Capillary for stripping back reflected light

Abstract

Some embodiments may include a fiber laser comprising two or more input fibers and an output fiber for delivering a beam to a workpiece. The fiber laser may include a combiner having ends and a length, wherein the combiner is arranged to release a portion of back-reflected light received from the output fiber at the output end of the combiner along its length. The combiner includes: a capillary for surrounding a portion of the two or more input fibers at the input end of the combiner, the capillary having an end and a length between the ends of the capillary; and a cladding light stripper (CLS) defined by a portion of the length of the capillary, wherein the CLS provides release of that portion of the back-reflected light. Other embodiments may be disclosed and / or claimed.

Description

[0001] priority

[0002] This application claims priority to U.S. Provisional Application No. 62 / 968,085, filed January 30, 2020, entitled “CAPILLARY CLADDING LIGHT STRIPPERFOR COMBINER,” and U.S. Provisional Application No. 62 / 968,087, filed January 30, 2020, entitled “THERMALPATH OPTIMIZED OPTICAL SIGNAL COMBINER HOUSING,” each of which is incorporated herein by reference. Technical Field

[0003] This disclosure relates to fiber lasers. Background Technology

[0004] Fiber lasers are widely used in industrial processes (e.g., cutting, welding, cladding, heat treatment, etc.). In some fiber lasers, the optical gain medium comprises one or more active fibers with a core doped with rare-earth elements. The rare-earth elements can be optically excited (“pumped”) from one or more semiconductor laser sources. Attached Figure Description

[0005] The accompanying drawings are incorporated in and constitute a part of this specification and, together with the description, explain the advantages and principles of the currently disclosed technology, wherein the same reference numerals denote the same elements.

[0006] Figure 1A shows a schematic diagram of a known combiner with a capillary.

[0007] Figures 1B and 1C show cross-sectional views taken along section line A of Figure 1A according to various embodiments.

[0008] Figure 2 A side view of a capillary for stripping back-reflected light, according to various embodiments, is shown.

[0009] Figure 3A and Figure 3B Various embodiments are shown respectively. Figure 2 Side and top views of the light-stripped portion of the capillary.

[0010] Figure 3C The following are illustrated according to various embodiments. Figure 3A The sectional view taken by section line B.

[0011] Figure 4 The adoption according to various embodiments is shown. Figure 2 A top view of a capillary fiber laser.

[0012] Figure 5 A side view of another capillary for stripping back-reflected light, according to various embodiments, is shown.

[0013] Figure 6 An isometric view of a thermally optimized optical signal combiner housing according to various embodiments is shown, with the housing cover removed.

[0014] Figure 7 Various embodiments are shown. Figure 6 A side view of the housing of a thermally optimized optical signal combiner, with an attached cover.

[0015] Figure 8 Various embodiments are shown. Figure 6 A partially transparent isometric view of the housing of the thermally optimized optical signal combiner, with an attached cover.

[0016] Figure 9 Illustrations are shown according to various embodiments. Figure 6 Partially transparent isometric view of the housing of the thermal path optimized optical signal combiner, and a detailed view of the fasteners.

[0017] Figure 10 The following are illustrated according to different embodiments. Figure 9 The image shows a cut of a fastener. Figure 6 A partially transparent isometric cross-sectional view of the housing of the thermal path optimized optical signal combiner. Detailed Implementation

[0018] The singular forms “a,” “an,” and “the” used in this application and claims include the plural forms unless the context clearly specifies otherwise. Additionally, the term “comprising…” means “including…”. Furthermore, the term “coupled (connected)…” does not exclude the existence of intermediate elements between coupled (connected) items. The systems, apparatuses, and methods described herein should not be construed as limiting in any way. Rather, this disclosure relates to all novel and non-obvious features and aspects of the various disclosed embodiments (individually and in various combinations and sub-combinations of each other). The term “or” means “and / or,” not “exclusive or” (unless specifically indicated).

