Optical fiber generating a rotating light beam.

Abstract

To provide an optical fiber for generating an optical beam with an annular beam shape directly in the optical fiber (i.e., without any free-space optics).SOLUTION: An optical fiber may include a first core, a second core, and a cladding surrounding the first core and the second core. The second core may be at an off-center position with respect to the center of the optical fiber, or the second core may include an azimuthally nonuniform section at the off-center position. The second core may twist about an axis of the optical fiber along the length of the optical fiber, and the second core twisted about the axis may cause an optical beam fed to the second core at a first end of the optical fiber to be at least partially converted into a rotary optical beam at a second end of the optical fiber.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] [Related Applications] This application claims priority to U.S. Provisional Patent Application No. 62 / 978,037, filed February 18, 2020, for "FIBER FOR VARIABLE ROTARY BEAM GENERATION," the contents of which are incorporated herein by reference in their entirety.

[0002] FIELD OF THE DISCLOSURE The present disclosure relates generally to optical fibers and optical fibers that produce a rotating light beam. [Background technology]

[0003] The beam profile of a light beam has a significant impact on the processing performance associated with material processing performed with the light beam. For example, a light beam with an annular beam profile can enable excellent metal cutting (e.g., by a laser cutting system). However, the beam profiles of most fiber-delivered light beams are relatively simplified. For example, the beam profile can be a Gaussian or near-Gaussian profile for low beam parameter product (BPP) lasers (e.g., BPP of about 3 millimeter-millaridians (mm-mrad) or less) that can be used to process thin sheet metals (e.g., sheet metals having a thickness of about 3 mm or less) with tightly focused light beams. As another example, the beam profile can be a top-hat (sometimes called flat-top) profile for high BPP lasers (e.g., BPP greater than about 3 mm-mrad) that can be used to process thick sheet metals (e.g., sheet metals having a thickness greater than about 3 mm) with large beams. Summary of the Invention

[0004] According to some embodiments, the optical fiber may include a first core and a second core, at least one of: the second core being eccentrically positioned relative to a center of the optical fiber, and the second core including an azimuthally nonuniform portion at an eccentric position relative to a center of the optical fiber, the second core twisted about an axis of the optical fiber along a length of the optical fiber, and the twisting of the second core about the axis at least partially converts a light beam incident on the second core at a first end of the optical fiber into a rotating light beam at a second end of the optical fiber, and a cladding surrounding the first and second cores.

[0005] According to some embodiments, the beam generator may include an optical fiber having a second core, the second core being at least one of an eccentric position relative to a center of the optical fiber and including an azimuthally non-uniform portion at an eccentric position relative to a center of the optical fiber, the second core being twisted about an axis of the optical fiber along a length of the optical fiber, and the twisting of the second core about the axis at least partially converts an optical beam incident on the second core at a first end of the optical fiber into a rotated light beam at a second end of the optical fiber, and a cladding surrounding the first and second cores; a coupler that provides an input light beam to at least one of the first core of the optical fiber and the second core of the optical fiber at the first end of the optical fiber; and an output fiber that receives the rotated light beam from the second end of the optical fiber and generates an optical output based on the rotated light beam.

[0006] According to some embodiments, a method may include receiving an input light beam at a first end of an optical fiber, the optical fiber including a first core, a second core, and a cladding surrounding the first core and the second core, the second core being at least one of an eccentric position relative to a center of the optical fiber and the second core including an azimuthally non-uniform portion at an eccentric position relative to a center of the optical fiber, and the second core being twisted about an axis of the optical fiber along a length of the optical fiber; at least partially converting, by the optical fiber, the input light beam received by the second core into a rotated light beam, the input light beam being at least partially converted into the rotated light beam as a result of the twisting about the axis of the second core; and outputting the rotated light beam by the optical fiber. [Brief description of the drawings]

[0007] [Figure 1] Figure 1A is a diagram of an exemplary embodiment of a cross section of an optical fiber described herein. Figure 1B is a diagram of an exemplary embodiment of a beam generator including an exemplary embodiment of an optical fiber having a cross section as shown in Figure 1A described herein. Figure 1C is a diagram of another exemplary embodiment of an optical fiber having a cross section as shown in Figure 1A described herein. [Diagram 2] FIG. 1B is a diagram of an exemplary embodiment of a beam generator including an optical fiber having the cross-section shown in FIG. 1A described herein. [Diagram 3] Figure 3A is a diagram of an exemplary embodiment of a cross section of an optical fiber described herein. Figure 3B is a diagram of an exemplary embodiment of a beam generator including an optical fiber having the cross section shown in Figure 3A described herein. [Figure 4] 4A-4D are diagrams of exemplary embodiments of cross sections of optical fibers described herein. [Diagram 5] 5A-5C are diagrams of an exemplary embodiment of an optical fiber described herein. [Figure 6] 4 is a flow chart of an exemplary process for generating a rotating light beam. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The following detailed description of exemplary embodiments refers to the accompanying drawings, in which the same reference numbers in different drawings indicate the same or similar elements.

[0009] As mentioned above, the beam shapes of conventional fiber-delivered light beams are relatively simple (e.g., having a Gaussian or near-Gaussian profile, a top-hat profile, etc.). The generation of light beams with relatively advanced beam shapes, such as annular beam shapes (i.e., ring-shaped beams), generally requires expensive, dedicated, alignment-sensitive free-space optics, such as axicons, spiral phase plates, etc. Moreover, such optics typically need to be located in a processing head, distal to the fiber associated with the delivery of the light beam. The processing head is an opto-mechanical assembly that is exposed to accelerations and contamination (e.g., from smoke, metal chips, dust, etc.), and is therefore an undesirable location for expensive, alignment-sensitive, bulky, and / or heavy optical elements.

[0010] Furthermore, conventional techniques for generating optical beams having annular beam shapes in all-fiber architectures typically result in optical beams with poor beam quality. For example, conventional techniques may generate optical beams with too high BBP, excessive power in the center of the annulus, divergent beam edges (e.g., having a relatively long radial tail of power that causes poor processing quality), beams that remain annular for only a very short propagation distance before degradation, etc.

