A device for inserting a plurality of optical beams into a single-mode optical fibre, a guiding structure of which is composed of a core with a first refractive index, a cladding with a second refractive index, and a coating with a third refractive index. The device includes an optical mixer configured to insert, into the single-mode optical fibre, the plurality of optical beams, at least one of which has a distribution of its radial and angular electromagnetic amplitude with a maximum amplitude peak in the cladding.

A method for displaying virtual content to a user, the method includes determining an accommodation of the user's eyes. The method also includes delivering, through a first waveguide of a stack of waveguides, light rays having a first wavefront curvature based at least in part on the determined accommodation, wherein the first wavefront curvature corresponds to a focal distance of the determined accommodation. The method further includes delivering, through a second waveguide of the stack of waveguides, light rays having a second wavefront curvature, the second wavefront curvature associated with a predetermined margin of the focal distance of the determined accommodation.

A multicore polarization-maintaining fiber 10 includes a plurality of cores 11, a cladding 12 surrounding the plurality of cores 11, and a plurality of stress applying parts 15 provided sandwiching the plurality of cores 11 in a region surrounded by the outer circumferential surface of the cladding 12. The cross sectional area of the stress applying part 15 is greater than the cross sectional area of the core 11. Stress applying parts 15 of the plurality of stress applying parts 15 are disposed in a first direction, and stress applying parts 15 of the plurality of stress applying parts 15 are disposed in a second direction different from the first direction.

Advantageously, at least one embodiment of the present disclosure comprises a polarization maintaining PROFA (“PM-PROFA”) coupler in which the polarization axes of the individual vanishing core waveguides thereof are oriented or aligned without the need to adjust the orientation of each individual VC waveguide.

An optical combiner includes: an optical fiber bundle formed by a plurality of first optical fibers; and a second optical fiber including an end surface joined to an end surface of the optical fiber bundle by fusion-splicing. The plurality of first optical fibers includes a predetermined first optical fiber and other first optical fibers. The predetermined first optical fiber is composed of one or more materials having higher softening temperatures than one or more materials of the other first optical fibers.

A planar waveguide having M×N number of cores and to which M number of fibers having N number of cores are connected. In the planar waveguide, in a connecting end surface of the planar waveguide to which the fibers are connected, P number of fibers having Q number of cores are connected, M×N is equal to P×Q, the planar waveguide includes a plurality of the cores arranged in a horizontal direction at the same height position in the planar waveguide, and a laminated structure having the cores at different positions in a height direction, so as to be aligned with the cores of the fibers connected to the connecting end surface, and the positions of the M×N number of cores are constant in the height direction, and change only in the horizontal direction.

A multi-core optical amplifying fiber device includes a plurality of multi-core optical amplifying fibers including a plurality of core portions doped with amplification medium and a cladding portion formed at outer peripheries of the plurality of core portions; and a connection portion connecting the core portions of the plurality of multi-core optical amplifying fibers to one another. The connection portion connects the core portions to restrain deviation, between every connected core portions, of amplification gain for a total length of the core portions connected one another.

An optical sensor includes an optical fiber inscribed with a repeated refraction pattern such that light scattered from a location on the optical fiber is scattered at multiple frequencies in a range of frequencies. The inscribed patterns overlap at every measurement point along at least a portion of the length of the sensor. An optical sensing system including control circuitry coupled to the optical fiber detects measurement scatter data from the optical fiber over the range of frequencies, determines a change in the detected measurement scatter data over the range of frequencies, and extracts a parameter describing a state of the optical fiber from the determined change in the detected measurement scatter data. The sensor may be made by inscribing a first light refracting pattern on the optical fiber at every measurement point along at least a portion of the length of the sensor and inscribing a second light refracting pattern on the optical fiber that overlaps the first inscribed light refracting pattern at every measurement point along at least that portion of the length of the sensor.

A multicore fiber is provided. The multicore fiber includes a plurality of cores spaced apart from one another, and a cladding surrounding the plurality of cores and defining a substantially rectangular or cross-sectional shape having four corners. Each corner has a radius of curvature of less than 1000 microns. The multicore fiber may be drawn from a preform in a circular draw furnace in which a ratio of a maximum cross-sectional dimension of the preform to an inside diameter of the preform to an inside diameter of the draw furnace is greater than 0.60. The multicore fiber may have maxima reference surface.

The present embodiment relates to a CMCF including a structure to achieve more efficient reduction in transmission loss by suppressing decrease in concentration of alkali metal due to diffusion of alkali metal. In the CMCF including a plurality of cores, a power coupling coefficient h between adjacent cores is set to 1×10.sup.−3/m or more, to maintain an optical coupling state between the adjacent cores. In addition, alkali metal contributing to reduction in transmission loss is added to each of the cores such that a stress maximum value σ_.sub.max between adjacent cores has a negative value.