Abstract: Various embodiments are disclosed herein with generally relate to an optical communication system using a photonic lantern. In at least one embodiment, the optical system comprises: an optical transmitter coupled to a signal transmitting path; an optical receiver coupled to a signal receiving path; a photonic lantern, the photonic lantern extending between a first open end and a second open end, the first end comprising an opening to a single multi-mode fiber, and the second end comprising a plurality of single mode fibers that are adiabatically coupled to the multi-mode fiber, the plurality of single-mode fibers includes a single-mode fiber adapted to carry a fundamental optical mode and the remaining single-mode fibers adapted to carry higher-order optical modes, wherein, the single-mode fiber is coupled to the optical transmitting path, the remaining single-mode fibers are coupled to the optical receiving path.

Abstract: An optical signal processing apparatus of an embodiment is an optical signal processing apparatus for separating and detecting an optical signal transmitted in a mode division multiplexing optical communication method by signal processing based on a multi-input multi-output (MIMO)-type linear filter. The device includes a signal processing unit configured to estimate weighting factors of the MIMO-type linear filter by sequential calculation based on an affine projection method.

Abstract: A method of receiving, by a receiving terminal, a signal in optical wireless communication is proposed. The method may comprise: establishing a communication link for performing the optical wireless communication with a transmitting terminal; receiving an optical signal from the transmitting terminal through the communication link; and performing interference cancelation on the optical signal. Here, establishing the communication link comprises transmitting and receiving initial information with the transmitting terminal, wherein the initial information may include an orbital angular momentum (OAM) mode applied to the optical signal. In addition, the interference cancelation may be performed on the basis of the OAM mode.

Abstract: A device for inserting a plurality of optical beams into a single-mode optical fibre, a guiding structure of which is composed of a core with a first refractive index, a cladding with a second refractive index, and a coating with a third refractive index. The device includes an optical mixer configured to insert, into the single-mode optical fibre, the plurality of optical beams, at least one of which has a distribution of its radial and angular electromagnetic amplitude with a maximum amplitude peak in the cladding.

Abstract: A bit interleaving method applying a bit permutation process to a QC LDPC codeword made up of N cyclic blocks of Q bits each, dividing the processed codeword into constellation words of M bits each, and applying an intra-cyclic-block permutation process to the cyclic blocks, where the codeword is divided into F×N/M folding sections of M/F cyclic blocks each and the constellation words are each associated with one of the folding sections, and the bit permutation process is applied such that the constellation words are each made up of F bits from each of M/F different cyclic blocks in the associated section, after the permutation process.

Abstract: An optical transmission system includes a plurality of transmission paths that transmit a mode multiplexing signal, and one or more mode permutation units provided between the transmission paths. The mode permutation unit performs mode permutation to interchange modes to be used between at least some optical signals among respective optical signals of a plurality of types of modes that are multiplexed to the mode multiplexing signal input from the transmission path on an input side, and outputs the mode multiplexing signal subjected to the mode permutation to the transmission path on an output side.

Abstract: An interference compensation unit in an OAM reception apparatus removes the interference component caused by horizontally polarized waves relative to vertically polarized waves from a first mode vertical component reception signal obtained by an OAM reception unit using both a first mode horizontal component reception signal and a second mode horizontal component reception signal.

Abstract: A system for structuring a directed energy beam includes one or more coherent light sources that emit one or more initial light beams, one or more spatial light modulators that modulate the one or more initial light beams, and a beam combiner that coherently adds orbital angular momentum beams to create a reconfigurable spatial region of localized power that forms the directed energy beam. Each spatial light modulator is loaded with a pattern that receives an incident light beam and outputs an orbital angular momentum beam. The pattern encodes one or more orthogonal orbital angular momentum functions. Characteristically, each orbital angular momentum having an associated complex weight with which each orbital angular momentum beam is weighted in forming the coherent addition.

Abstract: A system includes mode division multiplexing (MDM) processing circuitry for applying an orbital angular momentum (OAM) to each of a first group of a plurality of input signals and multiplexing the OAM processed signals together. Second processing circuitry performs wavelength distribution multiplexing (WDM) on a second group of the plurality of input signals, wherein the WDM processed signals and the MDM processed signals are orthogonal to one another. Combining circuitry combines the WDM processed signals and the MDM processed signals. Polarization processing circuitry adds polarization to at least one of the WDM processed signals, and the MDM processed signals and a transmitter transmits the combine and polarized processed signal over a link.