[0011] Some embodiments described herein provide an optical fiber that generates a light beam having an annular beam shape directly in the optical fiber (i.e., without free space optics). For example, the generated light beam may be a rotating light beam (e.g., a light beam propagating through the optical fiber along a helical trajectory), thereby generating a light beam having an annular beam shape. In some embodiments, the rotational nature of the light beam can be maintained (e.g., as the light beam exits the optical fiber), such that, for example, a laser spot projected from the optical fiber onto a workpiece exhibits an annular beam profile with sharp edges and high beam quality. In this manner, generating a light beam having an annular beam shape directly in the optical fiber can facilitate improved material processing.

[0012] In some implementations, the optical fiber can include multiple waveguiding regions that generate light beams of various shapes, such as the simplified beam shapes described above, annular beam shapes, etc. For example, an input light beam can be fed into one waveguiding region to generate an output light beam having a first shape, or into another waveguiding region to generate another output light beam having a second shape. In some implementations, the optical fiber can include multiple waveguiding regions that generate rotating light beams, where each rotating light beam has a different annular beam shape. In this way, the optical fiber can generate output light beams with different shapes for different applications (e.g., processing different materials, processing materials of different thicknesses, etc.).

[0013] FIGURE 1A is a diagram of an exemplary embodiment of a cross section 100 of an optical fiber described herein. As shown in FIGURE 1A, an optical fiber (also referred to herein as a rotator fiber) that generates a rotating light beam can include a first core and a second core, where the second core is eccentrically positioned relative to a center of the optical fiber. As shown in FIGURE 1A, the first core can be located at the center of the optical fiber (e.g., as shown by the intersection of the dashed lines), and the second core can be located eccentrically relative to the center of the optical fiber. As also shown in FIGURE 1A, the optical fiber can include a cladding surrounding the first core and the second core.

[0014] In some embodiments, the first and second cores may have the same refractive index, as shown by shading in FIG. 1A. In other embodiments, the first and second cores may have different refractive indices. Additionally or alternatively, the first and / or second cores may have a refractive index greater than the refractive index of the cladding. In this manner, the first core may form a first waveguiding region that propagates light along the length of the optical fiber, and the second core may form a second waveguiding region that propagates light along the length of the optical fiber.

[0015] FIG. 1B is a diagram of an exemplary embodiment of a beam generator 102 including an exemplary embodiment of an optical fiber (e.g., a rotating fiber) having a cross-section 100 as shown in FIG. 1A. As shown in FIG. 1B, the second core may be twisted about the axis of the rotating fiber (e.g., the center of the rotating fiber) along the length of the rotating fiber. In some embodiments, the first core may also be twisted about the axis of the rotating fiber, although such twisting of the first core may not be visible because the first core is positioned at the center of the rotating fiber in FIGS. 1A-1C. Thus, the refractive index profile (defined by the refractive indices of the first core, the second core, and the cladding) of the rotating fiber may rotate (e.g., with a period) along the length of the rotating fiber, with a transverse center of rotation identified at the center of the cladding, as shown in FIG. 1A by the dashed intersection point. In some embodiments, the twisting of the second core about its axis may at least partially convert an input light beam (e.g., a non-rotating light beam) incident on an input end of the rotating fiber into a rotated light beam at an output end of the rotating fiber, as will be described in more detail below.

[0016] 1B, in some embodiments, the rotating fiber can be disposed between the coupler and the output fiber. In some embodiments, the rotating fiber and the output fiber can be fusion spliced ​​(e.g., using fiber fusion splicing techniques).

[0017] As shown in FIG. 1B, the beam generator 102 may include a coupler that provides an input light beam to the rotating fiber. In some implementations, the coupler may be an active device that can receive the input light beam and direct the input light beam and / or portions of the input light beam to one or more cores and / or waveguiding regions. For example, the coupler may mechanically move the input light beam in free space to selectively couple it to different waveguiding regions by moving lenses, tilting mirrors, etc. Additionally or alternatively, the coupler may use mechanical and / or opto-mechanical beam steering in the optical fiber, such as bending a graded index optical fiber, bending an optical fiber carrying a laterally expanded beam, bending and / or twisting an optical fiber carrying one or more defined polarization modes, etc. In some embodiments, the coupler may use non-mechanical beam steering, such as an acousto-optic modulator, an electro-optic modulator, a polarization-based modulator, and / or a thermal modulator, inserted in free space and / or monolithically between the input fiber and the rotating fiber (e.g., using bonding, splicing, etc.).

[0018] Additionally or alternatively, the coupler may be a passive device capable of receiving multiple input light beams and coupling each of the input light beams into one of the waveguiding regions of the rotating fiber. Such multiple input beams may be generated, for example, by multiple lasers, each of which may be independently controlled to generate a desired power level at each of the waveguiding regions of the rotating fiber.

[0019] In some implementations, the coupler may provide an input light beam (e.g., an optical input) at a first end of the rotating fiber to a first core of the rotating fiber and / or a second core of the rotating fiber. For example, the coupler may receive an input light beam from an input fiber and / or a laser and provide the input light beam to the first end of the rotating fiber. In some implementations, the input light beam may include light propagating in one or more non-rotating waveguide modes.

[0020] In some embodiments, when the coupler provides an input light beam to the first core of the rotating fiber, the input light beam can pass through the first core of the rotating fiber, and the rotating fiber can generate an output light beam that is not a rotated light beam. For example, because the refractive index profile of the first core is rotationally uniform about the axis of rotation, the output light beam can have the same or similar properties as the input light beam (e.g., light propagating in one or more non-rotating guided modes). In some embodiments, the output light beam generated by the first core is not a rotated light beam, but the input light beam can experience circular birefringence during passage through the first core.

