A laser-written waveguide comprising, an optical substrate having a first refractive index, a plurality of laser-written tracks buried within the optical substrate and having a second refractive index lower than the first refractive index, one or more concentric geometric regions bounding the plurality of laser-written tracks and a waveguide channel delimited by said concentric geometric regions, wherein said waveguide channel is configured to allow formation of an optical mode.

A method of processing by controlling one or more beam characteristics of an optical beam may include: launching the optical beam into a first length of fiber having a first refractive-index profile (RIP); coupling the optical beam from the first length of fiber into a second length of fiber having a second RIP and one or more confinement regions; modifying the one or more beam characteristics of the optical beam in the first length of fiber, in the second length of fiber, or in the first and second lengths of fiber; confining the modified one or more beam characteristics of the optical beam within the one or more confinement regions of the second length of fiber; and/or generating an output beam, having the modified one or more beam characteristics of the optical beam, from the second length of fiber. The first RIP may differ from the second RIP.

Disclosed herein are methods, apparatus, and systems for providing an optical beam delivery system, comprising an optical fiber including a first length of fiber comprising a first RIP formed to enable, at least in part, modification of one or more beam characteristics of an optical beam by a perturbation assembly arranged to modify the one or more beam characteristics, the perturbation assembly coupled to the first length of fiber or integral with the first length of fiber, or a combination thereof and a second length of fiber coupled to the first length of fiber and having a second RIP formed to preserve at least a portion of the one or more beam characteristics of the optical beam modified by the perturbation assembly within one or more first confinement regions. The optical beam delivery system may include an optical system coupled to the second length of fiber including one or more free-space optics configured to receive and transmit an optical beam comprising the modified one or more beam characteristics.

Optical coupling techniques between an optical fiber and another optical device, such as a planar optical waveguide, or a probed region are disclosed. An optical fiber for lateral optical coupling includes a cladding, a core disposed in the cladding, a reflecting structure inclined relative to the fiber axis, and a light-converging structure embedded in the cladding. The reflecting structure is configured to reflect light between the core and a lateral coupling path extending and providing lateral optical coupling between the core and an exterior of the fiber. The cladding-embedded light-converging structure is configured to intercept and converge light traveling along the lateral coupling path. In some implementations, the optical fiber is a fiber-optic transition coupled between a main optical fiber and another optical device or a probed region. A coupled optical system including an optical fiber coupled to another optical device is also disclosed.

Disclosed herein are methods, apparatus, and systems for providing an optical beam delivery device, comprising a first length of fiber comprising a first RIP formed to enable modification of one or more beam characteristics of an optical beam by a perturbation device and a second length of fiber having a second RIP coupled to the first length of fiber, the second RIP formed to confine at least a portion of the modified beam characteristics of the optical beam within one or more confinement regions.

A method for forming an article includes providing a material having a first material property; forming a melt pool by exposing the material to an optical beam having at least one beam characteristic, wherein the melt pool has at least one melt pool property determinative of a second material property of the material; and modifying the at least one beam characteristic in response to a change in the melt pool property.

Optical coupling techniques between an optical fiber and another optical device, such as a planar optical waveguide, or a probed region are disclosed. An optical fiber for lateral optical coupling includes a cladding, a core disposed in the cladding, a reflecting structure inclined relative to the fiber axis, and a light-converging structure embedded in the cladding. The reflecting structure is configured to reflect light between the core and a lateral coupling path extending and providing lateral optical coupling between the core and an exterior of the fiber. The cladding-embedded light-converging structure is configured to intercept and converge light traveling along the lateral coupling path. In some implementations, the optical fiber is a fiber-optic transition coupled between a main optical fiber and another optical device or a probed region. A coupled optical system including an optical fiber coupled to another optical device is also disclosed.

A fiber panel, a light module, and a method for transmitting light using the fiber panel are provided. The fiber panel includes a plurality of optical fibers; and wherein each of the optical fibers have at least one base surface, and the fibers being arranged such that the at least one base surface of each optical fiber have a common orientation with each other.

A method for forming an article includes providing a material having a first material property; forming a melt pool by exposing the material to an optical beam having at least one beam characteristic, wherein the melt pool has at least one melt pool property determinative of a second material property of the material; and modifying the at least one beam characteristic in response to a change in the melt pool property.

A hollow core photonic crystal fiber (PCF) including an outer cladding region and seven hollow tubes surrounded by the outer cladding region. Each of the hollow tubes is fused to the outer cladding to form a ring defining an inner cladding region and a hollow core region surrounded by the inner cladding region. The hollow tubes are not touching each other, but are arranged with distance to adjacent hollow tubes. The hollow tubes each have an average outer diameter d2 and an average inner diameter d1, wherein d1/d2 is equal to or larger than about 0.8, such as equal to or larger than about 0.85, such as equal to or larger than about 0.9. Also, a laser system.