Apparatus, system and method for compact active fiber packaging of fiber lasers

Abstract

An embodiment relates to a compact fiber packaging apparatus configured to guide an active fiber as part of a high-power fiber laser. The apparatus may include a base having a front side and a rear side. The front side includes a variable-radius front spiral groove that extends incrementally from an innermost front loop having an innermost radius to an outermost front loop having an outermost radius, and the rear side includes a variable-radius rear spiral groove that extends incrementally from an outermost rear loop having an outermost radius to an innermost rear loop having an innermost radius. The front spiral groove extends from the innermost front loop to the outermost front loop, and the outermost front loop connects with the outermost rear loop of the rear spiral groove and terminates at the innermost rear loop.

Description

[Technical Field]

[0001] Cross-reference to related applications / priority claims This application claims domestic and international priority from Israel Patent Application No. 298391, filed November 13, 2022, entitled "APPARATUS, SYSTEM AND METHOD FOR COMPACT FIBER PACKAGING OF A FIBER LASER," which is incorporated herein by reference in its entirety. [Background technology]

[0002] Fiber lasers are based on one or more amplification stages that occur within a doped optical fiber (active fiber).

[0003] The active fiber is excited by pump light emitted from at least one fiber-coupled diode. The pump light enters the cladding of the fiber, propagates through the core, and interacts with dopants in the doped fiber section. The interaction of the pump light with the dopants results in the emission of light within the fiber core. The characteristics of the light emitted from a fiber laser are set by a Bragg grating in oscillator-based lasers or by a signal from a previous amplification stage in amplifier-based lasers.

[0004] The design of high-power lasers requires careful design of the device architecture to position and support the fiber, especially at the final amplification level of high-power light, which can cause heating of the active fiber. Device design considerations are to maintain adequate fiber temperature and eliminate or prevent thermal mode instability (TMI), while maintaining a compact laser design.

[0005] For example, the device should be configured to ensure that sufficient heat is removed from the fiber during operation while protecting the fiber from external stress sources that could cause damage to the fiber and / or degradation of the signal transmitted through the fiber. For example, the fiber should not be bent at too sharp an angle to prevent some of the transmitted light from leaking out instead of being reflected within the fiber core (which would reduce gain). Furthermore, excessive bending of the fiber can cause the fiber to break or become damaged.

[0006] The foregoing is provided as a general overview of the related art in this field and is not to be construed as an admission that the information contained therein constitutes prior art to the present patent application.

[0007] The figures illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.

[0008] For simplicity and clarity of illustration, elements shown in the figures are not necessarily drawn to scale. For example, the dimensions of some elements may be exaggerated relative to other elements for clarity of presentation. Furthermore, reference numerals may be repeated among the figures to indicate corresponding or similar elements. Reference to previously presented elements is implied without necessarily further citation to the figure or description in which they appear. The number of elements shown in the figures should not be construed as limiting in any way and is for illustrative purposes only. The figures are listed below. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic side view of a compact active fiber packaging apparatus according to some embodiments. [Figure 2] 1 is a schematic front view of a compact active fiber packaging device according to some embodiments. [Figure 3]1 is a schematic partial front view of a compact active fiber packaging apparatus according to some embodiments. [Figure 4] 1 is a schematic rear view of a compact active fiber packaging apparatus according to some embodiments. [Figure 5A] 1 is a schematic partial rear view of a compact active fiber packaging apparatus according to some embodiments. [Figure 5B] 1 is a schematic partial cross-sectional view of a compact active fiber packaging device according to some embodiments. [Figure 6] 1 is a further schematic diagram of a compact active fiber packaging device with housed fiber according to some embodiments. [Figure 7] 1 is a schematic partial view of an outer base surface of a compact active fiber packaging device with a housed fiber, according to some embodiments. [Figure 8] FIG. 1 is another schematic diagram of a compact active fiber packaging apparatus according to some embodiments. [Figure 9A-9B] 1 is a schematic diagram of an inlet track of a compact active fiber packaging apparatus with housed fibers, according to some embodiments. [Figure 10] FIG. 10 is yet another schematic diagram of a compact active fiber packaging apparatus according to some embodiments. [Figure 11A] 1 is another schematic cross-sectional view of a compact active fiber packaging device according to some embodiments. [Figure 11B] 1 is a schematic diagram of an inverted cross section of an outer base surface of a compact active fiber packaging device according to some embodiments. [Figures 12A-12B] 1 is a schematic partial front view of a compact active fiber packaging device according to some embodiments. [Figure 13A]1A-1C are schematic front and side views of alternative compact active fiber packaging devices according to some embodiments. [Figure 13B] 1 is a schematic rear side view of an alternative compact active fiber packaging apparatus according to some embodiments. [Figures 14A-14B] 1 is a schematic diagram of a fluid conduit of a compact active fiber packaging device according to some embodiments. [Figure 15A] 1 illustrates a local coordinate system for a compact active fiber packaging device, according to some embodiments. [Figures 15B-15F] 1A-1C are schematic cross-sectional views of fluid conduits according to respective embodiments. [Figure 16] FIG. 10 is a cross-sectional view of a fluid conduit according to a further embodiment. [Figure 17] 1 is a schematic diagram of a cooling system for cooling an optical fiber housed by a compact active fiber packaging device, according to some embodiments. [Figure 18] 1 is a flowchart of a method of using a compact active fiber packaging apparatus according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention relates to a fiber laser. More particularly, the present invention relates to a packaging device for an active fiber of a fiber laser. The packaging device has a relatively compact shape for housing the active fiber. The active fiber is part of an oscillator-based laser or an amplifier-based laser.

[0011] Despite its relatively compact form factor, the device exhibits relatively high operational stability (e.g., prevents the occurrence of thermal mode instability (TMI) for given operating characteristics) combined with relatively efficient cooling characteristics. For example, the device may be configured such that the TMI-related threshold is not exceeded, or never exceeded, during operation. In other words, the device may be configured such that the fiber housed by the device may enable amplification below the TMI-related threshold.

[0012] As a result, during operation, embodiments of the present device configuration ensure that the low mode input laser light characteristics remain constant or substantially constant along the entire length of the active fiber.

