected from the group consisting of silica (SiO2), phosphate (P2O5), boron oxide (B2O3), fluorine (F), aluminum oxide (Al2O3), and combinations thereof, and the outer cladding, which is the secondary cladding, may include polyacrylate (PA).

[0099] In one embodiment, the third jacket (312) serves as a buffer, protector, and heat transfer agent and may include, for example, one selected from the group consisting of polyacrylate (PA), polyimide (PI), nylon, polycarbonate (PC), polyvinyl chloride (PVC), silicone resin, urethane resin, fluorinated resin, ester resin, and combinations thereof.

[0100] In one embodiment, the third jacket (312) may include a metal coating layer. For example, the metal coating layer of the second jacket (212) may include one selected from the group consisting of titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), zirconium (Zr), palladium (Pd), silver (Ag), indium (In), tin (Sn), platinum (Pt), gold (Au), lead (Pb), bismuth (Bi), and combinations thereof.

[0101] Referring to FIG. 5, in one embodiment, the stress-improving material (40) may include silica (SiO2) and a stress-improving component, and the stress-improving component may include one selected from the group consisting of, for example, sodium oxide (Na2O), potassium oxide (K2O), calcium oxide (CaO), boron oxide (B2O3), germanium oxide (GeO2), phosphorus oxide (P2O5) and combinations thereof.

[0102] In one embodiment, the diameter of the cross-section in the thickness direction of the stress-applying material (40) may be about 5 μm to about 300 μm, for example, about 10 μm to about 200 μm.

[0103] In another embodiment according to the present invention, a fiber laser light source is provided comprising the fiber composite (100, 200, 300, 400), wherein, in the forward light with respect to the laser output direction, the difference (I2-I1) between the laser peak intensity (I1) (unit: dBm) and the stimulated Brillouin scattering (SBS) peak intensity (I2) (unit: dBm) in the light output spectrum is about -22.00 dB to about -50.00 dB.

[0104] In the calculation of dBm unit values ​​in the field of optical communication, dBm - dBm = dB is used. By applying a fiber optic composite to the fiber laser light source, the above-mentioned fiber laser light source can exhibit an SBS peak with a relatively low intensity of approximately -22.00 dB to approximately -50.00 dB relative to the laser peak in the light in the forward direction relative to the laser output direction. The difference (I2-I1) between the laser peak intensity (I1) (unit: dBm) for the above-mentioned forward light and the stimulated Brillouin scattering (SBS) peak intensity (I2) (unit: dBm) is approximately -22.00 dB to approximately -50.00 dB, e.g., approximately -23.00 dB to approximately -50.00 dB, e.g., approximately -24.00 dB to approximately -50.00 dB, e.g., approximately -25.00 dB to approximately -50.00 dB, e.g., approximately -26.00 dB to approximately -50.00 dB, e.g., approximately -27.00 dB to approximately -50.00 dB, e.g., approximately -28.00 dB to approximately -50.00 dB, e.g., approximately -29.00 dB to approximately -50.00 dB, e.g., approximately It can be -30.00 dB to about -50.00 dB.

[0105] In one embodiment, the fiber laser light source, in the reverse direction light relative to the laser output direction, may have a difference (I2-I1) between the laser peak intensity (I1) (unit: dBm) and the stimulated Brillouin scattering (SBS) peak intensity (I2) (unit: dBm) in the optical output spectrum of about 25.00 dB to about -30.00 dB. In the reverse direction light relative to the laser output direction, the SBS peak signal may appear relatively strong compared to the laser peak, or the laser peak may appear strong compared to the SBS peak. At this time, the SBS peak may exhibit an intensity with a difference of about 25.00 dB to about -30.00 dB compared to the laser peak. Specifically, regarding the reverse light with respect to the laser output direction, the difference (I2-I1) between the laser peak intensity (I1) (unit: dBm) and the stimulated Brillouin scattering (SBS) peak intensity (I2) (unit: dBm) in the optical output spectrum is approximately 25.00 dB to approximately -30.00 dB, for example, approximately 24.00 dB to approximately -30.00 dB, for example, approximately 23.00 dB to approximately -30.00 dB, for example, approximately 22.00 dB to approximately -30.00 dB, for example, 21.00 dB to approximately -30.00 dB, for example, approximately 20.00 dB to approximately -30.00 dB, for example, approximately 19.00 dB to approximately -30.00 dB, for example, approximately 18.00 dB to approximately -30.00 dB, e.g., about 17.00 dB to about -30.00 dB, e.g., about 16.00 dB to about -30.00 dB, e.g., about 15.00 dB to about -30.00 dB, e.g., about 14.00 dB to about -30.00 dB, e.g., about 13.00 dB to about -30.00 dB, e.g., about 12.00 dB to about -30.00 dB, e.g., about 11.00 dB to about -30.00 dB, e.g., about 10.00 dB to about -30.It may be 00 dB, for example, about 20.00 dB to about -20.00 dB, for example, about 20.00 dB to about -15.00 dB, for example, about 20.00 dB to about -10.00 dB, for example, about 20.00 dB to about -5.00 dB, for example, about 20.00 dB to about 0.00 dB.

