Abstract: An optical connection structure which permits easy and automatic alignment between the optical axes of optical fibers and the optical axes of cores of an optical waveguide, and a production method which ensures that an optical waveguide for the optical connection structure can be efficiently produced with higher dimensional accuracy are provided. An over-cladding layer of the optical waveguide includes an extension portion provided in a longitudinal end portion thereof, and optical fiber fixing grooves are provided in the extension portion as extending along extension lines of cores coaxially with the cores and each having opposite ends, one of which is open in an end face of the extension portion and the other of which is closed. Optical fibers are fitted and fixed in the respective optical fiber fixing grooves. The over-cladding layer further includes a boundary portion (6) provided between the other closed ends of the optical fiber fixing grooves and the cores.

Abstract: An optical transmission module has an optical transmission path in which optical transmission is performed between a first circuit board and a second circuit board disposed opposite the first circuit board. The optical transmission path has a folded structure having a bending radius. A circumferential portion drawn by the bending radius is provided substantially perpendicular to board surfaces of the first circuit board and the second circuit board.

Abstract: An optical component includes a multicore optical fiber and an I/O optical fiber. The multicore optical fiber has longitudinally extending cores within a common cladding. The cores are arranged on a circumference of a circle centered at a fiber axis in an end face of the multicore optical fiber. Both end faces of the multicore optical fiber are connected to each other such that the cores of the multicore optical fiber are optically connected to each other. Both end faces of the multicore optical fiber are adapted to rotate relative to each other about the fiber axis.

Abstract: An optical antenna and methods for optical beam steering are provided. One optical planar antenna includes a linear waveguide within a substrate and having a fiber interface. The optical planar antenna also includes a planar waveguide within the substrate, a first diffractive optical element configured to couple the linear waveguide to the planar waveguide and a second diffractive optical element configured to couple the planar waveguide to free space.

Abstract: A low-profile optical communications module is provided that has two generally flat optical connector modules that slidingly engage one another to allow optical signals to be coupled between the optical connector modules. Because of the generally flat shapes of the optical connector modules and the manner in which they slidingly engage on another, the optical communications module has a very low profile that makes it well suited for use in thin devices, such as laptop and notebook computers and other electronics devices.

Abstract: An optical switch structure and a method for fabricating the optical switch structure provide at least two ring waveguides located and formed supported over a substrate. At least one of the at least two ring waveguides includes at least one PIN diode integral with the ring waveguide as a tuning component for an optical switch device that derives from the optical switch structure. The PIN diode includes different doped silicon slab regions internal to and external to the ring waveguide, and an intrinsic region there between that includes the ring waveguide. The method uses two photolithographic process steps, and also preferably a silicon-on-insulator substrate, to provide the ring waveguides formed of a monocrystalline silicon semiconductor material.

Abstract: A system for routing optical signals includes a waveguide array and a cylindrical resonator lying across the waveguide array, the cylindrical resonator having independently controllable tangential interfaces with each of the waveguides within the waveguide array. A method of selectively routing an optical signal between waveguides includes selecting a optical signal to route; determining the desired path the optical signal; tuning a first controllable interface between a cylindrical resonator and a source waveguide to extract the optical signal from the source waveguide; and tuning a second independently controllable interface between the cylindrical resonator and a destination waveguide to deposit the optical signal into the destination waveguide.

Abstract: An optical modulator includes a modulator that modulates an input light of light by using an input signal. The optical modulator further includes a compensation circuit that compensates the phase of a signal light in accordance with an input current, the signal light being the input light modulated by the modulator. The optical modulator further includes a detector that detects the difference between the phase of the signal light compensated by the compensation circuit and the phase of an input signal that is input to the modulator. The optical modulator further includes an adjustment circuit that adjusts, in accordance with the phase difference detected by the detector, the input current that is input to the compensation circuit.

