Abstract: The invention concerns an apparatus and its use for laser welding. A laser welding apparatus comprise at least one first laser device, each providing at least one first optical feed fiber with a first laser beam; at least one second laser device, each providing at least one second optical feed fiber with a second laser beam; means for generating a composite laser beam comprising a first output laser beam and a second output laser beam for welding a workpiece; wherein the first output laser beam has a circular cross-section and the second output laser beam has an annular shape concentric to the first output laser beam. The second laser device is a fiber laser device or a fiber-coupled laser device.

Abstract: Laser welding methods include focusing laser radiation onto a first metal sheet disposed on a metal part, optionally with one or more intervening metal sheets therebetween. The laser radiation is steered to trace at least one spiral path to spot-weld together the metal parts. The laser radiation includes a center beam and an annular beam to maintain a stable keyhole. One method is tailored to weld aluminum parts, e.g., with high gas content and/or dissimilar compositions, and the laser radiation traces first an outward spiral path and then an inward spiral path. The center beam is pulsed during one segment of the inward spiral path. Another method is tailored to weld steel or copper parts having a coating at an interface therebetween, and the laser radiation traces an inward spiral path. The interface may be a zero-gap interface, or a non-zero gap may exist.

Abstract: Laser welding methods include focusing laser radiation onto a first metal sheet disposed on a metal part, optionally with one or more intervening metal sheets therebetween. The laser radiation is steered to trace at least one spiral path to spot-weld together the metal parts. The laser radiation includes a center beam and an annular beam to maintain a stable keyhole. One method is tailored to weld aluminum parts, e.g., with high gas content and/or dissimilar compositions, and the laser radiation traces first an outward spiral path and then an inward spiral path. The center beam is pulsed during one segment of the inward spiral path. Another method is tailored to weld steel or copper parts having a coating at an interface therebetween, and the laser radiation traces an inward spiral path. The interface may be a zero-gap interface, or a non-zero gap may exist.

Abstract: Laser welding methods include focusing laser radiation onto a first metal sheet disposed on a metal part, optionally with one or more intervening metal sheets therebetween. The laser radiation is steered to trace at least one spiral path to spot-weld together the metal parts. The laser radiation includes a center beam and an annular beam to maintain a stable keyhole. One method is tailored to weld aluminum parts, e.g., with high gas content and/or dissimilar compositions, and the laser radiation traces first an outward spiral path and then an inward spiral path. The center beam is pulsed during one segment of the inward spiral path. Another method is tailored to weld steel or copper parts having a coating at an interface therebetween, and the laser radiation traces an inward spiral path. The interface may be a zero-gap interface, or a non-zero gap may exist.

Abstract: A method for laser keyhole welding a stack of metal foils to a metal tab is disclosed. The method independently adjusts power in a focused center beam and power in a focused annular beam to form a weld through all the foils and the tab. The annular beam provides sufficient power to heat the metal to about melting temperature, widen a mouth of a keyhole, and stabilize a melt pool. The center beam provides sufficient additional power to form the keyhole. The power of the annular beam is sustained for a longer time than the power of the center beam. A plurality of such welds is formed to provide mechanical strength and electrical conductivity.

Abstract: A method for laser welding a pair of metal pins delivers a laser beam to a work-side of the pair of metal pins where a respective pair of surfaces of the metal pins are adjacent to each other and face in the same direction. The laser beam first traces a first path on the work-side to form a melt pool by keyhole welding. The first path crosses an interface between the metal pins. After tracing the first path, the laser beam is switched to trace a second path on the work-side with the laser beam at a delivered rate of energy per unit path length that is less than the one used for the first path. The second path crosses the interface and is within the first path. The method is well-suited for welding of hairpin and I-pin stators.

Abstract: A method for laser keyhole welding a stack of metal foils to a metal tab is disclosed. The method independently adjusts power in a focused center beam and power in a focused annular beam to form a weld through all the foils and the tab. The annular beam provides sufficient power to heat the metal to about melting temperature, widen a mouth of a keyhole, and stabilize a melt pool. The center beam provides sufficient additional power to form the keyhole. The power of the annular beam is sustained for a longer time than the power of the center beam. A plurality of such welds is formed to provide mechanical strength and electrical conductivity.

