Beam scanning in optical fibers

Abstract

An intra-fiber beam scanning system can include an input fiber for providing a beam; a feeding fiber including an imaging bundle having a plurality of cores embedded in a first cladding surrounded by a second cladding; and an intra-fiber beam displacer including a first multi-bend beam displacer coupled to the input fiber, a graded-index fiber following the first multi-bend beam displacer, and a second multi-bend beam displacer following the graded-index fiber and coupled to the feeding fiber. In some embodiments, the first multi-bend beam displacer is actuated a first amount and the second multi-bend beam displacer is actuated a second amount to displace the beam in two dimensions and deliver the beam to one or more target cores in the imaging bundle.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims priority to U.S. Provisional Patent Application No. 63 / 261,905, entitled “Beam Scanning in Fiber,” filed on September 30, 2021. The disclosure of that prior application is considered a part of and incorporated by reference into this patent application. Technical Field

[0003] The present invention generally relates to guiding or otherwise sending a light beam through a graded-index optical fiber having a set of bends with a bend period that matches or nearly matches the pitch of the graded-index optical fiber, and more particularly to an all-fiber beam routing system that utilizes bent graded-index optical fibers to controllably illuminate different cores in an imaging fiber bundle that includes multiple cores arranged in an array. Background Art

[0004] Laser material processing can be used for cutting, drilling, welding, brazing, surface annealing, alloying, hardening and / or other applications. Specifically, laser material processing generally involves using one or more optical fibers to deliver a high power and / or high intensity laser beam to a workpiece on which the laser material processing is to be performed. For example, a typical fiber-optic delivered laser material processing system may include a laser source (e.g., one or more fiber laser modules), an optical coupler unit, a delivery fiber (typically 10-50 meters in length and contained in a transmission cable that can be plugged in at one or both ends), and a processing head. The processing head is an optical assembly that includes a receptacle for the delivery fiber, optics for projecting laser power, and any components required for laser-based processing. In operation, the laser source transmits laser light emission into the optical coupler unit (e.g., through free space or through a separate optical fiber), and the optical coupler unit may transmit the emission internally through the optical fiber or through free space, may amplify or reduce the emission, and couple the laser emission into the delivery fiber. The delivery fiber then transmits the laser light to the processing head, which projects the laser light onto the workpiece associated with the material processing task being performed. Advantages of laser material processing can therefore include high productivity, the non-contact nature of the process, improved quality, and / or high precision and mobility of the laser beam's delivery point, among others.

[0005] One challenge that arises in the context of laser material processing relates to fiber beam shaping (e.g., for cutting, welding, and / or other applications), which is an increasingly important aspect of high-power laser material processing. For example, in some cases, the high power and excellent beam quality of a fiber laser can be exploited to perform "keyhole welding" with a high aspect ratio penetration profile in a narrow fusion zone with low distortion and minimal heat-affected zone. In other examples, a larger laser spot size with a lower power density can be used to perform shallower "conduction welding," which can be used for aesthetic welds and / or minimize the need for post-processing steps. In yet other examples, processing different materials or materials with different thicknesses may require different characteristics of the beam (e.g., some materials may require a high brightness, small spot size, while other materials may require a larger, more divergent beam). Therefore, in order to control and / or change the characteristics of the beam, a laser system with beam shaping capabilities and the ability to cycle or transition between multiple states may be ideal. Summary of the Invention

[0006] In some embodiments, an optical assembly includes an input fiber providing a light beam; a feeding fiber including an imaging bundle having a plurality of cores embedded in a first cladding surrounded by a second cladding; and an intra-fiber beam displacer including a first multi-bend beam displacer coupled to the input fiber, a graded-index fiber following the first multi-bend beam displacer, and a second multi-bend beam displacer following the graded-index fiber and coupled to the feeding fiber, wherein the first multi-bend beam displacer is actuated a first amount and the second multi-bend beam displacer is actuated a second amount to displace the light beam in two dimensions and deliver the light beam into one or more target cores in the imaging bundle.

[0007] In some embodiments, a method includes providing a beam from an input fiber to an intra-fiber beam displacer, wherein the intra-fiber beam displacer includes a first multi-bend beam displacer coupled to the input fiber, a graded-index fiber following the first multi-bend beam displacer, and a second multi-bend beam displacer following the graded-index fiber and coupled to a feeder fiber, and wherein the feeder fiber includes an imaging bundle having a plurality of cores embedded in a first cladding surrounded by a second cladding; actuating the first multi-bend beam displacer a first amount to displace the beam along a first spatial axis; and actuating the second multi-bend beam displacer a second amount to displace the beam along a second spatial axis, wherein the first and second multi-bend beam displacers are actuated to control Cartesian coordinates representing a position of the beam in two dimensions and deliver the beam into one or more target cores in the imaging bundle.

[0008] In some embodiments, an optical assembly includes: an input fiber providing a light beam; a feeding fiber including a plurality of cores arranged in an array and embedded in a first cladding surrounded by a second cladding; and an intra-fiber beam displacer including a multi-bend beam displacer and a graded-index fiber coupled between the input fiber and the feeding fiber, wherein the multi-bend beam displacer is actuated to apply a set of bends in the graded-index fiber to shift the light beam in a spatial dimension and deliver the light beam to one or more target cores in an imaging bundle. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a schematic diagram of a graded-index optical fiber.

[0010] Figure 2 is a schematic diagram of one or more embodiments of a bending device that can be used to impart one or more bends in a graded-index optical fiber.

[0011] Figure 3 is a schematic diagram of one or more example embodiments of a plurality of bending devices arranged in a cascade configuration.

[0012] Figures 4A-4C is an example graph relating the propagation length of a graded-index optical fiber operated using the bending apparatus and methods described herein.

[0013] Figure 5 is a flow chart of an example process for imparting a set of bends in a graded-index optical fiber using one or more bending devices.

[0014] Figures 6A-6C is a schematic diagram of one or more exemplary embodiments of an all-fiber beam routing system that utilizes a bent graded-index optical fiber to controllably illuminate different cores in an imaging fiber bundle that includes multiple cores arranged in an array. DETAILED DESCRIPTION

[0015] The following detailed description of example embodiments refers to the accompanying drawings, in which the same reference numerals in different drawings may represent the same or similar elements.

[0016] As described above, fiber beam shaping is an increasingly important aspect of high-power (e.g., greater than 100 watts (W)) laser material processing and / or other applications that may require a rasterizable fiber source (e.g., light detection and ranging (LIDAR) and / or endoscopic microscopy, etc.). For example, in the context of laser material processing, lasers that can control and vary beam characteristics are desirable because different materials, materials with different thicknesses, and / or different material processing techniques may require beams with different characteristics. For example, for thin stainless steel (e.g., stainless steel with a thickness of less than 3 millimeters (mm)), a small spot with high brightness is generally desired, while for thicker mild steel (e.g., steel with a thickness of greater than 12 mm), a larger, more divergent beam may be required. Additionally or alternatively, in some applications, it may be desirable to generate addressable beam positions. For example, in a laser material processing system using a standard imaging (e.g., non-scanning) processing head, addressable beam positions may be required to controllably illuminate different cores in a fiber bundle so that a scannable laser beam can be delivered to a workpiece. However, existing techniques are typically configured to use a coupler box with moving optics to illuminate different cores in a fiber bundle in free space, which tends to be more expensive and less reliable than beam scanning techniques performed entirely in the fiber. Addressable beam positions can be created in the processing head by using high-speed scanning mirrors, but this technique increases cost and complexity and requires a more advanced processing head.