[0019] The disclosed systems, methods, and apparatuses are not limited to any particular aspect or feature or combination thereof, nor are they required to possess any one or more particular advantages or problems to be solved. Any operational theories are provided for ease of explanation, but the disclosed systems, methods, and apparatuses are not limited to these operational theories. Although the operations of some disclosed methods are described in a specific sequential order for ease of presentation, it should be understood that this descriptive method includes rearrangements unless the specific language described below requires a particular order. For example, the sequentially described operations may be rearranged or performed simultaneously in some cases. Furthermore, for simplicity, the accompanying drawings may not show the various ways in which the disclosed systems, methods, and apparatuses can be used in conjunction with other systems, methods, and apparatuses.

[0020] Additionally, the description sometimes uses terms such as “produce” and “provide” to describe the disclosed methods. These terms are high-level abstractions of the actual operations performed. The actual operations corresponding to these terms will vary depending on the specific implementation and are readily recognizable to those skilled in the art. In some examples, values, processes, or apparatus are referred to as “lowest,” “best,” “minimum,” etc. It should be understood that such descriptions intentionally indicate that a selection can be made from a number of functional alternatives used, and that such selection is not necessarily better, smaller, or otherwise preferred than other options.

[0021] The examples are described using directions such as "above," "below," "up," and "down." These terms are used for ease of description and do not imply any specific spatial direction.

[0022] Capillary tubes used to strip away back-reflected light

[0023] Figure 1A shows a schematic diagram of a known combiner with a capillary tube 5. The capillary tube 5 surrounds the input fiber 1 received at a first end of the combiner. The output fiber 2 can be fused to a second end of the combiner. Figure 1B shows a cross-sectional view taken along section line A in the direction of the arrow. Figure 1C shows a cross-sectional view taken along section line A in the opposite direction of the arrow (showing the core 8 and non-core 9 of the output fiber). Figures 1A to 1C show an example of a known combiner in which the capillary tube 5 has a tapered portion 6, but other combiners are known to have non-tapered capillary tubes (e.g., with a uniform outer diameter from end to end).

[0024] When a high-power fiber laser is used for material processing (e.g., cutting or welding), some light reflected from the workpiece is coupled back into the fiber and propagates back to the laser. If the laser has a capillary type combiner, such as the combiners in Figures 1A to 1C, or any combiner with a capillary (tapered or non-tapered), some light will pass through the combiner and travel backward in the core and cladding of the fiber into which the combiner is input.

[0025] However, some of the back-reflected light may also couple into the capillary. The light coupled into the capillary can be absorbed by any bonding material that holds the capillary in place (in the case of high-refractive-index materials), or it can travel through the entire capillary and exit from its end face (in the case of low-refractive-index bonding materials). In the former case, the bonding material will burn out; in the latter case, the input fiber and / or other components inside the laser may be damaged.

[0026] To avoid these problems, a cladding light stripper can be fabricated on the capillary. This may cause any light coupled into the capillary to scatter beyond the length of the capillary, which can prevent burn-out of the bonding material and / or damage to the input fiber and / or other components inside the fiber laser.

[0027] Figure 2 A side view of a capillary 15 for stripping back-reflected light according to various embodiments is shown. The capillary 15 has ends 11 and 12 and a length. Ends 11 and 12 may be similar in any respect to the ends of the capillary 5 of FIG. 1A; for example, the first end 11 may surround a portion of two or more input optical fibers (each input optical fiber may be similar in any respect to a single optical fiber in input optical fiber 1 shown in FIG. 1), and the second end 12 may be fused to an output optical fiber (which may be similar in any respect to output optical fiber 2 shown in FIG. 1).

[0028] The length of the capillary 15 includes optical stripping features 19 to strip back-reflected light traveling through the capillary 15. The optical stripping features 19 can be provided by any method now known or developed hereafter for fabricating cladding optical strippers (CLS). In this example, the optical stripping features 19 are provided by creating lateral grooves using a CO2 laser. In other examples, a CO2 laser can be used to create one or more continuous helical grooves around the exterior of the capillary 15.

[0029] In other embodiments, a roughened surface on the exterior of capillary 15 can be provided by adding material to the exterior of capillary 15 (in addition to or instead of removing material from capillary 15). In other embodiments, the photo-stripping feature 19 can be provided by otherwise agitating the exterior of capillary 15 (e.g., immersing capillary 15 in a fluid).

