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.

A specialized, dispersion-controlled fiber is particularly configured to exhibit a relatively uniform dispersion (D) over a broad spectral range (for example, 1000 nm to 2000 nm). The specialized fiber exhibits an essentially constant attenuation () over this same spectral range so that the fiber is defined as having a high figure of merit (FoM) where FoM is defined as |D|/. The specialized fiber is well-suited for use as a pulse stretcher, providing the ability to separate out wavelength constituents of an extremely short (fs, ps) broadband pulse into the ns range, for example.

An embodiment of a system for performing measurements in a downhole environment includes an optical interrogation assembly configured to emit a pulsed optical signal, the pulsed optical signal including a selected wavelength, and an optical fiber configured to be disposed in a borehole in an earth formation and configured to receive the pulsed optical signal, the optical fiber having at least one measurement location disposed therein and configured to at least partially reflect the pulsed optical signal. The optical fiber has a core and a cladding, at least a portion of the core made from at least substantially pure silica, and the optical fiber has a refractive index profile configured to have a zero dispersion wavelength that is greater than the selected wavelength.

Methods, apparatus, and systems comprising a fiber-coupled laser and time-varying beam characteristics. A laser may generate an optical beam that is launched into one or more lengths of fiber, at least one of which comprises a confinement region that is optically coupled to an output. A perturbation device may modulate, through action upon the one or more lengths of fiber, a beam characteristic over a time period during which the laser is energized. A controller may cause the perturbation device to act upon the one or more lengths of fiber to impart a time-averaged beam characteristic and/or to induce a continuous variation in one or more beam characteristics during system use. A process monitor may sense a metric external to the optical system, and a feedback signal from the process monitor may be coupled into the controller. Dynamic beam characteristics may be modulated based on the feedback signal.

Disclosed herein are methods, apparatus, and systems for a multi-operation optical beam delivery device having a laser source to generate the optical beam. A beam characteristic conditioner that, in response to a control input indicating a change between the different laser process operations, controllably modifies the beam characteristics for a corresponding laser process operation of the different laser process operations. A delivery fiber has an input end coupled to the beam characteristic conditioner and an output end coupled to a process head for performing the corresponding laser process operation.

A specialized, dispersion-controlled fiber is particularly configured to exhibit a relatively uniform dispersion (D) over a broad spectral range (for example, 1000 nm to 2000 nm). The specialized fiber exhibits an essentially constant attenuation () over this same spectral range so that the fiber is defined as having a high figure of merit (FoM) where FoM is defined as |D|/. The specialized fiber is well-suited for use as a pulse stretcher, providing the ability to separate out wavelength constituents of an extremely short (fs, ps) broadband pulse into the ns range, for example.

A specialized, dispersion-controlled fiber is particularly configured to exhibit a relatively uniform dispersion (D) over a broad spectral range (for example, 1000 nm to 2000 nm). The specialized fiber exhibits an essentially constant attenuation () over this same spectral range so that the fiber is defined as having a high figure of merit (FoM) where FoM is defined as |D|/. The specialized fiber is well-suited for use as a pulse stretcher, providing the ability to separate out wavelength constituents of an extremely short (fs, ps) broadband pulse into the ns range, for example.

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.

The invention concerns an apparatus and its use for laser processing. The invention also concerns a method and an optical component. According to the invention, at a first laser device, providing a first optical feed fiber and a second laser device providing a second optical feed fiber is provided. A beam combining means connected to the first and second feed fibers and to a multi-core optical fiber is adapted to form a composite laser beam by having the first optical feed fiber aligned with a first core of the multi-core optical fiber and the second optical feed fiber aligned with at least one second core of the multi-core optical fiber. The first and second cores outputs a composite laser beam to a workpiece to be processed. A control unit controls power density of at least one of first and second laser beams of the composite laser beam in at least one of: in response to approaching a change point in direction of cutting progression and to cause change in relation between the power density of the first output laser beam and power density of the second output laser beam in accordance with thickness of the workpiece being cut.

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.