[0021] In some implementations, when the coupler provides an input light beam to the second core of the rotating fiber, as the light propagates through the rotating fiber, the rotating fiber generates a rotated light beam from the input light beam due to twisting of the second core along the length of the rotating fiber. In other words, the rotating fiber can at least partially convert the input light beam into a rotated light beam by the second core (e.g., by at least partially converting one or more non-rotating guided modes into at least one rotating guided mode). Thus, the output light beam can include light propagating in at least one rotating guided mode and / or at least one rotating leaky wave. In some implementations, the rotated light beam can have an annular beam shape due to the light propagating in at least one rotating guided mode and / or at least one rotating leaky wave. The rotated light beam can be output via an output fiber (e.g., for material processing such as metal cutting).

[0022] In some embodiments, the coupler and / or beam generator 102 may be controlled to provide the input light beam to a first core or a second core of the rotating fiber. For example, in an application using a non-rotating light beam, the coupler and / or beam generator 102 may be controlled to provide the input light beam to a first core such that the rotating fiber generates an output light beam that is not a rotating light beam. As another example, in an application using a rotating light beam, the coupler and / or beam generator 102 may be controlled to provide the input light beam to a second core such that the rotating fiber generates an output light beam that is a rotating light beam.

[0023] In this manner, the beam generator 102, including the coupler and the rotating fiber, can be controlled to provide one of a number of types of output light beams based on the intended use of the output light beam. In other words, the beam generator 102 can excite (e.g., on demand) different rotated light beams out of a single rotating fiber by directing (e.g., with a coupler) light into different waveguiding regions (e.g., first core, second core, etc.). In some implementations, the rotating fiber can also be referred to as a multi-rotary fiber because it includes at least two waveguiding regions that are subject to different rotation magnitudes and can generate output light beams of different sizes, birefringence, and rotational orientations at the output end of the rotating fiber when excited and / or illuminated by an input light beam.

[0024] As shown in Figure IB, the output fiber can receive the output light beam from the rotating fiber. In some embodiments, the output fiber can include a first waveguide region that receives the light beam from a first core of the optical fiber and a second waveguide region that receives the rotated light beam from a second core of the optical fiber, as further described herein with respect to Figures 5A-5C.

[0025] Figure 1C is a diagram of another exemplary embodiment 104 of an optical fiber (e.g., a rotating fiber) having the cross-section shown in Figure 1A. As shown in Figure 1C, in some embodiments, the rotating fiber can be tapered such that the size of the rotating fiber at a first end of the rotating fiber (e.g., an input end, an end adjacent to a coupler, etc.) is smaller than the size of the rotating fiber at a second end of the rotating fiber (e.g., an output end, an end spliced ​​to an output fiber, etc.).

[0026] As also shown in Figure 1C, the twist rate about the optical axis of the second core can increase from a first twist rate (e.g., a zero or near-zero twist rate) toward a first end of the rotatable fiber to a second twist rate toward a second end of the rotatable fiber. Such a rotatable fiber can generate a rotated light beam having a uniform shape, power distribution, etc. Although the rotatable fiber is shown in Figure 1C as straight, the rotatable fiber can have any shape.

[0027] Additionally or alternatively, although the rotating fiber is shown in Figure 1C as tapered, the rotating fiber may have a gradually increasing twist rate (as shown) and the diameter of the rotating fiber may remain constant from the first end to the second end. Such a rotating fiber may generate a rotating light beam having a uniform shape, power distribution, etc., without increasing the size of the output light beam compared to the size of the input light beam.

[0028] As mentioned above, Figures 1A-1C are merely exemplary. Other examples are contemplated and may differ from those described with respect to Figures 1A-1C. For example, while the cross sections of the first and second cores in Figure 1A have the same shape and size in some embodiments, the first core can have a first cross section and the second core can have a second cross section, where the first and second cross sections have different shapes and / or sizes. For example, the first core can have a circular cross section and the second core can have a rectangular cross section. As another example, the first and second cores can have circular cross sections with different radii. Additionally or alternatively, the first and second cores can have cross sections that include other elements and / or portions as further detailed with respect to Figures 3A and 4A-4D.

[0029] Figure 2 is a diagram of an exemplary embodiment of a beam generator 200 including an optical fiber (e.g., a rotating fiber) having the cross-section shown in Figure 1A. As shown in Figure 2, the beam generator 200 may include a coupler, a rotating fiber, and an output fiber. In some embodiments, the coupler may receive an input light beam and provide the input light beam to a first core or a second core of the rotating fiber.

[0030] In some embodiments, the rotating fiber can be a tapered rotating fiber (e.g., similar to the rotating fiber described herein with respect to FIG. 1C), as shown in FIG 2. Additionally or alternatively, the rotating fiber can be a non-tapered rotating fiber (e.g., similar to the rotating fiber described herein with respect to FIG. 1B).

[0031] In some embodiments, light from an input light beam can propagate through the rotating fiber, and the rotating fiber can provide the light to an output fiber. As described herein with respect to Figure 1C, and further described herein with respect to Figures 5A-5C, the output fiber can include a first waveguiding region that receives the light beam from a first core of the optical fiber and a second waveguiding region that receives the rotated light beam from a second core of the optical fiber.

[0032] As shown in Figure 2, the beam generator 200 may generate two types of output light beams. For example, if the coupler feeds the input light beam into a first core of the rotating fiber, as shown in the upper output light beam of Figure 2, the beam generator 200 may generate an output light beam with similar characteristics to the input light beam. If the coupler feeds the input light beam into a second core of the rotating fiber, as shown in the lower output light beam of Figure 2, the beam generator 200 may generate a circular and / or rotating light beam.