[0030] In this example, the light stripping feature 19 is disposed on the top of the capillary 15, such that the stripped light is released from the top of the capillary 15. Figure 3A and Figure 3B The side view and top view of the light stripping portion of the capillary 15 are shown respectively. Figure 3C It shows along Figure 3A The cross-sectional view is taken by section line B. This shows that the groove has a variable depth, although this is not necessary (in other examples, the groove may have a uniform depth).

[0031] Refer again Figure 2 The light stripping feature 19 can be disposed on other portions of the capillary 15, for example, completely surrounding the capillary 15, which can scatter back-reflected light above, below, and to the sides of the capillary 15. The position of the light stripping feature 15 can be selected to guide the stripped light to a desired location consistent with the heat dissipation device of the fiber laser.

[0032] exist Figure 2 In this embodiment, the optical stripping feature 19 is provided only on the non-tapered portion of the capillary 15. In other embodiments, the optical stripping feature 19 may be provided on another portion of the capillary, for example, on the tapered portion or on both portions.

[0033] Figure 4 A top view of a fiber laser 400 is shown, which includes... Figure 2 The combiner of capillary 15. A portion 401 of the back-reflected light is released from the length of the combiner. Different portions 402 of the back-reflected light are released from the ends of the combiner. Portions 402 may include back-reflected light transmitted through the combiner by traveling backward through the core and cladding of the fiber input to the combiner. Portions 402 of light may include a reduced amount of light coupled into the capillary (due to light stripping feature 19). Figure 2 This prevents the bonding material from burning out and / or damage to the input fiber and / or other components inside the fiber laser. In this example, the capillary tapers toward the output of the combiner, but this is not necessary in embodiments with a taper (and in various embodiments, no taper of the capillary is required).

[0034] Figure 5 A side view of another capillary 515 for stripping back-reflected light according to various embodiments is shown. This capillary 515 does not have a tapered portion (e.g., a consistent outer diameter from end to end). This capillary 515 also has a consistent inner diameter, and the ends 511 and 512 are identical, but other embodiments may have inconsistent inner diameters and / or different ends. The light stripping feature 519 may be similar in any respect to light stripping feature 19 ( Figure 2 (or any other optical stripping feature described herein.)

[0035] In various embodiments, any capillary may be ( wholly or partially) enclosed within a housing. The housing may define a chamber, and at least a portion of the capillary having the photo-ablation feature may be disposed within the chamber. The chamber may be sized to provide a gap between the interior of the chamber and the portion of the capillary corresponding to the photo-ablation feature on the exterior.

[0036] The interior of the housing may be arranged to absorb light of wavelengths associated with the back-reflected light. In some embodiments, this may include roughening the interior of the housing. The housing may be formed of any material, and in some embodiments, the selected material may be chosen to optimize thermal conductivity (so that the heat generated by absorbing the back-reflected light can be dissipated quickly).

[0037] In any of the embodiments described herein, the diameter of the core of the output fiber may be larger than the outer diameter of the surface of the output end of the combiner (the capillary may taper toward the output end of the combiner). Although this may cause back-reflected light to enter the surface of the taper end of the capillary from the overlapping portion of the core, the light stripping characteristics of the capillary combiner can compensate for this to prevent damage due to heating, as described herein. Any combiner described herein may be a pump combiner or a signal combiner.

[0038] The various embodiments described above provide a capillary for stripping back-reflected light. In some of these embodiments, the capillary may optionally be arranged within a housing to collect heat from the stripped light. In embodiments employing a housing, the housing may optionally utilize any thermal path-optimized optical signal combiner housing features described herein. In other embodiments employing a housing, the housing may include several other thermal management or encapsulation features now known or developed thereafter.

[0039] Thermal path optimized optical signal combiner housing

[0040] Fiber optic assemblies (e.g., fiber optic assemblies including capillaries for stripping back-reflected light, some other combiner, or any other fiber optic assembly) may need to be encapsulated in a housing to minimize mechanical stress while still providing good thermal performance. The available materials represent a trade-off between the coefficient of thermal expansion and thermal conductivity. Materials whose coefficient of thermal expansion closely matches that of the optical assembly typically have lower thermal conductivity, but materials that provide improved thermal conductivity typically have a coefficient of thermal expansion higher than the preferred coefficient.

[0041] During normal combiner operation, a relatively low, constant level of energy needs to be dissipated. To maintain consistent optical characteristics, this energy needs to be removed with minimal localized heating to minimize thermal expansion of the components. This reduces stress variations on the optical components, which can lead to changes in their performance.

