140results about "Optical mode multiplex systems" patented technology

The invention discloses a method of an optical anti-turbulence device for polarization multiplexing spatial optical communication. The mode demultiplexer is connected with the optical fiber; the single-mode optical fiber array is respectively coupled with each spatial intrinsic mode decomposed by the mode demultiplexer; the polarization CBC chip is connected with the other end of the single-mode optical fiber array; the driving control module is connected with the polarization CBC chip; the polarization multiplexing optical communication digital coherent receiver (Rx) is connected with the polarization CBC chip through a single-mode optical fiber; through the arrangement of the polarization CBC chip, the compatibility of a polarization multiplexing technology and a mode multiplexing coherent beam combination technology is realized, the problem of polarization dimension information loss or strong crosstalk caused by the use of a polarization state rotator (PSR) and a polarization maintaining optical fiber in the prior art is solved, modulation information of two orthogonal polarization dimensions is completely reserved, the communication bandwidth is improved, and the communication efficiency is improved. And the communication efficiency is greatly improved.

The invention relates to the technical field of multi-plane light conversion, in particular to a multi-dimensional demultiplexing and frequency mixing system based on an MPLC and an optimization design method of the multi-dimensional demultiplexing and frequency mixing system. The system comprises an input module used for inputting multimode signal light and local oscillation light; the MPLC module is used for realizing unitary transformation of light in any space, comprises N cascaded phase transformation areas and is integrated on the reflecting mirror or the transmitting mirror; the phase transformation regions are phase plates or metasurfaces, and at least one phase transformation region is a metasurface; and the output module is used for receiving the single-mode Gaussian light spots after demultiplexing and frequency mixing. According to the invention, different phases of different wavelengths and different polarization states are regulated and controlled through the metasurface; parallel demultiplexing of wavelengths, polarization and modes in multimode signals can be realized.

The invention discloses a relay device and method for long-distance few-mode optical fiber communication, and belongs to the field of optical communication. According to the device, firstly, optical signals transmitted in a few-mode optical fiber are separated into a plurality of independent mode channels through a mode decomposition multiplexer; then, an adjustable light delay unit is configured in each channel, and compensation is carried out according to a difference mode group delay difference pre-calculated or actually measured by a few-mode optical fiber parameter; furthermore, a dimmable amplifier is used for amplifying the signal, power monitoring is carried out at the output end of the amplifier through an optical fiber beam splitter and a photoelectric detector, closed-loop feedback control is formed, and gain of each channel is adjusted in a self-adaptive mode to eliminate mode-dependent loss. According to the invention, signal distortion can be effectively suppressed in an optical domain, the complexity of digital signal processing of a receiving end is reduced, and the transmission distance and the transmission capacity of a few-mode optical fiber mode division multiplexing communication system are remarkably improved.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a transmitter of orbital angular momentum (OAM) multiplexing based communication may transmit, to a receiver of the OAM multiplexing based communication, a configuration message that indicates a configured set of transmitter circles. The transmitter may transmit, to the receiver, at least one data stream using the configured set of transmitter circles. Numerous other aspects are provided.

An optical communication system can include a multiplexer / demultiplexer. The multiplexer / demultiplexer can transfer a first optical data signal between a first single-mode fiber and a first propagation mode of a few-mode fiber. The first propagation mode can have a first effective refractive index. The multiplexer / demultiplexer can transfer a second optical data signal between a second single-mode fiber and a combination of a second propagation mode of the few-mode fiber and a third propagation mode of the few-mode fiber. The second propagation mode and the third propagation mode can have a same effective refractive index that differs from the first effective refractive index. During propagation within the few-mode fiber, the second optical data signal can couple bidirectionally between the second propagation mode and the third propagation mode, while being substantially isolated from the first optical data signal in the first propagation mode.