[0017] Therefore, an important factor in designing a laser system with beam shaping and / or beam routing capabilities is to provide the ability to cycle or switch between multiple states that produce beams with different characteristics and / or the ability to arbitrarily shift the beam in one or more dimensions. However, an actuation method is required to switch between the different states, which is a challenge for kilowatt (kW) lasers because the actuation method must be essentially lossless. For example, switches used in telecommunications and / or datacom applications may produce losses of 0.5 decibels (dB) or more, which is unacceptable for such high powers. In addition to the desire to keep the entire system in an optical fiber to improve manufacturability and reduce alignment tolerances, the need to provide a lossless actuation method to switch between the different states greatly limits the possible actuation options. Although a simple actuation method would be to have two laser engines that can be turned on and off independently, this actuation method significantly increases the cost of the system.

[0018] Graded-index fiber provides a possible alternative to two independently controlled laser engines. Specifically, a graded-index fiber typically has a refractive index profile whose square is parabolic or nearly parabolic, as shown in the following equation:

[0019]

[0020] Where n1 is the peak (or maximum) refractive index, r is the radial coordinate (e.g., the distance from the center of the graded-index fiber), and f is the focal length of the graded-index fiber, which is related to the pitch of the graded-index fiber. Therefore, bending the graded-index fiber generally results in a translation of the center of the beam that is proportional to the curvature of the bend (1 / local bend radius (R bend ). The displacement (Δx) also depends on the properties of the graded-index fiber, such as the focal length (f) and the peak / maximum refractive index (n1) of the graded-index fiber, as shown in the following equation:

[0021]

[0022] Therefore, one potential approach to providing an all-fiber beam switch is to use a graded-index fiber and adiabatically bend the graded-index fiber to varying degrees, so that different beam offset positions within the fiber can be achieved depending on the curvature of the bend. However, for larger offsets, adiabatically bending requires a longer bent fiber length and a larger overall bend angle, and can generate significant stress on the fiber, which can lead to breakage. Furthermore, if such an offset is desired to achieve variable offset launch into a second fiber (e.g., a multi-core fiber, a multi-spin fiber, and / or other suitable optical fiber), stress occurs precisely at the splice point, making splice optimization more difficult and making the splice more susceptible to failure.

[0023] Some embodiments described herein relate to a device and method that utilizes the periodic re-imaging properties of a graded-index fiber, sends a light beam within the fiber, or translates a light beam in space using a series of well-controlled bends. In this way, by using a series of smaller bends rather than a single long adiabatic bend, some embodiments described herein can achieve a greater range of beam control (e.g., relative to a single bend), since large bends may be limited by local stresses applied to the fiber. Additionally or alternatively, a single short bend (rather than a series of bends) can be formed at a well-controlled location in the graded-index fiber, which can reduce stress on the graded-index fiber and reduce the need for the bending device to precisely adapt to the period or pitch of a particular graded-index fiber. Furthermore, by routing the light beam within the fiber, some embodiments described herein can eliminate or reduce input / output coupling losses in the routing device and improve manufacturability with reduced alignment tolerances. Furthermore, some embodiments described herein can be used to route a light beam in space and angle, enabling a controlled two-dimensional light beam to be emitted from the fiber. In some embodiments, the devices and methods described herein can be used in kW fiber bundle shaping or other areas such as LIDAR, endoscopic microscopy, and / or any other suitable application that may require a rastered fiber source.

[0024] For example, some embodiments described herein can be used to manipulate the spatial position of a beam within an optical fiber to deliver a scannable beam to a workpiece via an all-fiber delivery system compatible with standard imaging (e.g., non-scanning) processing heads. For example, some embodiments described herein relate to an optical assembly comprising two cascaded beam shifters that can be configured to work together to shift a beam by an arbitrary amount in a two-dimensional plane before launching it into a feeder fiber comprising a plurality of fiber cores arranged in a two-dimensional array. In this way, the beam can be shifted in two dimensions to illuminate different cores in an imaging fiber bundle. Alternatively, in some embodiments, a single beam shifter can be used to impart a bend in a graded-index fiber in any rotational direction about the fiber axis, which can provide radial coordinate control of the beam's two-dimensional position. Alternatively, in some embodiments, a single beam shifter can be used to shift a beam in one dimension to provide a one-dimensional scannable output to a one-dimensional array of cores, which can be useful in applications where the processing head is moved simultaneously relative to the workpiece. Thus, as described herein, some embodiments relate to an all-fiber system that can be used to apply a resonant multi-bend actuator to a graded-index optical fiber to move a light beam within the fiber in one or more dimensions, which, in addition to being less expensive and more reliable than systems that rely on coupler boxes with moving optics to achieve beam scanning in free space, can also provide an all-fiber delivery system that is compatible with non-scanning processing heads.

[0025] Figure 1 An example 100 of a graded-index fiber is shown. More specifically, as described herein, the square of the refractive index profile of the graded-index fiber can be parabolic or near-parabolic (e.g., in the core region), where the refractive index varies smoothly in the radial direction from the axis of the graded-index fiber to a certain radial position. In other words, the graded-index fiber has a refractive index profile that is parabolic or near-parabolic in cross-section, and the refractive index profile is uniform along the length of the graded-index fiber. Therefore, light propagating through the graded-index fiber follows a periodic trajectory that passes through the parabolic or near-parabolic refractive index profile of the graded-index fiber. For example, as Figure 1 As shown, one or more light rays originating from a point light source (eg, a laser source and / or an input optical fiber coupled to a laser source, etc.) can propagate through a graded-index optical fiber.

[0026] Due to the periodic imaging properties of graded-index fibers, a point source of light is precisely re-imaged at every pitch (and imaged but inverted every half-pitch). Mathematically, a ray of light traveling through a single pitch of a graded-index fiber is calculated as four consecutive Fourier transforms, representing collimation (e.g., in the first quarter pitch), focusing to an inverted image (e.g., in the second quarter pitch), collimation (e.g., in the third quarter pitch), and focusing again (e.g., in the fourth quarter pitch). In some embodiments, when the graded-index fiber is drawn, the pitch of the graded-index fiber is determined by the core diameter and the numerical aperture. In some embodiments, as described herein, the bending period of a graded-index fiber having periodic bends matches or nearly matches the pitch of the graded-index fiber, resulting in stronger and more versatile beam path modifications compared to adiabatic bending.

[0027] As mentioned above, Figure 1 are provided as examples. Other examples may differ from those described in Figure 1 described.

[0028] Figure 2 FIG2 is a schematic diagram of one or more example embodiments 200 of a bending device 210 that can be used to impart one or more bends in a graded-index optical fiber 215. In some embodiments, as described herein, the bending device 210 can be designed to impart a series of bends to the graded-index optical fiber 215 in alternating directions at every odd-numbered quarter pitch (e.g., starting from the first quarter pitch and every half pitch) based on the periodic imaging behavior of the graded-index optical fiber 215. In this manner, the series of bends can have a bending period that matches or nearly matches the pitch of the graded-index optical fiber 215. For example, for a perfect optical fiber, the period of the bending device 210 would be equal to the pitch of the graded-index optical fiber 215. However, due to optical fiber manufacturing tolerances, the manufactured pitch may deviate from the nominal value. To correct for deviations between the manufactured pitch and the nominal value, the bending device 210 can be manufactured with a period shorter than the pitch of the graded-index optical fiber 215, and the bending device 210 can be placed on a goniometer platform 220 (e.g., a device that measures angles or allows an object to be rotated to a certain position). In some embodiments, the goniometer platform 220 can include a knob or other rotational mechanism to rotate the bending device 210 relative to the graded-index fiber 215, thereby extending the effective period applied to the graded-index fiber 215 and enabling in-situ adjustment of the period of the perturbation that causes the bend to be formed in the graded-index fiber 215.