[0013] As used herein, the term "compact shape" refers to a device that occupies a relatively small volume relative to a desired gain or output power. In some embodiments, the term "compact shape" refers to a device that occupies a relatively small area relative to a desired gain or output power. For example, the area that must be occupied by a prior art device to achieve a desired gain and / or output power may have to be at least two times larger than that of a device according to an embodiment disclosed herein.

[0014] As the temperature of the fiber increases, the refractive index of the fiber increases, which may result in a need to reduce the bend radius to maintain the same stripping efficiency or higher order mode effectiveness as before the fiber temperature increased.

[0015] Since the amount of heat generated in the fiber decreases along the fiber from input to output, the bend radius of the fiber needs to be matched to the temperature profile of the fiber, because a decrease in the bend radius at low temperatures can cause the main mode (laser output) to dissipate. Therefore, the risk of exhibiting TMI or exceeding the threshold associated with TMI is increased in the first few inner loops of the active fiber, where most of the pump power is absorbed.

[0016] Stripping of higher order modes is possible by bending the fiber so that the radius of curvature is between the lower and upper stripping radii.

[0017] Known arrangements disclose configurations in which the fiber is spiraled from the fiber inlet in the direction of pump light propagation, initially spiraling to a smaller radius, from an outer spiral loop with a larger radius to an inner spiral loop with a smaller radius. However, such known arrangements prevent or are counterproductive to stripping of higher modes in the initial (larger) fiber loop. As a result, in such initial smaller radius configurations, the TMI threshold is reached at a relatively low laser power, thereby limiting the laser power that can be extracted from the active laser. Such configurations can be counterproductive to maximizing the output power that can be extracted from a fiber laser without approaching the TMI threshold already in the initial loop, let alone passing it.

[0018] An active fiber packaging apparatus according to an embodiment is configured to enable relatively tight coiling of the active fiber in a relatively compact fiber packaging geometry according to the temperature profile of the fiber, thus stripping all modes larger than the main mode, thus reducing TMI or preventing TMI-related thresholds from being exceeded while maintaining lasing output power.

[0019] 1 and 2. In some embodiments, an active fiber packaging apparatus 10000 includes a base 11000 configured to allow double-sided spiral packaging of the same fiber, for example, wound with a relatively small radius of curvature.

[0020] The device 10000 is configured to accommodate the same fiber such that adjacent active fiber portions on the same side of the plate are sufficiently insulated and / or isolated (e.g., separated) from each other to prevent any (e.g., evanescent) interaction between two adjacent or neighboring active fiber portions.

[0021] The base 11000 of the device 10000 includes an annular leading side 11100 and an annular trailing side 11200. The annular leading side 11100 is bounded by an outer leading edge 11102 and an inner leading edge 11104. The annular trailing side 11200 is bounded by an outer trailing edge 11202 and an inner trailing edge 11204.

[0022] The device 10000 further includes an exterior or outer base surface 11300 that extends from the outer leading edge 11102 of the forward side to the outer trailing edge 11202 of the annular aft side 11200 to form a plate-like body or base. The device 10000 further includes an inner base surface 11400 that extends from the inner leading edge 11104 of the annular forward side 11100 to the inner trailing edge 11204 of the annular aft side 11200 to form a plate-like body or base.

[0023] An outer base surface 11300 extends between an outer leading edge 11102 and an outer trailing edge 11202, and an inner base surface 11400 extends between an inner leading edge 11104 and an inner trailing edge 11204 to form an annular plate-like body.

[0024] In some examples, the annular front side 11100 and the annular rear side 11200 may have a generally circular shape. Thus, in some examples, the base 11000 may be disk-shaped. The terms "annular front side" and "annular rear side" may be referred to herein simply as "front side" and "rear side," respectively.

[0025] Although the embodiments discussed herein refer to devices including a generally circular or disc-shaped base, this should not be construed as limiting in any way. For example, in some instances, the outer surface and / or the front and / or rear sides can define a non-circular cylindrical shape. In some instances, the front and rear sides can have dissimilar geometric shapes.

[0026] In some embodiments, the outer base surface 11300 has an outer surface channel configured to accommodate a portion of the fiber. In some embodiments, the inner base surface 11400 has an inner surface channel 11402 configured to accommodate a portion of the fiber.

[0027] The front side 11100 includes a front spiral groove 11110, and the rear side 11200 of the base 11000 includes a rear spiral groove 11210. The outer base surface 11300 includes an outer (also referred to as external) surface passage 11302 (e.g., grooves and / or loops) for communicatively coupling the front spiral groove 11110 and the rear spiral groove 11210 to enable accommodation of the same optical fiber by the inner surface passage 11402, the front spiral groove 11110, the outer surface passage 11302, and the rear spiral groove 11210. In some examples, the base 11000 can also include a fiber ingress track and a fiber egress track.

[0028] The device 10000 is configured to accommodate the active fiber within its operating specifications. The device allows for the active fiber to be accommodated in a manner that avoids excessive twisting and / or bending, which may result in power loss and / or inoperability of the active fiber.

[0029] In some embodiments, the base 11000 has a thickness sufficient to include a conduit through which a cooling fluid (e.g., air, gas and / or fluid) can flow to cool the active fiber housed by the device.

[0030] According to some embodiments, the device 10000 may be integrally formed or monolithically integrated from the same material. In some instances, the device may be manufactured using additive manufacturing (also known as 3D printing) or casting techniques. In some embodiments, the device may be assembled from separate parts.

[0031] In some examples, the base 11000 of the device 10000 can have a thickness of 12 mm or less, 8 mm or less, or 6 mm or less, and can be made of a variety of materials, including, for example, aluminum, copper, etc. The base of the device can include or consist of a material with a relatively high thermal conductivity to allow for the removal or transfer of heat from the fibers through the material by a cooling fluid during operation. In some examples, the thermal conductivity of the base can be, for example, 250 W / mk · is.

[0032] The elements of the front side 11100 can lie on or define a virtual front plane Pfront, and the elements of the rear side 11200 can lie on or define a virtual back plane Pback, for example, as illustrated herein.

[0033] In some examples, the annular plate-like body has a height (also referred to as thickness) H, an outer front diameter D1front, an inner front diameter D2front, and an outer back diameter D1back, an inner back diameter D2back. In some embodiments, the height of the outer base surface 11300 can be different from the height of the inner base surface 11400.