Abstract: An optical receiver includes: a first calculation unit that obtains a log likelihood ratio for each M-dimension (M is a natural number), based on a received signal; and a second calculation unit that obtains a log likelihood ratio of an N dimensional symbol (N is a natural number), based on the log likelihood ratio for each M-dimension.

Abstract: The disclosed systems, structures, and methods are directed to a multiple-input multiple-output (MIMO) receiver. The MIMO receiver includes at least two receiver antenna elements to receive radiated MIMO signal beams containing superposed order modes and to generate antenna element output signals based on the received MIMO signal beams. The receiver antenna elements are spatially separated by a distance. A variable ratio combining unit operates to switch between the antenna output signals based on a high-rate periodic waveform that emulates unidirectional movement by the antenna elements to produce a pseudo-Doppler frequency shift. The variable ratio combining unit further modulates the antenna output signals based on the periodic waveform to impart a fractional pseudo-Doppler shift to each MIMO mode and combines the modulated antenna element output signals in accordance with the fractional pseudo-Doppler shift to facilitate separation of the MIMO modes.

Abstract: An expanded beam ferrule includes a first ferrule halve having first reflective surfaces and a second ferrule halve having second reflective surfaces, which together retain optical fibers. The pair of reflective surfaces output collimated light parallel to the mid-plane of the ferrule. An external sleeve aligns the external surface of two similar ferrules, with corresponding second reflective surfaces of the ferrules facing each other. Output light from an optical fiber held in one ferrule is bent twice by the pair of reflective surfaces, with beam divergence after the first bent, and collimation after the second bent. The collimated light is transmitted to the facing second reflective surface in a facing second ferrule aligned by the sleeve, which is subject to optical reshaping in reverse to that undertaken in the first ferrule, so as to converge and focus light to input to the optical fiber held in the other ferrule.

Abstract: The disclosed systems, structures, and methods are directed to an orbital angular momentum (OAM) receiver. The OAM receiver includes at least two receiver antenna elements to receive radiated OAM signal beams containing superposed order modes and to generate antenna element output signals based on the received OAM signal beams. The receiver antenna elements are positioned tangentially along a circular locus and spatially separated by a distance. A variable ratio combining unit operates to switch between the antenna output signals based on a high-rate periodic waveform that emulates unidirectional movement by the antenna elements to produce a pseudo-Doppler frequency shift. The variable ratio combining unit further modulates the antenna output signals based on the periodic waveform to impart a fractional pseudo-Doppler shift to each OAM mode and combines the modulated antenna element output signals in accordance with the fractional pseudo-Doppler shift to facilitate separation of the OAM modes.

Abstract: An optical communication system is arranged to bring out potential capabilities of mode-division multiplexing (MDM). The optical communication system includes a hologram medium in which holograms are multiplex-recorded so as to correspond to respective spatial modes of signal light transmitted by a multi-mode fiber (MMF). A phase plate modulates phases of the respective spatial modes so as to reduce a spatial overlap between the spatial modes, and is provided on a side of the hologram medium on which signal light enters the hologram medium.

Abstract: This patent document provides optical processing and switching of optical channels based on mode-division multiplexing (MDM) and wavelength division multiplexing (WDM).

Abstract: Systems and methods for orbital angular momentum (OAM)-based multidimensional wireless communication. The OAM-based multidimensional wireless communication is preformed with a transmitter for generating an RF modulated signal carrying a data sequence. Further included is an OAM antenna array including OAM antenna elements, each of which includes an azimuthal phase shifter and an antenna element. The azimuthal phase shifter shifts an azimuthal phase term of a wavefront generated by the antenna element such that the OAM antenna element imposes the multidimensional modulated signal on a pre-determined OAM mode of a carrier signal corresponding to the azimuthal phase term.