[0033] As also shown in FIG. 2, the output light beams may each have a larger diameter than the input light beam. In some implementations, at least a portion of the increase in diameter of the light beam (e.g., from the input light beam to the output light beam) may be due to an increase in the cross-sectional size of the first and / or second core along a portion of the length of the rotating fiber. For example, as shown in FIG. 2, the cross-sectional size of the rotating fiber at a first end of the rotating fiber (e.g., the input end, the end adjacent to the coupler, etc.) may be smaller than the cross-sectional size of the rotating fiber at a second end of the rotating fiber (e.g., the output end, the end spliced ​​to the output fiber, etc.). Similarly, as also shown in FIG. 2, the cross-sectional size of the first and / or second core at a first end of the rotating fiber (e.g., the input end, the end adjacent to the coupler, etc.) may be smaller than the cross-sectional size of the first and / or second core at a second end of the rotating fiber (e.g., the output end, the end spliced ​​to the output fiber, etc.).

[0034] In some implementations, when the coupler provides an input light beam to a first core of the rotatable fiber, the beam generator 200 may generate an output light beam having the same size as the input light beam. For example, the cross-sectional size of the first core at the first end of the rotatable fiber may be the same as the cross-sectional size of the first core at the second end of the rotatable fiber.

[0035] As noted above, Figure 2 is merely an example, and other examples are contemplated and may differ from those described with respect to Figure 2.

[0036] 3A is a diagram of an exemplary embodiment 300 of a cross section of an optical fiber (e.g., a rotating fiber). As shown in FIG. 3A, the rotating fiber includes a first core, a second core, and a cladding. As also shown in FIG. 3A, the first core can be inserted into the second core such that the second core can surround the first core, and the cladding can surround the second core. In some implementations, as shown in FIG. 3A, the first core can be positioned at the center of the rotating fiber.

[0037] In some embodiments, the second core can be positioned at an eccentric location relative to the center of the rotating fiber. For example, as shown in FIG. 3A, the geometric center of the second core can be positioned at an eccentric location relative to the center of the rotating fiber.

[0038] As shown by the shading in Figure 3A, the first core and the second core may have different refractive indices. In some embodiments, the difference in refractive index between the first core and the second core may be large enough to prevent light propagating through the first core from entering the second core and / or prevent light propagating through the second core from entering the first core. In this manner, the first core and the second core may provide two separate light propagation paths through the rotating fiber.

[0039] In some embodiments, the second core may be twisted about the axis of the rotating fiber (e.g., the center of the rotating fiber) along the length of the rotating fiber as described herein with respect to FIG. 1B such that an input light beam (e.g., a non-rotating light beam) incident on an input end of the rotating fiber may be at least partially converted to a rotated light beam at an output end of the rotating fiber. In some embodiments, the first core may also be twisted about the axis of the rotating fiber, although such twisting of the first core may not be visible because the first core is positioned at the center of the rotating fiber. Additionally or alternatively, the rotating fiber may be tapered as described herein with respect to FIG. 1C.

[0040] 3B is a diagram of an exemplary embodiment of a beam generator 302 including an optical fiber (e.g., a rotating fiber) having the cross-section shown in FIG. 3A. As shown in FIG. 3B, the beam generator 302 can include a coupler, a rotating fiber, and an output fiber. In some implementations, the coupler and output fiber can be similar to the coupler and output fiber described herein with respect to FIG.

[0041] As shown in FIG. 3B, the beam generator 302 may generate two types of output light beams. For example, as shown in the upper output light beam of FIG. 3B, if the coupler feeds the input light beam into a first core of the rotating fiber, the beam generator 302 may generate an output light beam having similar characteristics to the input light beam. As shown in the lower output light beam of FIG. 3B, if the coupler feeds the input light beam into a second core of the rotating fiber, the beam generator 302 may generate an output light beam having a larger size compared to the input light beam. As also shown in the lower output light beam of FIG. 3B, a portion of the input light beam may be converted by the rotating fiber into a rotating light beam. For example, the lower output light beam may have similar characteristics to a light beam having a Gaussian profile as well as a light beam having a top hat profile. Such characteristics may be obtained from a rotating fiber having a uniform diameter along the length of the rotating fiber as shown in FIG. 3B and a constant twist rate (e.g., pitch) along the length of the rotating fiber (as shown in the rotating fiber of FIG. 1B).

[0042] As noted above, Figures 3A and 3B are merely examples, and other examples are contemplated and may differ from those described with respect to Figures 3A and 3B.

[0043] 4A-4D are diagrams of exemplary embodiments of cross sections 402, 404, 406, 408 of optical fibers (eg, rotating fibers).

[0044] As shown in FIG. 4A, the cross section 402 of the rotating fiber may include a central core located at the center of the rotating fiber and three or more cores located at eccentric positions relative to the center of the rotating fiber. In some implementations, three cores may be located at eccentric positions relative to the center of the rotating fiber, where each eccentric position has a different radial distance to the center of the optical fiber. For example, as shown in FIG. 4A, a first core, a second core, and a third core may be located at eccentric positions relative to the center of the rotating fiber, where the eccentric positions of the first core, the second core, and the third core have radial distances R1, R2, and R3, respectively, to the center of the optical fiber.

[0045] In some embodiments, the central core can be similar to the first core described with respect to Figure 1 A, while the three cores positioned at the eccentric positions can be similar to the second core described with respect to Figure 1 A. For example, the central core can be untwisted about the axis of the rotating fiber (e.g., the center of the rotating fiber) along the length of the rotating fiber, and the three cores positioned at the eccentric positions can be twisted about the axis of the rotating fiber along the length of the rotating fiber.

[0046] Additionally or alternatively, when an input light beam is fed into the central core, the rotating fiber may generate an output light beam similar to the input light beam. When an input light beam is fed into one of the three cores positioned at eccentric positions, the rotating fiber may generate an output light beam that is a rotating light beam. Furthermore, each of the three cores may generate a rotating light beam with different characteristics (e.g., different diameters, different powers, etc.) (e.g., due to different radial distances R1, R2, and R3 to the center of the optical fiber).