Abstract: Disclosed is an optical delay element that makes use of a line-defect waveguide of a photonic crystal, in which long optical delay time and small group speed dispersion are rendered compatible with each other and in which waveform distortion that might otherwise be produced in processing an ultra-high speed signal is eliminated. Two line-defect waveguides 5 and 11, having different pillar diameters and group velocity dispersions of opposite signs, are interconnected by a line-defect waveguide 8, the pillar diameters of which are gradually varied from one 5 of the line-defect waveguides to the other line-defect waveguide 11, such as to compensate for group speed dispersion as well as to maintain an optical delay effect.

Abstract: An optical multiplexing/demultiplexing device comprise a plurality of propagation waveguides comprising an input waveguide capable of receiving input light and an output waveguide outputting light of a given wavelength among the wavelengths included in the input light and resonance waveguide that is an optical waveguide provided between adjoining waveguides and extends in a longitudinal direction in which both the adjoining waveguides extend, wherein the adjoining waveguides are an adjoining pair among the propagation waveguides. The distance between the resonance waveguide and each of the adjoining waveguides of the resonance waveguide and a length in the longitudinal direction of the resonance waveguide are set so as to form a transition part, wherein when a light comprising a transition wavelength set to the transition part passes through the transition part of one of the adjoining waveguides, the light of the transition wavelength component shifts to the other adjoining propagation waveguide.

Abstract: A device, system, and method for the electro-optic modulation of light. The device includes a substrate having a first ring waveguide and a second ring waveguide on the surface. The device includes a first p-doped region inside the first ring waveguide and a second p-doped region inside the second ring waveguide. The device includes a first n-doped region interposed between the first ring waveguide and the second ring waveguide, a second n-doped region outside the first ring waveguide, and a third n-doped region out the second ring waveguide. The device includes a first linear waveguide located on the surface adjacent to the first ring waveguide and the second ring waveguide. The device includes a fourth n-doped region on the surface located adjacent to the first linear waveguide. The device includes a control circuit configured to modulate light in the first linear waveguide using a voltage source and electrical connections.

Abstract: To provide a photoelectric converter capable of reducing the height of the device. The photoelectric converter includes: a light emitting element or a light receiving element; an IC circuit for transmitting/receiving an electric signal to/from the light emitting element or the light receiving element; a mount substrate adapted to be mounted on one surface from the side on which the light emitting element emits light, or the side on which the light receiving element receives light; an electric connector adapted to be provided on the one surface or the other surface of the mount substrate, and to be attached and detached to and from an external connector; and a waveguide adapted to be provided on the mount substrate along the one surface or the other surface of the mount substrate, and to be optically coupled to the light emitting element or the light receiving element.

Abstract: An optical transmission system includes an optical emitting source, a plurality of optical fiber connectors, a first optical fiber, a plurality of second optical fibers, a plurality of third optical fibers, and a plurality of optical receiving terminals. The optical emitting source is configured for emitting optical signals. The first optical fiber connects the optical emitting source to one of the optical fiber connectors. Each of the second optical fibers is connected between two adjacent of the optical fiber connectors. Each of the third optical fibers is connected between a respective one of the optical fiber connectors and a respective one of the optical receiving terminals.

Abstract: An optical device may include a substrate and an optical waveguide carried by the substrate and having a notch therein defining a feed optical waveguide and a longitudinal optical waveguide section on opposite longitudinal sides of the notch. The optical device may also include a transverse optical waveguide section carried by the substrate and transversely aligned with the feed optical waveguide adjacent the notch. The optical device may further include an elastomeric waveguide switch body configured to be moved between a first position within the notch and operative to switch light from the feed optical waveguide to the longitudinal optical waveguide section, and a second position removed from the notch and operative to switch light from the optical waveguide to the transverse optical waveguide section.

