An optical multiplexing and demultiplexing method of the present disclosure includes arranging, face to face, a polished surface of a coated optical fiber whose side surface is polished to a core or a vicinity of the core and a polished surface of a plurality of optical waveguides that are arranged in parallel in a longitudinal plane and that each have different propagation constants and whose side surfaces are polished to cores corresponding one to one therewith or vicinities of the cores; and aligning the polished surface of the coated optical fiber and the polished surface of the plurality of optical waveguides so that desired branching ratio is obtained from one end of the coated optical fiber to the end, distal to the former end, of one optical waveguide of the plurality of optical waveguides by relatively moving the polished surface of the coated optical fiber and the polished surface of the plurality of optical waveguides.

An optoelectronic device includes a substrate and at least three emitters, which are disposed on the substrate and are configured to emit respective beams of light. A plurality of waveguides are disposed on the substrate and have respective input ends coupled to receive the beams of light from respective ones of the emitters, and curve adiabatically from the input ends to respective output ends of the waveguides, which are arranged on the substrate in an array having a predefined pitch. Control circuitry is configured to apply a temporal modulation independently to each of the beams of light.

The invention relates to an optical waveguide with two or more light-guiding cores (1a-1e) extending continuously along the longitudinal extension of the optical waveguide, parallel to one another and spaced apart from one another, from one end of the optical waveguide to the other, and with a first cladding (2) enclosing the cores (1a-1e). It is an object of the invention to provide a multicore optical waveguide for high-power operation with reduced system complexity compared to the prior art. This object is achieved by the invention in that the cores (1a-1e) are arranged relative to one another and are spaced apart from one another in such a way that the propagation modes of the light propagating in the optical waveguide at a working wavelength couple to one another, the length of the optical waveguide being selected such that the light coupled into only a single one of the cores (1a-1e) at one end of the optical waveguide first spreads to the other cores (1a-1e) during propagation through the optical waveguide and, after passing through the optical waveguide, leaves the optical waveguide again at the other end from a single core (1a) with at least 60%, preferably at least 75%, of the total light power propagating in the optical waveguide. The invention also relates to a laser system with such an optical waveguide as an optical amplifier, and a method for guiding light in an optical waveguide.

Configurations for an optical device used for light splitting and wavelength locking are disclosed. The optical device may be a two by three coupler with a first waveguide coupled to a second waveguide, and a third waveguide coupled to the second waveguide. The first and third waveguides may receive input light and optically couple light to the second waveguide. The output signals of the first, second, and third waveguides may have a constant phase difference from one another over a broadband wavelength range, which may allow for phase unwrapping. By phase unwrapping the output signals over an FSR and performing further phase unwrapping over the broadband wavelength range, a continuous signal may be produced and used to sequentially lock each wavelength of light emitted by light sources over the broadband wavelength range.

An example optical fiber signal mode conversion apparatus includes a non-single-mode optical fiber and a single-mode optical fiber. The single-mode optical fiber forms, with the non-single-mode optical fiber, a first coupling region and a second coupling region along a signal transmission direction in the non-single-mode optical fiber, where an effective refractive index of a fundamental mode signal of the single-mode optical fiber in the first coupling region is equal to an effective refractive index of a signal in a first mode, the signal in the first mode is coupled to a fundamental mode channel of the single-mode optical fiber, and an effective refractive index of the fundamental mode signal of the single-mode optical fiber in the second coupling region is equal to an effective refractive index of a signal in a second mode.

An optical waveguide device that enables single-mode coupling between cores to be coupled by controlling optical signal intensity variation due to an MPI. The optical waveguide device includes a first device end surface, a second device end surface, a waveguide, and a cladding layer. The waveguide has a first waveguide end surface and a second waveguide end surface, and light beams of a plurality of modes having different orders are guided. Further, the waveguide has one or more bent portions. The cladding layer has a refractive index lower than a refractive index of the waveguide. The waveguide has a waveguide length L of 5×10.sup.6 [nm] or more and 100×10.sup.6 [nm] or less, and has a structure in which an inter-mode group delay time difference Δβ1 satisfies a condition given by |Δβ1|≤½×10.sup.−12 [s]/L.

A photonic chip is disclosed that comprises a cladding material and an edge coupler. The edge coupler comprises a composite guiding structure that comprises a plurality of substantially parallel planar layers of optical guiding material. Each layer of the composite guiding structure extends into the cladding material, wherein each layer is aligned at a first edge of the photonic chip. The layers overlap along a first axis which is perpendicular to a plane of the planar layers of optical guiding material. The photonic chip is arranged for deposition of a waveguide on the cladding material, the waveguide being arranged to at least partially overlap along the first axis with a layer of the composite guiding structure.

Also disclosed is a method of manufacturing a photonic chip.

An integrated optical device fabricated in the back end of line process located within the vertical span of the metal stack and having one or more advantages over a corresponding integrated optical device fabricated in the silicon on insulator layer.

An object is to provide an optical communication system capable of controlling the output ratio by port and by wavelength for incident light of different wavelengths, a method of determining the split ratio of an uneven-split optical splitter for controlling the output ratio by port and by wavelength, and a transmission range determination method for the optical communication system. The split ratio determination method for an uneven-split optical splitter according to the present invention uses the melt-draw distance to adjust the split ratio of each fiber-optic splitter included in the uneven-split optical splitter such that the light output from the farthest ONUs among each of the ports connected under the ports B to M of the uneven-split optical splitter arrives with the minimum reception sensitivity at OLT receivers in a PON system.

There is described an optical fiber coupler generally having: a first optical fiber having a longitudinally extending multimode guiding region and a first taper portion longitudinally extending between first and second locations of the first optical fiber, the first taper portion having a dimension progressively decreasing along a first taper direction from the first location to the second location; a second optical fiber having a longitudinally extending multimode guiding region and a second taper portion longitudinally extending between third and fourth locations of the second optical fiber, the second taper portion having a dimension progressively decreasing along a second taper direction from the third location to the fourth location; and a coupling region where at least a portion of the first taper portion is optically coupled to a portion of the second taper portion, with the first and second taper directions being opposite to one another.