Abstract: A device for providing an expanded mode field from a single mode optical waveguide is formed by fusing a length of single mode optical fiber with a length of fiber rod absent a cladding and adiabatically tapering the fused region. The length of single mode fiber has a core having a refractive index nco and a cladding having a refractive index ncl, wherein ncl<nco and wherein the cladding has an outer diameter ?. The length of fiber rod absent the cladding has a refractive index of the fiber rod is substantially the same as the cladding index ncl of the single mode optical fiber. The outer diameter of the length of fiber rod is ?, the same as the cladding diameter of the single mode fiber.

Abstract: A device for providing an expanded mode field from a single mode optical waveguide is formed by fusing a length of single mode optical fiber with a length of fiber rod absent a cladding and adiabatically tapering the fused region. The length of single mode fiber has a core having a refractive index nco and a cladding having a refractive index ncl, wherein ncl<nco and wherein the cladding has an outer diameter ?. The length of fiber rod absent the cladding has a refractive index of the fiber rod is substantially the same as the cladding index ncl of the single mode optical fiber. The outer diameter of the length of fiber rod is ?, the same as the cladding diameter of the single mode fiber.

Abstract: A method and system for the controlled irradiation of optical fibers in a process for fabricating optical fiber components such as Bragg grating devices. A beam of ultraviolet light is passed through a narrow slit in a mask to form a narrow beam of light. The narrow beam is focused into a line image that is directed onto the optical fiber to produce a photo-induced refractive index change in the optical fiber. The intensity and configuration of the line image as it impinges the optical fiber is controlled to reduce detrimental effects to the fiber.

Abstract: A two-channel optical fiber fused coupler comprising two optical fibers, each with a core and cladding, fused together at a narrow tapered waist. The first channel is at a wavelength of .lambda..sub.1 and the second channel is at a wavelength of .lambda..sub.2 where .lambda..sub.2 is longer than .lambda..sub.1. The coupler is fabricated to have a characteristic wavelength .lambda..sub.0 such that for wavelengths .lambda..sub.2 longer than .lambda..sub.0 coupling occurs and for wavelenghts .lambda..sub.1 shorter that .lambda..sub.0 the light at .lambda..sub.1 is core guided throughout the coupler and thus does not couple across.

Abstract: This invention relates to a method of creating an index grating in an optical fiber comprising disposing a slit mask containing one or more slits over a side of an optical fiber, illuminating the fiber through the slit mask by substantially monochromatic ultraviolet light for a short interval, whereby an index grating line is created and stored in the core of the fiber.