Abstract: A light transmission assembly includes a light circuit board and a light transmission module. The board is embedded with waveguide layers, the waveguides layers includes core wires and shielding lays sandwiching the core wires, the waveguide layers defines a second light port portion of which the core wires defines vertical end faces. The light transmission module includes a base and a first light port portion projecting from a first face of the base, the first light port portion defines vertical end faces, the base defines a slanting surface at a second face opposite to the first face thereof. The first and second light port portions are aligned with each other when the light transmission module is coupled with light circuit board so that light lines go directly from the core wires through the light transmission module and reflect at the slant surface.

Abstract: A method for imaging light from a plurality of laser diodes (504) onto a multi-channel light valve (6) includes applying light from the plurality of laser diodes to a fiber waveguide (508) wherein each of the plurality of laser diodes is coupled to the fiber waveguide; guiding the light from the fiber waveguide through a planar lightwave circuit (PLC) (408) wherein light from the plurality of laser diodes is combined in the PLC; splitting the combined light in the PLC; and directing the split light from the PLC onto the multi-channel light valve.

Abstract: A connector assembly for optically coupling a first optical device mounted on a first substrate to a second optical device mounted on a second substrate, where the first and second substrates are orthogonally oriented to each other, is presented. The connector assembly includes two connectors. The first connector has an optical waveguide array. The optical waveguide array further includes multiple parallel optical waveguides that are continuously redirected by a mirror oriented at a 45 degree angle to the optical waveguides. Likewise, the second connector also has an optical waveguide array further include multiple parallel optical waveguides continuously redirected by a mirror oriented at a 45 degree angle to the optical waveguides. The first connector is oriented orthogonally to the second connector and the first and second connectors are optically welded together in a back-to-back configuration.

Abstract: Beam couplers and splitters are disclosed herein. An embodiment of a beam coupler and splitter includes a first waveguide including a bevel and a bend, and a second waveguide including a bevel complementarily shaped to the first waveguide bevel. The first waveguide bevel is configured to totally internally reflect at least some light incident thereon. The second waveguide is coupled to the first waveguide such that i) the second waveguide bevel is adjacent to at least a portion of the first waveguide bevel, and ii) a predetermined coupling ratio is achieved.

Abstract: A waveguide mounting portion (102) is formed at one portion of an optical fiber (100). The waveguide mounting portion (102) is formed by cutting away one portion of the optical fiber (100) in the direction of extension of the optical fiber (100) at a cross-section passing through a core (120) of the optical fiber (100). A first concave portion (122) is formed in the waveguide mounting portion (102). The first concave portion (122) is formed by removing the core (120) of the optical fiber (100). A ridge type waveguide (220) is inserted into the first concave portion (122).

Abstract: There is provided a SSC chip whose yield may be improved and whose processing steps may be simplified as compare to those of a prior art PLC chip having a light waveguide circuit to which a spot-size converter (SSC) is added, a fiber array attached with the SSC chip, a PLC module attached with the SSC chip and a method for manufacturing the SSC chip. The SSC chip has four spot-size converters and is fabricated separately from a PLC chip. Each SSC has a straight waveguide having the same core width and height with an end of an input/output waveguide of the PLC chip, a horizontally tapered waveguide in which the core width is enlarged in a tapered shape in the horizontal direction from the core width of the straight waveguide, a vertically tapered waveguide in which the core height is enlarged in a tapered shape in the vertical direction from the core height of the horizontally tapered waveguide and a spot-size enlarged portion whose core width and core height are both enlarged.

Abstract: An embodiment of the invention relates to an optical resonator. The optical resonator includes an input optical waveguide and a closed loop coupled to the input optical waveguide. The closed loop is adapted to receive light from the input optical waveguide, wherein the closed loop includes at least one hole formed within a portion of the closed loop.

Abstract: An electro-optic modulator comprising a first region of silicon material and a second region of non-silicon material. The second region may at least partially overlap the first region to create a lateral overlap region. An optical waveguide of the modulator may be included in the lateral overlap region and comprise of both the silicon and the non-silicon material. The refractive index of at least one of the silicon material and the non-silicon material within the optical waveguide may change based on an electrical difference applied between electrical contacts of the modulator.