[0106] All matters concerning the above-mentioned optical fiber composite (100, 200, 300, 400) and the sub-components of the above-mentioned optical fiber composite may be applied in an integrated manner to the above-mentioned optical fiber laser light source, not only when repeatedly described below, but also when not repeatedly described below.

[0107] In the above fiber laser light source, the fiber composite comprises a fibrous laser core; and at least one fibrous heating core adjacent to the laser core, wherein the heating core radiates heat having a temperature gradient, and the heat radiated from the heating core can be applied to the laser core. By applying a fiber composite comprising a composite structure of the laser core and the heating core to the fiber laser light source, it may be more advantageous to emit a high-power laser without noise.

[0108] In one embodiment, the fiber laser light source may emit light having a substantially single wavelength within a wavelength range of about 500 nm to about 2200 nm. Specifically, the linewidth of the single wavelength may be about 0 to about 100 GHz, for example, about 0 to about 50 GHz, for example, about 0 to about 20 GHz, for example, about 0 to about 15 GHz, for example, about 0 to about 1 GHz, for example, about 0 to about 100 MHz, for example, about 0 to about 50 MHz, for example, about 0 to about 25 MHz, for example, about 0 to about 20 MHz, for example, about 0 to about 15 MHz. Here, light having a 'single wavelength' should be understood as a concept that encompasses not only cases where the linewidth is 0, but also light having a narrow linewidth within the aforementioned numerical range. The above fiber laser light source may be more advantageous for emitting a high-output laser without noise while having such a narrow linewidth as the fiber composite is applied.

[0109] Referring to FIG. 2, in the fiber laser light source according to one embodiment, the fiber composite (100) may include the fibrous laser core (10) and a first peripheral portion (11) surrounding the laser core (10), and may include the fibrous heating core (20) and a second peripheral portion (21) surrounding the heating core (20). Additionally, the fiber composite (100) may include a heat transfer region (30) that simultaneously surrounds the first peripheral portion (11) and the second peripheral portion (21). By having a structure in which the heat transfer region (30) simultaneously surrounds the first peripheral portion (11) and the second peripheral portion (21), it can function as a medium for transferring heat radiated from the heating core (20) to the laser core (10) (the flow of heat is indicated by an arrow in FIG. 2).

[0110] Referring to FIG. 3, in the fiber laser light source according to one embodiment, the fiber composite (200) comprises a fibrous laser core (10) and at least one fibrous heating core (20) adjacent to the laser core (10), and the heating core (20) radiates heat (H) having a temperature gradient (the flow of radiated heat is shown by the arrow in FIG. 3), and the heat radiated from the heating core (20) can be applied to the laser core (10). Additionally, the fiber composite (200) may further comprise a third peripheral portion (31) that simultaneously surrounds the laser core (10) and the heating core (20).

[0111] Referring to FIG. 4, in the fiber laser light source according to one embodiment, the fiber composite (300) comprises a fibrous laser core (10) and two or more fibrous heating cores (20) adjacent to the laser core (10), wherein the heating cores (20) radiate heat (H) having a temperature gradient (the flow of radiated heat is shown by the arrows in FIG. 4), and the heat radiated from the heating cores (20) can be applied to the laser core (10). Additionally, the fiber composite (200) may further comprise a third peripheral portion (31) that simultaneously surrounds the laser core (10) and the heating cores (20).

