The rolled photonic fibers presents two codependent, technologically exploitable features for light and color manipulation: regularity on the nanoscale that is superposed with microscale cylindrical symmetry, resulting in wavelength selective scattering of light in a wide range of directions. The bio-inspired photonic fibers combine the spectral filtering capabilities and color brilliance of a planar Bragg stack compounded with a large angular scattering range introduced by the microscale curvature, which also decreases the strong directional chromaticity variation usually associated with flat multilayer reflectors. Transparent and elastic synthetic materials equip the multilayer interference fibers with high reflectance that is dynamically tuned by longitudinal mechanical strain. A two-fold elongation of the elastic fibers results in a shift of reflection peak center wavelength of over 200 nm.

Illuminating coherent or partially coherent light may be directed over an optical fiber and may be despeckled by vibrating the optical fiber or by increasing the number of modes and modal dispersion. An exemplary embodiment is directed to an optical fiber attached to a vibrating device operable to vibrate the optical fiber above a threshold frequency. Another exemplary embodiment is directed to an optical fiber configured to have a refractive index profile operable to increase the number of modes and modal dispersion.

According to some embodiments a fiber sensor comprises: an optical fiber configured for operation at a wavelength from about 300 nm to about 2000 nm, and further defined by a transmission end, a another end, a fiber outer diameter and a fiber length, the fiber comprising: (a) a hybrid core comprising a single mode core portion and a multi-mode core portion; and (b) a cladding surrounding the hybrid core.

A double-clad (DC) polarization-maintaining (PM) optical fiber comprises a core, an inner cladding, an outer cladding, and stress rods. The core has a core refractive index (n.sub.core). The inner cladding is located radially exterior to the core and has an inner cladding refractive index (n.sub.1), which is less than n.sub.core. The stress rods are located in the inner cladding, and each stress rod has a stress rod refractive index (n.sub.2), which is substantially matched to n.sub.1. The outer cladding is located radially exterior to the inner cladding. The outer cladding has an outer cladding refractive index (n.sub.out), which is less than n.sub.1.

A bending-resistant low-crosstalk photonic orbital angular momentum (OAM) optical fiber waveguide. An optical fiber sequentially comprises, from the center to the outside, a first core layer (1), a second core layer (2), a first cladding layer (3), a second cladding layer (4), and a third cladding layer (5), wherein the third cladding layer (5) is the thickest, the first core layer (1) is the second thickest, and the first cladding layer (3) is the thinnest; the refractive index of the first cladding layer (3) is the lowest, the refractive index of the second cladding layer (4) is the second lowest, and the refractive index of the second core layer (2) is the highest. The waveguide structure can effectively regulate the output of different OAM modes, and an effective refractive index difference between modes is greater than 210.sup.4, the modes are easy to separate, and multiplexing and demultiplexing are facilitated.

A bending-resistant low-crosstalk photonic orbital angular momentum (OAM) optical fiber waveguide. An optical fiber sequentially comprises, from the center to the outside, a first core layer (1), a second core layer (2), a first cladding layer (3), a second cladding layer (4), and a third cladding layer (5), wherein the third cladding layer (5) is the thickest, the first core layer (1) is the second thickest, and the first cladding layer (3) is the thinnest; the refractive index of the first cladding layer (3) is the lowest, the refractive index of the second cladding layer (4) is the second lowest, and the refractive index of the second core layer (2) is the highest. The waveguide structure can effectively regulate the output of different OAM modes, and an effective refractive index difference between modes is greater than 210.sup.4, the modes are easy to separate, and multiplexing and demultiplexing are facilitated.

The present invention relates to an optical fiber (100, 101, 103, 105, 107) having a core region (102) and a cladding region (104). In particular, the cladding region (104) has exactly one down-doped region (210, 310) and an undoped region (212, 312). The down doped region (210, 310) is a continuous region adjacent to core region (102) such that radial position of minimum relative refractive index (214, 314) of the optical fiber (100, 101, 103, 105, 107) is within 3 micrometers (m) from interface between the down doped region (210, 310) and the undoped region (212, 312). Further, the mode field diameter of the optical fiber (100, 101, 103, 105, 107) is in range of 8.8 m to 9.6 m at a wavelength 1310 nanometres (nm), and cable cut-off of the optical fiber (100, 101, 103, 105, 107) is less than or equal to 1260 nm.

A waveguide that includes a first cladding layer, the first cladding layer having an index of refraction, n.sub.3; a gradient index layer positioned adjacent the first cladding layer; an assist layer positioned adjacent the gradient index layer, the assist layer having an index of refraction, n.sub.2; a core layer positioned adjacent the assist layer, the core layer having an index of refraction, n.sub.1; and a second cladding layer, the second cladding layer having an index of refraction, n.sub.4, wherein n.sub.1 is greater than n.sub.2, n.sub.3, and n.sub.4; and n.sub.2 is greater than n.sub.3 and n.sub.4.

An optical fiber that complies with ITU-T G.657.A2 recommendations. The optical fiber comprises an inner cladding that is adjacent to the core, thereby extending from a core radius (r.sub.core) to an inner cladding radius (r.sub.inner_clad). The inner cladding refractive index decreases approximately linearly as a function of radius (r), thereby decreasing approximately linearly from a first inner cladding relative refractive index (.sub.inner_clad_1) to a second inner cladding relative refractive index (.sub.inner_clad_2). The ratio of r.sub.inner_clad to r.sub.core is between approximately 3.2 and approximately 4.2 (3.2r.sub.inner_clad/r.sub.core4.2).

Multimode beam combiners include at least one gradient-step index optical fiber in which a refractive index difference at a core/cladding interface is selected to provide a numerical aperture so as to provide stable, uniform beam output. One or more such fibers is formed into a tapered bundle than can be shaped to provide a selected illuminated aperture. The fibers in the bundle can be separated by respective tapered claddings so as to be optically coupled or uncoupled. Illumination systems can include a plurality of such fibers coupled to a plurality of laser diodes or other light sources.