[0047] As shown in FIG. 4B, the cross section 404 of the rotating fiber can include a first core, a second core, a groove region, and a cladding. In some implementations, as shown in FIG. 4B, the first core can be inserted within the second core, and a groove region (e.g., a cladding low index groove region, etc.) can be positioned between the first and second cores. The first core can be positioned at the center of the rotating fiber, and the second core can be off-center relative to the center of the rotating fiber (e.g., the geometric center of the second core can be off-center relative to the center of the rotating fiber). The cladding can surround the first core, the second core, and the groove region, as also shown in FIG. 4B.

[0048] In some embodiments, the first core may be similar to the first core described with respect to Figures 1A and / or 3A, and the second core may be similar to the second core described with respect to Figure 3A. As shown by the shading in Figure 4B, the first and second cores may have the same refractive index. In some embodiments, a groove region between the first and second cores may prevent light propagating through the first core from entering the second core and / or prevent light propagating through the second core from entering the first core. In this manner, the first and second cores may provide two separate light propagation paths through the rotating fiber.

[0049] Additionally or alternatively, when an input light beam is provided to the first core, the rotating fiber may generate an output light beam similar to the input light beam, and when an input light beam is provided to the second core, the rotating fiber may generate an output light beam that is the rotating light beam.

[0050] As shown in FIG. 4C, the cross section 406 of the rotating fiber can include a first core, a second core, a groove region, a first insert (e.g., a first insert element), a second insert (e.g., a second insert element), and a cladding. In some embodiments, the first core can be inserted into the second core, and a groove region (e.g., a cladding low index region, etc.) can be positioned between the first and second cores, as shown in FIG. 4C. The first core can be positioned at the center of the rotating fiber, and the second core can also be positioned at the center of the rotating fiber (e.g., the geometric center of the second core can be positioned at the center of the rotating fiber). Thus, in some embodiments, the first and second cores can be concentric. The cladding can surround the first core, the second core, the groove region, the first insert, and the second insert, as also shown in FIG. 4C.

[0051] In some embodiments, the first core may be similar to the first core described with respect to FIG. 1A. As shown by shading in FIG. 4C, the first and second cores may have the same refractive index. In some embodiments, a groove region between the first and second cores may prevent light propagating through the first core from entering the second core and / or prevent light propagating through the second core from entering the first core. In this manner, the first and second cores may provide two separate light propagation paths through the rotating fiber.

[0052] As shown in FIG. 4C, a first insert (e.g., a first rod-shaped insert) and a second insert (e.g., a second rod-shaped insert) can be positioned within the second core. As shown by the shading in FIG. 4C, the first insert and the second insert can have a different refractive index than the refractive index of the second core. For example, the first insert and the second insert can have a lower refractive index than the refractive index of the second core. In some embodiments, the first insert and / or the second insert can be formed from doped silica, undoped silica, etc.

[0053] As shown in FIG. 4C, the first insert and / or the second insert can have a circular cross-sectional shape. In some embodiments, the first insert and / or the second insert can have a cross-sectional shape other than circular (e.g., rectangular, triangular, star, hexagonal, octagonal, etc.). Additionally or alternatively, the first insert and / or the second insert may not have the same shape as one another. In some embodiments, the rotating fiber may include one insert or more than two inserts (e.g., three inserts, four inserts, five inserts, etc.) to perform the same function.

[0054] In some embodiments, the first and second inserts can make a portion of the second core azimuthally non-uniform, and the azimuthally non-uniform portion can be eccentric relative to the center of the rotating fiber. In some embodiments, twisting the cross section 406 shown in FIG. 4C along the length of the rotating fiber can convert the light beam in the second core into a rotated light beam. That is, the azimuthally non-uniform eccentric portion can twist about an axis to at least partially convert an input light beam incident on a first end of the rotating fiber into a rotated light beam at a second end of the rotating fiber. In some embodiments, the twist rate of the azimuthally non-uniform eccentric portion about the axis of the rotating fiber can increase from a first twist rate at the first end of the rotating fiber to a second twist rate at the second end of the rotating fiber, similar to that described with respect to FIG. 1C.

[0055] Additionally or alternatively, when an input light beam is provided to the first core, the rotating fiber may generate an output light beam similar to the input light beam, and when an input light beam is provided to the second core, the rotating fiber may generate an output light beam that is the rotating light beam.

[0056] As shown in FIG. 4D, the cross section 408 of the rotating fiber can include a first core, a second core, a groove region, an insert (e.g., an insert element), and a cladding. In some embodiments, as shown in FIG. 4D, the first core can be inserted into the second core, and a groove region (e.g., a cladding low index groove region, etc.) can be positioned between the first core and the second core and between the first core and the insert. The first core can be positioned at the center of the rotating fiber, and the second core can also be positioned at the center of the rotating fiber (e.g., the geometric center of the second core can be positioned at the center of the rotating fiber). As shown in FIG. 4D, the cladding can surround the first core, the second core, the groove region, and the insert.

[0057] In some embodiments, the first core can be similar to the first core described with respect to Figure 1 A. For example, the first core can form a first waveguiding region for light propagating through the rotating fiber.

[0058] As shown in Figure 4D, an insert may be inserted into the second core and cladding. The insert may have the same refractive index as the second core, as shown by the shading in Figure 4D. In this manner, the second core and the insert may form a second waveguiding region in the rotating fiber.

[0059] As shown by the shading in Figure 4D, the first core, the second core, and the insert may have the same refractive index. In some embodiments, a groove region between the first waveguiding region (e.g., formed by the core) and the second waveguiding region (e.g., formed by the second core and the insert) may prevent light propagating in the first waveguiding region from entering the second waveguiding region and / or prevent light propagating in the second waveguiding region from entering the first waveguiding region. In this manner, the first and second waveguiding regions may provide two separate light propagation paths through the rotating fiber.

[0060] In some embodiments, the insert can make a portion of the second waveguiding region azimuthally non-uniform, and the azimuthally non-uniform portion can be off-center relative to the center of the rotating fiber. In some embodiments, twisting the cross section 408 shown in Figure 4D along the length of the rotating fiber can convert the light beam in the second waveguiding region into a rotated light beam in a similar manner as described with respect to Figure 4C.