[0029] As described herein, for a given acceptable level of curvature imposed on the graded-index fiber 215, the bending device 210 can allow the displacement of the optical beam to be approximately 4N times greater than when using a single adiabatic bend, where N is the number of pitches in the graded-index fiber 215. In other words, for a target amount of beam displacement, the bending device 210 is able to achieve the beam displacement using a bend curvature on the graded-index fiber 215 that is approximately 1 / 4N times greater. Thus, the bending device 210 utilizes the bending properties of the graded-index fiber 215 more efficiently than adiabatic bending. In this manner, the bending device 210 imposes much less stress on the graded-index fiber 215, provides much greater performance, and significantly simplifies the mechanical implementation.

[0030] like Figure 2 As shown, a graded-index fiber 215 having a nominal length of N pitches passes through a bending device 210. In some embodiments, the bending device 210 has one or more protrusions 235, 245 whose period (Λ) matches or nearly matches the pitch of the graded-index fiber 215 (e.g., is less than the pitch by a threshold amount). In a neutral setting, the protrusions 235, 245 of the bending device 210 do not contact, or barely contact, the graded-index fiber 215. Thus, in the neutral setting, the protrusions 235, 245 exert no force on the graded-index fiber 215. Generally speaking, as described above, light launched axially at the entrance of the graded-index fiber 215 exits axially (Δx = 0) and is precisely re-imaged. This fiber state is particularly useful for producing a nominally undisturbed, high-beam-quality output state.

[0031] In some embodiments, the bending device 210 includes an actuation mechanism 225, such as a micrometer knob and / or other suitable actuator, that can be adjusted to move the first portion 230 of the bending device 210 toward the second portion 240 of the bending device 210. In some embodiments, when the actuation mechanism 225 is adjusted to move the first portion 230 toward the second portion 240, the protrusions 235, 245 cause the graded-index optical fiber 215 to bend in a wave-like pattern. In some embodiments, the bending device 210 can be aligned such that one or more protrusions 235 of the first portion 230 and one or more protrusions 245 of the second portion 240 are aligned with odd-numbered quarter-pitch lengths of the graded-index optical fiber 215. Thus, when the protrusions 235, 245 cause the graded-index optical fiber 215 to bend in the wave-like pattern, a series of bends can be formed in the graded-index optical fiber 215, with the first bend in the series aligned with the first quarter-pitch length of the graded-index optical fiber 215, and each bend in the series of bends being separated from an adjacent bend by a half-pitch length. Thus, the series of bends formed in the graded-index fiber 215 resonates with the natural period of the graded-index fiber 215. Small local bends are equivalent to introducing tilt in the graded-index fiber 215, and because the Fourier transform of tilt is offset, the resulting effect is that the light beam propagating through the graded-index fiber 215 is gradually offset from the center of the graded-index fiber 215 every half pitch, as shown by curve 250. The bends (or tilts) occurring at each half pitch are of opposite sign relative to the axis of the graded-index fiber 215, which compensates for the image-flipping behavior of the graded-index fiber 215 every half pitch and allows for constructive addition of offset. Thus, the total offset can be controlled by the number of periods in the bending device 210 and the degree to which the two portions 230, 240 of the bending device 210 are moved toward each other.

[0032] In some embodiments, as Figure 2The bending device 210, in the configuration shown, can provide a bend whose strength is independent of the focal length of the first-order graded-index fiber 215. In this manner, the graded-index fiber 215 can be freely selected based on other system constraints, such as better mode matching with an input fiber coupled to the graded-index fiber 215 to provide a beam to the graded-index fiber 215, and / or better mode matching with an output fiber coupled to the graded-index fiber 215 to receive the beam after it passes through the graded-index fiber 215, etc. In this case, the period of the bending device 210 (e.g., the periodicity of the protrusions 235, 245 that cause the bend in the graded-index fiber 215) can be adjusted to correspond to the pitch of the graded-index fiber 215. In general, the beam-moving behavior of the bending device 210 does not strongly depend on the exact shape of the periodic curve induced in the graded-index fiber 215. For example, the graded-index fiber 215 can be bent into a sinusoidal pattern or other smoothly varying oscillating curve, an alternating sequence of circular arcs, and / or a sequence of straight or nearly straight segments connected by sharp bends near odd quarter-pitch locations, etc. For example, as Figure 2 As shown, the graded-index optical fiber 215 can have a natural elastic bend shape when bent by a near-point contact actuator, which produces a smoothly varying curve that approximates a sinusoidal curve.

[0033] In a numerical example of the bending device 210, the input beam provided by the input optical fiber may have a spot diameter of 50 microns and a divergence of 0.1 radians. Using a fused silica graded-index optical fiber 215 with a focal length of 750 microns and a numerical aperture (NA) of 0.21, and considering the stress-optical effect caused by bending in the graded-index optical fiber 215, four alternating bends of 2.4 degrees each, spaced half the pitch length (3.5 mm) apart, are used (e.g., corresponding to two pitches of the graded-index optical fiber 215, as shown in FIG. Figure 2 (as shown), a beam position shift of 100 microns can be produced, which is a practical and useful amount compared to the actual 50 micron beam size. The actual bend angle of 2.4 degrees is relatively small and acts directly on the graded-index fiber 215 without causing damage to the graded-index fiber 215 and without requiring complex fiber processing or geometry.

[0034] In some embodiments, two multi-bend devices 210 can be cascaded, one after the other, with the multi-bend devices 210 oriented in perpendicular directions relative to each other (e.g., as Figure 3 and Figure 6A, and described in further detail below). For example, where the axis of the graded-index optical fiber 210 is arranged along the z-direction, the first multi-bend device 210 can operate in the xz plane and the second multi-bend device 210 can operate in the yz plane. Thus, the two multi-bend devices 210 can be independently adjusted to allow the user to arbitrarily move the beam in the xy plane or to arbitrarily shift the beam in space, which provides a useful capability in many applications that require a rasterizable or addressable beam position. Additionally or alternatively, two-dimensional addressing capability can be achieved using a single multi-bend device 210 that can be actuated in any lateral desired direction. For example, Figure 2 The bending device 210 shown can also be rotated about the fiber axis (e.g., using a rotating mechanism). Additionally or alternatively, the actuating surface in contact with the graded-index fiber 215 can be a small ring or hole in a flat stack of tabs that can move the graded-index fiber 215 in two dimensions at each actuator. Using a two-dimensional adjustment stage instead of Figure 2 The one-dimensional stage shown allows adjustment of the motion imposed on the ring or hole in both the x-direction and the y-direction.

[0035] In some embodiments, the bending device 210 is manufactured with high precision, as simulations indicate that the desired deflection is on the order of 10 micrometers (μm). Therefore, the protrusions 235, 245 can be manufactured to have precisely the same height, or at least to have a precisely mirrored relationship between the various portions. For example, in some embodiments, the bending device 210 can be manufactured with high precision using wire-cut electrical discharge machining and / or other suitable techniques.

