An optical communication device includes two optical transmitting devices, two optical receiving devices, an optical path component, and an optical fiber adapter. A first converging lens packaged in each of the optical transmitting devices converges a light beam emitted by a light source, and provides the converged light beam for the optical path component. A second converging lens packaged in each of the optical receiving devices converges a light beam from the optical path component, and provides the converged light beam for a photoelectric detection element. The optical path of the optical communication device is simplified and the process costs are reduced. In addition, the quantity of used lenses is reduced, correspondingly reducing the quantity of optical coupling dimensions between mechanical parts and improving production efficiency of combined passive optical network (Combo PON) products.

In some implementations, an optical fiber may include a core and a cladding surrounding the core. The core and the cladding may provide light guidance along the optical fiber in a light propagation direction. The core may have a taper in the light propagation direction in a section of the optical fiber. A diameter of the core may decrease independently of a diameter of the cladding in the section of the optical fiber.

The disclosure relates to an optical connection device reducing a connection loss between an SCF and an MCF. The optical connection device includes plural relay fibers and a capillary having third and fourth end faces. Each relay fiber includes a first core of Δ1, a second core of Δ2, and a cladding of Δ3. The capillary includes a tapered portion with an outer diameter ratio R of the fourth end face to the third end face of 0.2 or less. In each relay fiber, a value of Formula (V2−V1)/R falls within a range from 156% μm.sup.2 to 177% μm.sup.2, V1 (% μm.sup.2) is given by (π.Math.r1.sub.b.sup.2)×(Δ1−Δ2) by using a radius r1.sub.b (μm) of the first core, and V2 (% μm.sup.2) is given by (π.Math.r2.sub.b.sup.2)×(Δ1−Δ2) by using a radius r2.sub.b (μm) of the second core.

An optical coupler includes: input-type optical fibers; an output-type optical fiber; and radiant light processing units. The input-type optical fibers are bundled at leading end side to form a fiber bundle portion, and leading end portion of the fiber bundle portion is connected to the output-type optical fiber. In at least either the input-type optical fibers or the output-type optical fiber, a tapered portion is formed in which cross-sectional area is tapered to become narrower in light traveling direction indicating direction from the input-type optical fibers toward the output-type optical fiber. The number of the tapered portion is equal to or greater than two. Each radiant light processing unit is disposed to mutually overlap with one of the tapered portions or away from one of the tapered portions in the light traveling direction, and is disposed on outer periphery of the input-type optical fibers or the output-type optical fiber.

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.

A system and a method for optical sensing of single molecule or molecules in various concentrations are provided. The optical sensor system comprises a first fiber, a second fiber, a light source and a detection device. The first fiber and the second fiber are fused together to form an optical coupler. The first fiber serves as the passageway for the analyte, while the second fiber serves as the waveguide for the light that will interact with the said analyte. One end of the second fiber is connected to the light source (e.g. laser), and the opposite end is connected to the detection device (e.g. spectrometer). The analyte is introduced into the first fiber through one of its ends, and is allowed to flow through inside the hollow core of the said first fiber. When light is delivered through the input end of the second fiber, the evanescent light is formed in the optical coupler and is allowed to interact with the analyte in the first fiber. One scenario in this analyte-light interaction results in, for example, the generation of Raman emission that is used as the probing signal. The spectrum of the Raman emission is analyzed by the detection device to determine the presence of target molecule.

An electro-optic beam controller, material processing apparatus, or optical amplifier, and corresponding methods, can include an actively controlled, waveguide-based, optical spatial mode conversion device. The conversion device can include a coupler, which can be a photonic lantern, configured to combine light beams into a common light beam; a sensor configured to measure at least one characteristic of the common light beam; and a controller configured to modulate optical parameters of the individual, respective light beams to set one or more spatial modes of the common light beam. Actively controlled and modulated devices can be used to maintain a stable, diffraction-limited beam for use in an amplification, communications, imaging, laser radar, switching, or laser material processing system. Embodiments can also be used to maintain a fundamental or other spatial mode in an optical fiber even while scaling to kilowatt power.

The invention relates to an optical assembly for producing such. The invention also relates to the use of the optical assembly. Laser radiation received via a bundle of individual optical feed fibers is guided to a fiber laser fiber. Each feed fiber has a cladding layer surrounding the core of the fiber to provide total internal reflection in said core, and the cladding layers of the fibers are fused at least partially together to form a zone containing the cores of the feed fibers arranged in a cylindrical configuration inside said zone This configuration provides the shaping of an annular laser beam that can be fed into a fiber laser fiber having an annular light guiding zone and to present the annular laser beam e.g. to a workpiece.

A multichannel optical coupler array can include a coupler housing structure and longitudinal waveguides. At least one of the longitudinal waveguides can be a vanishing core waveguide having an inner vanishing core having a first refractive index (N-1), an outer core having a second refractive index (N-2), and an outer cladding having a third refractive index (N-3). A refractive index transition between N-1 and N-2 can have a function form N(r), where r is a transverse distance from the inner vanishing core center. The function N(r) can be a smooth function having a positive average of the second derivative or function N(r) can be a step function with at least one step approximating the smooth function. The coupler housing structure may have non-circular holes formed by convex-shaped housing structure elements.