[0034] It should be noted that the term "diameter" as used herein may refer to the maximum distance between two points on a respective edge. For example, the phrase "outer front diameter" refers to the maximum distance between two points along edge 11102.

[0035] The outer front diameter D1front and the outer back diameter D1back may be at least 8 to at least 20 times larger than the height H of the outer surface so that the base may be considered "flat." In some examples, the front outer diameter D1front and the back outer diameter D1back may be equal in size. In some examples, the front outer diameter D1front and the back outer diameter D1back may be different in size.

[0036] In some examples, the virtual front plane Pfront and / or the virtual rear plane Pback may each be definable by a single normal vector, i.e., the virtual front plane Pfront and / or the virtual rear plane Pback may be a flat surface. In some examples, the virtual front plane Pfront and / or the virtual rear plane Pback may resemble a deformed (i.e., non-linear) plane, i.e., a curved surface (e.g., having a single or multiple curves).

[0037] In some examples, the front inner diameter D2front and the rear inner diameter D2back may be equal in size. In some examples, the front inner diameter D2front and the rear inner diameter D2back may have different sizes.

[0038] 3 and 4, the front spiral groove 11110 has a variable radius Rfront that extends incrementally from an innermost front loop 11112 having an innermost radius Rfront (minimum) to an outermost front loop 11114 having an outermost radius Rfront (maximum) relative to a front center point Ofront.

[0039] The front spiral groove 111110, which extends from the innermost front loop 11112 to the outermost front loop 11114, connects continuously with the outermost rear loop 11214 (FIG. 4) of the rear spiral groove 11210, which extends to terminate at the innermost rear loop 11212. In this way, the packaging device 10000 can accommodate the same fiber laser.

[0040] As shown in FIG. 5A, the rear spiral groove 11210 has a gradually decreasing variable radius Rback relative to a rear center point Oback, from an outermost rear loop 11214 having an outermost radius Rback (maximum) to an innermost rear loop 11212 having an innermost radius Rback (minimum).

[0041] Referring now to FIG. 5B, a groove 11111 of the front spiral groove 11110 may be formed by two adjacent ridges 11119 that are elevated relative to the base surface 11120 of the same groove. In some examples, two adjacent grooves may share a common ridge. Similarly, a groove of the rear spiral groove 11210 may be formed by two adjacent ridges that are elevated relative to the base of the same groove. In some examples, two adjacent rear spiral grooves may share a common ridge.

[0042] In some examples, the width and / or height of the front spiral groove 11110 and the rear spiral groove 11210 may be substantially the same. In some examples, the width and / or height of at least two loops of the front spiral groove 11110 and / or at least two loops of the rear spiral groove 11210 may be different from one another.

[0043] In some embodiments, the front spiral groove 11110 and the rear spiral groove 11210 have a configuration that allows the fiber to be placed therein while preventing twists and bends that could otherwise lead to losses. The circular shape of the densely packed loops in each spiral groove allows for maximizing the curvature losses of higher order modes to help suppress thermal mode instabilities.

[0044] According to some embodiments, the front spiral groove 11110 and the rear spiral groove 11210 extend along spiral paths having radii and lengths that enable suppression of thermal mode instabilities during operation of the active fiber for given operating parameter values ​​of the active fiber housed in the spiral grooves.

[0045] In some embodiments, the spatial density of the spiral grooves may be constant or may vary. In some instances, the spatial groove density may decrease or increase with increasing radius. In some instances, the anterior side 11100 and posterior side 11200 may have the same spiral groove characteristics.

[0046] In some other examples, the front side 11100 and the back side 11200 may have different spiral groove characteristics.

[0047] According to some embodiments, the loops of the front spiral groove 11110 and / or the loops of the rear spiral groove 11210 may each follow a path of a plurality of arcuate loops, which may define various spiral paths, including, for example, an Archimedes spiral, a Fermat spiral, a Fibonacci spiral, a hyperbolic spiral, a Nielsen spiral, or a Doppler spiral. In some examples, the spiral loops may define a substantially elliptical or oval path. In some examples, the front spiral groove 11110 and / or the rear spiral groove 11210 may not have any straight portions.

[0048] In some embodiments, the front side 11100 and the rear side 11200 may be parallel or substantially parallel to one another. In some other embodiments, the front side 11100 and the rear side 11200 may be non-parallel. In some examples, the ridges and / or bases of the front spiral groove 11110 and / or the rear spiral groove 11210 may be used as a reference for determining whether the front side 11100 and the rear side 11200 are parallel or non-parallel to one another. In some embodiments, the ridges and / or bases of the front spiral groove 11110 may be coplanar or non-coplanar. In some embodiments, the ridges and / or bases of the rear spiral groove 11210 may be coplanar or non-coplanar. In some implementations, the ridges of the front spiral groove 11110 may lie on and thus define a virtual front plane Pfront. In some examples, the ridge of the posterior spiral groove 11210 may lie on and thus define the imaginary posterior plane Pback.

[0049] In some embodiments, Ofront and Oback may lie on or define an axis of rotational symmetry Z of the disk-shaped base, which may be common to both the front side 11100 and the rear side 11200. In some other embodiments, Ofront and / or Oback may be offset relative to the axis of rotational symmetry Z of the disk-shaped base. In some other implementations, the front side 11100 and the rear side 11200 may have different axes of rotational symmetry.

[0050] In some examples, the loops of the front spiral groove 11110 and / or the rear spiral groove 11210 can be configured to be mathematically definable in terms of Ofront and Oback, respectively.

[0051] In some examples, the loops of the front spiral groove 11110 and / or the rear spiral groove 11210 may not be configured to be mathematically definable in terms of Ofront and / or Oback, respectively.

[0052] Simply to simplify the following discussion, all radii discussed herein will be considered to have a common center point. However, this should not be construed as limiting in any way. Thus, the at least two leading spiral grooves can have different center points and / or the at least two trailing spiral grooves can have different center points.