[0036] As mentioned above, Figure 2 are provided as one or more examples. Other examples may differ from those described in Figure 2 For example, Figure 2 The number and arrangement of components shown in the FIGURES are provided as examples. In practice, Figure 2 The arrangement shown in FIG may include Figure 2 More components, fewer components, different components, or differently arranged components than shown in . Additionally or alternatively, Figure 2 A set of components (e.g., one or more components) in a Figure 2 One or more functions performed by another group of components in a .

[0037] Figure 3 is a schematic diagram of one or more example embodiments 300 of a plurality of bending devices arranged in a cascade configuration. Figure 3As shown, an input fiber 310 is coupled to a first bending device 320 and a second bending device 330 arranged in a cascade configuration, with a quarter-pitch graded-index fiber 340 located between the two bending devices 320, 330. In some embodiments, the bending devices 320, 330 can operate on the same axis, perpendicular axes, or other relative angles. For example, in Figure 3 In the embodiment, the bending devices 320, 330 are arranged to operate on a perpendicular axis. Thus, the first bending device 320 can control the angle at which the light beam exits the quarter-pitch graded-index fiber 340 in the y-direction, and the second bending device 330 can control the spatial offset of the light beam in the x-direction. Combining two bending devices 320, 330 with the quarter-pitch graded-index fiber 340 between the two bending devices 320, 330 allows control of both the beam offset on the perpendicular axis and the beam deflection angle (e.g., near field and far field, respectively), thereby generating deflected light. If the two bending devices 320, 330 are oriented on the same axis, then the two bending devices 320, 330 can generate meridional light, again independently adjusting the beam offset and deflection angle. In some embodiments, the quarter-pitch graded-index fiber 340 between the two bending devices 320, 330 can be the same as or different from that in the multi-bend device, and / or the quarter-pitch graded-index fiber 340 can include multiple graded-index elements whose net effect is equivalent to one quarter-pitch graded-index element.

[0038] In some embodiments, the two stages 320, 330 can be combined into a multi-bend device in which the graded-index fiber 340 can be bent at every quarter pitch, rather than at every odd-numbered quarter pitch. In this case, the odd-numbered quarter pitch bends can adjust the beam offset and the even-numbered quarter pitch bends can adjust the beam angle, measured from the output end, in the case where the total length is not an integer number of half pitches. If the odd-numbered quarter pitch bends are oriented perpendicular to the even-numbered bends, then the overall bent fiber shape will be approximately helical and the output light will be skewed. On the other hand, if the two sets of bends are parallel, then the output light will be meridional. Since typical quarter pitch lengths are on the order of one (1) mm or less, such a device may require a complex actuation system, especially if the design goal is to provide full two-dimensional addressability in terms of both beam offset and beam deflection. In addition, to provide equal sensitivity to both offset and deflection, the graded-index fiber 340 can have a focal length that makes the quarter pitch beam size approximately the same as the input beam size provided by the input fiber 310. Thus, for the beam size of interest, the graded-index fiber 340 can have a focal length of several hundred microns. Additionally, or alternatively, the input beam size can be adjusted first (e.g., using a single quarter-pitch graded-index fiber with appropriate focusing strength) to change the beam size to the desired new beam size, and then the more preferred focal length of the extended graded-index fiber can be used for the curved array.

[0039] In some embodiments, as described herein, the bend formed in the graded-index fiber 340 can have any periodic bend shape, with the bend period being equal to or approximately equal to the pitch of the graded-index fiber 340. Thus, the bend formed in the graded-index fiber 340 can be used to control the spatial properties of light carried by the graded-index fiber 340. In some embodiments, the bend can be two-dimensional (e.g., in the xz plane, where z is the average propagation direction, such as a simple sinusoid), or the bend can be three-dimensional (e.g., in the x, y, and z directions, such as a circular spiral, an elliptical spiral, and / or a more complex three-dimensional shape that is periodic in the z direction, etc.). In some embodiments, the bend period can be precisely matched to the pitch of the graded-index fiber, or the bend period can be nearly matched to the pitch of the graded-index fiber by 25%, 10%, 3%, and / or other suitable ranges. Therefore, to match or nearly match the pitch of the graded-index fiber, the deviation between the bend period and the pitch of the graded-index fiber may need to meet (e.g., be less than and / or equal to) a threshold value (e.g., ±10% or less). In some embodiments, depending on the bend shape, the bending device can steer the beam in the near field (offset position), the far field (beam pointing direction), or both. Thus, forming a bend in the graded-index fiber 340 that matches or nearly matches the pitch of the graded-index fiber 340 provides greater versatility than adiabatic bending, which is typically limited to controlling the near field.

[0040] Furthermore, in some embodiments, a single bend can be formed in the graded-index fiber 340. Typically, when a single bend is used, the single bend is substantially equal to or shorter than half the pitch of the graded-index fiber 340, and the center of the single bend is located at a position in the graded-index fiber 215 that is at least one-quarter of the pitch from one end of the graded-index fiber 215. In this case, some embodiments described herein can significantly enhance the bending effect compared to adiabatic bending. For example, in some embodiments, a splice assembly can include an input fiber that provides a beam, a graded-index fiber coupled to the input fiber (and having a length that is half the pitch relative to the imaging pitch length of the graded-index fiber), and an output fiber capable of receiving a modified beam position from the graded-index fiber, wherein the bend is applied to the graded-index fiber, centered in the middle of the graded-index fiber, and strongest at the middle of the graded-index fiber. In some embodiments, the bend may or may not extend into the input and / or output fibers, but is generally weaker in the input and / or output fibers than in the graded-index fiber to minimize bending stress applied to the splice. In this case, the splice assembly may differ from a typical adiabatic bend fiber in that most of the length of the bend should be equal to or shorter than the half-pitch of the graded-index fiber, which is typically about 1-5 mm, and if the goal is to move only the near field, the strongest bend point will not be applied at the output splice point, but rather about a quarter of the pitch before the output splice, similar to an adiabatic bend.

[0041] In some embodiments, the optical system can include an actuation mechanism that allows adjustment of the bend shape, thereby achieving at least two states of the output beam (e.g., an undisturbed state and a modified state). However, in the simplest case, a static periodic bend shape can be imparted to the graded-index fiber 340, such that a given input state is statically converted to a different output state (e.g., a beam position and / or beam pointing different from the input). An example of such a device can include an all-fiber rotating beam generator, in which the induced fiber bend shape can be helical, and the output beam can be simultaneously deviated from the fiber axis and tilted perpendicular to the deviation direction, thereby generating a skew signature and orbital angular momentum. If the graded-index fiber 340 is spliced to an output step-index or ring-index fiber with a radius that matches the spatial offset and an NA that matches the beam tilt angle, the deflected, skewed beam can be captured and retained in a rotated beam. Such a static rotating beam generator can be implemented in an integrated form by fabricating a fiber preform (including a graded-index core that is offset from the fiber's central axis) and rotating the fiber during the drawing process so that the offset core effectively follows a helical path (even though the exterior of the fiber appears straight). If the helical pitch, determined by the rotation rate relative to the draw rate during the fiber drawing process, is equal to or nearly equal to the graded-index pitch, then the helical core fiber can produce static lateral offsets and beam deflections (e.g., a skewed beam carrying orbital angular momentum), which can produce a toroidal rotated beam when the graded-index fiber 340 is coupled into an output fiber (e.g., a step-index or ring fiber) of appropriate diameter and NA to guide the rotated beam. In this way, some embodiments described herein can produce a compact and simple-to-manufacture rotated beam. For example, the structure can be only a few millimeters or centimeters long, does not require tapering, has simple fiber preform preparation, and can provide efficient conversion to a rotated beam in terms of both power and brightness.