Abstract: The invention concerns an apparatus and its use for laser processing. The invention also concerns a method and an optical component. According to the invention, at a first laser device, providing a first optical feed fiber and a second laser device providing a second optical feed fiber is provided. A beam combining means connected to the first and second feed fibers and to a multi-core optical fiber is adapted to form a composite laser beam by having the first optical feed fiber aligned with a first core of the multi-core optical fiber and the second optical feed fiber aligned with at least one second core of the multi-core optical fiber. The first and second cores outputs a composite laser beam to a workpiece to be processed.

Abstract: An apparatus and its use for laser processing along with a method and an optical component. A first laser device provides a first optical feed fiber and a second laser device provides a second optical feed fiber. A beam combining means connected to the first and second feed fibers and to a multi-core optical fiber is adapted to form a composite laser beam by having the first optical feed fiber aligned with a first core of the multi-core optical fiber and the second optical feed fiber aligned with at least one second core of the multi-core optical fiber. The first and second cores outputs a composite laser beam to a workpiece to be processed. A control unit individually controls the power density of the output laser beams.

Abstract: A pump reflector for efficiently recycling unabsorbed pump radiation in a diode-pumped fiber laser includes a core for guiding a laser beam, a pump cladding, and a tapered capillary tube. Pump radiation is adiabatically guided in the tapered capillary tube, which includes a mirror that is reflective for the pump radiation. The pump reflector may be packaged as a fiber component for co-propagating or counter-propagating fiber laser amplifiers and resonators.

Abstract: The invention relates to a method and apparatus for processing substrates, such as glass and semiconductor wafers. The method comprises directing to the substrate from a laser source a plurality of sequential focused laser pulses having a predetermined duration, pulsing frequency and focal spot diameter, the pulses being capable of locally melting the substrate, and moving the laser source and the substrate with respect to each other at a predetermined moving velocity so that a structurally modified zone is formed to the substrate. According to the invention, the pulse duration is in the range of 20-100 ps, pulsing frequency at least 1 MHz and moving velocity adjusted such that the distance between successive pulses is less than ? of the diameter of the focal spot. The invention can be utilized, for example, for efficient dicing, scribing and welding of materials which are normally transparent.

Abstract: The invention concerns a method of fusing and electrically contacting a first insulating substrate (28A) having at least one first conductive layer (29A) thereon with at least one second insulating substrate (28B) having at least one second conductive layer (29B) thereon, the method comprising: stacking the first and second substrates (28A, 28B) such that an interface zone is formed between them, the interface zone comprising an electrical contacting zone where at least one first conductive layers (29A) faces and is at least partially aligned with at least one second conductive layer (29B), and a substrate fusing zone where the insulating substrates (28A, 28B) directly face each other; focusing to the interface zone of the substrates (28A, 28B) through one of the substrates (28A, 28B) a plurality of sequential focused laser pulses from a laser source, the pulse duration, pulse frequency and pulse power of the laser light being chosen to provide local melting the substrate (28A, 28B) materials and the conducti

Abstract: The invention relates to a pump coupler (2) and a manufacturing method. The pump coupler (2) comprises a least one signal fiber (50) for outputting optical energy, multiple pump fibers (31) for inputting optical energy into the signal fiber (50), and a coupling structure (40) for coupling the optical energy of the pump fibers (31) into the signal fiber (50). A signal feed-through fiber (32) goes through the coupling structure (40). In accordance with the invention the coupling structure (40) is a tapering capillary tube (40) having a first wide end (65) and a second narrow end (70), the pump fibers (31) are connected to the wide end of the capillary tube (40), and at least the narrow end (70) of the capillary tube (70) is collapsed around the signal fiber (32).

Abstract: An active multimode optical fiber consisting of a first core section (11), a thin barrier layer (12) material having a thickness (d2) and a lower refractive index than that of the first core section by an index difference (?n), a second core section (13) having a refractive index equal or higher than that of the first core section, and a cladding (14) having an index lower than that of the first core section. Said index difference and said thickness are selected so that a fundamental core mode couples less strongly with said cladding modes than higher order core modes. A scheme of changing the symmetry of the fiber for reduced sensitivity of the fundamental mode of the first core section to resonance effects.