[0053] 6 and 7. In some embodiments, the front spiral groove 11110 extends from the innermost front loop 11112 to the outermost front loop 11114 and is continuously connected with the outermost rear loop 11214 of the rear spiral groove 11210 via an outer base surface 11300 that may include an outer surface path 11302, which may be embodied, for example, as a track, groove, and / or step, configured to accommodate and support a portion of the active fiber 500 extending from the outermost front loop 11114 to the outermost rear loop 11214. In some examples, the outer surface path 11302 may have a thread-like, curved, or arc-like configuration, for example, defining a partial loop or at least one full loop of a helical path.

[0054] The outer surface paths 11302 can have an oblique or angled orientation θ relative to the orientation of the front side 11100 and the back side 11200. In some examples, the angular orientation θ of the outer surface paths 11302 can be constant, while in other examples, the angular orientation θ of the outer surface paths 11302 can vary along the route traversed by the path. In some examples, the outer surface paths 11302 can define a helical shape. The outer surface paths 11302 are configured to avoid over-bending of the corresponding active fiber portions.

[0055] As previously described herein, the inner base surface 11400 includes an inner surface channel or track 11402, implemented, for example, as a groove, track, and / or step, extending from an exit of the fiber entry track (or input section) 11116 to continuously accommodate or guide fiber portions of the active fiber 500. The inner channel 11402 extends from an inner channel entrance 11403 to an inner channel exit 11404 at the innermost front loop 11112 of the front spiral groove 11110. In some embodiments, the fiber entry track 11116 can extend generally linearly. In some embodiments, the fiber entry track 11116 can be linear and, as it approaches the track exit, become at least partially curved or arcuate, for example, to approximate or gradually approximate the curvature of the inner channel 11402.

[0056] The internal pathways 11402 may have an oblique or angled orientation relative to the orientation of the front side 11100 and the back side 11200. In some examples, the angular orientation of the internal pathways 11402 may be constant, while in other examples, the angular orientation of the internal pathways 11402 may vary along the path traversed by the pathway. In some examples, the internal pathways 11402 may define a helical shape. The internal pathways 11402 may be configured to avoid over-bending of the corresponding active fiber portion.

[0057] In some examples, the inner surface path 11402 may cover the entire circumference of the inner base surface 11400. In some examples, the inner surface path 11402 may cover only a partial circumference along the inner base surface 11400. In some examples, the inner surface path 11402 may cover multiple full circumferences of the inner base surface 11400. In some examples, the inner surface path 11402 may cover at least one full circumference of the inner base surface 11400 as well as additional partial circumferences. Correspondingly, the inner surface path 11402 may traverse only a partial loop of a helical path, one or more complete loops of a helical path, or one or more complete loops as well as additional partial loops of a helical path, for example. In some examples, the inner surface path 11402 may have a thread-like configuration.

[0058] 8, 9A, and 9B. In some embodiments, the fiber entry track 11116 extends from a front fiber track inlet 11117 in the outer base surface 11300 and terminates at a front fiber track outlet 11118 at an inner surface channel inlet 11403 of the inner surface channel 11402. In some examples, the fiber entry track 11116 is disposed within the base 11000 below the loop of the front spiral groove 11110 between the front spiral groove 11110 and the outer surface channel 11302, and can extend, for example, partially or completely linearly. For example, the fiber entry track 11116 extends below the front spiral groove 11000 from the outer base surface 11300 to the inner base surface 11400.

[0059] In this way, the portion of the fiber contained within the fiber entry track 11116 does not engage or interfere with the portion of the fiber contained by the front spiral groove 111110 and the rear spiral groove 11210.

[0060] The front fiber track exit 11118 and the inner surface path entrance 11403 can define a first inner transition region. The inner surface path exit 11404 and the entrance to the innermost front loop 11112 can define a second inner transition region. In some examples, the first inner transition region between the front fiber track exit 11118 and the inner surface path 11402 and the second inner transition region between the inner surface path exit 11404 and the entrance to the innermost front loop 11112 may be configured to avoid over-bending of the active fiber 500, for example, at the respective transition regions and along the inner surface path 11402.

[0061] Referring further to FIG. 10 , as described herein above, the outer base surface 11300 includes an outer surface path 11302 having an outer base track inlet 11303 and an outer base track outlet 11304. The outer surface path 11302 extends from the outlet 11115 of the outermost front loop 11114 to the inlet 11215 of the outermost rear loop 11214. The outer base track inlet 11303 and the outlet of the outermost front loop 11114 form or define a first outer transition region, and the outer base track outlet 11304 and the inlet of the outermost rear loop 11214 form or define a second outer transition region. The first and second outer transition regions can be configured, for example, to avoid overbending of the fiber 500 at their respective transition regions along the outer surface path 11302.

[0062] In some examples, the outer surface path 11302 may cover the entire circumference of the outer base surface 11300. In some examples, the outer surface path 11302 may cover only a partial circumference along the outer base surface 11300. In some examples, the outer surface path 11302 may cover multiple full circumferences of the outer base surface 11300. In some examples, the outer surface path 11302 may cover at least one full circumference as well as additional partial circumferences of the outer base surface 11300. Correspondingly, the outer surface path 11302 may traverse only a partial loop of the helical path, one or more complete loops of the helical path, or one or more complete loops as well as additional partial loops of the helical path, for example.

[0063] 11A and 11B, in some embodiments, the exterior path 11302 has a stepped cross-section in a first (upright) orientation A along an upright section 11302A that decreases in step height (e.g., progressively) relative to an imaginary front plane Pfront as it extends from the front side 11100 toward the back side 11200, for example, until the stepped cross-section flips to a second (flipped) orientation B, and the exterior path 11302 extends along a second section 11302B that increases in step height (e.g., progressively) relative to the imaginary front plane Pfront.

[0064] For example, the exterior surface pathway 11302 may have a generally L-shaped cross-sectional profile along a radial direction of the device, which may switch or alternate from a first (e.g., upright) orientation A to a second (e.g., inverted) orientation B relative to the front side 11100.

[0065] Inverting the outer surface channel 11302 from the upright outer channel section 11302A to the inverted outer channel section 11302B may facilitate form-fitting accommodation of a portion of the active fiber 500 along the outer base surface 11300. For example, in this manner, the fiber 500 is supported from below by the upright outer channel section 11302A and from above by the inverted outer channel section 11302B.

[0066] Additionally, the described configuration facilitates continuous storage of fiber portions from the outermost front loops to the outer surface paths, and further facilitates continuous storage of fiber portions from the outer surface paths to the outermost rear loops.