[0042] In some embodiments, in addition to and / or as an alternative to the aforementioned actuation mechanisms, various options can be used as the actuation mechanism to provide two or more output states. For example, in some embodiments, the actuation mechanism can provide full addressability by controlling the two-dimensional lateral position of the graded-index fiber at each half-pitch position, each quarter-pitch position, and / or using a microcontroller array, among others. In another example, the actuation mechanism can be arranged to switch between a straight fiber configuration and a helical fiber configuration by holding the graded-index fiber straight and slightly tensioned to provide the straight state, and by twisting the graded-index fiber while providing a slight slack in tension, such that the graded-index fiber adopts a helical configuration with a predetermined pitch. In another example, switching between a straight fiber configuration and a helical fiber configuration can be achieved by winding the graded-index fiber with a predetermined number of turns around a second (non-optical) optical fiber of appropriate diameter and stiffness, and either slackening the non-optical fiber while tensioning the fiber to provide the straight fiber configuration, or slackening the non-optical fiber while tensioning the fiber to force the fiber into a helical configuration.

[0043] As mentioned above, Figure 3 are provided as one or more examples. Other examples may differ from those described in Figure 3 For example, Figure 3 The number and arrangement of components shown in the FIGURES are provided as examples. In practice, Figure 3 The arrangement shown may include Figure 3 More components, fewer components, different components, or differently arranged components as shown. Additionally or alternatively, Figure 3 A set of components (e.g., one or more components) in a Figure 3 One or more functions performed by another group of components in a .

[0044] Figures 4A-4C Example graphs 400, 410, 420 are shown relating to the propagation length of a graded-index optical fiber operated using one or more bending devices and / or one or more methods described herein. Figure 4A As shown, graph 400 shows the ray trajectories in a graded-index fiber, showing a single ray propagating around an integer number of pitches. The source NA is 0.1. Figure 4B As shown, curve 410 shows the lowest order linear polarization fundamental mode (LP01) of a 50 μm and NA=0.22 step-index fiber, which is launched into different graded-index fibers and propagates through a certain number of pitches. Figure 4CCurve 420 shows how even with a perfect graded-index fiber, its "aberrations" affect the beam based on changing spot size. Higher-order modes of the same input fiber propagate through a certain number of pitches with the same graded index. Because these modes are less well-matched to the size of the graded-index fiber, the higher-order modes experience more aberrations per pitch and expand more rapidly.

[0045] Therefore, one challenge with the bending apparatus and methods described herein is obtaining an accurate length for the graded-index fiber. If the length of the graded-index fiber is significantly longer or shorter than an integer multiple of the pitch, the input beam may have a "blurred" image and have power at a higher radius, which may result in a loss of brightness (e.g., an increased beam parameter product (BPP)) when coupled into the delivery fiber. Figure 4A As shown, for tight dimensional tolerances of approximately 5 μm, the length tolerance is independent of the graded-index fiber focal length and depends solely on the input beam NA. For larger tolerances, focal length may be a factor, and smaller focal lengths are more forgiving. The most forgiving configuration is to choose a graded-index focal length that produces exactly the same spot size in both the near-field and far-field (e.g., matching the graded index to the input beam size). For the input beam radius (w) and divergence (θ), the appropriate graded-index focal length is f = w / θ. In this case, the beam does not change size as it propagates (although the shape of the beam may oscillate subtly). In this case, the length of the graded-index fiber is unimportant, and the position of the starting point of the bend array relative to the starting point of the graded-index fiber is also unimportant. However, the period of the bend array is well matched to the graded-index pitch, and the position of the final bend relative to the end of the graded-index fiber is controlled, thereby achieving the desired control of the near-field and / or far-field.

[0046] Furthermore, an additional design consideration is that graded-index "lenses" have aberrations, similar to free-space components. For example, even a graded-index fiber with a perfectly parabolic refractive index profile will not achieve an exact image at each pitch, but will have small errors that accumulate as more pitches are used. These errors depend strongly on the NA and the size of the input beam. For example, if the input is a single fundamental mode in a 50 μm diameter step-index fiber with an NA of 0.22, then Figure 4B As shown in , in a graded-index fiber at the correct focal length, this input can be almost perfectly re-imaged even after 100 pitches. However, different modes are selected in this input fiber that have poor overlap with the corresponding modes in the graded-index fiber, as shown in Figure 4CAs shown, even with a perfect choice of fiber length, the aberrations per pitch for the same graded-index fiber that maintains the spot size of the LP01 mode group of that input fiber become progressively larger. In general, for a given input fiber, as the NA increases, the number of graded-index pitches before significant aberrations appear will decrease. This is mathematically analogous to using a series of lenses, each with a small amount of spherical aberration. Therefore, in some embodiments, the number of pitches in a length of graded-index fiber can be selected to meet a threshold based on one or more metrics related to the accumulated error per pitch of the graded-index fiber. For example, Figure 4C As shown, after a propagation length of approximately ten (10) pitches, the aberrations increase significantly, and thus, in one example, a series of bends may be formed in a length of graded-index fiber comprising ten pitches or less.

[0047] In some embodiments, the exact length of the graded-index fiber may not be an integer multiple of the pitch in applications where brightness needs to be maintained. In some embodiments, the device length can be selected to minimize the spot size rather than providing a perfect integer number of pitches (similar to aligning a free-space system with the circle of minimum confusion, as opposed to paraxial focus). Additionally, depending on the light source, small modifications can be made to the refractive index profile to correct for different aberrations. In this way, the refractive index profile design will not be an exact parabola, but rather a slightly different function, while still being characterized as a graded-index.

[0048] Additionally, aberration considerations may affect the number of perturbation cycles used. A high NA source may only provide a small number of pitches before the beam "blurs," while a low NA source may use more pitches. Additionally, the deflection and tolerances required on the micrometer stage may be a factor. In automated systems, the micrometer may be replaced with piezoelectric or similar materials to achieve sub-second actuation. Additionally, some embodiments described herein may have mechanisms for changing the effective length to avoid excessive cleaving and polishing to achieve a precise length (e.g., by using heat, longitudinal stress, compressive stress, and / or other suitable techniques to change the optical path length).

[0049] As mentioned above, Figures 4A-4C Provided as one or more examples. Other examples may differ from those described in Figures 4A-4C described.

[0050] Figure 5 is a flow chart of an example process 500 for applying a set of bends in a graded-index optical fiber using one or more bending devices.

[0051] like Figure 5As shown, process 500 may include routing a graded-index optical fiber through one or more bending devices, wherein the one or more bending devices include one or more protrusions, the one or more protrusions having a periodicity that matches or nearly matches the pitch of the graded-index optical fiber (block 510). For example, in some embodiments, as described above, the graded-index optical fiber 100, 215, 340 may be routed through one or more bending devices 210, 320, 330. In some embodiments, the one or more bending devices 210, 320, 330 include one or more protrusions 235, 245, the one or more protrusions 235, 245 having a periodicity that matches or nearly matches the pitch of the graded-index optical fiber 100, 215, 340.

[0052] like Figure 5 As further shown in FIG5 , process 500 may include actuating a first portion of one or more bending devices toward a second portion of one or more bending devices such that one or more protrusions induce a series of bends in the graded-index optical fiber, wherein the periodicity of the one or more protrusions is such that the series of bends has a bend period that matches or nearly matches the pitch of the graded-index optical fiber (block 520). For example, in some embodiments, the first portion 230 of one or more bending devices 210, 320, 330 may be actuated toward the second portion 240 of one or more bending devices 210, 320, 330 such that one or more protrusions 235, 245 induce a series of bends in the graded-index optical fiber 100, 215, 340. In some embodiments, the periodicity of the one or more protrusions 235, 245 is such that the series of bends has a bend period that matches or nearly matches the pitch of the graded-index optical fiber 100, 215, 340.

