An optical fiber comprises, from a center to a periphery, a fiber core of undoped silica; a cladding layer; and a coating of polyacrylate, wherein the fiber core has a radius of 5 to 7 m and an ellipticity of less than 1.5%, the cladding layer with an ellipticity of less than 0.4% comprises inner, intermediate, and outer cladding layers, the inner cladding layer being doped with fluorine of 5 to 12 m thickness, and refractive index difference to fiber core of 0.4 to 0.2%, the outer cladding layer being undoped quartz of 25 to 45 m thickness, and the coating comprises an inner coating of 25 to 40 m thickness, and an outer coating of 25 to 35 m thickness and an ellipticity of less than 2%. The optical fiber has high durability and large effective transmission area, a method and system for preparing such optical fiber are also disclosed.

A space-division multiplexed optical fiber includes a relatively high refractive index optical core region surrounded by alternating regions of relatively low and relative high refractive index material, forming concentric high index rings around the core. The optical core region supports propagation of light along at least a first radial mode associated with the optical core region and a high index ring region supports propagation of light along at least a second radial mode associated with the high index ring region. The second radial mode is different from the first radial mode.

A high bandwidth radiation-resistant multimode optical fiber includes a core and a cladding layer surrounding the core. The core is a fluorine-doped quartz glass layer with a graded refractive index distribution and a distribution power exponent of 1.7-2.2. The core has R1 of 15-35 m and 1%min of 0.8% to 1.2%. The cladding layer has an inner cladding layer having R2 of 15-38 m and 2% of 0.8% to 1.2% and/or a depressed inner cladding layer having R3 of 15-55 m and 3 of 1.0% to 1.4%, an intermediate cladding layer having R4 of 15.5-58 m and 4 of 0.7% to 0.2% a depressed cladding layer hasving R5 of 16-60 m and 5 of 0.8% to 1.2%, and an outer cladding layer sequentially formed from inside to outside. The outer cladding layer is a pure silica glass layer.

An optical fiber manufacturing method includes setting a first holding member and a rod inside a glass pipe, the first holding member made of glass and having plural holes formed, so that the rod is supported by the first holding member; filling glass particles between the rod and a glass pipe inner wall; holding the rod such that the rod and the filled glass particles are enclosed by the glass pipe inner wall and the first and second holding members, and sealing one end of the glass pipe and manufacturing an intermediate; and manufacturing an optical fiber from the intermediate, wherein a bulk density of the first and second holding members is set with reference to a bulk density of a filling portion made from the glass particles, and the predetermined range is determined according to a core diameter permissible variation range in its longitudinal direction.

A quantum communications system includes a quantum key generation system having a photonic quantum bit generator, a dispersion compensating optical fiber link, and a photon detector unit and a communications network having a signal generator, a signal channel, and a signal receiver. The dispersion compensating optical fiber link extends between and optically couples the photonic quantum bit generator and the photon detector unit. Further, the dispersion compensating optical fiber link is structurally configured to induce dispersion at an absolute dispersion rate of about 9 ps/(nm)km or less and induce attenuation at an attenuation rate of about 0.18 dB/Km or less such that the quantum key bit information of a plurality of photons output by the one or more photonic quantum bit generators is receivable at the photon detector unit at a bit rate of at least about 10 Gbit/sec.

An image acquisition device including: an imaging optical system forming two images having parallax; and an element acquiring the parallax images, the imaging optical system includes: a first negative lens group having negative refractive power; a first positive lens group having positive refractive power; and a second positive lens group having positive refractive power, the first negative lens group includes two negative lens groups disposed side by side in the parallax direction and having central axes respectively, the first positive lens group is a common lens group having a single central axis, and light rays emitted from the negative lens groups pass therethrough, the second positive lens group includes two positive lens groups disposed side by side in the parallax direction and having central axes respectively and the first positive lens group includes a moving lens group moved along the central axis of the first positive lens group.

The present disclosure provides an optical fiber (100). The optical fiber (100) includes a core region (102). The core region (102) is defined by a region around central longitudinal axis (112) of the optical fiber (100). In addition, the core region (100) has a first annular region (106). The first annular region (106) is defined from the central longitudinal axis (112) to a first radius from the central longitudinal axis. Moreover, the core region (102) has a second annular region (108). The second annular region (108) is defined from the first radius to a second radius. Further, the core region (102) has a third annular region (110). The third annular region (110) is defined from the second radius to a third radius. Also, the optical fiber (100) includes a cladding (104). The cladding region (104) has a fourth radius.

An optical combiner includes: a plurality of first input optical fibers that each include a core; a bridge fiber that includes a bridge input surface connected to the cores of the plurality of first input optical fibers, a diameter reduction portion having a diameter that decreases away from the bridge input surface along an optical axis of the optical combiner, and a bridge output surface located opposite to the bridge input surface along the optical axis; an intermediate optical fiber that includes a core connected to the bridge output surface of the bridge fiber; a second input optical fiber that includes a core; and an output optical fiber that includes a first optical waveguide connected to the core of the intermediate optical fiber, and a second optical waveguide connected to the core of the second input optical fiber.

Provided is a few-mode optical fiber. The optical fiber includes: a core and a cladding enclosing the core. The cladding includes: a first inner cladding surrounding the core; a first high-refractive-index mode filter layer surrounding the first inner cladding; a second inner cladding surrounding the first high-refractive-index mode filter layer; a second high-refractive-index mode filter layer surrounding the second inner cladding; and an outer cladding surrounding the second high-refractive-index mode filter layer.

Single mode optical fibers with a chlorine doped core and a cladding having a fluorine doped trench region are disclosed. The optical fiber includes a chlorine doped silica core having a core alpha 10, a core radius r.sub.1 and maximum refractive index delta .sub.1max % and a Cl concentration0.9 wt %. The optical fiber also has a cladding surrounding the core, the cladding having an inner and an outer cladding. The inner cladding has first and second cladding regions. The optical fiber has mode field diameter at 1310 nm of larger than 9 microns, a cable cutoff wavelength of 1260 nm, a zero dispersion wavelength .sub.0, where 1300 nm.sub.01324 nm, and bend loss at 1550 nm for a 20 mm mandrel of less than 0.5 dB/turn.