Disclosed herein are methods, apparatus, and systems for perturbing an optical beam propagating within a first length of fiber to adjust one or more beam characteristics of the optical beam in the first length of fiber or a second length of fiber or a combination thereof, coupling the perturbed optical beam into a second length of fiber and maintaining at least a portion of one or more adjusted beam characteristics within a second length of fiber having.

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.

A hollow-core photonic bandgap fiber having a hollow core and a cladding which surrounds the core at a core boundary and comprises a lattice or network of struts and interstitial nodes which together define an array of cavities, wherein a ratio between a difference in a length of a longest and shortest pitch spacing of the nodes at the core boundary to an average pitch spacing at the core boundary is less than about 0.3.

The present invention is generally directed to a photonic bad gap fiber and/or fiber preform with a central structured region comprising a first non-silica based glass and a jacket comprising a second non-silica based glass surrounding the central structured region, where the Littleton softening temperature of the second glass is at least one but no more than ten degrees Celsius lower than the Littleton softening temperature of the first glass, or where the base ten logarithm of the glass viscosity in poise of the second glass is at least 0.01 but no more than 2 lower than the base ten logarithm of the glass viscosity in poise of the first glass at a fiber draw temperature. Also disclosed is a method of making a photonic bad gap fiber and/or fiber preform.

An object is to provide a beam propagating method capable of satisfying desired output power and a desired propagation distance and a required condition of beam quality and a method of designing an optical fiber designing the structure of an optical fiber. According to the present invention, an effective core cross-sectional area A.sub.eff is calculated based on desired specification values and, by appropriately adjusting the structure of an optical fiber satisfying the effective core cross-sectional area and the number of modes to be propagated, the structure of the optical fiber is determined. In this way, by controlling the excitation ratio of a high-order mode at the time of coupling laser light in the optical fiber designed as above, light of high-output laser can be propagated a long distance with the beam quality maintained.

A Photonic Crystal Fiber (PCF) a method of its production and a supercontinuum light source comprising such PCF. The PCF has a longitudinal axis and includes a core extending along the length of said longitudinal axis and a cladding region surrounding the core. At least the cladding region includes a plurality of microstructures in the form of inclusions extending along the longitudinal axis of the PCF in at least a microstructured length section. In at least a degradation resistant length section of the microstructured length section the PCF includes hydrogen and/or deuterium. In at least the degradation resistant length section the PCF further includes a main coating surrounding the cladding region, which main coating is hermetic for the hydrogen and/or deuterium at a temperature below T.sub.h, wherein T.sub.h is at least about 50 C., preferably 50 C.<T.sub.h<250 C.

The invention relates to a microstructured optical fiber for generating supercontinuum light. The optical fiber comprises a core and a cladding region surrounding the core. The optical fiber comprises a first fiber length section, a second fiber length section as well as an intermediate fiber length section between said first and second fiber length sections. The first fiber length section has a core with a first characteristic core diameter larger than about 7 m. The second fiber length section has a core with a second characteristic core diameter, smaller than said first characteristic core diameter. The intermediate length section of the optical fiber comprises a core which is tapered from said first characteristic core diameter to said second characteristic core diameter over a tapered length. The invention also relates to a supercontinuum light source comprising an optical fiber according to the invention and a pump light source.

Microstructured optical fiber (MOF) includes a cladding extending a length between first and second ends. The cladding includes an inner porous microstructure that at least partially surrounds a hollow core. A perimeter contour of the hollow core has a non-uniform radial distance from a center axis of the cladding such that first segments of the cladding along the perimeter contour have a shorter radial distance from the center axis relative to second segments of the cladding along the perimeter contour. The cladding receives and propagates light energy through the hollow core, and the inner porous microstructure substantially confines the light energy within the hollow core. The cladding defines at least one port hole that extends radially from an exterior surface of the cladding to the hollow core. Each port hole penetrates the perimeter contour of the hollow core through one of the second segments of the cladding.

A supercontinuum optical pulse source provides a combined supercontinuum, and can comprise one or more seed pulse sources; first and second optical amplifiers arranged along first and second respective optical paths, wherein the first and second optical amplifiers are configured to amplify one or more optical signals generated by the one or more seed pulse sources; a first microstructured light-guiding member arranged along the first optical path and configured to generate supercontinuum light responsive to an optical signal propagating along the first optical path; a second microstructured light-guiding member arranged along the second optical path and configured to generate supercontinuum light responsive to an optical signal propagating along the second optical path; a supercontinuum-combining member to combine supercontinuum generated in at least the first and second microstructured light-guiding members to form a combined supercontinuum; wherein the supercontinuum-combining member comprises an output fibre, wherein the output fibre comprises a silica-based multimode optical fibre supporting a plurality of spatial modes at one or more wavelengths of the combined supercontinuum; wherein the supercontinuum-combining member has one or more input fibres which support no more than four spatial modes at any wavelength within the combined supercontinuum; and wherein the output fibre of the supercontinuum-combining member supports no more than four spatial modes at any wavelength within the combined supercontinuum.

An optically active element, such as a photonic crystal, is formed by creating a matrix (1) in which an optically active material is dispersed, and generating one or more void structures (2, 3) in the matrix. The matrix (1) may comprise polymer dispersed liquid crystal. The void structures (2, 3) may be generated by laser ablation. Properties of the optically active element may be tuned by thermal effects, or via the application of electric, magnetic, or polarised electromagnetic fields. The element may be adapted for use in beam steering, fluid detection, tunable lasers, polarisation multiplexing, and optical switching.