[0053] Process 500 may include additional embodiments, such as any single embodiment or any combination of the embodiments described below, and / or in combination with one or more other processes and / or embodiments described elsewhere herein.

[0054] For example, in a first embodiment, the one or more bending devices may include a first bending device 320 arranged to induce a first series of bends in the graded-index optical fiber in a first direction, and a second bending device 330 following the first bending device 320 to induce a second series of bends in the graded-index optical fiber in a second direction.

[0055] In the second embodiment, alone or in combination with the first embodiment, the first series of bends in the first direction and the second series of bends in the second direction may be perpendicular to each other or parallel to each other.

[0056] In a third embodiment, alone or in combination with one or more of the first and second embodiments, a first series of bent and manipulated optical beams passes through a graded-index fiber in the near field and a second series of bent and manipulated optical beams passes through the graded-index fiber in the far field.

[0057] In a fourth embodiment, alone or in combination with one or more of the first to third embodiments, process 500 includes rotating one or more bending devices relative to a graded-index optical fiber, wherein a period of the one or more protrusions is shorter than a pitch of the graded-index optical fiber, and rotating the one or more bending devices relative to the graded-index optical fiber extends the bending period such that the bending period matches or nearly matches the pitch of the graded-index optical fiber.

[0058] In a fifth embodiment, alone or in combination with one or more of the first to fourth embodiments, a series of bends are formed in a graded-index optical fiber in two or three dimensions.

[0059] although Figure 5 Example steps of process 500 are shown, but in some embodiments, process 500 may include more Figure 5 Those step blocks shown may be more step blocks, fewer step blocks, different step blocks, or differently arranged step blocks. Additionally or alternatively, two or more step blocks of process 500 may be executed in parallel.

[0060] Figures 6A-6C is a schematic diagram of one or more exemplary embodiments 600 of an all-fiber beam routing system that utilizes a bent, graded-index optical fiber to controllably illuminate different cores in an imaging fiber bundle that includes a plurality of cores arranged in an array. Thus, as described in further detail herein, the exemplary embodiment(s) 600 can be used to deliver a scannable laser beam to a workpiece via an all-fiber delivery system that is compatible with standard imaging processing heads that may lack beam scanning capabilities. For example, Figure 6A As shown, the all-fiber delivery system may include an input fiber 610 coupled to a first multi-bend beam displacer 620 and a second multi-bend beam displacer 630, the first multi-bend beam displacer 620 and the second multi-bend beam displacer 630 being arranged in a cascade configuration with a graded-index fiber (GRIN) 640 disposed between the two multi-bend beam displacers 620, 630. In some embodiments, the multi-bend beam displacers 620, 630 may operate on the same axis, perpendicular axes, or other angles relative to each other. For example, in Figure 6AIn the embodiment of the present invention, the multi-bend beam shifters 620, 630 are arranged to operate on perpendicular axes (shown as multi-bend in y and multi-bend in x, respectively). Thus, in one example described herein, the first multi-bend beam shifter 620 can introduce a spatial shift on a first spatial axis (e.g., in the x-direction), and the second multi-bend beam shifter 630 can introduce a spatial shift on a second spatial axis (e.g., in the y-direction).

[0061] In some embodiments, as described herein, Figure 6A The cascade configuration shown can be used to manipulate the position of a light beam within an optical fiber. In addition, in some embodiments described herein, the cascade configuration can be used to deliver a scannable light beam to a workpiece via an all-fiber delivery system that can be compatible with standard imaging processing heads (e.g., non-scanning processing heads). For example, a resonant multi-bend actuator can be applied to a GRIN fiber 640 to shift the light beam in the GRIN fiber 640 using a near-field shifting configuration. In some embodiments, as shown, the first multi-bend beam shifter 620 is followed by a GRIN fiber segment 640 that includes an integer (m) number of half-pitch MHPs: m*HP, which can include the case of zero (0) half-pitch (e.g., m=0). As Figure 6A As further shown in FIG, GRIN fiber segment 640 may be followed by a second multi-bend beam displacer 630. In some embodiments, second multi-bend beam displacer 630 may also be configured to introduce near-field displacement, but along a different spatial axis than first multi-bend beam displacer 620. The two multi-bend beam displacers 620, 630 may work together to displace the beam by an arbitrary amount in a two-dimensional (2D) plane before launching it into a feeder fiber containing an imaging fiber bundle 650 having multiple cores arranged in an array. Thus, when the two multi-bend beam displacers 620, 630 are actuated by different amounts, the user can control which core the light exits at the end of the processing fiber, thereby allowing the user to shift the beam in two dimensions. Additionally or alternatively, the same effect may be achieved using a single multi-bend actuator that can apply bends in any rotational direction about the fiber axis (e.g., providing radial coordinate control as opposed to Cartesian control). In some embodiments, a standard imaging processing head may image the beam displacement onto a workpiece. Controlling the near-field position of the beam on the workpiece in this way is equivalent to introducing a 2D spatial beam scanner in the processing head, in addition to requiring a custom processing head, through a galvanometer mirror system, a rotating prism and / or other arrangements that are typically expensive to design and manufacture.

[0062] In some embodiments, as described herein, the cores of the imaging fiber bundle 650 can be arranged in an array, which can have any suitable 1D or 2D geometry. For example, Figure 6BIllustrates example 2D geometries 650-1, 650-2, 650-3, 650-4, 650-5 in which the cores of the imaging fiber bundle 650 can be arranged. As Figure 6B shown, the imaging fiber bundle 650 can generally include a cladding-core structure in which multiple cores (labeled n1, which represents the refractive index of the core) are embedded in a first (inner) cladding (labeled n2, which represents the refractive index of the inner cladding). As Figure 6B further shown, the inner cladding is surrounded by a second (outer) cladding (labeled n3, which represents the refractive index of the outer cladding). For example, in some embodiments, the inner cladding can be surrounded by the outer cladding to prevent light emitted between the cores from leaking out of the fiber. Although all examples 650-1 to 650-5 show cores with a uniform refractive index (n1), uniform size and / or shape embedded in a cladding with a uniform refractive index (n2), the cores can have different refractive indices, different sizes and / or different shapes. However, generally, to ensure guidance within the core and avoid loss of power emitted between cores, the inequality n3 < n2 < n1 can be maintained (e.g., the refractive index n3 of the outer cladding material is less than the refractive index n2 of the inner cladding, and the refractive index n2 of the inner cladding is less than the refractive index n1 of the core). In some embodiments, the cores can have the same or comparable size relative to the input beam, or the cores can be slightly larger than the input beam such that the beam is completely contained within one core at a time. Alternatively, in some embodiments, the cores can be smaller than the input beam, which can allow multiple cores to be independently filled to provide smoother beam movement.

[0063] In some embodiments, the cores can be encapsulated in the imaging fiber bundle 650 in a manner that minimizes the total area of the material forming the inner cladding. For example, in some embodiments, the total area of the inner cladding can be minimized by designing the lattice structure of the core array into a close-packed configuration (e.g., a dense arrangement of congruent circles) and / or by shaping the cores into triangles, squares, hexagons, and / or other shapes. Thereby, minimizing the total area of the inner cladding material enables smaller beam offsets, and in the case where the beam fills multiple cores simultaneously, a smaller portion of the light is emitted into the cladding material rather than the desired core combination. However, in some embodiments, the cores can be separated by a minimum distance (e.g., 5 μm) to prevent power from escaping from one core to an adjacent core via the evanescent effect.