[0112] Referring to FIG. 5, in the fiber laser light source according to one embodiment, the fiber composite (400) comprises a fibrous laser core (10) and at least one fibrous heating core (20) adjacent to the laser core (10), the heating core (20) emits heat (H) having a temperature gradient (the flow of heat is shown by an arrow in FIG. 5), the heat emitted from the heating core (20) is applied to the laser core (10), and may include at least one fibrous stress imparting material (40) adjacent to the laser core (10).

[0113] FIGS. 2 to 5 illustrate the structure of a cross-section of an optical fiber composite according to one embodiment of the present invention, which is cut in a direction perpendicular to the longitudinal direction, that is, cut in the thickness direction. Although not shown in the drawings, the number and shape of the laser core (10), the heating core (20), and the stress-applying material (40) may vary in various ways. For example, the shape of the cross-section of each of the laser core (10), the heating core (20), and the stress-applying material (40) may be circular, elliptical, square, triangular, ring-shaped, etc., as shown in FIGS. 2 to 5. In addition, the number of each of the laser core (10), the heating core (20), and the stress-applying material (40) may be singular or plural, for example, one or more, two or more, for example, three or more, for example, four or more, for example, ten or fewer, for example, nine or fewer, for example, eight or fewer, etc.

[0114] According to one embodiment, a Master Oscillator Power Amplifier (MOPA) optical circuit structure may be applied to the fiber laser light source. The MOPA optical circuit structure is a circuit structure that emits a high-output laser through multi-stage amplification of a seed beam of several kHz. While it offers the technical advantage of emitting a high-output laser through amplification, noise such as stimulated Brillouin scattering (SBS) is also amplified during the amplification process; therefore, controlling such noise is one of the critical issues for improving laser quality. According to one embodiment, by applying the fiber composite, the fiber laser light source can effectively control the amplification of noise that occurs when applying the MOPA optical circuit structure. As a result, compared to applying other optical circuit structures, the advantage of maximizing the effect of controlling SBS scattering when applying the MOPA optical circuit structure can be realized.

[0115] FIG. 7 schematically illustrates the circuit structure of a fiber laser light source (700) to which the MOPA structure is applied according to one embodiment. Referring to FIG. 7, the fiber laser light source (700) to which the MOPA optical circuit structure is applied includes a seed beam (701); a first amplification module (703) and a second amplification module (705), wherein the first amplification module (703) includes a first pump light source (713) and a first optical fiber (733), and the second amplification module (705) includes a second pump light source (715) and a second optical fiber (735), and the optical fiber composite may be applied to at least one of the first optical fiber (733) and the second optical fiber (735). A beam having a linewidth of several to tens of kHz emitted from the seed beam (701) is incident on the first amplification module (703) and amplified, and then incident on the second amplification module (705) and amplified once more. Through this multi-stage amplification, the effective laser light is amplified, and by applying the optical fiber composite according to one embodiment to at least one of the first optical fiber (733) and the second optical fiber (735), the amplification of noise such as stimulated Brillouin scattering (SBS) is effectively suppressed, thereby enabling the emission of a high-output and high-quality laser.

[0116] In one embodiment, when a MOPA optical circuit structure as described above is applied to the fiber laser light source (700), light in the forward direction with respect to the laser output direction can be extracted at the rear end of the second amplification module (705). Specifically, light after being amplified through the second amplification module (705) and then finally output can be extracted.

[0117] In one embodiment, when a MOPA optical circuit structure as described above is applied to the fiber laser light source (700), light in the backward direction relative to the laser output direction can be extracted at the front end of the second amplification module (705). In another embodiment, light in the backward direction relative to the laser output direction can be extracted after being amplified through the second amplification module (705) and before being finally output.

[0118] In one embodiment, the fiber laser light source (700) may further include a first optical isolator (OI) (702) at the rear end of the seed beam (701). The first optical isolator (702) can prevent the laser light emitted from the seed beam (701) from traveling in the reverse direction and control the signal light source to travel in a desired direction.

[0119] In one embodiment, the first amplification module (703) may further include a first optical coupler (OC) (723) at the front end of the first optical fiber (733). The first optical coupler (723) may perform the function of amplifying the laser light emitted from the seed beam (701) by the pump light by transmitting the laser light emitted from the seed beam (701) to the first optical fiber (733) within the first amplification module (703) and simultaneously transmitting the pump light emitted from the pump light source (713) to the first optical fiber (733).

