An optical fibre includes a glass core defined by a central core region surrounded by an outer core region. The glass core has a core thickness of 3.5 to 6 micrometers. The central core region has a centerline dip. The central dip has a centerline width in range of about 0 to 3 micrometers. The outer core region has a core alpha in a range of 3-8. The optical fibre includes a buffer clad region, a trench region and an outer cladding region. The outer cladding region has at least one of an outer cladding thickness in range of 41.5 to 46.5 micrometers and an outer cladding relative refractive index near zero.

A single mode optical fiber, comprising: (i) a silica based core having a step refractive index profile with an alpha of greater than 10, a relative refractive index Δ.sub.1MAX, and an outer radius r.sub.1, wherein 6.25 microns>r.sub.1≥4.75 microns, the core further comprising Cl, Ge, or a combination thereof; (ii) a first cladding region in contact with and surrounding the core, the first cladding region having a relative refractive index Δ.sub.2MIN, an inner radius r.sub.1, and an outer radius r.sub.2, wherein r.sub.2<20 microns; and (iii) an outer cladding region surrounding the first cladding region, the outer cladding region having a relative refractive index Δ.sub.3. The fiber<1300 nm, a 22m cable cutoff wavelength<1260 nm; and a bend loss<0.005 dB/turn when the optical fiber is bent around a 30 mm mandrel; <0.5 dB/turn when the fiber is bent around a 20 mm mandrel.

An MCF according to the disclosure has a structure preventing deterioration in quality of optical transmission signals. The MCF comprises cores, a common cladding, and a coating. Any of the cores has a coating leakage loss of 0.01 dB/km or more at a wavelength within a wavelength range of from 850 nm to 1700 nm. The coating includes a leaked light propagation suppressive coating layer having a first optical property or a second optical property to light with a wavelength within a wavelength range of from 850 nm to 1700 nm or from 1260 nm to 1625 nm. The first optical property is defined by, as an attenuation index of the light, an absorbance per 1 μm thickness being 0.1 dB or more. The second optical property is defined by a product of absorbance per 1 μm thickness and a thickness being 0.1 dB or more.

The disclosed embodiments generally relate to extruding multiple layers of micro- to nano-polymer layers in a tubular shape. In particular, the aspects of the disclosed embodiments are directed to a method for producing a Bragg reflector comprising co-extrusion of micro- to nano-polymer layers in a tubular shape.

A bandpass filter may include a set of layers. The set of layers may include a first subset of layers. The first subset of layers may include hydrogenated germanium (Ge:H) with a first refractive index. The set of layers may include a second subset of layers. The second subset of layers may include a material with a second refractive index. The second refractive index may be less than the first refractive index.

Embodiments of the invention are directed a waveguide having a first waveguide segment that includes a set of first waveguide segment confinement parameters; a second waveguide segment having routing bends and a set of second waveguide segment confinement parameters; and a third waveguide segment having a set of third waveguide segment confinement parameters. The waveguide is configured to guide optical data according to an asymmetric optical-loss performance curve that is a plot of the sets of first, second, and third waveguide segment confinement parameters on a first axis; and a level of optical-loss performance that results from the sets of first, second, and third waveguide segment confinement parameters on a second axis. The sets of first, second, and third waveguide segment confinement parameters are configured to, collectively, maximize a predetermined worst-case optical-loss performance level of the asymmetric optical-loss performance curve within a range of waveguide fabrication tolerances.

An item such as a fabric-based item may have a layer of fabric such as a layer of woven fabric. The fabric layer may include warp and weft strands. The fabric may cover keys in a keyboard or may be used in forming other structures in the fabric-based item. Each key may have an illuminated key label. Portions of the fabric may be processed by pressing heated protrusions on a textured mold into polymer optical fibers in the fabric. The protrusions form corresponding light-scattering recesses in cladding portions of the optical fibers. Light-emitting diodes or other light sources may be coupled to respective end surfaces of the optical fibers. The light-emitting diodes emit light that is emitted from the thermally imprinted light-emitting regions formed by pressing the heated protrusions into the optical fibers.

An optical fiber includes a core that propagates a light that includes a wavelength equal to or larger than 1000 nm and equal to or smaller than 1100 nm. The light propagates in the core at least in an LP01 mode and an LP11 mode. A difference between a propagation constant of the light in the LP01 mode and a propagation constant of the light in the LP11 mode is 1735 rad/m or larger and 4000 rad/m or smaller.

An optical fiber includes a glass fiber and a coating resin covering an outer periphery of the glass fiber. The glass fiber includes a core, an inner cladding, a trench, and an outer cladding. An outer diameter of the glass fiber is 99 m or larger and 101 m or smaller. An outer diameter of the coating resin is 160 m or larger and 170 m or smaller. A mode field diameter for light having a wavelength of 1310 nm is 7.2 m or larger and 8.2 m or smaller. Bending loss at a wavelength of 1550 nm when wound in a ring shape having a radius of 10 mm is 0.1 dB/turn or less. Bending loss at the wavelength of 1550 nm when wound in the ring shape having the radius of 7.5 mm is 0.5 dB/turn or less.

Fiber bending mechanisms vary beam characteristics by deflecting or bending one or more fibers, by urging portions of one or more fibers toward a fiber shaping surface having a selectable curvature, or by selecting a fiber length that is to be urged toward the fiber shaping surface. In some examples, a fiber is secured to a flexible plate to conform to a variable curvature of the flexible plate. In other examples, a variable length of a fiber is pulled or pushed toward a fiber shaping surface, and the length of the fiber or a curvature of the flexible plate provide modification of fiber beam characteristics.