[0042] Alongside normal combiner operation, other operating scenarios need to be considered. When a laser cuts through a reflective metal, a typical scenario is that a portion of the cutting light may be reflected and potentially travel back to the laser via the fiber optic cable. The reflected light in the fiber cladding is easily stripped before the combiner, but the light reflected into the fiber core may eventually enter the combiner. A significant percentage of this energy may be dissipated within the combiner assembly. Typically, these energy events peak at the start of the cut, before the laser has penetrated the material. These events are short-lived but can cause localized heating of the combiner components. Furthermore, many other situations can generate high or sustained back-reflection power (e.g., welding or additive manufacturing).

[0043] The solution to the aforementioned localized thermal stress problem in optical systems is to minimize thermal stress by selecting a housing material whose coefficient of thermal expansion closely matches that of the optical components. The optical components can then be directly mounted onto the housing. To minimize thermal resistance, the housing can be directly mounted onto a cold plate.

[0044] By tightly attaching the housing to the cold plate, the effects of materials with low thermal conductivity are minimized. The use of materials with low thermal expansion and controlled heating provides a thermally and dimensionally stable platform for the optical components during normal operation. Closely matched coefficients of thermal expansion minimize potential mechanical stresses that may arise from temperature variations during transport and storage.

[0045] During the obstructed cleaving process, energy from the material being cleaved may be reflected back into the output fiber. This reflected energy can be released from several regions of the combiner optics. In high-power laser systems, hundreds of watts of back-reflected energy may be released from the fiber core into the combiner assembly.

[0046] Typically, these are likely to be short-term events, as the laser head may trigger a system shutdown, or the laser may penetrate metal, thus reducing the energy reflected back into the system.

[0047] Materials with low thermal expansion are generally not good thermal conductors, and the housing may be affected by localized heating due to these short-term events. This can lead to localized heating of the optical components and the housing itself.

[0048] It may still be necessary to control the energy loss from backreflection cutting. In various embodiments, a cover with a surface that is more absorbent than the housing is used to control the energy loss. The cover material can have a significantly higher thermal conductivity than the housing material. These characteristics allow the cover to absorb a higher percentage of backreflected energy while minimizing surface temperature. By using a material with high specific heat and good thermal conductivity, the lost energy can be conducted and temporarily stored within the cover.

[0049] A controlled thermal path can be provided for the cover to lead to the housing. This allows stored energy to dissipate over a time interval significantly longer than the initial thermal event. This controlled heat dissipation can limit temperature rise in the housing and optical components.

[0050] Heat transfer through the cover can be controlled by limiting the clamping force on the housing. This limited clamping force also allows the cover to expand independently of the housing, thereby minimizing mechanical stress. Since the clamping force of the housing on the radiator (e.g., cold plate) may be higher than the clamping force of the cover on the housing, heat transfer to the cold plate may be higher. This combination of clamping forces can control the rate of heat transfer as heat travels from the cover through the housing and into the radiator, and thus control the temperature rise of the housing.

[0051] This combination of materials and installation provides an optimized thermal path during normal forward operation and controlled energy dissipation during high-energy short-term back reflection events.

[0052] The aforementioned thermal management features can be applied to other fiber-based components, not just combiners (and not just combiners with capillaries featuring integrated cladding strippers). It can be used with any fiber-optic component that must dissipate heat. These thermal management features can also be applied to other situations that may generate high or sustained back-reflection power (e.g., welding, additive manufacturing).

[0053] Figure 6 An isometric view of a thermally optimized optical signal combiner housing 635 according to various embodiments is shown, with the housing cover removed. Figure 7 A side view of a thermally optimized optical signal combiner housing 635 according to various embodiments is shown, in which a cover 725 (which may also be referred to as a plate cover) is attached.

[0054] refer to Figure 6 The housing 635 may have a first side thermally coupled to a heat sink 625 (e.g., a cold plate). A second side (e.g., an opposite second side) of the housing 635 defines the bottom and / or sides of the chamber 639. The top of the chamber 639 may be defined by the lower side of the cover 725. Figure 7 In this embodiment, chamber 639 may be exposed to air.

