In the examples provided herein, a mounting substrate includes a plurality of filter chips, where each filter chip includes a thin film filter coating on a surface of a different substrate, and the plurality of filter chips are positioned adjacent to each other in a row. A first edge of a first filter chip is flush with a first edge of the mounting substrate, a second edge of the first filter chip is flush with a second edge of the mounting substrate, and the first edge and second edge share a common corner. The flush edges of the first filter chip and the mounting substrate are reference surfaces, the plurality of filter chips are coupled to the mounting substrate via an epoxy, and the reference surfaces are to mate to connector reference surfaces on a connector.

A fiber optic cable and connector assembly is disclosed. In one aspect, the assembly includes a cable optical fiber, an optical fiber stub and a beam expanding fiber segment optically coupled between the cable optical fiber and the optical fiber stub. The optical fiber stub has a constant mode field diameter along its length and has a larger mode field diameter than the cable optical fiber. In another aspect, a fiber optic cable and connector assembly includes a fiber optic connector mounted at the end of a fiber optic cable. The fiber optic connector includes a ferrule assembly including an expanded beam fiber segment supported within the ferrule. The expanded beam fiber segment can be constructed such that the expanded beam fiber segment is polished first and then cleaved to an exact pitch length. The expanded beam fiber segment can be fusion spliced to a single mode optical fiber at a splice location behind the ferrule.

Optical fiber connections and their applications in downhole assemblies are described herein. The downhole assembly includes a well completion element with an end that couples with a corresponding well completion element. An optical fiber extends along at least a portion of the well completion element and transmits an optical signal using a first mode. The well completion element includes an optical fiber connector that is coupled to the optical fiber. The connector also includes a mode converter that receives the optical signal from the optical fiber and converts the optical signal from the first mode to a second larger mode. This second larger mode may be more robustly communicated to a corresponding optical fiber connector affixed to the corresponding well completion element.

A fiber coupling assembly for interfacing solid core and a hollow core optical fibers includes first and second fiber optic ferrules each having a bore between proximal and distal end faces thereof. At least one ferrule end face is non-perpendicular to longitudinal axes of the ferrules. A bore of one ferrule contains a hollow core optical fiber, and a bore of the other optic ferrule contains a solid core optical fiber with a mode field diameter (MFD) transition region, to bridge a MFD mismatch between the fibers. An air gap may be provided between at least portions of ferrules at an inter-ferrule region. A fiber optic ferrule includes a bore that is non-parallel with a longitudinal axis of the ferrule, and at least one end face that is non-perpendicular to the longitudinal axis, with an optical fiber in the bore optionally including a MFD transition region.

In various aspects, an optical connector with a built-in photodetector for detecting light in the optical connector; an adapter for detachably receiving an optical connector, comprising an electrode configured to electrically contact an electrode of the optical connector; a connection apparatus comprising an arrangement of adapters for detachably receiving a plurality of optical connectors, each adapter comprising an electrode configured to electrically contact an electrode of the respective optical connector; a system with an interface configured to make an optical connection with an optical connector and a processing unit configured to receive from the connector an indication and to generate a feedback signal indicative of said indication; and/or an optical connector responsive to light to generate an electrical signal is provided.

A ferrule with a fiber of this disclosure includes: a ferrule including a positioning hole, a plurality of fiber holes, and an endface perpendicular to an axial direction of the fiber holes; a lensed fiber with a GRIN lens that has been fusion spliced to a tip of an optical fiber; and a plate that can transmit light propagating through the optical fiber, the plate being attached to the endface of the ferrule, the plate being contacted against with an endface of the lensed fiber that has been inserted into each of the fiber holes, wherein the ferrule is formed with a recess that is depressed from the endface of the ferrule, a refractive index matching material is filled in a space surrounded with the plate and the recess.

A fiber optical superconducting nanowire detector with increased detector efficiency, fabricated directly on the tip of the input optical fiber. The fabrication on the tip of the fiber allows precise alignment of the detector to the fiber core, where the field mode is maximal. This construction maximizes the coupling efficiency to close to unity, without the need for complex alignment procedures, such as the need to align the input fiber with a previously fabricated device. The device includes a high-Q optical cavity, such that any photon entering the device will be reflected to and fro within the cavity numerous times, thereby increasing its chances of absorption by the nanowire structure. This is achieved by using dedicated cavity mirrors with very high reflectivity, with the meander nanowire structure contained within the cavity between the end mirrors, such that photons impinge on the nanowire structure with every traverse of the cavity.

A coupling device for an optical waveguide includes an optical waveguide connection for a first optical waveguide. The coupling device includes an optical filter arranged in a beam path between a laser light source and the optical waveguide connection which reflects light of a first wavelength range or a first polarization direction and transmits light of a second wavelength range or a second polarization direction.

Fiber optic connectors are provided that include a substrate having a groove therein, an optical fiber that is at least partly in the groove, an optical mode field converter or other focusing reflector that is positioned to receive an optical signal that is output from the optical fiber and a housing that surrounds the substrate and the optical fiber.

A fiber structure includes first and second optical fibers disposed such that tip portions thereof butt and a sheet-shaped saturable absorber sandwiched between the tip portion of the first optical fiber and the tip portion of the second optical fiber. Each of the tip portions of the first optical fiber and the second optical fiber has a core, a cladding provided around the core, and a ferrule provided around the cladding. The tip portion of the first optical fiber has a protruding shape protruding to a tip side. The saturable absorber has an adhering part at least adhering to the core of the first optical fiber and a non-adhering part present around the adhering part and not adhering to the tip portion of the first optical fiber.