# US 10,768,373 B2 · Optical fiber structures and methods for varying laser beam profile > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,768,373 B2 - Document ID: US10768373B2 - Status: Granted - Kind: B2 - Application number: 16/201,333 - Filed: 2018-11-27 - Published: 2019-04-18 - Granted: 2020-09-08 - Earliest claimed: 2016-04-06 - Assignees: Teradiode, Inc. - Applicants: Wang-Long Zhou; Francisco Villarreal-Saucedo; Parviz Tayebati; Bien Chann - Inventors: Wang-Long Zhou; Francisco Villarreal-Saucedo; Parviz Tayebati; Bien Chann - Web page: https://patentgrep.com/patent/US10768373B2 ## CPC - G02B 6/32: having lens focusing means {positioned between opposed fibre ends (with lens being an integral part of the single fibre end G02B6/262)} - G02B 6/02042: {Multicore optical fibres} - G02B 6/03644: {arranged - + -} - G02B 6/34: utilising prism or grating {(G02B6/293 takes precedence)} - G02B 17/00: Systems with reflecting surfaces, with or without refracting elements - H01S 5/005: {Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping (H01S5/026, H01S5/18388 take precedence)} - G02B 6/4214: {the intermediate optical element having redirecting reflective means, e.g. mirrors, prisms for deflecting the radiation from horizontal to down- or upward direction toward a device (G02B6/4246 takes precedence)} - G02B 2006/12104: {Mirror; Reflectors or the like} - G02B 2006/12121: {Laser} - H01S 5/0071: {for beam steering, e.g. using a mirror outside the cavity to change the beam direction} - H01S 5/143: {Littman-Metcalf configuration, e.g. laser - grating - mirror} - H01S 5/4031: {Edge-emitting structures} - H01S 5/405: {Two-dimensional arrays} - H01S 5/4062: {with an external cavity or using internal filters, e.g. Talbot filters} - H01S 5/4087: {emitting more than one wavelength} - H01S 2301/20: Lasers with a special output beam profile or cross-section, e.g. non-Gaussian - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL ## Abstract In various embodiments, the beam parameter product and/or numerical aperture of a laser beam is adjusted utilizing a step-clad optical fiber having a central core, a first cladding, an annular core, and a second cladding. ## Claims ### Claim 1 A step-clad optical fiber for use in a laser system comprising (i) a beam source for emission of an input laser beam and (ii) a controller for adjusting a position, at an input end of the step-clad optical fiber, of the input laser beam relative to a longitudinal axis of the step-clad optical fiber, whereby a resulting output beam is emitted from an output end of the step-clad optical fiber opposite the input end, the step-clad optical fiber comprising: a central core having a first refractive index; surrounding the central core, a first cladding having a second refractive index smaller than the first refractive index; surrounding the first cladding, a first annular core having a third refractive index larger than the second refractive index; surrounding the first annular core, a second cladding having a fourth refractive index smaller than the third refractive index; surrounding the second cladding, a second annular core having a fifth refractive index larger than the fourth refractive index; and surrounding the second annular core, a third cladding having a sixth refractive index smaller than the fifth refractive index, wherein (i) the third refractive index is larger than the first refractive index, and/or (ii) the fifth refractive index is larger than the first refractive index, and wherein the second annular core is configured for the in-coupling and transmission of at least a portion of the input laser beam, whereby light from the input laser beam coupled into the second annular core is emitted as at least a portion of the output beam. ### Claim 2 (depends on 1) The step-clad optical fiber of claim 1, wherein the third refractive index is substantially equal to the first refractive index. ### Claim 3 (depends on 1) The step-clad optical fiber of claim 1, wherein the second refractive index is larger than the fourth refractive index. ### Claim 4 (depends on 1) The step-clad optical fiber of claim 1, wherein the second refractive index is larger than the sixth refractive index. ### Claim 5 (depends on 1) The step-clad optical fiber of claim 1, wherein a numerical aperture of the first cladding is larger than 0.12. ### Claim 6 (depends on 1) The step-clad optical fiber of claim 1, wherein a thickness of the first cladding ranges from approximately 40 μm to approximately 100 μm. ### Claim 7 (depends on 1) The step-clad optical fiber of claim 1, wherein a thickness of the first annular core ranges from approximately 60 μm to approximately 150 μm. ### Claim 8 (depends on 1) The step-clad optical fiber of claim 1, wherein a ratio of a diameter of the first cladding to a diameter of the central core ranges between 1.2 and 3. ### Claim 9 (depends on 1) The step-clad optical fiber of claim 1, wherein a ratio of a diameter of the first annular core to a diameter of the central core ranges between 1.5 and 6.5. ### Claim 10 (depends on 1) The step-clad optical fiber of claim 1, further