Provided are a monitoring device, a monitoring method, and an optical transmission system which are adapted for an increase in the number of cores of a multi-core optical fiber transmission path and suitable for crosstalk monitoring. The monitoring device monitors a multi-core optical fiber transmission path having a plurality of use cores and at least one or more non-use cores, and comprises: an applying means for applying, at a start point of the multi-core optical fiber transmission path, dithering to signal light propagating in the use cores; a monitoring means for monitoring the power of the non-use cores at an input side of a relay in the multi-core optical fiber transmission path; and a separating means for separating a monitoring result from the monitoring means into power components from the plurality of use cores.

A supporting member supports a peeled end portion formed at an end portion in longitudinal direction representing first direction of an optical fiber, the optical fiber including: a core wire including a core and a cladding; and a jacket configured to enclose the core wire, the jacket being removed at the peeled end portion to expose the core wire. The supporting member includes: a first member; a second member fixed to the first member; a housing portion provided between the first member and the second member, the housing portion extending along the peeled end portion and being configured to house the peeled end portion; and a processed member housed in the housing portion and provided around the peeled end portion, the processed member being configured to cause transmission or scattering of light leaking from the peeled end portion.

A supporting member supports a peeled end portion formed at an end portion in longitudinal direction representing first direction of an optical fiber, the optical fiber including: a core wire including a core and a cladding; and a jacket configured to enclose the core wire, the jacket being removed at the peeled end portion to expose the core wire. The supporting member includes: a first member; a second member fixed to the first member; a housing portion provided between the first member and the second member, the housing portion extending along the peeled end portion and being configured to house the peeled end portion; and a processed member housed in the housing portion and provided around the peeled end portion, the processed member being configured to cause transmission or scattering of light leaking from the peeled end portion.

The present disclosure relates to an optical fiber or the like that can be adapted to an optical transceiver for a short wavelength band of 850 nm or more and 1060 nm or less while maintaining compatibility with an SMF of the related art. An optical fiber of one embodiment includes a core, a cladding, and a resin coating, and has a mode field diameter of 8.2 .Math.m or more and 9.6 .Math.m or less at a wavelength of 1310 nm, a cable cutoff wavelength of an LP11 mode of 1060 nm or more and 1260 nm or less, and a cable cutoff wavelength of an LP02 mode of 1060 nm or less.

An optical fiber has a central axis. The optical fiber includes a core made of silica glass and extending along the central axis, a cladding made of silica glass and surrounding the core, the cladding extending along the central axis, and a coating layer made of resin and surrounding the cladding, the coating layer extending along the central axis. An outer diameter of the cladding varies along the central axis. A residual stress in a direction along the central axis varies along the central axis, the residual stress being averaged over the core and the cladding in a cross section perpendicular to the central axis. A deviation from an average value of the outer diameter and a deviation from an average value of the residual stress have signs opposite to each other.

An optical fiber has a central axis. The optical fiber includes a core made of silica glass and extending along the central axis, a cladding made of silica glass and surrounding the core, the cladding extending along the central axis, and a coating layer made of resin and surrounding the cladding, the coating layer extending along the central axis. An outer diameter of the cladding varies along the central axis. A residual stress in a direction along the central axis varies along the central axis, the residual stress being averaged over the core and the cladding in a cross section perpendicular to the central axis. A deviation from an average value of the outer diameter and a deviation from an average value of the residual stress have signs opposite to each other.

An optical fiber connection structure includes: a multi-core fiber; a plurality of single-core fibers; a first lens having a focal length of f1 (mm); and a second lens having a focal length of f2 (mm). A core pitch of the multi-core fiber is P1 (μm), a mode field diameter on the first end face of each core is MFD1 (μm), a core pitch of multiple single-core fibers is P2 (μm), a mode field diameter of a light beam on the second end face of each core is MFD2 (μm), and the following formulas are satisfied.

(P1/P2)×0.9≤f1/f2≤(P1/P2)×1.1, and

(P1/P2)×0.9≤MFD1/MFD2≤(P1/P2)×1.1

The present disclosure provides an optical fibre. The optical fibre includes a core extended from a central longitudinal axis to a first radius r1. Further, the optical fibre includes a first trench region extended from a second radius r2 to a third radius r3, a second trench region extended from the third radius r3 to a fourth radius r4 and a cladding region extended from the fourth radius r4 to a fifth radius r5.

A delivery fiber assembly suitable for delivering broad band light and including a delivery fiber and a connector member. The delivery fiber has a length, an input end for launching light, and a delivery end. The delivery fiber includes along its length a core region and a cladding region surrounding the core region, the cladding region includes a cladding background material having a refractive index N.sub.bg and a plurality of microstructures in the form of inclusions of solid material having refractive index up to N.sub.inc and extending in the length of the longitudinal axis of the delivery fiber, wherein N.sub.inc<N.sub.bg. The plurality of inclusions in the cladding region is arranged in a cross-sectional pattern including at least two rings of inclusions surrounding the core region. The connector member is mounted to the delivery fiber at a delivery end section of the delivery fiber including the delivery end.

A network device includes an enclosure, a multi-chip module (MCM), an optical-to-optical connector, and a multi-core fiber (MCF) interconnect. The enclosure has a panel. The MCM is inside the enclosure. The optical-to-optical connector, which is mounted on the panel of the enclosure, is configured to transfer a plurality of optical communication signals. The MCF interconnect has a first end coupled to the MCM and a second end connected to the optical-to-optical connector on the panel, for routing the plurality of optical communication signals between the MCM and the panel.