[0064] In some embodiments, referring again to Figure 6A , the axes of the multi-bend beam shifters 620, 630 can correspond to the preferred axes of the core lattice in the imaging fiber bundle 650. For example, in Figure 6BIn a hexagonal packing array (e.g., where the circular fiber cores are arranged in a hexagonal pattern) as shown in the example geometry 650-1 in FIG, the multi-bend beam shifters 620, 630 can be oriented such that one multi-bend beam shifter 620 / 630 shifts the beam along a horizontal axis and the other multi-bend beam shifter 620 / 630 shifts the beam along a line that is sixty (60) degrees from the horizontal axis (e.g., the axes of the multi-bend beam shifters 620, 630 can correspond to the axes of the basis vectors of the lattice that defines the structure of the imaging fiber bundle 650). Thus, in some embodiments, the axes of the multi-bend beam shifters 620, 630 need not be perpendicular to each other.

[0065] As described elsewhere herein (e.g., reference Figure 2 As described above, at a fixed position along the fiber, a multibend beam router will only move the beam in a specific direction with a specific sign. In other words, if the multibend is configured to move the fiber along the x-axis, whether the first bend pushes the fiber in the +x direction or the -x direction will determine whether the beam is offset in the +x direction or the -x direction. Therefore, in some embodiments, the input fiber can be offset-spliced or the array of cores in the processing fiber can be eccentric so that only movement in the +x and +y directions is required to illuminate different cores. Alternatively, the entire multibend device or one side of the multibend device can be moved along the length of the fiber and reconfigured along the half-pitch of the GRIN fiber 640 so that a single multibend can move the beam in the +x or -x direction. Alternatively, the multibend can be configured so that each bend is individually addressable (e.g., by an array of linear actuators or a similar arrangement) or addressable in pairs, groups, or other groupings to achieve the same effect.

[0066] In some embodiments, reference Figure 6C, a scannable beam can be delivered to the workpiece along one axis via a single fiber beam shifter (e.g., a resonant multi-bend or a simple non-resonant bender), launched into a ribbon fiber bundle or similar fiber having a one-dimensional (1D) array of cores. In some embodiments, the 1D array of cores can then provide a 1D scannable output, which is useful in applications where the processing head is moved simultaneously relative to the workpiece (e.g., 1D scanning can impart a lateral "wobble" to a beam used for cutting or welding). In addition, similar to the 2D case described above, the bender can be reconfigurable so as to provide a beam shift in a positive or negative direction along the fiber ribbon. Thus, where the cores in the imaging fiber bundle are arranged in a 1D array (e.g., the cores are placed along one spatial axis), a single beam shifter 620 / 630 can operate along only one spatial axis (e.g., the spatial axis of the 1D core array) to controllably illuminate one or more cores in the 1D array. Alternatively, the ID core array can be reconfigured into a 2D core array using fused fiber bundles or the like, converting the ID beam excursions into in-plane motion between the different cores in a prescribed order or sequence.

[0067] Thus, in some embodiments, an optical assembly as described herein may include: an input optical fiber 610 for providing a light beam; a feeding optical fiber including an imaging bundle 650 having an optical fiber embedded in a second cladding (at Figure 6B The first cladding (marked as n3 in Figure 6B Multiple cores (marked as n2 in Figure 6B and an intra-fiber beam displacer comprising: a first multi-bend beam displacer 620 coupled to an input fiber 610, a graded-index fiber 640 following the first multi-bend beam displacer 620, and a second multi-bend beam displacer 630 following the graded-index fiber 640 and coupled into a feeding fiber 650. In some embodiments, the first multi-bend beam displacer 620 is actuated a first amount and the second multi-bend beam displacer 630 is actuated a second amount to displace the beam in two dimensions and to deliver the beam to one or more target cores in the imaging bundle 650. For example, the first multi-bend beam displacer 620 can be actuated a first amount to displace the beam along a first spatial axis, and the second multi-bend beam displacer 630 can be actuated a second amount to displace the beam along a second spatial axis, wherein the first spatial axis and the second spatial axis can correspond to preferential axes of a lattice structure in which the plurality of cores are arranged.

[0068] In some embodiments, the first multi-bend beam shifter 620 and the second multi-bend beam shifter 630 are actuated to shift the beam in the near field. In some embodiments, the length of the graded-index fiber is an integer number of half-pitch lengths, and the plurality of cores each have a refractive index greater than the refractive index of the first cladding, which has a refractive index greater than the refractive index of the second cladding. In some embodiments, the plurality of cores can have a uniform refractive index, uniform diameter, and / or uniform shape, or the refractive index, diameter, and / or shape can vary between the cores. In some embodiments, the plurality of cores can be arranged within the imaging beam 650 in a 2D array comprising a lattice structure having a close-packed configuration with minimal spacing between adjacent cores. In some embodiments, the diameters of the plurality of cores can be greater than or within a threshold of the beam diameter such that the beam is completely contained within one target core at a time. Alternatively, in some embodiments, the diameters of the plurality of cores can be less than the beam diameter such that the beam can independently fill multiple target cores.

[0069] Thus, as described herein, an all-fiber beam scanning method can include providing a beam from an input fiber 610 to an intra-fiber beam shifter including a first multi-bend beam shifter 620 coupled to the input fiber 610, a graded-index fiber 640 following the first multi-bend beam shifter 620, and a second multi-bend beam shifter 630 following the graded-index fiber 640 and coupled into a feeding fiber. The feeding fiber can include an imaging bundle 650 having an imaging bundle 650 embedded in a first cladding (at Figure 6B Multiple cores (marked as n2 in Figure 6B The first cladding is covered by the second cladding (in Figure 6B In some embodiments, the all-fiber beam scanning method can further include actuating the first multi-bend beam shifter 620 by a first amount to shift the beam along the first spatial axis, and actuating the second multi-bend beam shifter 630 by a second amount to shift the beam along the second spatial axis, wherein the first multi-bend beam shifter 620 and the second multi-bend beam shifter 630 are actuated to control Cartesian coordinates representing the position of the beam in two dimensions and deliver the beam into one or more target fiber cores in the imaging bundle 650.

[0070] Additionally or alternatively, as described herein, an optical assembly can include: an input fiber 610 providing a light beam; a feed fiber including a plurality of cores (labeled n1) arranged in an array and embedded in a first cladding (labeled n2) surrounded by a second cladding (labeled n3); and an intra-fiber beam displacer including multi-bend beam displacers 620 and / or 630 and a graded-index fiber 640 coupled between the input fiber 610 and the feed fiber 650. In some embodiments, the multi-bend beam displacers 620 / 630 can be actuated to apply a set of bends in the graded-index fiber 640, thereby shifting the light beam in a spatial dimension and directing the light beam to one or more target cores in the array. For example, in some embodiments, the multi-bend beam displacers 620 / 630 can be actuated to control a radial coordinate representing a position of the light beam within the graded-index fiber 640 (e.g., a 2D position when the array is a 2D array). Alternatively, in some embodiments, the array can be a 1D array in which multiple cores are arranged along a single spatial axis, whereby a single multi-bend beam shifter 620 / 630 shifts the beam along the single spatial axis to illuminate one or more cores in the 1D array.