Abstract: The present disclosure provides a few mode optical fiber (100). The few mode optical fiber (100) includes a core region (102). A core region (102) defined by a region around a central longitudinal axis (116) of the few mode optical fiber (100). In addition, the core region (102) has a first annular region (106) extended from central longitudinal axis (116) to radius r1, a second annular region (108) extended from radius r1 to radius r2, a third annular region (110) extended from radius r2 to radius r3, a fourth annular region (112) extended from radius r3 to radius r4 and a fifth annular region (114) extended from radius r4 to radius r5. Also, the few mode optical fiber (100) has a cladding defined by the sixth annular region (104) extended from radius r5 to radius r6.

Abstract: A transmission device transmits multiplexed signals obtained by multiplexing signals of N systems corresponding to N Orbital Angular Momentum (OAM) propagation modes. The transmission device includes: an array antenna that includes M antenna elements disposed in a lattice on a plane when viewed from the plane; and a transmitter that multiplies signals obtained by branching each of the signals of N systems into M signals by weighting coefficients of phase shift angles based on angles of the respective M antenna elements with respect to a reference axis passing through a reference point viewed from the reference point on the plane according to the OAM propagation modes, multiplexes the signals of N systems multiplied by the weighting coefficients of the phase shift angles, and transmits signals obtained by the multiplexing from the M antenna elements. M and N are integers equal to or larger than 2.

Abstract: A method and system for remote sensing. The method includes applying an orbital angular momentum (OAM) mode on a light beam to generate an OAM light beam having an optical OAM spectrum, exposing a target object to the OAM light beam such that the target object absorbs energy of the OAM light beam to generate ultrasonic emissions, the ultrasonic emissions having a reflected OAM spectrum associated with the target object, and generating a high resolution image of the target object based on the reflected OAM spectrum.

Abstract: An example apparatus includes a mode selective detector, a measurement module, a difference calculator and a threshold and alarm module. The mode selective detector detects a plurality of modes of a spatially multiplexed signal. The measurement module measures a parameter for the plurality of modes of the spatially multiplexed signal, wherein the parameter is a power or a signal to noise ratio (SNR). The difference calculator compares the measured parameter among a subset modes and/or among a known set of unperturbed parameters and determines a differential, the subset including at least one mode. The threshold and alarm module sets an alarm indicator when the differential is out of bounds.

Abstract: A Mode Division Multiplexed Passive Optical Network (MDM-PON) apparatus includes: a non-mode selective multiplexer which includes a first end where three or more single-mode optical fibers are spaced apart from each other by a predetermined distance, and a second end where cores of the three or more single-mode optical fibers are tapered such that a gap between the three or more single-mode optical fibers is narrower than the predetermined distance while the three or more single-mode optical fibers are spaced apart from each other by an equal distance; an optical line terminal (OLT) which is connected to the second end through a few-mode fiber, and transmits a downstream optical signal; and three or more optical network units (ONUs) which is connected to the first end through the three or more single-mode optical fibers, and transmits upstream optical signals.

Abstract: In at least one aspect, a device for Orbital Angular Momentum (OAM) based optical communication includes a first spatial light modulator configured to down-convert a first plurality of higher-order OAM modes from a communication signal to a second plurality of higher-order OAM modes and a first Gaussian mode, a second spatial light modulator configured to drop the first Gaussian mode and add a second Gaussian mode to the second plurality of higher-order OAM modes, and a third spatial light modulator configured to up-convert the second plurality of higher-order OAM modes and the second Gaussian mode to a third plurality of higher-order OAM modes for further communications.

Abstract: A low-loss few-mode fiber relates to the technical field of optical communications and related sensing devices, and includes, from inside to outside, a core layer (1), a fluorine-doped quartz inner cladding (2), a fluorine-doped quartz second core layer (3), a fluorine-doped quartz depressed cladding (4) and a fluorine-doped quartz outer cladding (5); germanium element is not doped within the core layer (1), the refractive index of the core layer (1) is in gradient distribution, and the distribution is a power-exponent distribution; the maximum value of difference in relative refractive index between the core layer (1) and the fluorine-doped quartz inner cladding (2) is 0.3% to 0.9%; the relative refractive index difference of the fluorine-doped quartz inner cladding (2) with respect to synthetic quartz is ?0.3% to ?0.5%; the difference in relative refractive index between the fluorine-doped quartz second core layer (3) and the fluorine-doped quartz inner cladding (2) is 0.05% to 0.