Abstract: Techniques for designing optical devices that can be manufactured in volume are disclosed. In an exemplary an optical assembly, to ensure that all collimators are on one side to facilitate efficient packaging, all collimators are positioned on both sides of a substrate. Thus one or more beam folding components are used to fold a light beam up and down through the collimators on top of the substrate and bottom of the substrate.

Abstract: There is provided an optical device including a first optical waveguide of a directional coupler, a second optical waveguide connected to the first optical waveguide and which guides light, and a common cladding of the first and second optical waveguides, wherein: the common cladding of the first and second optical waveguides includes a first cladding and a second cladding, the second cladding being provided on the first cladding and having a higher refractive index than the first cladding; the first optical waveguide and the second optical waveguide are formed continuously on the first cladding with a constant width and a constant height and are integrated with each other, and a cross sectional shape of each of the first and second optical waveguides is a rectangular shape that is longest in a direction orthogonal to a surface of the first cladding.

Abstract: An optical transmitter includes three or more emission optical fibers that are three-dimensionally arranged, a single reception optical fiber, and an optical path converting component to optically couple the emission optical fibers to the reception optical fiber. The optical path converting component includes optical transmission portions that are optically coupled to the three or more emission optical fibers one to one, respectively, and optically coupled commonly to the single reception optical fiber. Entry ends of the optical transmission portions are aligned with exit ends of the three or more emission optical fibers, respectively. Exit ends of the optical transmission portions are aligned, as a whole, with an entry end of the single reception optical fiber. The exit ends of the optical transmission portions are arranged substantially parallel to one another and in closer proximity to one another than the entry ends of the optical transmission portions.

Abstract: In aspects of the invention, photonic crystal fiber and a GI fiber form an emission portion of a first single-mode optical fiber. Specifically, in some aspects of the invention, the photonic crystal fiber is connected to an emission-side end face of the first single-mode optical fiber. The GI fiber can connected to an emission-side end face of the photonic crystal fiber. The refractive index of the GI fiber in the direction in which light is concentrated changes in the radial direction.

Abstract: The present invention provides improved collimating lens assemblies (32) which include: a singlemode fiber (38) terminating in a distal end; a step-index multimode fiber (44) having a proximal end abutting to the singlemode fiber distal end, and having a distal end; a graded-index multimode fiber (45) having a proximal end abutting the step-index multimode fiber distal end, and having a distal end; and a collimating lens (34) longitudinally spaced from the graded-index multimode fiber distal end by an intermediate air gap (43), and operatively arranged to collimate light rays emanating from the graded-index multimode fiber distal end. The improved collimating lens assembly is characterized by the fact that there is no epoxy, silicone gel or index-matching material between the graded-index multimode fiber distal end and the collimating lens.

Abstract: Tunable resonator systems and methods for tuning resonator systems are disclosed. In one aspect, a resonator system includes an array of resonators disposed adjacent to a waveguide, at least one temperature sensor located adjacent to the array of resonators, and a resonator control electronically connected to the at least one temperature sensor. Each resonator has a resonance frequency in a resonator frequency comb and channels with frequencies in a channel frequency comb are transmitted in the waveguide. Resonance frequencies in the resonator frequency comb are to be adjusted in response to ambient temperature changes detected by the at least one temperature sensors to align the resonance frequency comb with the channel frequency comb.

Abstract: An optical microresonator is configured as an optical microbubble formed along a section of an optical microcapillary. The curvature of the outer surface of the microbubble creates an optical resonator with a geometry that encourages the circulating WGMs to remain confined in the central region of the bubble, creating a high Q optical resonator. The resonator may be tuned by modifying the physical properties of the microbubble, allowing the resonator to be used as an optical filter. The resonator may also be used as a sensor or laser by introducing the material to be sensed (or the active laser material) into the microcapillary along which the microbubble is formed.