Methods, systems, and devices for connection setup in an orbital angular momentum (OAM)-based communication system are described. A first device and a second device may establish an OAM communications connection between the devices. The first device and the second device may exchange a series of messages over a downlink communications link and an uplink communications link according to an OAM mode. Based on OAM related parameters or OAM related information included in the messages, the first device and the second device may achieve a successful directional alignment (co-axial alignment) between the first device and the second device. The first device and the second device may determine one or more orbital angular momentum modes for communication between the first device and the second device based on the establishing the directional alignment.

A method and apparatus are provided. The method includes receiving, at a TE0 mode add / drop filter, a TE0 mode optical signal having a first wavelength and a second wavelength, and transmitting, from the TE0 mode add / drop filter, the TE0 mode optical signal having the first wavelength and the second wavelength towards a Bragg grating, without converting the TE0 mode optical signal having the first wavelength and the second wavelength to another mode. The method further includes receiving, at the TE0 mode add / drop filter, a reflected TE1 mode optical signal having the first wavelength from the Bragg grating, and transmitting, from the TE0 mode add / drop filter, the reflected TE1 mode optical signal having the first wavelength towards a photodetector, without converting the reflected TE1 mode optical signal having the first wavelength to another mode.

The invention discloses a multi-mode optical switch and a multi-mode optical transmission system, and relates to the technical field of optical switchs.The multi-mode optical switch comprises a first beam splitter, an optical signal modulation assembly and a second beam splitter, and the first beam splitter is provided with an input port, a first output port and a second output port; the signal input end of the optical signal modulation assembly is connected to the first output port. The second beam splitter is provided with a third input port, a fourth input port, a third output port and a fourth output port, the third input port is connected to the second output port, and the fourth input port is connected to the signal output end of the optical signal modulation assembly; according to the technical scheme provided by the invention, the integrity of the multi-mode signal can be maintained, and meanwhile, the sub-millisecond-level high-speed switching is realized.

The invention relates to an underwater point cloud data transmission system and method based on vortex light mode division multiplexing, and the system comprises a point cloud data transmission module which is used for modulating the three-dimensional point cloud data of a measured target into two paths of laser signals, carrying out the first preprocessing of the two paths of laser signals, and transmitting an underwater space light signal; and the point cloud data receiving module is used for receiving the underwater space optical signal, performing second preprocessing on the underwater space optical signal, and generating user service data. According to the invention, a double-path vortex optical space division multiplexing technology is adopted, synchronization of target detection and data return is realized, and key technical problems of poor real-time performance, weak anti-interference capability and the like in the aspect of underwater three-dimensional point cloud data acquisition are effectively solved.

Intensity control units 40A and 40B acquire the intensity of backscattered light when inputting signal light of two or more modes for each core in a multicore optical fiber 10, which has two or more cores and in which two or more modes propagate to each of the cores, so that the transmission direction of light differs between adjacent cores, and output a control signal for reducing the input optical power of a high-order mode other than a basic mode of the signal light by a predetermined amount so as to reduce the influence of the high-order mode on the basic mode.

The invention discloses a mode division multiplexing optical fiber communication phase calibration method based on CNN-LSTM, and belongs to the technical field of optical fiber communication. By constructing a double-input CNN-LSTM hybrid neural network architecture, MIMO input signals and original target signals of mode division multiplexing optical fiber communication are obtained, data preprocessing is carried out, and the spatial feature extraction capability of a convolutional neural network and the time sequence modeling capability of a long-short-term memory network are combined, so that the MIMO input signals and the original target signals of mode division multiplexing optical fiber communication are obtained. Effective compensation of phase noise in long-distance strong-coupling mode division multiplexing optical fiber communication is realized, and a double-branch network comprising an image input layer, a convolutional layer, an LSTM layer, a deep connection layer and a user-defined phase calibration layer is constructed by separating complex MIMO signals into real and imaginary parts and generating a sliding window training sample. The problems that a traditional algorithm is limited in phase noise compensation capacity and poor in convergence performance under the strong coupling condition are effectively solved, and the balance performance and the transmission quality of a mode division multiplexing optical fiber communication system are remarkably improved.