[0061] Additionally or alternatively, the insert may be part of the second core, for example the second core may include an azimuthally non-uniform portion formed by an insert at an eccentric location relative to the center of the rotating fiber and another portion, such as a ring-shaped portion as shown in FIG.

[0062] In some embodiments, when an input light beam is provided to a first waveguiding region (e.g., formed by a core), the rotating fiber can generate an output light beam similar to the input light beam, and when the input light beam is provided to a second waveguiding region (e.g., formed by a second core and an insert), the rotating fiber can generate an output light beam that is the rotated light beam.

[0063] As noted above, Figures 4A-4D are merely exemplary. Other examples are contemplated and may differ from those described with respect to Figures 4A-4D. For example, while the cross sections of Figures 4A-4D include elements and / or portions having circular and / or ring shapes, other exemplary embodiments may include elements and / or portions having different and / or non-circular shapes, such as rectangular, triangular, star-shaped, partial ring-shaped, etc. As another example, other exemplary embodiments may include fewer elements and / or portions than the cross sections of Figures 4A-4D, or more elements and / or portions than the cross sections of Figures 4A-4D.

[0064] 5A-5C are diagrams of exemplary embodiments of output fibers 502, 504, and 506. For example, the output fibers shown in and described with respect to Figures 1B, 2, and 3B may include output fibers 502, 504, and / or 506. In some embodiments, output fibers 502, 504, and 506 may be non-rotating fibers and may include multiple waveguiding regions that maintain different output light beams generated by multiple rotating fibers.

[0065] As shown in FIG. 5A, the output fiber 502 may be a step-index ring fiber and may include a central core, an inner cladding, a ring core, and an outer cladding. The inner cladding may surround the central core, and the ring core may surround the inner cladding. The outer cladding may surround the ring core. As shown in FIG. 5A, the central core, the inner cladding, the ring core, and the outer cladding may have refractive indices n1, n2, n3, and n4, respectively, where n1 is greater than n2 and n3 is greater than n2 and n4. In some embodiments, n2 may be greater than n4. Additionally or alternatively, n1 may be equal to n3. In some embodiments, the output fiber 502 may include additional ring cores and / or additional cladding layers (e.g., inner cladding).

[0066] In some implementations, the radial thickness of the central core, inner cladding, ring core, and / or outer cladding may correspond to the location of the core and / or waveguiding region of the rotating fiber that provides light to the output fiber 502. For example, if the beam generator includes a rotating fiber having a cross section 100 as shown in and described with respect to FIG. 1A and an output fiber 502, the central core of the output fiber 502 may have a radial thickness corresponding to the radial thickness of the first core, and the ring core of the output fiber 502 may have a radial thickness corresponding to the radial thickness of the second core. Additionally or alternatively, the radial thickness of the inner cladding of the output fiber 502 may correspond to the radial distance of the edges of the first and second cores. In this manner, light propagating through the first and second cores of the rotating fiber may enter and propagate through the central core and ring core, respectively, of the output fiber 502. Additionally or alternatively, the inner cladding may prevent light propagating through the central core from entering the ring core and may prevent light propagating through the ring core from entering the central core. Thus, in some embodiments, the output fiber 502 may include a first waveguide region that receives a light beam from a first waveguide region and / or a first core of the rotating fiber, and a second waveguide region that receives another light beam (e.g., a rotating light beam) from a second waveguide region and / or a second core of the rotating fiber.

[0067] In some implementations, the output fiber 502 may receive an azimuthally asymmetric (e.g., rotationally asymmetric) input light beam (e.g., a rotating light beam) from a rotating fiber. The output fiber 502 may form an azimuthally symmetric (e.g., rotationally symmetric) output light beam (e.g., by incoherent averaging of modes) by propagating the input light beam along the length of the output fiber 502.

[0068] As shown in FIG. 5B, the output fiber 504 may be a pedestal fiber and may include a central core, a pedestal, and an outer cladding. The pedestal may surround the central core, and the outer cladding may surround the pedestal. As shown in FIG. 5B, the central core, the pedestal, and the outer cladding may have refractive indices n1, n2, and n3, respectively, where n1 is greater than n2 and n2 is greater than n3. In some implementations, the output fiber 504 may include an additional pedestal layer between the pedestal and the outer cladding, in which case the refractive index decreases monotonically from the central core to the outer cladding.

[0069] In some embodiments, the radial thickness of the central core, pedestal, and / or outer cladding may correspond to the location of the core and / or waveguiding region of the rotating fiber that provides light to the output fiber 504, as described herein with respect to FIG. 5A and output fiber 502. Additionally or alternatively, the output fiber 504 may form an azimuthally symmetric output light beam from an azimuthally asymmetric input light beam, as described herein with respect to FIG. 5A and output fiber 502.

[0070] As shown in FIG. 5C, the output fiber 506 can be a graded-index fiber and can include a graded-index core and an outer cladding, where the outer cladding surrounds the graded-index core. In some embodiments, the graded-index core can have a monotonically decreasing graded-index profile, such as a parabolic or near-parabolic refractive index profile, which can correspond to a pedestal fiber with an infinite number of closely spaced pedestals. Additionally or alternatively, the strength of the graded-index profile can be selected to correspond to a type of output light beam from the rotating optical fiber with respect to radial position and angular momentum. For example, the strength of the graded-index profile can be selected to maintain the size of the beam exiting the first guiding region of the rotating fiber, the second guiding region of the rotating fiber, etc. In some embodiments, the strength of the graded-index profile may be selected to maintain a particular beam size for different input beams based on size and angular momentum (e.g., the graded-index fiber may be mode-matched to the rotating fiber and / or averaged between the mode-matched best cases of the first and second guiding regions). Additionally or alternatively, the output fiber 506 may form an azimuthally symmetric output light beam from an azimuthally asymmetric input light beam in a manner similar to that described herein with respect to FIG. 5A and output fiber 502.