Abstract: A method of implementing Orbital Angular Momentum (OAM) for radio communications in general and LTE in particular. Common prior art so far recreate the vorticity (axial rotation of the Poynting vector) by using ring-shaped antenna arrays. This application proposes to create the vorticity in signal processing without the need of any space diversity (i.e. work with a single antenna). An Hilbert transform is applied in frequency domain to the Fourier transform of the analytical representation of a band-limited OFDM signal. The Hilbert transform is then approximated by a development in series into orthogonal twisted modes. This can be seen as an inverse Fourier transform of the complex analytical signal. Therefore an OAM IFFT based transmitter is proposed where parallel IFFTs are performed for each OAM mode and superimposed.

Abstract: An optical amplifier includes a multi-mode pump laser module, a multi-mode waveguide, a multi-mode to multiple single-mode fiber converter module and a plurality of single-mode cores. The multi-mode pump laser module emits pump light having a plurality of modes to the multi-mode fiber or waveguide. The multi-mode waveguide propagates the emitted pump light to the converter module. The converter module receives the pump light and distributes the pump light approximately uniformly to a plurality of single-mode cores.

Abstract: The present invention relates generally to multimode optical fibers (MMFs) and methods for optimizing said MMFs for transmission for at least two optical wavelengths. In an embodiment, the present invention is a multimode optical fiber optimized for multi-wavelength transmission in communication systems utilizing VCSEL transceivers, where the MMF has a bandwidth designed to maximize channel reach for multiple wavelengths, and/or where the MMF minimizes for wavelength dependent optical power penalties at one or more wavelength.

Abstract: Systems and methods for transmitting data, including encoding one or more streams of input data using one or more adaptive Low Density Parity Check (LDPC) encoders, wherein the encoders generate one or more signal constellations; modulate one or more signals using hybrid multidimensional coded modulation; apply orthogonal prolate spheroidal wave functions as electrical basis functions; generate one or more spectral band group signals by selecting and combining two or more spectral band groups with center frequencies that are orthogonal to each other; and spectral-mode-multiplex and transmit the one or more adaptive LDPC-coded data streams including the one or more spectral band group signals combined into corresponding spatial modes over a transmission medium.

Abstract: A multi-core optical fiber includes a plurality of core portions, and a cladding portion positioned at outer peripheries of the plurality of core portions, the cladding portion having a refractive index lower than a maximum refractive index of each of the core portions, in which each of the core portions propagates light only with predetermined number, which is equal to or greater than 2, of propagation modes, and an effective core area at wavelength of 1550 nm of each of the propagation modes is equal to or greater than 120 ?m2.

Abstract: An optical receiver comprising an optical-to-electrical converter and a digital processor having one or more equalizer stages. The optical-to-electrical converter is configured to mix an optical input signal and an optical local-oscillator signal to generate a plurality of electrical digital measures of the optical input signal. The digital processor is configured to process the electrical digital measures to recover the data carried by the optical input signal. At least one of the equalizer stages is configured to perform signal-equalization processing in which the electrical digital measures and/or digital signals derived from the electrical digital measures are being treated as linear combinations of arbitrarily coupled signals, rather than one or more pairs of 90-degree phase-locked I and Q signals.

Abstract: Systems and methods for encoding streams of input data using at least two nonbinary low density parity check (NB-LDPC) encoders; generating NB-LDPC coded optimum signal constellations; performing orthogonal frequency division multiplexing (OFDM) on the NB-LDPC coded four-dimensional (4-D) optimum signal constellations; generating signals using mappers, the mappers configured to assign bits of signals to the signal constellations and to associate the bits of the one or more signals with signal constellation points. Output of the 4-D mappers is modulated using a 4-D OFDM transmitter and a 4-D modulator onto a transmission medium using block coded-modulation, and the modulated output is transmitted by mode-multiplexing independent 4-D OFDM data streams onto fiber.

Abstract: An example apparatus includes a mode selective detector, a measurement module, a difference calculator and a threshold and alarm module. The mode selective detector detects a plurality of modes of a spatially multiplexed signal. The measurement module measures a parameter for the plurality of modes of the spatially multiplexed signal, wherein the parameter is a power or a signal to noise ratio (SNR). The difference calculator compares the measured parameter among a subset modes and/or among a known set of unperturbed parameters and determines a differential, the subset including at least one mode. The threshold and alarm module sets an alarm indicator when the differential is out of bounds.

