Nano-particle based mode strippers for removing undesirable laser energy for laser systems. Nano-particle mode strippers having matched indices of refraction to the outer cladding remove cladding light converting it into heat. There are provided fibers having evanescent mode strippers having annular outer cores and claddings.

An optical connector ferrule comprises a body and a spacer. The body has a flat ferrule end surface facing a corresponding optical connector, and an optical fiber retaining hole opened in the ferrule end surface, an optical fiber being inserted and retained in the optical fiber retaining hole. The spacer is joined to the body, and at least a portion of the spacer is disposed on the ferrule end surface. The spacer defines an interval between the ferrule end surface and the corresponding optical connector, and includes an opening that allows an optical path extending from the optical fiber to pass therethrough.

A fiber optic cable assembly a termination assembly attached at the first and second ends of the ribbon. The ferrule has a polished contact surface that exposes ends of the optical fibers, and the contact surface forms an oblique angle relative to a plane normal to axes defined by the fibers. Each contact surface is slightly rotated clockwise or slightly rotated counter-clockwise with respect to the normal of the plane defined by the fiber array, so that when the second end of one cable assembly is mated to the first end of a second cable assembly in Key-Up to Key-Up Method B adapter configuration, the angled ferrule surfaces abut.

An air-gap HCF connector termination method and connector assembly for factory and field connector assembly termination for patch cables and trunk cables made from HCF, where in multitude of mechanisms can facilitate air-gap between the first and second HCF fiber end-faces, comprising preparing the HCF end-faces using appropriate cleaving methods including mechanical, ultrasonic and laser cleaving, such that the air-gap separation between first and second HCF's can be anywhere between 0.5-100 microns, where reflection at the connector interface is low with RL>35 dB, due to HCF propagation mode effective index matching with index of air.

An expanded beam ferrule includes a first ferrule halve having first reflective surfaces and a second ferrule halve having second reflective surfaces, which together retain optical fibers. The pair of reflective surfaces output collimated light parallel to the mid-plane of the ferrule. An external sleeve aligns the external surface of two similar ferrules, with corresponding second reflective surfaces of the ferrules facing each other. Output light from an optical fiber held in one ferrule is bent twice by the pair of reflective surfaces, with beam divergence after the first bent, and collimation after the second bent. The collimated light is transmitted to the facing second reflective surface in a facing second ferrule aligned by the sleeve, which is subject to optical reshaping in reverse to that undertaken in the first ferrule, so as to converge and focus light to input to the optical fiber held in the other ferrule.

A fiber optic connector contains a housing on which either a male or a female ferrule is mounted. A cable entering from one end of the fiber optic connector is spliced into multiple optical fibers. The tips of the optical fibers are coated with diamond-like carbon (DLC) thin films which are transparent for signal transmission within a wavelength range from 820 nm to 1625 nm. Two fiber optic connectors can be connected by intermating the male and the female ferrules, in which the two corresponding optical fibers are aligned with or without physical contact.

An expanded beam ferrule includes a first ferrule halve having first reflective surfaces and a second ferrule halve having second reflective surfaces, which together retain optical fibers. The pair of reflective surfaces output collimated light parallel to the mid-plane of the ferrule. An external sleeve aligns the external surface of two similar ferrules, with corresponding second reflective surfaces of the ferrules facing each other. Output light from an optical fiber held in one ferrule is bent twice by the pair of reflective surfaces, with beam divergence after the first bent, and collimation after the second bent. The collimated light is transmitted to the facing second reflective surface in a facing second ferrule aligned by the sleeve, which is subject to optical reshaping in reverse to that undertaken in the first ferrule, so as to converge and focus light to input to the optical fiber held in the other ferrule.

A ferrule includes a ferrule matrix, an optical fiber, and a dielectric reflective film. The optical fiber is disposed in an accommodating through hole of the ferrule matrix, and the dielectric reflective film covers an optical transmission surface of the optical fiber and a surface that is of the ferrule matrix and that faces a matching ferrule. The dielectric reflective film has a through hole, such that the dielectric reflective film does not shield a main optical path area of the optical transmission surface of the optical fiber. A reflective band of the dielectric reflective film includes at least a part of a communication band of the optical fiber. In this way, when light from the matching ferrule is transmitted to the ferrule matrix and the optical fiber, the dielectric reflective film reflects the light.

An optical connector ferrule comprises a body and a spacer. The body has a flat ferrule end surface facing a corresponding optical connector, and an optical fiber retaining hole opened in the ferrule end surface, an optical fiber being inserted and retained in the optical fiber retaining hole. The spacer is joined to the body, and at least a portion of the spacer is disposed on the ferrule end surface. The spacer defines an interval between the ferrule end surface and the corresponding optical connector, and includes an opening that allows an optical path extending from the optical fiber to pass therethrough.

An optical connector-equipped fiber (2A, 2B) has optical fibers (10a), a ferrule (11), guide holes, and a structure for regulating a space between end faces (11a) of the ferrules (11). A relative position between the end faces (11a) is fixed by guide pins being inserted into the guide holes. Normals with respect to leading end faces of the optical fibers are inclined with respect to optical axes of the optical fibers. MFDs of the optical fibers are gradually expanded toward the leading end faces and are maximized at the leading end faces. The optical axes of the pair of facing optical fibers that are optically coupled are not present on the same optical axis.