comprising: surrounding the third cladding, a third annular core having a seventh refractive index larger than the sixth refractive index; and surrounding the third annular core, a fourth cladding having an eighth refractive index smaller than the seventh refractive index, wherein the third annular core is configured for the in-coupling and transmission of at least a portion of the input laser beam, whereby light from the input laser beam coupled into the third annular core is emitted as at least a portion of the output beam. ### Claim 11 A laser system comprising: a beam source for emission of an input laser beam; a step-clad optical fiber having an input end and an output end opposite the input end, the step-clad optical fiber comprising (i) a central core having a first refractive index, (ii) surrounding the central core, a first cladding having a second refractive index smaller than the first refractive index, (iii) surrounding the first cladding, a first annular core having a third refractive index larger than the second refractive index, (iv) surrounding the first annular core, a second cladding having a fourth refractive index smaller than the third refractive index, (v) surrounding the second cladding, a second annular core having a fifth refractive index larger than the fourth refractive index, and (vi) surrounding the second annular core, a third cladding having a sixth refractive index smaller than the fifth refractive index; and a controller for (i) receiving a desired beam-quality parameter based on one or more properties of a workpiece to be processed, (ii) adjusting a position, at the input end of the step-clad optical fiber, of the input laser beam relative to a longitudinal axis of the step-clad optical fiber, whereby a resulting output beam having the desired beam-quality parameter is emitted from the output end of the step-clad optical fiber, and (iii) processing the workpiece with the output beam. ### Claim 12 (depends on 11) The laser system of claim 11, further comprising, responsive to the controller, an in-coupling mechanism for receiving the input laser beam and directing the input laser beam toward the input end of the step-clad optical fiber. ### Claim 13 (depends on 12) The laser system of claim 12, wherein the in-coupling mechanism comprises an optical element that is adjustable, in response to the controller, along at least one of (i) an axis substantially parallel to a propagation direction of the input laser beam or (ii) one or more axes substantially perpendicular to the propagation direction of the input laser beam. ### Claim 14 (depends on 13) The laser system of claim 13, wherein the optical element comprises one or more lenses, one or more mirrors, one or more prisms, and/or one or more gratings. ### Claim 15 (depends on 11) The laser system of claim 11, wherein the controller is configured to adjust the position of the input laser beam relative to the longitudinal axis of the step-clad optical fiber without modulating an output power of the input laser beam. ### Claim 16 A laser system comprising: a beam source for emission of an input laser beam; a step-clad optical fiber having an input end and an output end opposite the input end, the step-clad optical fiber comprising (i) a central core having a first refractive index, (ii) surrounding the central core, a first cladding having a second refractive index smaller than the first refractive index, (iii) surrounding the first cladding, a first annular core having a third refractive index larger than the second refractive index, (iv) surrounding the first annular core, a second cladding having a fourth refractive index smaller than the third refractive index, (v) surrounding the second cladding, a second annular core having a fifth refractive index larger than the fourth refractive index, and (vi) surrounding the second annular core, a third cladding having a sixth refractive index smaller than the fifth refractive index; and a controller for adjusting a position, at the input end of the step-clad optical fiber, of the input laser beam relative to a longitudinal axis of the step-clad optical fiber, whereby a resulting output beam is emitted from the output end of the step-clad optical fiber, wherein the beam source comprises: one or more beam emitters emitting a plurality of discrete beams; focusing optics for focusing the plurality of beams onto a dispersive element; the dispersive element for receiving and dispersing the received focused beams; and a partially reflective output coupler positioned to receive the dispersed beams, transmit a portion of the dispersed beams therethrough as the input laser beam, and reflect a second portion of the dispersed beams back to the dispersive element and thence to the one or more beam emitters to form an external lasing cavity, wherein the input laser beam is composed of multiple wavelengths. ### Claim 17 (depends on 16) The laser system of claim 16, wherein the dispersive element comprises a diffraction grating. ### Claim 18 (depends on 11) The laser system of claim 11, wherein the step-clad optical fiber comprises: