In various embodiments, the beam parameter product and/or numerical aperture of a laser beam is adjusted utilizing a step-clad optical fiber having a central core, a first cladding, an annular core, and a second cladding.

A laser system based on nonlinear pulse compression and a LMA optical fiber therefor are provided. The LMA optical fiber is configured to amplify seed light pulses and promote the onset of nonlinear spectral broadening. The LMA optical fiber includes a first section having constant core and cladding diameters and receiving and supporting propagation of the light pulses in multiple transversal modes. The first section is configured to suppress high order modes propagating therealong. The LMA optical fiber further includes a tapered second section receiving the fundamental mode from the first section, the core and cladding diameters increasing gradually along said second section so as to provide an adiabatic transition of the fundamental mode. The LMA optical fiber further includes an optional third section having constant core and cladding diameters. Dispersive compression of the light pulses outputted by the LMA optical fiber provides excellent beam quality and high peak powers.

An optical fiber with low attenuation and methods of making same are disclosed. The optical fiber has a core, an inner cladding surround the core, and an outer cladding surrounding the inner cladding. The outer cladding is chlorine-doped such that the relative refractive index varies as a function of radius. The radially varying relative refractive index profile of the outer cladding reduces excess stress in the core and inner cladding, which helps lower fiber attenuation while also reducing macrobend and microbend loss. A process of fabricating the optical fiber includes doping an overclad soot layer of a soot preform with chlorine and then removing a portion of the chlorine dopant from an outermost region of the overclad soot layer. The soot preform with the modified chlorine dopant profile is then sintered to form a glass preform, which can then be used for drawing the optical fiber.

An optical fiber having both low macrobend loss and low microbend loss. The fiber has a central core region, a first (inner) cladding region surrounding the central core region and having an outer radius r.sub.2>16 microns and relative refractive index .sub.2, and a second (outer) cladding region surrounding the first cladding region having relative refractive index, .sub.3, wherein .sub.1>.sub.3>.sub.2. The difference between .sub.3 and .sub.2 is greater than 0.12 percent. The fiber exhibits a 22 m cable cutoff less than or equal to 1260 nm, and r.sub.1/r.sub.2 is greater or equal to 0.24 and bend loss at 1550 nm for a 15 mm diameter mandrel of less than 0.5 dB/turn.

A single mode optical fiber including a germania doped silica central core region having outer radius r.sub.1 and refractive index .sub.1, a maximum refractive index .sub.1max, and 0.32%.sub.1max0.45%, and a core alpha profile (Core.sub.). In various embodiments, the optical fiber also contains a cladding region including: (i) a second inner cladding region or ring region surrounding the first inner cladding region; or (ii) an inner cladding region or pedestal region surrounding the germania doped silica central core region. The corresponding resultant optical fibers exhibit a 22 m cable cutoff less than or equal to 1260 nm, a macrobending loss at 1550 nm of 0.75 dB/turn on a 20 mm diameter mandrel, a zero dispersion wavelength, .sub.0, of 1300 nm.sub.01324 nm, and a mode field diameter at 1310 nm of 8.2 micronsMDF.sub.1310nm9.6 microns.

A dispersion shifted optical fiber where a radius r.sub.0 of a first center segment is 0.5 m to 2.8 m, and a relative refractive index difference .sub.0 is 0.4% or more and 0.9% or less. A radius r.sub.1 of a first segment is 1.8 m or more and 4.5 m or less. A radius r.sub.2 of a second segment is 4.0 m or more and 8.0 m or less, and a relative refractive index difference .sub.2 is 0.00% or more and 0.07% or less. A radius r.sub.3 of a third segment is 4.5 m or more and 8.5 m or less, and a relative refractive index difference .sub.3 is 0.285% or more and 0.5% or less. A radius r.sub.4 of a fourth segment is 8.0 m or more and 16.0 m or less, and a relative refractive index difference .sub.4 is 0.005% or more and 0.04% or less.

In various embodiments, the beam parameter product and/or numerical aperture of a laser beam is adjusted utilizing a step-clad optical fiber having a central core, a first cladding, an annular core, and a second cladding.

An optical fiber having both low macrobend loss and low microbend loss. The fiber has a central core region, a first (inner) cladding region surrounding the central core region and having an outer radius r.sub.2>16 microns and relative refractive index .sub.2, and a second (outer) cladding region surrounding the first cladding region having relative refractive index, .sub.3, wherein .sub.1>.sub.3>.sub.2. The difference between .sub.3 and .sub.2 is greater than 0.12 percent. The fiber exhibits a 22 m cable cutoff less than or equal to 1260 nm, and r.sub.1/r.sub.2 is greater or equal to 0.24 and bend loss at 1550 nm for a 15 mm diameter mandrel of less than 0.5 dB/turn.

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.

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.