[0071] As noted above, Figures 5A-5C are merely examples. Other examples are contemplated and may differ from those described with respect to Figures 5A-5C. For example, the output fiber may include a combination of one or more elements and / or portions of output fibers 502, 504, and / or 506.

[0072] FIG 6 is a flow chart of an exemplary process 600 for generating a rotating light beam. In some implementations, one or more process blocks of FIG 6 can be performed by an optical fiber (e.g., a rotating fiber having a cross-section as shown in and described with respect to FIG 1A, 3A, 4A, 4B, 4C, and / or 4D, etc.). In some implementations, one or more process blocks of FIG 6 can be performed by another device or devices that are separate from or include an optical fiber, such as a beam generator (e.g., beam generator 102, beam generator 200, beam generator 302, etc.), a coupler (e.g., a coupler as shown in and described with respect to FIG 1B, 2, and / or 3), an output fiber (e.g., an output fiber as shown in and described with respect to FIG 1B, 2, 3B, 5A, 5B, and / or 5C, etc.).

[0073] As shown in FIG. 6, the process 600 may include receiving an input light beam at a first end of an optical fiber, the optical fiber comprising a first core, a second core, and a cladding surrounding the first and second cores, the second core being at least one of an eccentric position relative to a center of the optical fiber and an azimuthally non-uniform portion at an eccentric position relative to a center of the optical fiber, and the second core being twisted about an axis of the optical fiber along the length of the optical fiber (Block 610). For example, as described above, an optical fiber (e.g., a rotating fiber) may receive an input light beam at a first end of the optical fiber. In some embodiments, the optical fiber comprises a first core, a second core, and a cladding surrounding the first and second cores. In some embodiments, the second core is at least one of an eccentric position relative to a center of the optical fiber and an azimuthally non-uniform portion at an eccentric position relative to a center of the optical fiber. In some embodiments, the second core is twisted about an axis of the optical fiber along the length of the optical fiber.

[0074] 6, the process 600 can include at least partially converting the input light beam received by the second core into a rotated light beam, where the input light beam is at least partially converted into a rotated light beam as a result of twisting about the axis of the second core (Block 620). For example, as described above, an optical fiber (e.g., a rotating fiber) can at least partially convert the input light beam received by the second core into a rotated light beam. In some implementations, the input light beam is at least partially converted into a rotated light beam as a result of twisting about the axis of the second core.

[0075] 6, the process 600 may include outputting a rotating light beam (Block 630). For example, as described above, an optical fiber (e.g., a rotating fiber) may output the rotating light beam.

[0076] Process 600 may include additional embodiments, such as any single embodiment or combination of embodiments described below and / or in conjunction with one or more other processes described elsewhere herein.

[0077] In a first embodiment, the process 600 includes providing an input light beam to at least one of the first and second cores at a first end of the optical fiber. For example, as described above, a coupler may provide an input light beam to at least one of the first and second cores at the first end of the optical fiber.

[0078] In a second embodiment, alone or in combination with the first embodiment, the process 600 includes receiving a rotated light beam that is not rotationally symmetric and outputting an azimuthally symmetric optical output based on the rotated light beam. For example, an output fiber may receive a rotated light beam that is not rotationally symmetric and output an azimuthally symmetric optical output based on the rotated light beam.

[0079] Although Figure 6 illustrates example blocks of process 600, in some implementations, process 600 may include additional blocks, fewer blocks than those illustrated in Figure 6, different blocks than those illustrated in Figure 5, or blocks in a different arrangement than those illustrated in Figure 6. Additionally or alternatively, two or more of the blocks of process 600 may be performed in parallel.

[0080] The above disclosure has been illustrated and described, but is not intended to be exhaustive or to limit the embodiments to the precise form disclosed. Modifications and variations can be made in light of the above disclosure or acquired from practice of the embodiments. Moreover, any of the embodiments described herein may be combined, unless the above disclosure clearly indicates why one or more embodiments cannot be combined.

[0081] Although particular combinations of features are claimed and / or disclosed in the specification, these combinations are not intended as limitations of the disclosure of various embodiments. Indeed, many of these features can be combined in ways not specifically claimed and / or disclosed in the specification. Although each dependent claim in the set may depend directly on only one claim, the disclosure of various embodiments includes each dependent claim in combination with every other claim in the set.

[0082] No element, act, or instruction used herein should be construed as critical or essential unless expressly stated as such. Additionally, the indefinite articles "a" and "an" as used herein are intended to include one or more items and can be used interchangeably with "one or more." Additionally, the definite article "the" as used herein is intended to include one or more items referenced in connection with the definite article "the" and can be used interchangeably with "one or more." Additionally, the term "set" as used herein is intended to include one or more items (e.g., related items, unrelated items, combinations of related and unrelated items, etc.) and can be used interchangeably with "one or more." When only one item is intended, the phrase "only one" or similar language is used. Additionally, the terms "has," "have," "having," and the like as used herein are intended to be open-ended terms. Additionally, the phrase "based on" is intended to mean "based at least in part on," unless otherwise indicated. Also, as used herein, the term "or" is intended to be inclusive when used in a list, and can be used interchangeably with "and / or," unless otherwise indicated (e.g., except when used in combination with "any" or "only one of").

Claims

1. An optical fiber, A first core; A second core, the second core is at a first eccentric position relative to a center of the optical fiber; and the second core includes an azimuthally non-uniform portion at a second eccentric location relative to a center of the optical fiber; At least one of the second core is twisted about an axis of the optical fiber along the length of the optical fiber; and a second core, wherein twisting of the second core about the axis at least partially converts a light beam incident on the second core at a first end of the optical fiber into a rotating light beam at a second end of the optical fiber; and a cladding surrounding the first core and the second core; Equipped with An optical fiber, wherein the first core and the second core are distinct cores that provide two separate light propagation paths through the optical fiber.

2. 2. The optical fiber of claim 1, wherein the twist rate of the second core about the axis increases from a first twist rate at the first end of the optical fiber to a second twist rate at the second end of the optical fiber.