Abstract: The invention relates to a device for coupling an optical fiber and a nanophotonic component formed on a first substrate, wherein the device comprises: an intermediate component formed on a second substrate including a first wave guide adapted for receiving light from the optical fiber and for transmitting the same to a first diffraction grating independently from the polarization of the incident light; second and third diffraction gratings formed on the first substrate and coupled to the nanophotonic component, the first diffraction grating being adapted to provide the first and second light beams respectively towards the second diffraction grating and the third diffraction grating, the first and second beams having perpendicular polarizations.

Abstract: The present invention provides a hybrid integrated optical module having a high coupling efficiency by suppressing a connection loss between waveguides. A hybrid integrated optical module according to an embodiment of the present invention is an optical module which integrates a semiconductor chip and a PLC chip. The semiconductor chip has a semiconductor waveguide and is mounted on a Si bench. The PLC chip includes a PLC substrate and an optical waveguide formed on the PLC substrate. An end face of the semiconductor chip protrudes from an end face of the Si bench toward the PLC chip side by a protrusion amount X. Gap adjustment (adjustment of a distance D) between the semiconductor waveguide and the optical waveguide becomes possible by setting a position where the end face of the semiconductor chip is brought into contact with an end face of the PLC chip to be a reference position (zero point).

Abstract: Embodiments relate to a branching waveguide circuit where two or more waveguides branch from a main waveguide defining between them an intermediate region ranging from said main waveguide. The intermediate region comprises a plurality of holes of cladding material extending from the top of the core layer into intermediate material, said holes being arranged so that the depth of said holes increases away from said main waveguide with an average slope of the hole depth versus distance to main waveguide. This way, loss due to transition between the main and branching waveguides may be reduced.

Abstract: A light guide of the tapered-waveguide type includes an input slab for expanding a projected image between an input end and an output end; and a tapered output slab arranged to receive rays from the said output end of the input slab, and to emit them at a point on its face that corresponds to the angle at which the ray is received. The taper is calculated so that all rays injected into the input end undergo the same number of reflections before leaving the output face. The thickness of the input slab light guide is greater in the transverse direction away from the center line, so that light travelling at the critical angle from the input face of the slab waveguide towards the output waveguide bounces the same number of times in the input slab, regardless of its fan-out angle, in order to further reduce image distortion.

Abstract: A side-hole optical cane for measuring pressure and/or temperature is disclosed. The side-hole cane has a light guiding core containing a sensor and a cladding containing symmetrical side-holes extending substantially parallel to the core. The side-holes cause an asymmetric stress across the core of the sensor creating a birefringent sensor. The sensor, preferably a Bragg grating, reflects a first and second wavelength each associated with orthogonal polarization vectors, wherein the degree of separation between the two is proportional to the pressure exerted on the core. The side-hole cane structure self-compensates and is insensitive to temperature variations when used as a pressure sensor, because temperature induces an equal shift in both the first and second wavelengths. Furthermore, the magnitude of these shifts can be monitored to deduce temperature, hence providing the side-hole cane additional temperature sensing capability that is unaffected by pressure.

Abstract: A system having an optical-coupling region for evanescently coupling light between first and second optical-waveguiding structures is disclosed. Within the optical-coupling region, the first and second optical-waveguiding structures exhibit mirror symmetry with respect to each other across or about at least one of a plane and an axis and include a segment that is not straight.

Abstract: A multi-channel dispersion compensator comprising an optical signal waveguide that forms an input end for receiving an optical signal and an output end for providing a filtered optical signal. The multi-channel dispersion compensator also includes a series of closed-loop resonators providing frequency delay to at least one channel of the optical signal. The optical signal waveguide and each closed-loop resonator form a tunable coupler having a coupling value. The coupling value for each tunable coupler is selected to minimize constant dispersion and linear slope dispersion of the optical signal. Methods of fabrication and use are also described.

