Light diffusing optical fibers for use illumination applications and which have a uniform color gradient that is angularly independent are disclosed herein along with methods for making such fibers. The light diffusing fibers are composed of a silica-based glass core that is coated with a number of layers including a scattering layer.

A hollow core fiber (HCF) has a cross section with a substantially-circular hollow core in a cladding lattice, an axial center and a reference direction that extends radially in one direction from the axial center. The HCF comprises modified holes that are located along linear paths that extend radially outward from the axial center. The modified holes, which are located at various radial distances from the axial center and at various azimuthal angles from the reference direction, have non-uniform modified properties. These non-uniform modified properties include radially-varying properties, azimuthally-varying properties, or a combination of radially-varying and azimuthally-varying properties.

Light diffusing optical fibers for use illumination applications and which have a uniform color gradient that is angularly independent are disclosed herein along with methods for making such fibers. The light diffusing fibers are composed of a silica-based glass core that is coated with a number of layers including a scattering layer.

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.

A substrate processing system includes a processing chamber. A pedestal and a showerhead are arranged in the processing chamber. A surface plasmon resonance (SPR) fiber has a central portion disposed in the processing chamber, and opposing ends disposed outside the processing chamber. A light source provides input light at one end of the SPR fiber, and a detector receives output light from the other end of the SPR fiber. Surface plasmon waves and evanescent waves constitute the output light, which is processed and analyzed to determine a condition of the processing chamber.

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.

An optical fiber which allows propagation of two or more modes, and in a case where a mode coupling coefficient between at least two modes among the two or more modes is h [1/km], the length of the optical fiber is z [km], and the amount XT of coupling between the two modes is represented by XT=10.Math.log.sub.10(zh) [dB], the amount XT of coupling satisfies Expression (A) described below.

XT+14 [dB](A)