The invention discloses a free space optical communication system based on a structured optical frequency comb, and belongs to the field of optical communication. Comprising an optical frequency comb generation system, a signal coding system, a spatial light modulation and demodulation system and a signal receiving system. The optical frequency comb generation system is used for modulating input continuous laser into an adjustable optical frequency comb with high repetition frequency, short pulse width and high power; the signal coding system is used for separating the light with different wavelengths in the optical frequency comb, independently coding the light with each wavelength, and finally combining the light with different wavelengths again; the spatial light modulation and demodulation system is used for coupling the Gaussian beam in the optical fiber into a free space and converting the Gaussian beam into structured light, demodulating the structured light after the structured light is transmitted to a receiving end and re-coupling the structured light back to the optical fiber; the signal receiving system is used for receiving and analyzing the optical signals. According to the invention, the optical frequency comb and the structured light are combined, and the problem that optical signals are easily influenced by atmospheric turbulence in free space optical communication can be effectively solved on the premise of ensuring large communication capacity.

To make it possible to design a multi-core optical fiber having a standard cladding diameter taken in consideration of manufacturability.SOLUTION: The present disclosure provides a multi-core optical fiber comprising: two or more cores through which two or more lightwave modes propagate; a cladding a refractive index of which is lower than that of the cores and which is disposed so as to include all the cores; and an outermost layer a refractive index of which is equal to or more than that of the cladding and less than that of the cores and which is disposed on a concentric axis so as to surround the cladding. A crosstalk between the cores in the highest order propagation mode propagating through the cores is -39 dB / km or less.SELECTED DRAWING: Figure 1

A multimode combiner is disclosed. In one aspect, a multimode combiner includes a first input waveguide, a second input waveguide, and an output waveguide disposed between the first and second input waveguides. The first input waveguide, the second input waveguide, and the output waveguide are arranged such that an optical signal transmitted through the multimode combiner has substantially the same optical power at an output of the output waveguide as the optical signal does at an input of either of the first and second input waveguides. A multiplexer and an apparatus including multimode combiners are also disclosed.

Aspects relate to photonic computing systems and methods of optically performing matrix vector multiplication. A photonic computing system includes a light source configured to generate a plurality of input optical signals having mutually different wavelengths, a plurality of optical encoders configured to encode the plurality of input optical signals with respective input values, a first wavelength division multiplexer (WDM) configured to spatially combine the encoded plurality of input optical signals into an input waveguide, a photonic multiplier coupled to the input waveguide and configured to generate a plurality of output optical signals each encoded with a respective output value representing a product of the respective input value and a common weight value, and a second WDM coupled to the photonic multiplier and configured to spatially separate the plurality of output optical signals.

Aspects of this technical solution are directed to multiplexed transmission by optical beam transmission. A method can include generating a first beam having a first frequency in an optical frequency range, generating a second beam including data and having a second frequency in the optical frequency range, converting the first beam and the second beam into a third beam including the data and having a third frequency based on a difference between the first frequency and the second frequency, and transforming the third beam into a fourth beam having a first angular distribution and including a first portion of the data, and into a fifth beam having a second angular distribution corresponding to the first angular distribution and including a second portion of the data.

The application relates to a unique optoelectronic module configured to operate simultaneously at high-speed bit rate and low speed bit rate, thanks to a reconfigurable system on a chip, i.e. a programmable unit on a chip. This reconfigurable system embeds the electronic circuitry of the low-speed channel(s), i.e. at least the driver when the link is a transmission channel, or at least the amplifier when the link is a receiver channel.

One aspect of the present invention is an optical transmission system including a transmitter connected to a transmission line having M spatial channels, and a receiver that receives a signal transmitted from the transmitter via the transmission line, wherein the transmitter includes: an allocator that allocates a transmission bit string transmitted to the transmission line into a bit string serving as a basic signal and a bit string serving as spatial channel information; a generator that generates N (M>N) signals from the bit string serving as the basic signal allocated by the allocator; and a selector that selects N spatial channels, through which the N signals generated by the generator are transmitted, from the M spatial channels on the basis of the bit string serving as the spatial channel information allocated by the allocator.

