In various embodiments, the beam parameter product and/or beam shape of a laser beam is adjusted by coupling the laser beam into an optical fiber of a fiber bundle and directing the laser beam onto one or more in-coupling locations on the input end of the optical fiber. The beam emitted at the output end of the optical fiber may be utilized to process a workpiece.

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.

A fiber coupling device (100) includes the following components: a wedge plate (102) for receiving light and refracting the light in a predetermined direction, a condenser lens (104) for collecting the light refracted by the wedge plate (102); and an optical fiber (107) having an incident surface for receiving the light collected by the condenser lens (104). The wedge plate (102) is held rotatable around the optical axis (200) of the light incident on the wedge plate (102). The light refracted by the wedge plate (102) and collected by the condenser lens (104) is incident on a different point on the incident surface depending on the rotation angle of the wedge plate (102).

There is provided a plastic optical fiber including a core and at least one layer of a clad formed on an outer circumferential surface of the core, wherein a transmission band is 100 MHz or wider, as measured under conditions of a wavelength of 650 nm and a launch NA=0.65; and a transmission loss is 350 dB/km or less, as measured under conditions of a wavelength of 650 nm and a launch NA=0.1, after exposure to an environment of a temperature of 105 C. for 1000 hours.

An optical fiber according to an embodiment includes a core having a single-peaked and graded refractive index profile, an inner cladding surrounding the core, and an outer cladding surrounding the inner cladding. The inner and outer claddings have refractive indices lower than the maximum refractive index of the core. A photosensitive region constituted by the core and the inner cladding contains a photosensitive material. The inner cladding has an outer diameter one time or more and two times or less the MFD of an LP.sub.01 mode in a 1310-nm wavelength band.

A hybrid mid-infrared-light transmitting glass fiber comprising a non-oxide infrared-light transmitting glass core, non-oxide glass inner cladding, and an oxide glass external cladding. In certain embodiments, the hybrid mid-infrared transmitting glass fiber is configured as a single mode fiber at a specific wavelength. In certain embodiments, the hybrid mid-infrared-light transmitting glass fiber is configured a polarization maintaining single mode fiber at a chosen specific wavelength.

In various embodiments, the beam parameter product and/or beam shape of a laser beam is adjusted by coupling the laser beam into an optical fiber of a fiber bundle and directing the laser beam onto one or more in-coupling locations on the input end of the optical fiber. The beam emitted at the output end of the optical fiber may be utilized to process a workpiece.

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.

The optical fibers disclosed have single mode and few mode optical transmission for VCSEL-based optical fiber transmission systems. The optical fibers have a cable cutoff wavelength .sub.d C of equal to or below 1260 nm thereby defining single mode operation at wavelengths greater than 1260 nm and few-mode operation at wavelengths in a wavelength range from 800 nm and 1100 nm. The mode-field diameter is in the range from 8.0 microns to 10.1 microns at 1310 nm. The optical fibers have an overfilled bandwidth OFL BW of at least 1GHz.Math.km at at least one wavelength in the wavelength range. The optical fibers have a single-step or two-step core and can have a trench refractive index profile. VCSEL based optical transmission systems and methods are disclosed that utilize both single core and multicore versions of the optical fiber.

There is described a multi-clad optical fiber for propagating an optical signal having at least a single mode. The multi-clad optical fiber generally has a fiber core, an inner cladding surrounding the fiber core, and at least an outer cladding surrounding the inner cladding, the multi-clad optical fiber having at least a taper portion extending along a longitudinal dimension z, the taper portion having a radial dimension progressively decreasing at a normalized slope exceeding an adiabaticity criterion of a conventional single-clad optical fiber propagating at least the single-mode across its single-mode core.