[0120] In one embodiment, the first amplification module (703) may further include a second optical isolator (OI) (743) at the rear end of the first optical fiber (733). The second optical isolator (743) can prevent the laser light amplified once through the first amplification module (703) from proceeding in the reverse direction and control it to proceed in a desired direction.

[0121] According to one embodiment, the fiber laser light source (700) may further include a mode field adapter (MFD) (704) between the first amplification module (703) and the second amplification module (705). The mode field adapter (704) can perform the function of converting and connecting the mode fields of the optical fibers used in the first amplification module (703) and the second amplification module (705) when they are different.

[0122] In one embodiment, the second amplification module (705) may further include a second optical coupler (725) disposed upstream of the second optical fiber (735). The second optical coupler (725) may perform the function of transmitting the laser light amplified by the first amplification module (703) to the second optical fiber (735) and simultaneously transmitting the pump light emitted from the pump light source (715) to the second optical fiber (735) to further amplify the laser light transmitted from the first amplification module (703).

[0123] In one embodiment, the second amplification module (705) may further include a pump stripper (PS) (745) disposed at the rear end of the second optical fiber (735). The pump stripper (745) may serve to remove residual pump light that is not used for laser light amplification before the final output of the laser light.

[0124] According to one embodiment, the fiber laser light source (700) may further include a collimator (706) at the rear end of the pump stripper (745). The collimator (706) may serve to ensure that the light rays of the fiber laser light source (700) are finally emitted in parallel.

[0125] In one embodiment, when a MOPA optical circuit structure as described above is applied to the fiber laser light source (700), the light in the forward direction with respect to the laser output direction can be extracted at the rear end of the second amplification module (705). Specifically, the light can be extracted after being amplified through the second amplification module (705) and then finally output through the collimator (706).

[0126] In one embodiment, when a MOPA optical circuit structure as described above is applied to the fiber laser light source (700), light in the reverse direction with respect to the laser output direction can be extracted at the front end of the second amplification module (705). Specifically, it can be extracted near the mode field connection element (704).

[0127] In another embodiment, the light in the reverse direction relative to the laser output direction can be extracted after being amplified through the second amplification module (705) and before being finally output. Specifically, the reverse light can be extracted at the downstream end of the pump stripper (745) and the upstream end of the collimator (706).

[0128] According to one embodiment, the fiber laser light source (700) may apply the fiber composite to the optical path from the pump stripper (745) to the collimator (705). The optical path after the pump stripper (745) constitutes the end region of the device, corresponding to the output end of the fiber laser light source. The fiber composite forms both the laser core (10) and the heating core (20) into fibers and arranges them adjacent to each other. Therefore, a temperature gradient can be formed in the laser core (10) without a separate cylindrical or similar mechanism for creating a temperature gradient, thereby realizing a technical advantage that the laser core is not exposed externally even when applied to the output end of the fiber laser light source.

[0129] In the fiber laser light source according to one embodiment, the length of the fiber composite may be about 2 m or more, for example, about 3 m or more, for example, about 4 m or more, for example, about 6 m or less, for example, about 5 m or less. In a fiber laser light source, noise such as stimulated Brillouin scattering (SBS) tends to increase as the optical path lengthens, but the fiber laser light source can obtain the advantage of effectively suppressing noise such as stimulated Brillouin scattering (SBS) despite the optical path lengthening by applying the fiber composite.

[0130] According to one embodiment, the fiber laser light source can emit light without stimulated Brillouin scattering (SBS) peaks. The absence of SBS peaks means that peaks recognized as SBS peaks in the spectrum are not visibly confirmed. By configuring at least a portion of the optical path with the fiber composite, the fiber laser light source can provide a temperature gradient in real time through the heating core (20) along the optical path penetrating the laser core (10), thereby achieving the effect of substantially eliminating stimulated Brillouin scattering (SBS).

[0131] Specific embodiments of the present invention are presented below. However, the embodiments described below are merely for the purpose of specifically illustrating or explaining the present invention, and the scope of the present invention is not to be interpreted as limited by this, and the scope of the present invention is determined by the claims.