[0067] The transition from the upright orientation A to the inverted orientation B can occur at the inverting section 11500. In some examples, the inverting section 11500 can be positioned where the fiber housed by the upright outer channel section 11302A covers about half of the circumference of the base. In some other examples, the inverting section 11500 can be positioned where the fiber portion housed by the upright outer channel section 11302A can cover less than half or more than half of the entire circumference of the base.

[0068] In some examples, the inverting section 11500 can have an outer surface portion that can be free from the outer surface channel 11302. The outer surface portion can have a smaller radius relative to the outer surface channel 11302 and thus be retracted or extended relative to the outer surface channel. In some other examples, there can be an overlap between the upright outer channel section 11302A and the inverted outer channel section 11302B. In some further examples, the outlet of the upright outer channel section 11302A can be aligned with the inlet of the inverted outer channel section 11302B.

[0069] 12A and 12B, as previously described herein, the outer surface path 11302 continuously connects the outlet of the outermost front loop 11114 (FIG. 12A) with the inlet of the outermost rear loop 11214 of the rear spiral groove 11210 (FIG. 12B), which terminate in the innermost rear loop 11212 with the innermost rear loop outlet interfacing with the inlet of the fiber exit track (or output section) 11216.

[0070] In some examples, the fiber exit track 11216 may have a curved or arcuate section with a radius of curvature that corresponds to the curvature of the inner base surface 11400. In some examples, the fiber exit track 11216 may have a ramp 11217 that guides the exit portion of the fiber toward the imaginary back plane Pback and, optionally, is inclined relative to the imaginary back plane Pback so as to extend beyond or intersect the imaginary back plane Pback.

[0071] In some other examples, the fiber exit track can be buried (not shown) disposed below the rear spiral groove 11210 and extending from the inner base surface 11400 to the outer base surface 11300. Optionally, the buried fiber exit track can guide the corresponding fiber portion away from the imaginary rear plane Pback and toward the imaginary front plane Pfront, for example, so that the entry point at the inner base surface 11400 is at a height between the front spiral groove 11110 and the rear spiral groove 11210 and extends onto the outer base surface 11300 at the exit point without engaging or intersecting the outer surface path 11302, allowing continuous accommodation of the active fiber. For example, the exit point of the buried fiber exit track can be offset relative to the outer surface path 11302. In some examples, the buried fiber exit track and corresponding surface path may be configured similarly as the fiber ingress track 11116, for example, to facilitate bidirectional pumping of the active fiber for optical amplification while ensuring removal of heat generated within the fiber housed within the buried fiber exit track. Thus, the fiber ingress track 11116 and the buried fiber exit track may simultaneously function both as an output for amplified output light and as an input for light to be amplified.

[0072] In some embodiments, the fiber inlet track 11116 and / or the fiber outlet track 11216 may be configured to facilitate connection (e.g., by welding) of input and output fibers to corresponding ends of active fibers housed by the apparatus 10000. For example, the fiber inlet track 11116 may be configured to facilitate (e.g., straight) splicing of the input fiber to an input portion of the active fiber, and / or the fiber outlet track 11216 may be configured to facilitate (e.g., straight) splicing of the output portion of the active fiber to an output fiber. In some examples, at least a portion of the fiber inlet track 11116 and / or the fiber outlet track 11216 may be straight or substantially straight to facilitate splicing of the active fiber input and output ends to the input and output fibers of a fiber-based laser amplification system.

[0073] The fiber-receiving grooves of device 10000, such as front spiral groove 11110, rear spiral groove 11210, fiber entry track 11116, and / or fiber exit track 11216, can have a variety of cross-sectional shapes when viewed along their respective longitudinal groove axes. The grooves can be, for example, U-shaped, V-shaped, or rectangular.

[0074] In some embodiments, desired fiber properties of the fiber housed by apparatus 10000, such as fiber loop curvature and / or fiber loop density, can be determined (e.g., measured) while also determining properties related to laser efficiency, such as pump power versus output power, as well as beam quality or mode content (M 2 ) can be determined experimentally, for example.

[0075] In some embodiments, the desired loop radii of the front spiral groove 11110 and the rear spiral groove 11210 are determined by the M 2can be considered to be in a desired range, which can be, for example, less than 1.4, less than 1.3, less than 1.2, or less than 1.1, while the power efficiency is monitored.

[0076] 13A and 13B. In some embodiments, the apparatus 10000 can be configured to facilitate selection and / or adjustment of the length of the active fiber (or a portion thereof) accommodated by the apparatus 10000 between the input of the fiber ingress track 11116 and the output of the fiber egress track 11216. Thus, the same apparatus can be employed to accommodate different lengths of active fiber in different setups. The front side 11100 and / or the rear side 11200 can be configured to facilitate skipping of loops (e.g., entire) of the front spiral groove 111110 and / or the rear spiral groove 11210, respectively, for example.

[0077] For example, if the loop is accommodated without skipping, the n of active fiber th The spiral groove part th The subsequent n of the active fiber can be accommodated by a loop of th+1 The part of the following n th+1 In the case of accommodation with skips, n loops of active fiber th The spiral groove part th The subsequent n of the active fiber can be accommodated by a loop of th+1 can accommodate a portion of, or n th+2 The spiral grooves are formed by the loops th+1 By skipping the loop.

[0078] For example, the front side 11100 may include one or more non-grooved sections 11250 (e.g., sections 11150A and 11150B), and / or the back side 11200 may include one or more non-grooved sections 11250 (e.g., sections 11250A and 11150B). Such non-grooved sections (also referred to as cutouts or windows) may allow for the fiber to be accommodated by skipping one or more selected loops of the corresponding spiral groove without having to lift the fiber over the groove of the loop selected to be skipped. According to some embodiments, such non-grooved sections provided in the spiral groove may have various shapes and / or sizes.

[0079] In some embodiments, the fiber can be coupled to the base 11000 by employing a fastening material applied to the groove portion of the device. For example, a fastening material can be applied to the fiber and / or the groove to permanently secure the fiber within the groove.