[0055] Refer again Figure 6 Optical fiber 615 can be mounted onto housing 635, and a portion of the length of optical fiber 615 for releasing back-reflected light can be positioned within chamber 639. In this embodiment, this portion of the length includes capillary 15 ( Figure 2In other embodiments, this portion of the length of fiber 615 may include another combiner, another optical component, or another fiber length capable of emitting light, such as a splice point.

[0056] The chamber 639 includes angled sides 638, which can be plated to form a reflective surface. This plating can have a different material than the housing, for example, gold or some other material that can form a highly reflective surface. As described herein, when from capillary 15 ( Figure 2 When back-reflected light is emitted, the light can be reflected away from the angled side 638 away from the optical fiber 615 (to avoid damaging components of the optical fiber 615). This can be done at the top of the chamber 639 (e.g., a portion of the underside of the cover 725). Figure 7 The light is received at the location. The lower portion of the cover 725 may be roughened or otherwise arranged to absorb the light received thereon.

[0057] The cover 725 may be made of the same material as the heat sink 625, or of some other material with good thermal conductivity (e.g., copper). Therefore, from the capillary 15 ( Figure 2 During or after an event in which back-reflected light is released, heat received by the underside of the cover 725 can move throughout the cover 725. The cover 725 can reach high temperatures, for example, high uniform temperatures, because the cover collects and temporarily stores heat, thereby protecting multiple sections of the optical fiber 615 from receiving that heat.

[0058] The housing 635 may be made of a material whose coefficient of thermal expansion closely matches that of the material of the optical fiber 615. In some embodiments, the housing material may be an Invar alloy or some other material having a closely matched coefficient of thermal expansion (the term "closely matched" as used herein may mean a closer match than that of the material of the cover 725). The housing material does not need to have the same thermal conductivity as the materials of the cover 725 and / or the heat sink 625. Therefore, if the housing 635 expands due to heat, the housing can expand in a similar manner to the optical fiber 615 mounted on the housing 635, which avoids physical stress on the optical fiber 615.

[0059] The clamping force between the cover 725 and the housing 635 can be less than the clamping force between the housing 635 and the heat sink 625. This allows the cover 725 to expand differently from the second side of the housing 635, and prevents expansion stress from being applied to the second side of the housing 635 (which, if applied to the second side, could potentially be applied to the optical fiber 615 mounted on the second side of the housing 635). Therefore, although the cover 725 ( Figure 7 It may expand differently from the housing 635, but will not damage the fiber 615.

[0060] Because of the lower clamping force between housing 635 and cover 725, and because of the reduced thermal conductivity of housing 635 (compared to cover 725 and / or heat sink 625), cover 725 can function as a “thermal battery.” Specifically, during or after an event that releases back-reflected light, cover 725 can rapidly reach a uniform temperature. Then, in a later time period, heat transfer through housing 635 from cover 725 to heat sink 625 can be controlled by the lower thermal conductivity of the material of housing 635 and / or the lower clamping force. During this process, housing 635 may never reach the same high temperature as cover 725, but even if it does, any expansion of housing 635 can be closely matched with any expansion of optical fiber 615.

[0061] Fastener 736 clamps the cover 725 to the second side of the housing 635. Figure 7 The fastener 736 may differ from the fastener 636 that clamps the first side of the housing 635 onto the heat sink 625. In this embodiment, the fastener 736 includes a shoulder screw and a spring washer 737, but in other embodiments, any spring fastener now known or developed hereafter may be used. Figure 8 and Figure 9 The attachment between the cover 725 and the second side of the housing 635 is shown.

[0062] Figure 10 The image shown is a section taken along a fastener 736 according to various embodiments. Figure 6 A partially transparent isometric cross-sectional view of the thermal path optimized optical signal combiner housing 635. In this example, the fastener 736 is a shouldered screw with a shoulder between the threaded portion and the head. The length of the shoulder controls how far the fastener 736 can be driven downwards. A spring washer 737 may be disposed in the gap between the bottom of the countersunk hole located on the underside of the head and the top of the cover 725.

