Abstract: A fiber optic dosimeter probe for sensing radiation dose including an optical fiber having a free end and a sensitive end, a window having a sensitive side and a rear side; a radiation sensitive layer between the sensitive end of the optical fiber and a sensitive side of the window, the radiation sensitive layer being made of a material having an optical property that changes with absorbed radiation dose, an amount of the material corresponding to a predetermined sensitivity to radiation; wherein the window and the optical fiber have a near water equivalent interaction with radiation and are MR compatible.

Abstract: The present disclosure relates to a multimode optical waveguide comprising a cladding and a core. The core of the multimode optical waveguide has a polygonal cross-section. The core forms a coil spun around the longitudinal axis of the cladding. The multimode optical waveguide may be used to realize a mode scrambler and a mode conditioner.

Abstract: Multi-cladding optical fibers to be used in the context of fiber amplifiers and fiber lasers are described herein. Embodiments of optical fibers include a rare-earth doped core into which the signal field is to be amplified. The doped core is surrounded by multiple claddings that guide the pump field to be absorbed by the reactive core material. The first cladding has a depressed refractive index to improve high-order mode bending losses without incurring significant fundamental mode bending losses.

Abstract: A fiber optic dosimeter probe for sensing radiation dose including an optical fiber having a free end and a sensitive end, a window having a sensitive side and a rear side; a radiation sensitive layer between the sensitive end of the optical fiber and a sensitive side of the window, the radiation sensitive layer being made of a material having an optical property that changes with absorbed radiation dose, an amount of the material corresponding to a predetermined sensitivity to radiation; wherein the window and the optical fiber have a near water equivalent interaction with radiation and are MR compatible.

Abstract: The invention provides a multi-clad fiber, with three claddings or more, where at least one intermediate cladding is inserted between an inner core and an outer core of the multi-clad fiber, for enlarging the cross-section of the fiber core or for increasing the dopant density in the core. The invention also provides an intermediate cladding having a multi-layer structure to better confine the pump power in a suitable pumping region of the fiber.

Abstract: An optical fiber comprises a singlemode core, and an inner cladding disposed around said core, an intermediate cladding disposed around said inner cladding and an outer cladding disposed around said intermediate cladding thereby forming a triple-clad geometry. The core is doped with rare-earth elements and represents the waveguide section of higher refractive index through which the signal is transmitted and amplified. A fiber coating is provided around said outer cladding. The core has a higher refractive index than said inner cladding, said inner cladding having a higher refractive index than said intermediate cladding, and said intermediate cladding having a higher refractive index than said outer cladding. The inner cladding has a fairly high refractive index to limit the numerical aperture (NA) of said core.

Abstract: The invention provides a multi-clad fiber, with three claddings or more, where at least one intermediate cladding is inserted between an inner core and an outer core of the multi-clad fiber, for enlarging the cross-section of the fiber core or for increasing the dopant density in the core. The invention also provides an intermediate cladding having a multi-layer structure to better confine the pump power in a suitable pumping region of the fiber.

Abstract: An optical fiber comprises a singlemode core, and an inner cladding disposed around said core, an intermediate cladding disposed around said inner cladding and an outer cladding disposed around said intermediate cladding thereby forming a triple-clad geometry. The core is doped with rare-earth elements and represents the waveguide section of higher refractive index through which the signal is transmitted and amplified. A fiber coating is provided around said outer cladding. The core has a higher refractive index than said inner cladding, said inner cladding having a higher refractive index than said intermediate cladding, and said intermediate cladding having a higher refractive index than said outer cladding. The inner cladding has a fairly high refractive index to limit the numerical aperture (NA) of said core.

Abstract: An all-glass multi-clad polygon-shaped convex optical fiber comprises a core having a core refractive index, a first glass cladding disposed around the core and having a first cladding refractive index that is lower than the core refractive index of the core, and at least a second glass cladding disposed around the first glass cladding and having a second cladding refractive index that is lower than the first cladding refractive index. The first and second claddings each have a convex polygonal cross-section, e.g. octagonal cross-sections. A method for fabricating such an optical fiber comprises the steps of: (i) mechanically machining an all-glass optical fiber preform having a core and a first cladding into an optical fiber preform having a convex polygonal cross-section; and (ii) fusing at least another glass cladding to the optical fiber preform, thereby resulting in the all-glass multi-clad polygon-shaped convex optical fiber.

Abstract: Disclosed is an optical device which combines a controlled level of attenuation, a high degree of wavelength insensitivity and a substantial decrease in modal interference problems. The optical device has a core having a core diameter and a core refractive index; an inner cladding having an inner cladding outer diameter less than ten times the core diameter and a refractive index less that the core refractive index; and an outer cladding having a refractive index higher that the inner cladding refractive index. At least one part of the core, the inner cladding or the outer cladding is doped with at least one absorbing element. Preferably, the core is doped with cobalt in an appropriate concentration, providing the same degree of attenuation at 1310 nm and 1550 nm, while also considerably reducing modal interference. The optical device can be used as an attenuator between a transmission fiber and a detection fiber or can be used to couple a transmission fiber directly to a detector.