[0080] Such fastening materials include, for example, potting materials, fiber recoat materials (such as Luvantix®), which may be applied to the fiber and / or groove. TM PC-373 or MyPolymers TM MY-137), thermal adhesive, and / or optically transparent adhesive (NuSil TM LS-3246). The fastening material can be applied to the front spiral groove 11110, the rear spiral groove 11210, the fiber entry track 11116, the fiber exit track 11216, the outer surface pathway 11302, and / or the inner surface pathway 11402.

[0081] The clamping material may be transparent to allow light to escape the fiber rather than be absorbed by it. Such unwanted absorption can cause hot spots that result in laser burn or potting material burn.

[0082] 14A and 14B, the apparatus 10000 may include cooling piping configured to allow a cooling fluid to flow through the piping to remove heat generated during operation of the active fiber contained in the apparatus 10000 through thermal convection and / or thermal conduction.

[0083] The cooling piping may include at least one fluid conduit 14100 extending from a fluid inlet conduit (also referred to as a fluid inlet connector) 14110 employed to receive fresh cooling fluid and terminating in a fluid outlet conduit (also referred to as a fluid outlet connector) 14120 employed to remove spent cooling fluid. The fluid conduit 14100 is disposed within the base 11000 between the front spiral groove 11110 and the rear spiral groove 11210. The routing of the fluid conduit shown in FIG. 14B is for illustrative purposes only and should not be construed as limiting.

[0084] 15A to 15E. Figure 15A shows a schematic representation of a local reference coordinate system, with axis X indicating the longitudinal direction of the fluid conduit 14100 as viewed in a cross-sectional plane that is perpendicular to the imaginary front or rear plane, axis Y pointing in the cross-sectional plane in a direction opposite to the radius R originating from the center point O of the base plate 11000, axes X, Z and Y all being perpendicular to one another. Axis Z can be considered to extend in a direction perpendicular to the imaginary front plane Pfront.

[0085] Simply to simplify the following discussion, and not to be construed as limiting, the fluid conduits 14100 shown in FIGS. 15B-15F have a substantially circular cross-sectional shape. In some examples, at least one fluid conduit 14100 may be positioned equidistant between the front spiral groove 11110 and the rear spiral groove 11210 (FIG. 15B). In some examples, one or more fluid conduits 14100 may be positioned closer to the front spiral groove 11110 than the rear spiral groove 11210, and / or one or more (other) conduits may be positioned closer to the rear spiral groove 11210 than the front spiral groove 11110, as shown in FIG. 15C, for example.

[0086] In some embodiments, the multiple fluid conduits 14100 may be arranged in the same plane. In some embodiments, the multiple conduits 14100 may be arranged in a 1 x n array, as shown schematically in FIG. 14A, which shows an example of one row and four columns in a cross-sectional perspective view relative to an imaginary plane defined by the front or rear elements of the base. In some other embodiments, the multiple conduits may be arranged in an m x n array, where m > 1 and n > 1, as shown, for example, in FIG. 15D. For example, the conduits may be arranged in two rows and four columns in the cross-sectional perspective view shown.

[0087] In some examples, the conduits may be arranged alternately in a plane defined by axes Y and Z, as shown in the example of FIG. 15E.

[0088] In some examples, the fluid conduit 14100 may have a ramp with respect to an imaginary front plane Pfront and / or an imaginary back plane Pback, for example, to traverse a generally helical path within the base. In some examples, the ramp (schematically shown as angle δ) may be such that the fluid conduit 14100 moves away from the imaginary front plane Pfront (see FIG. 15F) as it extends (e.g., circumferentially) within the base 11000. In some examples, the ramp may be in a direction such that the fluid conduit 14100 approaches the imaginary front plane Pfront as it extends (e.g., circumferentially) within the base 11000 in direction X.

[0089] The fluid inlet connector 14110 can extend in a direction Z generally perpendicular to the rear side 11200 from a distal inlet end 14112 (FIG. 14A) with respect to the base 11000 to terminate at a proximal inlet end 14114 (FIG. 14B). The proximal inlet end 14114 is in fluid communication with at least one fluid conduit 14100 extending, for example circumferentially, within the base 11000 to terminate at a proximal outlet end 14124 of an outlet conduit 14120 for removing used fluid conduit via a distal outlet end 14122.

[0090] In some embodiments, each of the plurality of fluid conduits can traverse a different path length, hi some instances, at least two of the plurality of fluid conduits can be concentrically arranged and at least partially cover a substantially circumferential path.

[0091] Optionally, the curvature of the fluid conduit 14100 may approximately correspond to the curvature of the front spiral groove 11110 and / or the rear spiral groove 11210.

[0092] The fluid conduits 14100 can have a variety of cross-sectional shapes, including, for example, circular or elliptical cross-sectional shapes; polygonal shapes such as triangular, rectangular, or diamond (see FIG. 14A) cross-sectional shapes; in some examples, at least two of the multiple fluid conduits 14100 can have different cross-sectional shapes; in some examples, the cross-sectional shape of the same fluid conduit can change along its longitudinal axis from a first cross-sectional shape to a second cross-sectional shape that is different from the first cross-sectional shape.

[0093] FIG. 16 shows another embodiment of an arrangement of fluid conduits 14100.

[0094] 17, the cooling system 17000 of the fiber packaging apparatus 10000 may include a pumping apparatus 17100 configured to impart energy to the inlet fluid 601 to cause the inlet fluid 601 to flow (e.g., circulate) through a heat exchanger or chiller 17200 that generates fresh cooling fluid 602 for circulation through one or more fluid conduits of the packaging apparatus 10000. In some examples, the inlet fluid 601 is cooled by an inlet heat exchanger of chiller fluid 701 and then discharged as spent heat exchanger or chiller fluid 702.

[0095] In some examples, fresh cooling fluid 602 enters the fluid conduit 14100 from the fluid inlet piping 17102 via the fluid inlet connector 14110, circulates through the fluid conduit to cool the active fiber during operation, leaves the conduit 14100 as spent cooling fluid 604, and enters the outlet piping 17120 via the outlet connector 14120.

[0096] In some embodiments, the cooling system 17000 can be considered to include a pumping device 17100 , an inlet pipe 17110 , a fluid inlet connector 14110 , a fluid conduit 14100 , a fluid outlet connector 14120 , and an outlet pipe 17120 .