Abstract: An optical mode transformer comprises a first waveguide including a first core, a first cladding and an end facet configured to be coupled to an optical fiber. A second waveguide comprises a second core and a second cladding, and is arranged with respect to the first waveguide so as to realize an evanescent optical coupling with the first waveguide. The second core comprises a tapered region, in at least a portion of which the evanescent coupling takes place. The first core and the second core are separated by a gap. A first refractive index contrast of the first waveguide is less than a second refractive index contrast of the second waveguide.

Abstract: Disclosed are resonant optical modulators, and methods of use thereof, that achieve constant photon populations in the resonator by simultaneously modulating at least two variable modulation parameters.

Abstract: An innovative micro-size photonic switch is presented. The photonic switch is comprised of: a mirror having a reflecting surface; an input waveguide; and an output tapered waveguide structure. The photonic switch further includes a switching mechanism disposed adjacent to the reflecting surface and operable to change the refractive index along the reflective surface and thereby shift the angle at which the optical signal reflects from the mirror. More specifically, the switching mechanism may operate to change concentration of free carrier distribution along the reflective surface and thereby displace the effective reflecting interface of the mirror. In this way, the optical signal can be directed to one of two or more output ports of the output tapered waveguide structure and finally exited by one output waveguide channel that is connected to the selected port of the output tapered waveguide structure.

Abstract: Systems, devices, and techniques are disclosed relating to dispersion devices that include a slot waveguide coupled with another waveguide such as a strip waveguide. For example, one or more structural parameters can be obtained for a dispersion device, including a slot waveguide coupled to a strip waveguide, to cause the dispersion device to produce dispersion, having a dispersion profile, for an electromagnetic wave propagated through the dispersion device, the one or more structural parameters including one or more of a slot thickness for a slot of the slot waveguide or a spacing thickness between the slot waveguide and the other waveguide; and making the dispersion device, including the slot waveguide and the other waveguide, according to the structural parameters.

Abstract: Provided are optical coupling devices and silicon photonics chips having the same. the optical coupling device may include a lower layer having a first region and a second region, a first core layer disposed on the lower layer, the first core layer including first and second waveguides disposed on the first and second regions, respectively, a clad layer covering the first waveguide, and a second core layer interposed between the clad layer and the lower layer to cover the second waveguide. The second waveguide has a width decreasing with increasing distance from the first region and a vertical thickness greater than that of the first waveguide.

Abstract: An arrayed waveguide grating optical multiplexer/demultiplexer according to the present invention including an input channel waveguide, an input slab waveguide, an arrayed waveguide, a polarization dependence eliminating means, an output slab waveguide, a temperature compensating means, and an output channel waveguide is characterized in that the temperature compensating means compensates for the temperature dependence of the optical path lengths in the channel waveguides of the arrayed waveguide, and the polarization dependence eliminating means eliminates the temperature dependence and the polarization dependence of the arrayed waveguide grating optical multiplexer/demultiplexer at the same time.

Abstract: An optical connector for reducing attenuation in a cable assembly. A support within the connector precludes bending of exposed fiber within the connector that might otherwise occur when the cable assembly is exposed to environmental conditions involving cyclic temperatures. In some embodiments, optical connector assemblies include an optical fiber jacket surrounding a plurality of optical fibers and a support member adjacent to the jacket. The support member includes channels for receiving regions of the optical fibers that are exposed exterior to the optical fiber jacket. The channels of the support member serve to prevent severe bending of the optical fibers which otherwise would give rise to significant signal attenuation. For multi-fiber optical connector assemblies described herein, even during harsh environmental conditions, the signal loss in the optical fibers may be less than about 0.5 dB. The support may be formed as an extension of a ferrule holder.