[0063] In the illustrated embodiment, fiber 615 ( Figure 6 The portion of the length of which is located in chamber 639 includes capillary 15 ( Figure 2 The light received on the cover 725 is back-reflected light. In other embodiments, the optical fiber used with the housing 635 may include another optical component (e.g., a combiner excluding capillary 15), and this combiner or other optical component may be positioned in the chamber 639, and the light received on the cover 725 may be back-reflected light or some other type of light. In various embodiments, more than one housing similar to housing 635 may be used in fiber lasers for different components arranged along the length of the optical fiber. Any splice point along the length of the optical fiber may emit some kind of light, and any such splice point may be positioned in a chamber of one of the housings.

[0064] Example

[0065] Example 1 is a fiber laser including two or more input fibers and an output fiber for transmitting a beam to a workpiece. The fiber laser includes: a combiner having an end and a length, wherein the combiner is arranged to release a portion of back-reflected light received from the output fiber at the output end of the combiner along its length; the combiner includes: a capillary for surrounding a portion of the two or more input fibers at the input end of the combiner, the capillary having an end and a length between the ends of the capillary; and a cladding light stripper (CLS) defined by a portion of the length of the capillary, wherein the CLS provides the release of that portion of the back-reflected light.

[0066] Example 2 includes the subject of Example 1 or any other example in this document, and also includes a housing that at least surrounds that portion of the length of the capillary, wherein a portion of the interior of the housing is arranged to absorb light of wavelengths associated with back-reflected light.

[0067] Example 3 includes the subject of any of Examples 1-2 or any other example herein, wherein the housing defines a chamber in which the portion of the length of the capillary is disposed, and the chamber is sized to provide a clearance between the interior of the chamber and the outer surface of the portion of the length of the capillary.

[0068] Example 4 includes the subject of any of Examples 1-3 or any other example herein, wherein the outer surface includes a notch arranged to guide back-reflected light into the interior of the housing, which is arranged to absorb a portion of light of a wavelength associated with the back-reflected light.

[0069] Example 5 includes the subject of any of Examples 1-4 or any other example in this document, wherein the outer surface of that portion of the length of the capillary is roughened.

[0070] Example 6 includes the subject of any of Examples 1-5 or any other example in this document, wherein the combiner includes a signal combiner.

[0071] Example 7 includes the subject of any of Examples 1-6 or any other example in this document, wherein the capillary tapers toward the output of the combiner, or includes a tapered portion.

[0072] Example 8 includes the subject of any of Examples 1-7 or any other example in this document, wherein this portion of the length of the capillary includes the non-tapered portion of the length of the capillary.

[0073] Example 9 includes the subject of any of Examples 1-8 or any other example herein, wherein the outer diameter of the surface of one end of the capillary is smaller than the diameter of the core of the output optical fiber, and some of the back-reflected light enters the surface of that end of the capillary from the overlapping portion of the core.

[0074] Example 10 includes the subject of any of Examples 1-9 or any other example in this document, wherein the output fiber is fused to the output of the combiner.

[0075] Example 11 is an optical fiber assembly including an optical fiber having a first end, a second end, and a length, wherein light is emitted from a portion of the length of the optical fiber. The optical fiber assembly includes: a heat sink; a housing having a first side and a second side, wherein the first side of the housing is thermally coupled to the heat sink, wherein a portion of the second side of the housing defines the bottom or side of a cavity, and said portion of the length of the optical fiber assembly is positioned within the cavity; and a cover thermally coupled to the second side of the housing, wherein a portion of the lower side of the cover defines the top of the cavity. According to various examples, the optical fiber assembly of Example 11 or any of Examples 12-30 or any other example herein may be part of a fiber laser of any of Examples 1-10.

[0076] Example 12 includes the subject of Example 11 or any other example in this document, wherein the housing is formed of a first material and the cover is formed of a second material different from the first material.

[0077] Example 13 includes the subject of any of Examples 11-12 or any other example in this document, wherein the coefficient of thermal expansion of the first material is more closely matched to the coefficient of thermal expansion of the optical fiber material compared to the second material.

[0078] Example 14 includes the subject of any of Examples 11-13 or any other example in this document, wherein the thermal conductivity of the second material is greater than that of the first material.

[0079] Example 15 includes the subject of any of Examples 11-14 or any other example in this document, wherein the heat sink is formed of a third material, wherein the thermal conductivity of the third material is greater than that of the first material.