[0097] In embodiments, the cooling system may be configured to recirculate the cooling fluid through the conduits multiple times.

[0098] Continuing with reference to Figure 18, as shown at block 18100, a method for guiding an active fiber includes: providing a compact fiber packaging device configured to house an active fiber, the device comprising:

[0099] a base having a front side and a rear side, the front side comprising a variable radius front spiral groove that extends incrementally from an innermost front loop having an innermost radius to an outermost front loop having an outermost radius, and the rear side comprising a variable radius rear spiral groove that extends incrementally from an outermost rear loop having an outermost radius to an innermost rear loop having an innermost radius; wherein the innermost radius is smaller than the outermost radius; the front spiral groove extends from the innermost front loop to the outermost front loop, the outermost front loop connecting with the outermost rear loop of the rear spiral groove and terminating in the innermost rear loop, the base having a thickness sufficient to contain a fluid conduit that allows cooled gas or cooled fluid to flow for cooling the active fiber.

[0100] The method may further include housing the active fiber in a front spiral groove and a rear spiral groove of the compact fiber packaging device, as shown at block 18200.

[0101] Additional Examples Example 1 relates to a compact fiber packaging device configured to guide an active fiber as part of a fiber laser amplifier, the device comprising: a base having a front side and a rear side; the front side comprising different front spiral grooves of variable radii that extend incrementally from an innermost front loop having an innermost radius to an outermost front loop having an outermost radius; the rear side comprising a rear spiral groove having a variable radius that extends gradually from an outermost rear loop having an outermost radius to an innermost rear loop having an innermost radius; The innermost radius is smaller than the outermost radius; The front spiral groove extends from the innermost front loop to the outermost front loop, the outermost front loop connecting with the outermost rear loop of the rear spiral groove and terminating at the innermost rear loop, and the base includes a fluid conduit that allows a cooled fluid to flow through the base for cooling the active fiber.

[0102] Example 2 includes the subject matter of Example 1, and optionally, the outermost front loop connects with the outermost rear loop of the rear spiral groove on the outer surface of the base, optionally in a helical path.

[0103] Example 3 includes the subject matter of any one or more of Examples 1 or 2, wherein the innermost front loop terminates in a front input section configured to splice an input fiber with the front input section, and / or the innermost rear loop terminates in a rear output section configured to splice an output fiber with the rear output section.

[0104] Example 4 includes the subject matter of Example 3, and optionally, the input section extends distally into the base below the front spiral groove, and the output section extends distally into the base below or above the rear spiral groove.

[0105] Example 5 includes the subject matter of example 4, optionally wherein the front input section and / or the rear output section are straight or curved sections.

[0106] Example 6 includes the subject matter of any one or more of Examples 1-5, optionally wherein the front spiral groove comprises a front loop and the rear spiral groove comprises a rear loop to allow accommodation of a corresponding portion of the active fiber.

[0107] Example 7 includes the subject matter of Example 6, optionally wherein the front loops and / or the rear loops are coplanar.

[0108] Example 8 includes the subject matter of any one or more of Examples 1-7, optionally wherein the base comprises one or more fluid conduits disposed within the base between the front spiral groove and the rear spiral groove, the one or more fluid conduits configured to allow flow of a cooling fluid for cooling an active fiber housed in the front spiral groove and the rear spiral groove by thermal conduction.

[0109] Example 9 includes the subject matter of Example 8, optionally wherein a plurality of the one or more fluid conduits are arranged to define a coplanar loop.

[0110] Example 10 includes the subject matter of any one or more of Examples 8-9, optionally, wherein the one or more fluid conduits have at least one fluid inlet and one fluid outlet.

[0111] Example 11 includes the subject matter of any one or more of Examples 1-10, optionally including fasteners for securing the active fiber within the front and rear spiral grooves.

[0112] Example 12 includes the subject matter of Example 11, optionally wherein the fastener comprises an adhesive and / or potting material.

[0113] Example 13 includes the subject matter of any one or more of the preceding examples, wherein the active fiber can be part of an oscillator-based laser or an amplifier-based laser.

[0114] Example 14 relates to a cooling system for cooling an apparatus, which may include, for example, one or more fluid conduits, a heat exchanger or chiller for cooling an inlet fluid to produce a cooling fluid, and a pumping device configured to impart energy to the cooling fluid to cause flow of the cooling fluid through the one or more fluid conduits.

[0115] Example 15 relates to a method for manufacturing a device, e.g., according to any one or more of Examples 1 to 12, the method including providing a base having a front side and a rear side;

[0116] the front side comprising a variable radius front spiral groove that extends incrementally from an innermost front loop having an innermost radius to an outermost front loop having an outermost radius;

[0117] the rear side comprising a variable radius rear spiral groove that extends tapered from an outermost rear loop having an outermost radius to an innermost rear loop having an innermost radius;

[0118] The innermost radius is smaller than the outermost radius;

[0119] The front spiral groove extends from the innermost front loop to the outermost front loop, the outermost front loop connecting with the outermost rear loop of the rear spiral groove and terminating at the innermost rear loop, and the base includes a fluid conduit allowing cooled gas or cooled fluid to flow for cooling the active fiber.

[0120] Example 16 relates to a method of guiding an active fiber as part of a fiber laser, the method including:

[0121] A compact fiber packaging device configured to house an active fiber, the device comprising:

[0122] a base having a front side and a rear side;

[0123] the front side comprising a variable radius front spiral groove that extends incrementally from an innermost front loop having an innermost radius to an outermost front loop having an outermost radius;

[0124] the rear side comprising a variable radius rear spiral groove that extends tapered from an outermost rear loop having an outermost radius to an innermost rear loop having an innermost radius;

[0125] The innermost radius is smaller than the outermost radius;

[0126] a front spiral groove extending from an innermost front loop to an outermost front loop, the outermost front loop connecting with an outermost rear loop of the rear spiral groove and terminating at the innermost rear loop; and

[0127] providing a device in which the base has a thickness sufficient to contain a fluid conduit through which cooled gas or cooled fluid can flow for cooling of the active fiber; and

[0128] The active fiber is accommodated in the front and rear spiral grooves of the compact fiber packaging device.