Abstract: An optical fiber mode coupling device, capable of being readily connected to a conventional optical fiber with a high degree of ruggedness, is provided. The inventive mode coupling device only allows transmission of at least one supported fiber mode therethrough, and is preferably configured to maximize the coupling, of at least one desired fiber mode, to the at least one supported fiber mode. Advantageously, the inventive mode coupling device is capable of performing the functions of a mode filter for the signal entering its first end, or serving as a mode conditioner for the signal entering its opposite second end.

Abstract: A tablet computer includes a main body and an optical port module mounted on a sidewall of the main body. The optical port module includes a mounting portion and at least one first optical fiber mounted on the mounting portion. The mounting portion forms a mounting surface and defines at least one first receiving hole. The at least one first optical fiber is received in corresponding first receiving hole. An end of the at least one first optical fiber protrudes from the mounting surface, for transmitting optical signals.

Abstract: Embodiments of the invention provide apparatuses and methods for phase correlated seeding of parametric mixer and for generating coherent frequency combs. The parametric mixer may use two phase-correlated optical waves with different carrier frequencies to generate new optical waves centered at frequencies differing from the input waves, while retaining the input wave coherent properties. In the case when parametric mixer is used to generate frequency combs with small frequency pitch, the phase correlation of the input (seed) waves can be achieved by electro-optical modulator and a single master laser. In the case when frequency comb possessing a frequency pitch that is larger than frequency modulation that can be affected by electro-optic modulator, the phase correlation of the input (seed) waves is achieved by combined use of an electro-optical modulator and injection locking to a single or multiple slave lasers.

Abstract: This document provides techniques, apparatus and designs for using electro-optic WGM resonators that support two different families of optical WGM modes with different quality factors in various applications. A radio frequency (RF) resonator is formed on the optical resonator and structured to supply an RF field and spatially overlaps the RF field of the RF resonator with the first and second optical whispering gallery modes to cause RF energy in the RF field at a first RF carrier frequency to couple with the first optical whispering gallery mode and RF energy in the RF field at a second RF carrier frequency to couple with the second optical whispering gallery mode.

Abstract: An optical device for generating a frequency comb includes an optical source and a first waveguide comprising a nonlinear optical medium operable to mix at least two input optical waves to generate a plurality of first optical waves. The optical device also includes a second waveguide concatenated to the first waveguide and characterized by a first dispersion characteristics and operable to compress the waveforms of the plurality of first optical waves and to reduce a frequency chirp introduced by the first waveguide. The optical device additionally includes a third waveguide concatenated to the second waveguide. The third waveguide comprises a nonlinear optical medium and is operable to mix the plurality of first optical waves to generate a plurality of second optical waves and to increase a total number of second optical waves with respect to a total number of first optical waves.

Abstract: An optical joint (1) includes a 2×2 MMI coupler (30) and a 2×2 MMI coupler (31) joined to the 2×2 MMI coupler (30). The 2×2 MMI coupler (30) includes a port (32) and a port (33) at one side. The 2×2 MMI coupler (31) includes a port (34) and a port (35) at one side. A light-absorbing region (20) is connected to the port (33), and a light-absorbing region (second light-absorbing section) (21) is connected to the port (34). A reflecting boundary (22) that reflects light propagated through the 2×2 MMI coupler (30) or the 2×2 MMI coupler (31) is formed at the junction portion between the 2×2 MMI coupler (30) and the 2×2 MMI coupler (31).

Abstract: An optical coupler is provided. It has a bundle of multimode fibers with a few-mode fiber in its centre. Such bundle is fused at one end which is the output end for the signal that is transmitted by the few-mode fiber. To make the coupler, this output end of the bundle is aligned and spliced with a large area core double clad fiber while preserving the modal content of the feed-through. A method for making such optical coupler is also provided. It includes the steps of bundling a central few-mode fiber with a plurality of multimode fibers and then fusing one end of such bundle and aligning it and splicing with a large core double clad fiber, while preserving fundamental mode transmission from one to the other.