[0080] Example 16 includes the subject of any of Examples 11-15 or any other example herein, wherein the bottom or side of the chamber has a first reflectivity, and the portion of the cover on the underside has a second reflectivity less than the first reflectivity.

[0081] Example 17 includes the subject of any of Examples 11-16 or any other example in this document, wherein the bottom or sides of the chamber are plated with a reflective metal.

[0082] Example 18 includes the subject of any of Examples 11-17 or any other example in this document, wherein the lower part of the cover is roughened.

[0083] Example 19 includes the subject of any of Examples 11-18 or any other example in this document, wherein the sides of the chamber are tilted to reflect the emitted light away from the optical fiber.

[0084] Example 20 includes the subject of any of Examples 11-19 or any other example in this document, wherein the interior of a chamber is exposed to air.

[0085] Example 21 includes the subject of any of Examples 11-20 or any other example herein, wherein the second end of the optical fiber is arranged to transmit a light beam to a workpiece, and the emitted light includes a portion of back-reflected light from the workpiece.

[0086] Example 22 includes the subject matter of any of Examples 11-21 or any other example herein, wherein a housing is mounted to a heat sink using a first fastener associated with a first clamping force, and a cover is mounted to a second side of the housing using a second fastener associated with a different second clamping force.

[0087] Example 23 includes the subject of any of Examples 11-22 or any other example in this document, wherein the second clamping force is less than the first clamping force.

[0088] Example 24 includes the subject of any of Examples 11-23 or any other example in this document, wherein the second fastener includes a spring fastener.

[0089] Example 25 includes the subject of any of Examples 11-24 or any other example in this document, wherein the spring fastener includes a spring washer and a shoulder screw.

[0090] Example 26 includes the subject of any of Examples 11-25 or any other example in this document, wherein the radiator includes a cold plate.

[0091] Example 27 includes the subject of any of Examples 11-26 or any other example herein, wherein the fiber optic assembly is arranged to collect heat in a cover during a first time period and then transfer a portion of the collected heat to a radiator through a housing during a subsequent second time period longer than the first time period.

[0092] Example 28 includes the subject matter of any of Examples 11-27 or any other example herein, wherein this portion of the length of the optical fiber includes a combiner having an end and a length, wherein the combiner is arranged to release a portion of the back-reflected light received from the output optical fiber at the output end of the combiner from its length.

[0093] Example 29 includes the subject matter of any of Examples 11-28 or any other example herein, wherein the portion of the optical fiber includes: two or more input optical fibers; and an output optical fiber for transmitting a beam of light to a workpiece; and a combiner having an end and a length, wherein the combiner includes a capillary to surround a portion of the two or more input optical fibers at an input end in the end of the combiner, wherein the output optical fiber is coupled to an output end in the end of the combiner.

[0094] Example 30 includes the subject of any of Examples 11-29 or any other example in this document, wherein this portion of the optical fiber includes splice points.

[0095] Given the many possible embodiments to which the disclosed technical principles can be applied, it should be recognized that the embodiments shown are merely preferred examples and should not be considered as limiting the scope of this disclosure. We claim all solutions within the scope and spirit of the appended claims as our invention.

Claims

1. A fiber laser comprising two or more input fibers and an output fiber for transmitting a beam to a workpiece, the fiber laser comprising: A combiner having an end and a length, wherein the combiner is arranged to receive a portion of back-reflected light reflected from the workpiece at an output end in the end of the combiner, the combiner comprising: A capillary tube for surrounding a portion of the two or more input optical fibers at the input end of the combiner, the capillary tube having an end and a length between the ends of the capillary tube; A light stripping device, integrated with a portion of the length of the capillary, wherein the light stripping device provides release of the portion of the back-reflected light; A housing comprising a first side and a second side opposite to the first side, wherein the first side is thermally coupled to a heat sink, and the second side is configured to surround a portion of the length of the capillary; and A cover, which is thermally bonded to the second side of the housing and cooperates with the second side to surround the portion of the length of the capillary; Wherein, the outer diameter of the surface of one end of the capillary is smaller than the diameter of the core of the output optical fiber, wherein some of the back-reflected light enters the surface of the one end of the capillary from the overlapping portion of the core, and The clamping force between the cover and the housing is less than the clamping force between the housing and the radiator.