Abstract: A system and method are provided for coupling a plurality of optical signals, such as data signals, between a corresponding plurality of single mode optical fibers (SMFs) and a multi-mode optical fiber (MMF), by optically coupling the optical signals of the SMFs with respective spaced-apart regions at a facet of the MMF, such that at least some of the regions partially overlap with a plurality of different spatial modes supported by the MMF.

Abstract: An apparatus inputs an input configured to receive an input optical signal, and an output configured to output an output optical signal. A superchannel converter is coupled between the input and the output. The superchannel converter is configured to convert N spatial modes of the input optical signal to M spatial modes of the output optical signal.

Abstract: An apparatus, e.g. an optical device, includes an optical transmitter and a mixer. The transmitter is configured to transmit a plurality of optical data channels that each include at least one spectral component at a same frequency. The mixer is configured to combine a first data channel with a second data channel. The combining is such that first and second optical channels output by the optical transmitter each include contributions from the first and second data channels at the same frequency.

Abstract: An optical passive repeater is provided. The repeater is operated under a state of polariton Bose-Einstein condensation (BEC). A phase transition from a thermal polariton state to a condensed polariton state is controlled, where system temperatures and densities are lower than thermal dissociation temperatures and nonlinear saturation densities, respectively. Original input multimode laser signals are transformed into final output single-mode laser signals. Thus, the polariton BEC passive repeater becomes a power-efficient and low-cost device to increase the reach of optical links without sacrificing its signal quality and integrity.

Abstract: An optical transport network based on multimode/multicore fibers includes a mode-multiplexer to multiplex independent data streams from one or more transmitters; a multimode erbium-doped fiber amplifier (MM EDFA) to compensate for MMF loss; a multimode optical add-drop multiplexer (MM OADM) to add and/or drop multimode channels in multimode networks; a multimode optical cross-connect; and a mode-demultiplexer to separate various mode streams to one or more receivers.

Abstract: 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.

Abstract: A method and a device for optical data transmission are proposed. Incoming optical signals having respective incoming waveguide modes are mapped into outgoing optical signals having respective outgoing waveguide modes, using optical spatial modulators, whose multiplicative patterns correspond to the respective electrical field patterns of the respective incoming or outgoing waveguide modes. An incoming optical signal, whose respective incoming waveguide mode is of an azimuthal order equal to zero, results in an outgoing optical signal, whose respective outgoing waveguide mode is of an azimuthal order equal to zero. Furthermore, two incoming optical signals, whose respective second incoming waveguide modes are of a same azimuthal order greater than zero, of a same radial order, and orthogonal to each other result in respective outgoing signals, whose respective outgoing waveguide modes are off a same azimuthal order greater than zero, of a same radial order and orthogonal to each other.

Abstract: An optical transmission apparatus includes: a transmission light source configured to generate single-mode light of a specific wavelength; a power coupler configured to split the light generated by the transmission light source into a plurality of light sections; at least one modulator configured to modulate an electrical signal carrying different data into at least one optical signal using the light section from the power coupler; and a mode multiplexer configured to convert the modulated optical signal into a different mode, and to transmit the mode-converted optical signal to a fiber.

Abstract: A laser source is configured for all-optical AM-FM up-conversion. In one exemplary embodiment, an amplitude modulated (AM) optical input signal containing a baseband signal at a sub-microwave frequency, is injected into the laser source. The amplitude of the AM optical input signal and the optical carrier frequency are adjusted so as to place the laser source in a period-one dynamical state characterized by a transitioning of the laser source from a free-running optical frequency to at least two optical frequencies having a separation distance equal to a period-one microwave frequency. As a result of the period-one dynamical state, a frequency modulated (FM) optical output signal containing the baseband signal carried at the period-one microwave frequency, is propagated out of the laser source. The period-one microwave frequency is operative as a sub-carrier signal.

Abstract: Systems and methods for transmitting data, including encoding one or more streams of input data using one or more adaptive Low Density Parity Check (LDPC) encoders, wherein the encoders generate one or more signal constellations; modulate one or more signals using hybrid multidimensional coded modulation; apply orthogonal prolate spheroidal wave functions as electrical basis functions; generate one or more spectral band group signals by selecting and combining two or more spectral band groups with center frequencies that are orthogonal to each other; and spectral-mode-multiplex and transmit the one or more adaptive LDPC-coded data streams including the one or more spectral band group signals combined into corresponding spatial modes over a transmission medium.