[0132]

[0133] <Preparation Example>

[0134] Preparation Example 1

[0135] A laser optical fiber is prepared in which a fibrous laser core comprising 85.5 mol% silica (SiO2), 9.5 mol% germanium oxide (GeO2), and 5 mol% aluminum oxide (Al2O3) is surrounded by a first cladding of 100 mol% silica (SiO2) along the entire length direction, and the first cladding is surrounded by a first jacket made of polyimide material. In the laser optical fiber, the diameter of the cross-section in the thickness direction of the laser core is 25 μm, the diameter of the first cladding is 300 μm, and the diameter of the first jacket is 450 μm. Next, a heating optical fiber is prepared in which a fibrous heating core comprising 91.6 mol% silica (SiO2), 4 mol% germanium oxide (GeO2), 3 mol% aluminum oxide (Al2O3), 0.8 mol% iron oxide (Fe2O3), 0.5 mol% cobalt oxide (Co2O3), and 0.1 mol% magnesium oxide (MgO) is surrounded by a second cladding of 100 mol% silica (SiO2) along the entire length direction, and the second cladding is surrounded by a second jacket made of polyacrylate material. In the heating optical fiber, the diameter of the cross-section in the thickness direction of the heating core is 30 μm, the diameter of the second cladding is 300 μm, and the diameter of the second jacket is 440 μm. Subsequently, the laser optical fiber and the heating optical fiber are simultaneously [conducted] with a heat transfer coefficient of 18 Btu in / (h·ft²). 2 An optical fiber composite is manufactured by processing it to be surrounded by an epoxy resin with a pH of 1.5°F.

[0136]

[0137] Preparation Example 2

[0138] The case in which the laser optical fiber is used alone without the heating optical fiber is designated as Manufacturing Example 2.

[0139]

[0140] <Examples and Comparative Examples>

[0141] Example 1

[0142] A fiber laser light source device was prepared by applying the fiber composite of Manufacturing Example 1 to the MOPA optical circuit structure of FIG. 7. Specifically, with reference to FIG. 7, the fiber composite of Manufacturing Example 1 was applied to the optical path between the second optical fiber (735) and the pump stripper (745) and the collimator (706). (Illustrated by a relatively thick line in FIG. 7). The laser optical fiber of Manufacturing Example 2 was applied to the optical path excluding the area where the fiber composite of Manufacturing Example 1 was applied.

[0143]

[0144] Comparative Example 1

[0145] In the MOPA optical circuit structure of Fig. 7, a fiber laser light source device was provided in which the laser optical fiber of Manufacturing Example 2 was applied throughout the entire optical path and the heating optical fiber was not applied.

[0146]

[0147] <Evaluation>

[0148] Experimental Example 1: Induced Brillouin Scattering (SBS) Reduction Effect

[0149] For the fiber laser light sources of Example 1 and Comparative Example 1, a graph (optical output spectrum) of optical power (unit: dBm) by wavelength (unit: nm) was derived for each of the forward and backward light with respect to the laser output direction, using an optical spectrum meter (Ando, ​​AQ6370) with a resolution of 0.02 nm. Specifically, referring to FIG. 7, the final output laser light was extracted as a forward output port (FOP) for extracting the forward light, and as a backward output port (BOP) for extracting the backward light, an optical coupler coupled with a mode field connector (704) was used, or an optical coupler was installed around the mode field connector (704) to extract the light. The results are as shown in Table 1 and FIG. 8 below.

[0150]

[0151] Experimental Example 2: Evaluation of Single-Wavelength Optical Output

[0152] For each of the fiber laser light sources of Example 1 and Comparative Example 1 above, the linewidth of the laser peak for the light at the forward output terminal (FOP) was measured using a delayed self-heterodyne interferometric method with an RF spectrum analyzer (Agilent, E4446A). The results are as shown in Table 1 below.