3. 10. The optical fiber of claim 1, wherein the first core is located at the center of the optical fiber; and An optical fiber in which a light beam incident on the first core at the first end of the optical fiber is not converted into a rotating light beam at the second end of the optical fiber.

4. 2. The optical fiber according to claim 1, wherein the first core is at a third eccentric position with respect to a center of the optical fiber; the third eccentric position is different from the first eccentric position when the second core is in the first eccentric position, the third eccentric position is different from the second eccentric position when the second core includes a non-uniform portion in the azimuth direction at the second eccentric position, the first core is twisted about the axis of the optical fiber along the length of the optical fiber; and The optical fiber, wherein twisting of the first core about the axis at least partially converts a light beam incident on the first core at the first end of the optical fiber into a rotating light beam at the second end of the optical fiber.

5. 5. The optical fiber according to claim 4, wherein the first eccentric position and the third eccentric position have different radial distances to a center of the optical fiber when the second core is at the first eccentric position; and The optical fiber, wherein the second eccentric position and the third eccentric position have different radial distances to a center of the optical fiber when the second core includes a non-uniform portion in the azimuth angle direction at the second eccentric position.

6. 2. The optical fiber according to claim 1, wherein the first core is inserted within the second core.

7. 10. The optical fiber of claim 1, wherein the first core is inserted within the second core, and a cladding low index trench region is positioned between the first core and the second core.

8. 10. The optical fiber of claim 1, further comprising one or more other cores at other eccentric positions relative to the center of the optical fiber; the one or more other cores are twisted about the axis of the optical fiber along the length of the optical fiber; and The optical fiber, wherein twisting of the one or more other cores about the axis at least partially converts a light beam incident on the one or more other cores at the first end of the optical fiber into a rotating light beam at the second end of the optical fiber.

9. 2. The optical fiber according to claim 1, wherein the first core and the second core have different refractive indices.

10. 10. The optical fiber of claim 1 , wherein the first core has a first cross section, the second core has a second cross section; and the first cross-section and the second cross-section have different shapes; and the first cross-section and the second cross-section have different sizes. At least one of the following:

11. 2. The optical fiber of claim 1, wherein a cross-sectional size of the optical fiber increases along a portion of the length of the optical fiber in a direction from said first end of the optical fiber to said second end of the optical fiber.

12. 2. The optical fiber according to claim 1, wherein the second core is a non-uniform portion in the azimuth direction at the second eccentric position relative to a center of the optical fiber; Another part and Including optical fiber.

13. 13. The optical fiber of claim 12, wherein said azimuthally non-uniform portion is an insert element inserted within said other portion.

14. 14. The optical fiber of claim 13, wherein the insert element is formed from doped or undoped silica.

15. 13. The optical fiber of claim 12, wherein the azimuthally nonuniform portion has a first refractive index; the other portion has a second refractive index; and The optical fiber, wherein the first refractive index is different from the second refractive index.

16. 13. The optical fiber of claim 12, wherein the other portion is a first portion; the second core includes a second azimuthally non-uniform portion; and The second portion of the optical fiber is at a different eccentric position relative to the center of the optical fiber.

17. 13. The optical fiber of claim 12, wherein said azimuthally non-uniform portion is an insert element inserted within said another portion and said cladding.

18. 13. The optical fiber of claim 12, wherein the first core and the second core are concentric.

19. 1. A beam generator comprising: It is an optical fiber, A first core; A second core, the second core is eccentrically positioned with respect to a center of the optical fiber; and the second core includes an azimuthally non-uniform portion at the eccentric position relative to a center of the optical fiber; At least one of the second core is twisted about the axis of the optical fiber along the length of the optical fiber; and a second core, wherein twisting of the second core about the axis at least partially converts a light beam incident on the second core at a first end of the optical fiber into a rotating light beam at a second end of the optical fiber; and a cladding surrounding the first core and the second core; Equipped with an optical fiber, the first core and the second core being distinct cores providing two separate light propagation paths through the optical fiber; a coupler at the first end of the optical fiber that provides an input light beam to at least one of the first core of the optical fiber and the second core of the optical fiber; an output fiber for receiving the rotated light beam from the second end of the optical fiber and generating a light output based on the rotated light beam; A beam generator comprising:

20. 20. The beam generator of claim 19, wherein the output fiber comprises: a first waveguide region that receives the light beam from the first core of the optical fiber; a second waveguide region for receiving the rotated light beam from the second core of the optical fiber; A beam generator comprising:

21. 20. The beam generator of claim 19, wherein the rotating light beam is not rotationally symmetric; and A beam generator in which the optical output generated by the output fiber based on the rotated optical beam is azimuthally symmetric.

22. 20. The beam generator of claim 19, wherein the output fiber comprises: Step index ring fiber, Pedestal fiber, and Graded Index Fiber A beam generator comprising at least one of:

23. 1. A method comprising: receiving an input light beam with an optical fiber at a first end of the optical fiber; the optical fiber includes a first core, a second core, and a cladding surrounding the first core and the second core; at least one of: the second core is at an eccentric position with respect to a center of the optical fiber; and the second core includes an azimuthally non-uniform portion at the eccentric position with respect to the center of the optical fiber; and the second core is twisted about an axis of the optical fiber along a length of the optical fiber; at least partially converting an input light beam received by the second core into a rotated light beam by the optical fiber; the input light beam being at least partially converted into the rotated light beam as a result of twisting of the second core about the axis; outputting the rotated light beam through the optical fiber; Including, The method, wherein the first core and the second core are distinct cores providing two separate light propagation paths through the optical fiber.

24. 24. The method of claim 23, providing the input light beam into at least one of the first core or the second core at a first end of the optical fiber by a coupler; The method further comprising:

25. 24. The method of claim 23, receiving the non-rotationally symmetric rotated light beam with an output fiber; outputting, via the output fiber, an azimuthally symmetric optical output based on the rotated light beam; The method further comprising:

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