The invention relates to an assembly for optical coupling and for mode-selective separation or overlaying of optical fields, to the use thereof and to a method for producing a waveguide-based optical coupling element (10) which is designed for mode-selective separation or overlaying of optical fields at a further optical coupling point (410) of an optical component (400). The assembly comprises at least one waveguide-based optical coupling element (10) having at least three optical coupling points (100, 370, 380), and at least one optical component (400) having at least one further optical coupling point (410), wherein at least one of the optical coupling points 100, 370, 380) is optically connected to the at least one further optical coupling point (410), and wherein the waveguide-based optical coupling element (10) is designed to transmit light highly efficiently and bidirectionally between eigenmodes (120, 260) associated with the first optical coupling point (100) and the second optical coupling point (370), and between eigenmodes (130, 280) associated with the first optical coupling point (100) and the third optical coupling point (380).

The technology disclosed in this patent document can be used to implement an optical device for generating broadband optical pulses, including an optical waveguide having different waveguide structures at different locations along the optical waveguide and with varying dimensions or pressure gradient that change adiabatically along the different locations to enable non-linear four wave mixing over a broad spectral range.

As described herein, a mode field adapter (MFA) comprises a first fiber including a core associated with a fundamental mode field diameter and a cladding with a diameter that decreases toward a waist. The MFA comprises a second fiber including a core associated with a fundamental mode field diameter that matches the fundamental mode field of the first fiber at the waist and a cladding with a diameter that matches the diameter of the cladding of the first fiber at the waist and increases from the waist of the second fiber. The cladding of the first fiber may be adiabatically etched such that a core-to-cladding ratio of the first fiber changes over a length of the first fiber, and the core and the cladding of the second fiber may be adiabatically tapered such that a core-to-cladding ratio of the second fiber is constant over a length of the second fiber.

A coupler including a first end that optically couples with a plurality of single-core optical fibers, a second end that optically couples with a multi-core optical fiber, and a plurality of cores that each extends from the first end to the second end. The plurality of cores comprising a first core such that an outer diameter of the first core at the first end is larger than an outer diameter of the first core at the second end. The coupler further includes an outer cladding surrounding the plurality of cores and extending from the first end to the second end such that an outer diameter of the outer cladding at the first end is larger than an outer diameter of the outer cladding at the second end. Additionally, the coupler is a single, contiguous, conical glass member that tapers from the first end to the second end.

The invention relates to a microstructured optical fiber for generating incoherent supercontinuum light upon feeding of pump light. The microstructured optical fiber has a first section and a second section. A cross-section through the second section perpendicularly to a longitudinal axis of the fiber has a second relative size of microstructure elements and preferably a second pitch that is smaller than a blue edge pitch for the second relative size of microstructure elements. The invention also relates to an incoherent supercontinuum source comprising a microstructured optical fiber according to the invention.

The present technology provides an illustrative method for preparing fibers with desirable optical characteristics. The method includes providing a fiber that comprises a core layer and a cladding layer located around the core layer. The method further includes applying a nanostructure template to the cladding layer to form one or more photonic nanostructures having nanostructure scales and compressing the core layer to cause the core layer to bulge and form air gaps between the core layer and the one or more photonic nanostructures.

The present invention is directed to an optical fiber grating having a core, that is capable of controlling the light signal transmission therethrough by causing at least one of: at least one spectral peak, and/or at least one spectral dip in its core light transmission spectrum, corresponding to at least one predetermined wavelength. The inventive optical fiber diffraction grating comprises at least one longitudinally positioned structural element of a predetermined geometric profile and that is configured for diffracting a portion of the transmitted light signal at at least one predefined wavelength thereof, from at least one core mode into at least one of: at least one cladding mode and/or at least one radiating mode. Various embodiments of a number of novel techniques for fabrication of the inventive optical fiber diffraction grating are provided, inclusive of a novel technique for fabricating the inventive grating from a single material. Advantageously, such novel fabrication techniques rely on configuration of a desired geometric profile for the at least one structural element portion of the novel grating, each profile comprising a number of readily configurable parameters that can be selected and/or adjusted during fabrication, to produce a variety of novel fiber diffraction gratings, each having a corresponding specific desirable core transmission spectrum having at least one of: least one spectral peak, and/or at least one spectral dip therein, corresponding to at least one specific desired wavelength, dependent on the configuration of the applicable geometric profile.

A method for manufacturing a capillary usable as part of a hollow-core photonic crystal fiber. The method includes obtaining a capillary having capillary wall including a first wall thickness; and chemically etching the capillary wall to reduce the wall thickness of the capillary wall. During performance of the etching, a control parameter is locally varied along the length of the capillary, the control parameter relating to reactivity of an etchant used in the etching, so as to control the etched wall thickness of the capillary wall along the capillary length. Also disclosed is a capillary manufactured by such a method and various devices including such a capillary.

An optical system comprising: an optical assembly having a first optical surface and a rear optical surface, said optical assembly comprising at least three optical elements; an optical fiber comprising a core portion with a mode field diameter (MFD) expanded region optically coupled to the rear optical surface of the optical assembly, the optical fiber comprising a core region doped with chlorine in a concentration greater than 0.5 wt %, wherein the MFD expanded region is less than 5 cm in length, and has MFD at the fiber end coupled to the optical assembly that is a least 20% greater than the MFD at other end of the optical fiber; an optical signal source coupled to first optical surface of the optical assembly, such that the optical signal provided by the optical signal source is routed along an optical path formed by the optical assembly to the mode field diameter expanded region of said optical fiber.

An optical fiber may comprise a core doped with one or more active ions to guide signal light from an input end of the optical fiber to an output end of the optical fiber, a cladding surrounding the core to guide pump light from the input end of the optical fiber to the output end of the optical fiber, and one or more inserts formed in the cladding surrounding the core. Each of the one or more inserts may have a geometry (e.g., a cross-sectional size, a helical pitch, and/or the like) that varies along a longitudinal length of the optical fiber, which may cause an absorption of the pump light to be modulated along the longitudinal length of the optical fiber.