[0153] Forward (@Wavelength [nm]) Reverse (@Wavelength [nm]) Linewidth [MHz] I1 [dBm] I2 [dBm] I2-I1 [dB] I1 [dBm] I2 [dBm] I2-I1 [dB] Comparative Example 1-3 1.80 @ 1550.12 - 51.94 @ 1550.20 - 20.14 - 69.62 @ 1550.12 - 42.26 @ 1550.1927.3624 Example 1-29.50 @ 1550.12 - 55.83 @ 1550.17 - 26.33 - 71.11 @ 1550.12 - 55.08 @ 1550.2016.0310

[0154] FIGS. 8(a) and (b) are optical output spectrum graphs measured at the forward output terminal and reverse output terminal of Comparative Example 1, respectively, and FIGS. 8(c) and (d) are optical output spectrum graphs measured at the forward output terminal and reverse output terminal of Example 1, respectively. In FIGS. 8, the position of the laser peak is indicated as 'Laser' with a solid arrow, and the SBS scattering peak is indicated as 'SBS' with a dotted arrow.

[0155] Referring to FIG. 8 (a) and (c), in the case of the fiber laser light source of Comparative Example 1, which does not apply a fiber composite, a large SBS peak occurs in the forward light compared to Example 1, and accordingly, severe distortion and noise occur in the light output spectrum and the linewidth is expanded. More specifically, regarding the laser light that propagates in the forward direction and is finally output, in the case of Example 1, the difference between the SBS scattering peak intensity (I2) value (unit: dBm) and the laser peak intensity (I1) value (unit: dBm) is -26.33 dB, whereas in Comparative Example 1, it is -20.14 dB, and as a result, it can be confirmed that the relative intensity of the SBS peak relative to the laser peak is smaller in Example 1 compared to Comparative Example 1.

[0156] Referring to FIG. 8(b) and (d), it can be seen that in the case of the fiber laser light source of Comparative Example 1, which does not apply a fiber composite, a relatively large SBS peak occurs even in the reverse direction light compared to Example 1. In the reverse direction light, the SBS peak appears larger than the laser peak, which allows for a more detailed comparison of the degree of SBS scattering. In the case of reverse direction light, it can be seen that in the case of Example 1, the difference between the SBS scattering peak intensity (I2) value (unit: dBm) and the laser peak intensity (I1) value (unit: dBm) is 16.03 dB, whereas in Comparative Example 1, it is 27.36 dB. That is, it can be seen that in the case of Example 1, the relative intensity of the SBS peak relative to the laser peak is smaller than in Comparative Example 1.

[0157] In addition, referring to the results in Table 1, the fiber laser light source of Example 1 output light with a linewidth of 10 MHz and a wavelength of 1550.12 nm with an intensity of -29.50 dBm when the fiber composite was applied, whereas the fiber laser light source of Comparative Example 1 output light with a linewidth of 24 MHz and a wavelength of 1550.12 nm with an intensity of -31.80 dBm. That is, it was found that the light source of Example 1 output light with a narrower linewidth at a higher intensity than that of Comparative Example 1.

[0158] It can be seen that, according to one embodiment, the fiber laser effectively removes noise caused by SBS scattering by having a laser core and a heating core arranged adjacently and applying heat with a temperature gradient generated from the heating core to the laser core. In addition, even when applied to an optical circuit structure, such as a MOPA optical circuit structure, where noise amplification inevitably increases as a multi-stage amplification process is performed for a high-power laser, the effect of effectively removing noise can be achieved.

[0159] [Explanation of the symbol]

[0160] 100, 200, 300, 400: Fiber optic complex

[0161] 10: Laser Core

[0162] 20: Heat core

[0163] 30: Heat transfer zone

[0164] 40: Stress imparting agent

[0165] 11: First Periphery

[0166] 111: 1st Cladding

[0167] 112: First Jacket

[0168] 21: Second Periphery

[0169] 211: Second Cladding

[0170] 212: The 2nd Jacket

[0171] 31: The Third Periphery

[0172] 311: Third Cladding

[0173] 312: The Third Jacket

[0174] 201: Heating area

[0175] 202: Non-thermal area

[0176] 700: Fiber optic laser

[0177] 701: Seed beam

[0178] 702: First Optical Isolator (OI)

[0179] 703: 1st Amplification Module

[0180] 713: First pump light source

[0181] 723: First Optical Coupler (OC)

[0182] 733: First optical fiber

[0183] 743: Second optical isolator

[0184] 704: Mode Field Adapter (MFD)

[0185] 705: Second Amplification Module

[0186] 715: Second pump light source

[0187] 725: Second optical coupler

[0188] 735: Second optical fiber

[0189] 745: Pump Stripper (PS)

[0190] 706: Collimator (COL)

[0191] The present invention relates to a fiber laser light source having a single wavelength. The present invention relates to a fiber composite exhibiting a narrow linewidth and high output capable of functioning as a high-power, high-quality laser light source, and a fiber laser light source comprising the same. According to the present invention, a single wavelength fiber laser light source having excellent spectral characteristics, no noise, and stable output characteristics can be provided. The single wavelength laser light source technology according to the present invention can be used in fiber sensor systems, remote optical measurement systems, and the development of high-power laser light sources.