surrounding the third cladding, a third annular core having a seventh refractive index larger than the sixth refractive index; and surrounding the third annular core, a fourth cladding having an eighth refractive index smaller than the seventh refractive index. ### Claim 19 A method of processing a workpiece with a laser beam, the method comprising: providing a step-clad optical fiber having an input end and an output end opposite the input end, the step-clad optical fiber comprising (i) a central core having a first refractive index, (ii) surrounding the central core, a first cladding having a second refractive index smaller than the first refractive index, (iii) surrounding the first cladding, a first annular core having a third refractive index larger than the second refractive index, (iv) surrounding the first annular core, a second cladding having a fourth refractive index smaller than the third refractive index, (v) surrounding the second cladding, a second annular core having a fifth refractive index larger than the fourth refractive index, and (vi) surrounding the second annular core, a third cladding having a sixth refractive index smaller than the fifth refractive index; selecting one or more in-coupling locations on the input end of the step-clad optical fiber based on at least one of a desired beam parameter product or a desired numerical aperture of an output beam; directing an input laser beam onto the one or more in-coupling locations on the input end of the step-clad optical fiber, whereby (i) the input laser beam is in-coupled into the step-clad optical fiber and emitted from the output end of the step-clad optical fiber as the output beam, and (ii) at least one of the beam parameter product or the numerical aperture of the output beam is determined at least in part by the one or more in-coupling locations; and processing a workpiece with the output beam having the at least one of the desired beam parameter product or the desired numerical aperture. ### Claim 20 A method of processing a workpiece with a laser beam, the method comprising: providing a step-clad optical fiber having an input end and an output end opposite the input end, the step-clad optical fiber comprising (i) a central core having a first refractive index, (ii) surrounding the central core, a first cladding having a second refractive index smaller than the first refractive index, (iii) surrounding the first cladding, a first annular core having a third refractive index larger than the second refractive index, (iv) surrounding the first annular core, a second cladding having a fourth refractive index smaller than the third refractive index, (v) surrounding the second cladding, a second annular core having a fifth refractive index larger than the fourth refractive index, and (vi) surrounding the second annular core, a third cladding having a sixth refractive index smaller than the fifth refractive index; directing an input laser beam onto one or more first in-coupling locations on the input end of the step-clad optical fiber, at least one first in-coupling locations being disposed on the central core; directing the input laser beam onto one or more second in-coupling locations on the input end of the step-clad optical fiber different from the one or more first in-coupling locations, at least one second in-coupling location being disposed outside of the central core, whereby at least one of a beam parameter product or a numerical aperture of the output beam is altered when the input laser beam is directed from the one or more first in-coupling locations to the one or more second in-coupling locations; and processing a workpiece with the output beam having the altered beam parameter product and/or the altered numerical aperture. ### Claim 21 (depends on 11) The laser system of claim 11, wherein the one or more properties of the workpiece comprise at least one of a composition of the workpiece, a thickness of the workpiece, a topography of the workpiece, or a distance to the workpiece. ### Claim 22 (depends on 11) The laser system of claim 11, wherein processing the workpiece comprises at least one of annealing, cutting, welding, or drilling. ### Claim 23 (depends on 19) The method of claim 19, wherein processing the workpiece comprises at least one of annealing, cutting, welding, or drilling. ### Claim 24 (depends on 20) The method of claim 20, wherein processing the workpiece comprises at least one of annealing, cutting, welding, or drilling. ### Claim 25 (depends on 1) The step-clad optical fiber of claim 1, wherein the first annular core is configured for the in-coupling and transmission of at least a portion of the input laser beam, whereby light from the input laser beam coupled into the first annular core is emitted as at least a portion of the output beam. ### Claim 26 (depends on 1) The step-clad optical fiber of claim 1, wherein the first cladding is configured for the in-coupling and transmission of at least a portion of the input laser beam, whereby light from the input laser beam coupled into the first cladding is emitted as at least a portion of the output beam.