Optical systems that employ concentric multi core fibers (MCFs) are discussed. Some of the systems discussed are based on the use of a concentric MCF that has a single mode core, capable of carrying a broadband data signal, and a multimode core, which carries optical signals that do not require as high a bandwidth as the broadband data signal. In one embodiment, the multimode core carries system management data. In another embodiment, the multimode core carries a high power optical signal that provides remote power. In another embodiment, the multimode core carries a pump signal for a downstream fiber amplifier. In yet another embodiment, the multimode core carries an optical signal, for example visible light, that can be used to verify connectivity.

An object of the present invention is to provide a core position recognition method, a connection method, and a connection apparatus that can simplify connection operations, and reduce rotational displacement and positional displacement. The connection apparatus according to the present invention includes a function capable of acquiring the rotation amount of an MCF during the bonding/fixing step. Specifically, the connection apparatus of the present invention uses an MCF with lines drawn on a side surface thereof, thereby recognizing the rotation amount of the MCF from the side surface, and calculating the absolute positions of the cores. The connection apparatus according to the present invention can recognize the absolute position s of the cores from a side image of an MCF in a state in which the MCF has been rotated. By forming a waveguide on a glass substrate serving as a connection destination so as to match the absolute positions of the cores, the rotational and positional displacements of the MCF can be eliminated, thus making it possible to reduce the connection loss.

An optical fiber sensor with high sensitivity and high spatial resolution is described. The optical fiber sensor includes a multicore fiber having cores configured to permit crosstalk between cores. Crosstalk corresponds to transfer of an optical signal from a core to another core and is used as a mechanism for sensing the external environment surrounding the multicore optical fiber. The degree of crosstalk depends on the relative refractive index profile of the cores and surrounding cladding, as well as on the spacing between cores. The external environment surrounding the multicore optical fiber and changes therein influence crosstalk between cores to permit sensing. The relative refractive index profiles of the cores are also configured to provide a group delay difference for optical signals propagating in different cores. The group delay difference facilitates the position of an external perturbation along the length of the multicore optical fiber.

A fiber optic assembly is provided including a support substrate having a substantially flat surface and a signal-fiber array supported on the support substrate. The signal-fiber array includes a plurality of optical fibers. At least some of the optical fiber of the plurality of optical fibers includes a first datum contact disposed between the optical fiber and an adjacent optical fiber and each of the optical fibers of the plurality of optical fibers includes a second datum contact disposed between each of the optical fibers of the plurality of optical fibers and the support substrate. A first datum surface is disposed at a top surface of each of the plurality of optical fibers opposite the support surface.

The invention is related to devices that couple light into and out of concentric multicore fibers (MCFs). One embodiment of the invention is directed to a multiplexing/demultiplexing coupler, formed using at least two diffractive optical elements, so that light from one of the cores of the concentric MCF exits the coupler along a first axis and the light from another of the cores of the MCF exits coupler along another axis displaced form the first axis. In another embodiment, an add/drop filter includes at least one diffractive optical element, and directs light from one core of the concentric MCF to one fiber and light from one or more other cores of the concentric MCF to another fiber. In another embodiment, a mixing coupler transmits light from inner and outer cores of a first concentric MCF respectively to outer and inner cores of a second concentric MCF.

Disclosed is an interferometric fiber optic sensor for detecting chemical substances. A light source a detector are connected to a light dividing element in an optical path with an optical fiber segment. The optical fiber segment is further optically coupled with a measuring element across a residual cavity. The measuring element further has a face adapted to be exposed to a test substance that may contain a chemical substance to be detected. The optical fiber segment and the measuring element can be held together so that there is only the residual cavity between them. The optical fiber segment is contained, at least along part of its length, within a capillary. A first end part of the capillary is joined with the measuring element while another portion of the capillary is joined or clenched on the optical fiber segment, so that the capillary, the optical fiber segment and the measuring element together form a fiber optic measuring probe as a part of the optical path with the light source and detector.

A microstructured multicore optical fibre (MMOF) includes a cladding in which a plurality of basic cells are formed that run along the MMOF. Each of the basic cells includes a core, and at least one of the basic cells is surrounded by a plurality of longitudinal areas that run parallel to the core along the MMOF and are arranged in a hexagonal arrangement around the core. The longitudinal areas are spaced by a lattice constant Λ. Sides of the hexagon can be shared with adjacent basic cells.

An optical assembly may comprise an input fiber to provide a beam, a process fiber comprising a ring-shaped outer core surrounded by a cladding, and a first beam shifter arranged to receive the beam from the input fiber and to shift the beam spatially to illuminate the ring-shaped outer core of the process fiber. The optical assembly may further comprise a second beam shifter arranged to receive the beam from the first beam shifter and to add skew to the beam that is launched into the ring-shaped outer core of the process fiber.

A multicore fiber includes: a cladding; a center core at a center of the cladding; and seven or more outer cores disposed at rotationally asymmetric positions on a circumference centered at the center of the cladding. Angles formed by adjacent ones of lines connecting the center core and respective ones of the outer cores are all 60° or less.

A polarization-maintaining multi-core fiber includes a plurality of fiber core areas and a main outer cladding. The fiber core areas include one central fiber core area, and two or more than two outer fiber core areas equidistantly and uniformly arranged around the central fiber core area that is a polarization-maintaining fiber core area. Each outer fiber core area includes a fiber core and an inner cladding surrounding a core layer. A portion outside the fiber core areas is the main outer cladding. The fiber can greatly enhance spectral efficiency of an optical transmission system, and improve fiber communication capacity. The arrangement of the polarization-maintaining fiber core area provides a waveguide structure with a function of maintaining polarized light, which can be used for transmission of local light.