Claims

1. Fibrous laser core; and It includes at least one fibrous heating core adjacent to the laser core, and The above-mentioned heating core radiates heat having a temperature gradient, and Heat radiated from the above heating core is applied to the above laser core, Fiber optic composite.

2. In Paragraph 1, The above laser core comprises silica (SiO2) and additive components, and The above additive component is one selected from the group consisting of germanium (Ge), phosphorus (P), boron (B), fluorine (F), aluminum (Al), lithium (Li), sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), bismuth (Bi), scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), preseodymium (Pr), neodymium (Nd), promedium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), ruthenium (Lu), and combinations thereof; or comprising an oxide derived from one selected from the group consisting of germanium (Ge), phosphorus (P), boron (B), fluorine (F), aluminum (Al), lithium (Li), sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), bismuth (Bi), scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), preseodymium (Pr), neodymium (Nd), promedium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), ruthenium (Lu), and combinations thereof, Fiber optic composite.

3. In Paragraph 1, The above heating core includes a heating region, and The above heating area satisfies 1) or 2) below, Fiber optic composite: 1) The heating region is continuous in the longitudinal direction 2) The heating region is discontinuous in the longitudinal direction 4. In Paragraph 1, The above heating core includes a heating region, and The above-mentioned heating region includes silica (SiO2) and a heating component, and The above exothermic component is scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), zirconium (Zr), niobium (Nb), molybdenum (Mo), technedium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), indium (In), tin (Sn), tungsten (W), radium (Ir), platinum (Pt), gold (Au), lead (Pb), bismuth (Bi), ruthenium (Lu), lanthanum (La), cerium (Ce), preseodymium (Pr), neodymium (Nd), promedium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), One selected from the group consisting of terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and combinations thereof; or Scandium (Sc), Titanium (Ti), Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu), Zinc (Zn), Gallium (Ga), Zirconium (Zr), Niobium (Nb), Molybdenum (Mo), Technedium (Tc), Ruthenium (Ru), Rhodium (Rh), Palladium (Pd), Silver (Ag), Cadmium (Cd), Indium (In), Tin (Sn), Tungsten (W), Iridium (Ir), Platinum (Pt), Gold (Au), Lead (Pb), Bismuth (Bi), Ruthenium (Lu), Lanthanum (La), Cerium (Ce), Preseodymium (Pr), Neodymium (Nd), Promedium (Pm), Samarium (Sm), Europium (Eu), Gadolinium (Gd), Terbium (Tb), Comprising an oxide derived from one selected from the group consisting of dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and combinations thereof, Fiber optic composite.

5. In Paragraph 1, A first peripheral portion surrounding the laser core; and It further includes a second peripheral portion surrounding the above-mentioned heating core, and A heat transfer region including a heat transfer region that simultaneously surrounds the first peripheral region and the second peripheral region. Fiber optic composite.

6. In Paragraph 1, A third peripheral portion further comprising simultaneously surrounding the laser core and the heating core, Fiber optic composite.

7. In Paragraph 1, further comprising at least one fibrous stress imparting material adjacent to the laser core, Fiber optic composite.

8. A fiber optic composite according to any of paragraphs 1 to 7, comprising In the case of forward light with respect to the laser output direction, A difference (I2-I1) between the laser peak intensity (I1) (unit: dBm) and the stimulated Brillouin scattering (SBS) peak intensity (I2) (unit: dBm) in the optical output spectrum is -22.00 dB to -50.00 dB, Fiber laser light source.

9. In Paragraph 8, Emitting single-wavelength light having a linewidth of 0 to 100 GHz within a wavelength range of 500 nm to 2200 nm, Fiber laser light source.

Images