[0129] In the description and claims of this application, the words "comprise," "include," and "have," and their forms, respectively, do not necessarily limit the members in the list with which the word may be associated. Furthermore, in the event of a conflict between this application and a document incorporated by reference, it is hereby intended that the present application shall control.

[0130] The various features and steps described above, and other known equivalents for each such feature or step, can be mixed and matched by those skilled in the art to perform methods according to the principles described herein. While this disclosure has been provided in the context of specific embodiments and examples, those skilled in the art will recognize that the disclosure extends beyond the specifically described embodiments to other alternative embodiments and / or uses, and obvious modifications and equivalents thereof. Accordingly, the disclosure is not intended to be limited by the specific disclosure of embodiments herein.

[0131] In this discussion, unless otherwise specified, adjectives such as "substantially" and "about" modifying a condition or relationship characteristic of one or more features of an apparatus embodiment are understood to mean that the condition or characteristic is defined within a tolerance range permitted for operation of the embodiment for its intended use.

[0132] Unless otherwise specified, the terms "about" and / or "close" in relation to a magnitude or value may mean within an inclusive range of -10% to +10% of the respective magnitude or value.

[0133] Unless otherwise specified, the terms "about" or "close" mean within or near an area or region of a location or portion of an object relative to another part or region of the object.

[0134] Terms of location such as "top," "below," "right," "left," "bottom," "below," "lower," "low," "top," "elevated," "high," "vertical," and "horizontal," and grammatical variations thereof, as used herein, do not necessarily indicate, for example, that a component at the "bottom" is below a component at the "top," or that a component at "below" is actually "below" another component, or that a component at "above" is actually "above" another component, because such orientation, components, or both may be flipped, rotated, moved in space, placed in a diagonal orientation or position, positioned horizontally or vertically, or similarly altered. Thus, it will be understood that the terms "bottom," "below," "top," and "above" may be used herein for illustrative purposes only, to illustrate the relative location or placement of particular components, to denote first and second components, or both.

[0135] "Coupled with" means "coupled with" either indirectly or directly.

[0136] As used herein, unless otherwise specified, the use of the hierarchical adjectives "first," "second," etc. to describe like objects indicates merely that different instances of like objects are being referred to and is not intended to imply that the objects so described must be in the given order, chronologically, sequentially, and / or otherwise.

[0137] The description of various embodiments of the present device has been presented for purposes of illustration, but is not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein has been selected to best explain the principles of the embodiments, practical applications or technical improvements to technology found in the market, or to enable those skilled in the art to understand the embodiments disclosed herein.

Claims

1. 1. A compact fiber packaging device configured to guide an active fiber as part of a high power fiber laser, comprising: a base having a front side and a rear side; the front side comprises a variable radius front spiral groove that extends incrementally from an innermost front loop having an innermost radius to an outermost front loop having an outermost radius; the rear side comprises a rear spiral groove having a variable radius that extends gradually from an outermost rear loop having an outermost radius to an innermost rear loop having an innermost radius; the innermost radius is smaller than the outermost radius; the front spiral groove extends from the innermost front loop to the outermost front loop, the outermost front loop connecting with the outermost rear loop of the rear spiral groove and terminating at the innermost rear loop; the base includes a fluid conduit that allows a cooled fluid to flow for cooling the active fiber; Compact fiber packaging equipment.

2. The device of claim 1 , wherein the outermost front loop connects with the outermost rear loop of the rear spiral groove on an outer surface of the base, optionally in a helical path.

3. 3. The apparatus of claim 1, wherein the innermost front loop terminates in a front input section configured to splice an input fiber with the front input section, and / or the innermost rear loop terminates in a rear output section configured to splice an output fiber with the rear output section.

4. The device of claim 3 , wherein the input section extends distally into the base below the front spiral groove and the output section extends distally into the base below or above the rear spiral groove.

5. 5. The apparatus of claim 4, wherein the front input section and / or the rear output section are straight sections.

6. The device according to any one of claims 1 to 5, wherein the front spiral groove comprises a front loop and the rear spiral groove comprises a rear loop allowing for accommodation of a corresponding portion of the active fiber.

7. The device of claim 6 , wherein the front loops and / or the rear loops are coplanar.

8. the base includes one or more fluid conduits disposed within the base between the front spiral groove and the rear spiral groove; the one or more fluid conduits are configured to allow a flow of a cooling fluid for cooling an active fiber that may be contained in the front spiral groove and the rear spiral groove by thermal conduction. An apparatus according to any one of claims 1 to 7.

9. The apparatus of claim 8 , wherein a plurality of the one or more fluid conduits are arranged to define a coplanar loop.

10. An apparatus according to any one of claims 8 to 9, wherein the one or more fluid conduits have at least one fluid inlet and one fluid outlet.

11. The apparatus of any one of claims 1 to 10, further comprising fasteners for fixing the active fiber within the front spiral groove and the rear spiral groove.

12. The device of claim 11 , wherein the fastener comprises an adhesive and / or a potting compound.

13. The device according to any one of claims 1 to 12, wherein the active fiber can be part of an oscillator-based laser or an amplifier-based laser.

14. 1. A cooling system for cooling a compact fiber packaging device configured to guide an active fiber as part of a high power fiber laser, the device comprising: a base having a front side and a rear side; the front side of the compact fiber packaging device comprises a variable radius front spiral groove that extends incrementally from an innermost front loop having an innermost radius to an outermost front loop having an outermost radius; the rear side comprises a variable radius rear spiral groove that extends tapered from an outermost rear loop having an outermost radius to an innermost rear loop having an innermost radius; The cooling system comprises: one or more fluid conduits disposed within the base between the front spiral groove and the rear spiral groove, the one or more fluid conduits configured to allow a flow of a cooling fluid for cooling an active fiber that may be contained in the front spiral groove and the rear spiral groove by thermal conduction; a heat exchanger and / or chiller for cooling the inlet fluid to produce a cooling fluid; a pumping device configured to energize the cooling fluid to induce flow of the cooling fluid through the one or more fluid conduits; A cooling system comprising:

15. The cooling system of claim 14 , wherein a plurality of the one or more fluid conduits are arranged to define a coplanar loop.

16. A cooling system according to any one of claims 14 to 15, wherein the one or more fluid conduits have at least one fluid inlet and a fluid outlet.

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