[0071] As mentioned above, Figures 6A-6C is provided as one or more examples. Other examples may be related to Figures 6A-6C The examples described are different. For example, Figures 6A-6C The number and arrangement of components shown in the are provided as one or more examples. In practice, Figures 6A-6C The arrangement shown in may include Figures 6A-6C More components, fewer components, different components, or differently arranged components than those shown in . Additionally or alternatively, Figures 6A-6C A set of components (e.g., one or more components) in a Figures 6A-6C One or more functions performed by another group of components in a .

[0072] The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the embodiments. Furthermore, any embodiments described herein may be combined, unless the foregoing disclosure explicitly provides reasons why one or more embodiments may not be combined.

[0073] As used herein, the term "component" is intended to be broadly interpreted as hardware, firmware, and / or a combination of hardware and software.

[0074] Even though particular combinations of features are set forth in the claims and / or disclosed in the specification, these combinations are not intended to limit the disclosure of the various embodiments. In fact, many of these features may be combined in ways not specifically set forth in the claims and / or disclosed in the specification. Although each dependent claim listed below may be directly dependent on only one claim, the disclosure of the various embodiments includes the combination of each dependent claim with every other claim in the claim group. As used herein, a phrase referring to "at least one" of a series of items refers to any combination of those items, including single members. For example, "at least one of a, b, or c" is intended to cover a, b, c, ab, ac, bc, and abc, as well as any combination of multiple identical items.

[0075] Unless explicitly described, any element, action or instruction used in this article should not be interpreted as key or necessary. In addition, as used herein, the articles "one" and "an" are intended to include one or more projects and can be used interchangeably with "one or more". In addition, as used herein, the article "the" is intended to include one or more projects related to the article "the" and can be used interchangeably with "the one or more". In addition, as used herein, the term "group" is intended to include one or more projects (for example, a combination of related projects, unrelated projects or related and unrelated projects) and can be used interchangeably with "one or more". If only one project is referred to, the phrase "only one" or similar language is used. In addition, as used herein, the terms "having", "with" etc. are intended to be open terms. In addition, the phrase "based on" is intended to represent "at least partially based on", unless otherwise explicitly stated. In addition, as used herein, the term "or" is inclusive when used in a series and can be used interchangeably with "and / or", unless otherwise explicitly stated (for example, if used in combination with "either" or "only one"). Additionally, for ease of description, spatially relative terms, such as "below," "lower," "above," "upper," etc., may be used herein to describe the relationship of one element or feature to other elements or features shown in the figures. Spatially relative terms are intended to encompass different orientations of the device, apparatus, and / or element in use or operation in addition to the orientation shown in the figures. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative descriptive terms used herein should be interpreted accordingly.

Claims

1. An optical component comprising: an input optical fiber for providing a light beam; a feeder fiber comprising an imaging bundle having a plurality of cores embedded in a first cladding surrounded by a second cladding; as well as an intra-fiber beam displacer comprising a first multi-bend beam displacer coupled to the input fiber, a graded-index fiber following the first multi-bend beam displacer, and a second multi-bend beam displacer following the graded-index fiber and coupled to the feeder fiber, wherein the first multi-bend beam displacer is actuated a first amount and the second multi-bend beam displacer is actuated a second amount to displace the beam in two dimensions and deliver the beam to one or more target cores in the imaging bundle.

2. The optical assembly of claim 1, wherein: The first and second multi-bend beam displacers are actuated to displace the beam in a near field.

3. The optical assembly of claim 1, wherein: The length of the graded-index optical fiber is an integer number of half pitches.

4. The optical assembly of claim 1, wherein: The first multiple-bend beam displacer is actuated the first amount to displace the beam along a first spatial axis, and the second multiple-bend beam displacer is actuated the second amount to displace the beam along a second spatial axis.

5. The optical assembly of claim 4, wherein: The first spatial axis and the second spatial axis correspond to preferential axes of a lattice structure in which the plurality of cores are arranged.

6. The optical assembly of claim 1, wherein: The refractive index of each of the plurality of cores is greater than the refractive index of the first cladding, and the refractive index of the first cladding is greater than the refractive index of the second cladding.

7. The optical assembly of claim 1, wherein: The plurality of cores have one or more of a uniform refractive index, a uniform diameter, or a uniform shape.

8. The optical assembly of claim 1, wherein: The plurality of fiber cores are arranged in a two-dimensional array within the imaging beam.

9. The optical assembly of claim 8, wherein: The two-dimensional array includes a lattice structure having a close-packed configuration with a minimum spacing between adjacent cores.

10. The optical assembly of claim 1, wherein: The diameters of the plurality of cores are greater than or within a threshold of the diameter of the light beam such that the light beam is completely contained within one target core at a time.

11. The optical assembly of claim 1 , wherein: The diameters of the plurality of cores are smaller than the diameter of the light beam, so that the light beam can independently fill a plurality of target cores.

12. The optical assembly of claim 1, wherein: The graded-index fiber has a refractive index profile that causes the optical beam to be re-imaged in the graded-index fiber with a bending period having a pitch length, and wherein the graded-index fiber includes a set of bends having a bending period that matches or nearly matches the pitch length of the graded-index fiber.

13. An all-fiber beam scanning method, comprising: Provides the beam from the input fiber to the intra-fiber beam shifter, wherein the intra-fiber beam displacer comprises: a first multi-bend beam displacer coupled to the input fiber, a graded-index fiber following the first multi-bend beam displacer, and a second multi-bend beam displacer following the graded-index fiber and coupled into the feed fiber, and wherein the feeder fiber comprises an imaging bundle having a plurality of fiber cores embedded in a first cladding, the first cladding being surrounded by a second cladding; actuating the first multi-bend beam displacer a first amount to displace the beam along a first spatial axis; and actuating the second multi-bend beam displacer a second amount to displace the beam along a second spatial axis, The first and second multi-bend beam shifters are actuated to control Cartesian coordinates representing positions of the beams in two dimensions and deliver the beams to one or more target cores in the imaging bundle.

14. The all-fiber beam scanning method according to claim 13, wherein: The first and second multi-bend beam displacers are actuated to displace the beam in a near field.

15. The all-fiber beam scanning method according to claim 13, wherein: The graded-index optical fiber has an integer number of half pitches.

16. The all-fiber beam scanning method according to claim 13, wherein: The refractive index of each of the plurality of cores is greater than the refractive index of the first cladding, and the refractive index of the first cladding is greater than the refractive index of the second cladding.

17. The all-fiber beam scanning method according to claim 13, wherein: The plurality of cores are arranged within the imaging beam in a two-dimensional array comprising a lattice structure having a close-packed configuration with minimal spacing between adjacent cores.

18. An optical assembly comprising: an input optical fiber for providing a light beam; a feeder optical fiber comprising a plurality of cores arranged in an array and embedded in a first cladding surrounded by a second cladding; as well as an intra-fiber beam displacer comprising a multi-bend beam displacer and a graded-index fiber coupled between the input fiber and the feed fiber, wherein the multi-bend beam displacer is actuated to apply a set of bends in the graded-index fiber, thereby shifting the beam in spatial dimensions and delivering the beam to one or more target cores in the array.

19. The optical assembly of claim 18, wherein: The multi-bend beam displacer is actuated to control a radial coordinate representing the position of the beam within the graded-index optical fiber.

20. The optical assembly of claim 18, wherein: The array is a one-dimensional array in which the plurality of cores are arranged along a single spatial axis.

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