Abstract: In one embodiment, an optical network includes multiple cross-connects configured to switch spatial modes in which signals are propagated across the network and multiple fiber links that extend between pairs of cross-connects, the fiber links including multimode optical fibers that support multiple spatial modes.

Abstract: A system and method for transmitting data, including one or more Low Density Parity Check (LDPC) encoders configured to encode one or more streams of input data; a signal constellation generation module configured to generate one or more signal constellations; one or more modulators configured to generate one or more signals using hybrid multidimensional coded modulation; a modified orthogonal polynomial generation module configured to generate modified orthogonal polynomials for use as electrical basis functions; and one or more mode-multiplexers and transmitters configured to mode-multiplex and transmit one or more LDPC-coded data streams over a transmission medium.

Abstract: Systems and methods for data transport are provided which encode streams of data using low density parity check (LDPC) encoders and map data streams to symbols, by assigning bits of symbols to a signal constellation and associating bits with constellation points. Constellation points are generated using a D-dimensional optimum signal constellation design (OSCD) method. The OSCD determines an optimum source distribution for an optical channel, generates D-dimensional training sequences from the optimum source distribution, determines new signal constellation points as the center of mass for each D-dimensional cluster of points, and repeats these steps until convergence or until a predetermined number of iterations is reached.

Abstract: An optical communication system is disclosed. The optical communication system comprises an optical transmitter and a substantially circular multi-mode optical fiber. The optical transmitter comprises a generator of at least two free space circular vortices and comprises an optical element configured to receive the at least two free space circular vortices and to couple them to an input facet of the optical fiber. The optical fiber is configured to receive at the input facet the at least two free space circular vortices and is configured to generate therefrom at least two corresponding guided circular vortices having respective propagation constants, wherein the values of the propagation constants at a defined frequency are different each other.

Abstract: A system includes a transmitter to multiplex a plurality of modulated optical signals and an unmodulated optical signal and to transmit the plurality of modulated optical signals and the unmodulated optical signal along a transmission path. The system also includes a receiver to de-multiplex each of the plurality of modulated optical signals and the unmodulated optical signal and to demodulate each of the plurality of modulated optical signals with the unmodulated optical signal to coherently detect a modulating signal from each of the plurality of modulated optical signals.

Abstract: Systems and methods for amplification are shown that include a pump preparation module configured to provide a pump output that includes a plurality of pump modes; an amplification module configured to accept a multimode signal input and the pump output, such that the pump output causes an amplification of a plurality of modes in the signal input to produce an amplified signal output; and a gain control module configured to adjust a balance of the plurality of pump modes in the pump output to produce a predetermined amplified signal output.

Abstract: An apparatus includes an optical transmitter having a plurality of optical data modulators and an end-face coupler. Each of the optical data modulators is configured to output a corresponding data-modulated optical carrier. The optical end-face coupler is configured to direct the data-modulated optical carriers into a pattern of light beams to illuminate an end-face of a multi-mode optical fiber with a pattern of light spots. The optical end-face coupler is configured to cause each of the data-modulated optical carriers to excite a set of orthonormal optical propagating modes of the multi-mode optical fiber. Some of the orthonormal optical propagating modes of the set have nontrivially differing intensity and/or phase profiles.

Abstract: A method and system for distributed spatial mode processing is disclosed where a plurality of optical signals is received via a plurality of spatial modes on a first optical link, spatial mode conversion is performed on the plurality of optical signals to switch the plurality of optical signals to different ones of the plurality of spatial modes and the plurality of optical signals is transmitted via the different ones of the plurality of spatial modes on a second optical link where spatial mode filtering may occur.

Abstract: A wavelength division multiplexer terminal with a multiplexer arrangement with a first switching matrix, and a demultiplexer arrangement with a second switching matrix allows flexibility for connection transceivers to ports of the wavelength division multiplexer and wavelength division demultiplexer respectively. Optical monitoring receivers are connected upstream the wavelength division multiplexer and downstream the wavelength division demultiplexer for managing and supervising connections.