2. The fiber laser according to claim 1, wherein, A portion of the interior of the housing is arranged to absorb light of wavelengths associated with the back-reflected light.

3. The fiber laser according to claim 2, wherein, The housing defines a chamber in which a portion of the length of the capillary is disposed, and the chamber is sized to provide a gap between the interior of the chamber and the outer surface of the portion of the length of the capillary.

4. The fiber laser according to claim 3, wherein, The outer surface includes a notch arranged to guide the back-reflected light into the interior of the housing, where a portion of the light is arranged to absorb wavelengths associated with the back-reflected light.

5. The fiber laser according to claim 1, wherein, The outer surface of a portion of the length of the capillary is roughened.

6. The fiber laser according to claim 1, wherein, The combiner includes a signal combiner.

7. The fiber laser according to claim 1, wherein, The capillary tapers toward the output end of the combiner, or includes a tapered portion.

8. The fiber laser according to claim 7, wherein, The length of the capillary, which integrates a portion of the optical stripping device, includes the non-tapered portion of the length of the capillary.

9. The fiber laser according to claim 1, wherein, The output optical fiber is fused to the output end of the combiner.

10. A fiber laser comprising two or more input fibers and an output fiber for transmitting a beam to a workpiece, the fiber laser comprising: A combiner having an end and a length, wherein the combiner is arranged to release from its length a portion of back-reflected light received from the output optical fiber at the output end of the combiner, the combiner comprising: A capillary tube for surrounding a portion of the two or more input optical fibers at the input end of the combiner, the capillary tube having an end and a length between the ends of the capillary tube; A cladding light stripper, defined by a portion of the length of the capillary, wherein the cladding light stripper provides release of the portion of the back-reflected light; A housing comprising a first side and a second side opposite to the first side, wherein the first side is thermally coupled to a heat sink, and the second side is configured to surround a portion of the length of the capillary; and A cover, which is thermally bonded to the second side of the housing and cooperates with the second side to surround the portion of the length of the capillary; Wherein, the outer diameter of the surface of one end of the capillary is smaller than the diameter of the core of the output optical fiber, wherein some of the back-reflected light enters the surface of the one end of the capillary from the overlapping portion of the core, and The clamping force between the cover and the housing is less than the clamping force between the housing and the radiator.

11. The fiber laser according to claim 10, wherein, A portion of the interior of the housing is arranged to absorb light of wavelengths associated with the back-reflected light.

12. The fiber laser according to claim 11, wherein, The housing defines a chamber in which a portion of the length of the capillary is disposed, and the chamber is sized to provide a gap between the interior of the chamber and the outer surface of the portion of the length of the capillary.

13. The fiber laser according to claim 12, wherein, The outer surface includes a notch arranged to guide the back-reflected light into the interior of the housing, where a portion of the light is arranged to absorb wavelengths associated with the back-reflected light.

14. The fiber laser according to claim 12, wherein, A portion of the second side of the housing defines the bottom or side of the chamber, and at least a portion of the length of the capillary is positioned within the chamber; as well as The lower portion of the cover defines the top of the chamber.

15. The fiber laser according to claim 14, wherein, The shell is formed of a first material, and the cover is formed of a second material different from the first material. Compared to the second material, the coefficient of thermal expansion of the first material is more closely matched to that of the optical fiber material, or The thermal conductivity of the second material is greater than that of the first material.

16. The fiber laser according to claim 15, wherein, The heat sink is formed of a third material, the thermal conductivity of which is greater than that of the first material.

17. The fiber laser according to claim 14, wherein: The bottom or side of the chamber has a first reflectivity, and the lower portion of the cover has a second reflectivity, the second reflectivity being less than the first reflectivity, or The side of the chamber is inclined to reflect the emitted light away from the optical fiber.

18. An optical fiber assembly, comprising: The fiber laser according to claim 10; The radiator; A portion of the second side of the housing defines the bottom or side of the chamber, and a portion of the length of the capillary is positioned within the chamber; as well as A portion of the lower side of the cover defines the top of the chamber.

19. The optical fiber assembly according to claim 18, wherein, The shell is formed of a first material, and the cover is formed of a second material different from the first material. Compared to the second material, the coefficient of thermal expansion of the first material is more closely matched to that of the optical fiber material, or The thermal conductivity of the second material is greater than that of the first material.

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