The application discloses a spatial-mode hybrid diversity receiving system for spatial laser communication. After a transmitting light beam passes through atmospheric turbulence, diffusion and distortion and other phenomena occur, spatial diversity and mode diversity are combined at a receiving end, an array of M receiving antennas is used to receive the diffused light beam to perform spatial diversity, a few-mode fiber supporting N modes is connected after each receiving antenna, high-order modes are converted into base modes by a mode demultiplexer and then output to a single-mode fiber to perform mode diversity, then a total of M*N branch signals are converted into electric signals by photoelectric detection modules, and finally, the branch signals are combined after digital signal processing. The application combines spatial diversity and mode diversity, can effectively compensate the influence of atmospheric turbulence on laser transmission, and is beneficial to spatial laser communication under more severe channel conditions.

A spatiotemporal optical multiplexer includes a storage optical cavity having a plurality of storage-cavity modes that are transversely separated, a dump optical cavity having a plurality of dump-cavity modes that are transversely separated, and a phase modulator located in the dump cavity and overlapping all of the dump-cavity modes. Each dump-cavity mode is coupled to a respective storage-cavity mode. The storage-cavity modes have the same storage-cavity resonant frequency while the dump-cavity modes have dump-cavity resonant frequencies that are distinct. The phase modulator is driven to simultaneously tune the dump-cavity resonant frequencies. At any time, no more than one dump-cavity mode is resonant with its respective storage-cavity mode. When this resonance occurs, the energy of the respective storage-cavity mode is coupled out of the storage cavity and through the dump cavity as an output pulse.

The invention discloses a multi-channel low-crosstalk multi-layer stepped annular optical fiber and a design method thereof, and belongs to the field of optical communication, and the multi-layer stepped annular optical fiber comprises n (n is greater than or equal to 5 and less than or equal to 10) nested annular structure layers which are sequentially the first to nth annular structure layers from inside to outside; the refractive index of the outermost annular structure layer is smaller than or equal to that of silicon dioxide; the refractive indexes of the first to (n-3) th annular structure layers are greater than the refractive index of the outermost annular structure layer; the refractive index of the (n-2) th embedded structure layer is equal to that of the outermost annular structure layer; the refractive index of the (n-1) th annular structure layer is smaller than that of the outermost annular structure layer; the refractive indexes of the adjacent annular structure layers are different; the width range of the first annular structure layer to the (n-1) th annular structure layer is 1-6 [mu] m and is smaller than the width of the outermost annular structure layer. The number of orbital angular momentum modes which can be supported by the optical fiber and are good in effective refractive index separation can be increased, and therefore the optical communication capacity is improved.

The invention discloses an active mode demultiplexing module which comprises a mode converter, two optical circulators and a bidirectional semiconductor optical amplifier. The mode converter is used for converting a high-order mode into a fundamental mode to complete primary mode demultiplexing, fundamental mode signals after primary demultiplexing are injected into the bidirectional semiconductor optical amplifier through the two optical circulators from the positive direction and the negative direction respectively, and the signals after being shaped by the bidirectional semiconductor optical amplifier are output by the corresponding optical circulators. A bidirectional symmetrical injection structure is formed, different propagation is beneficial to separation of different signals, and mutual interference, namely mode crosstalk, between forward and reverse signals can be effectively reduced, so that a mode demultiplexing function is better completed, and an output signal has higher signal quality than a primary demultiplexing signal. Besides, by optimizing and adjusting the driving current of the bidirectional semiconductor optical amplifier or an auxiliary optical pumping mode, not only can the gain of the mode channel be dynamically adjusted, but also the power balance of the mode channel and the demultiplexing of a high extinction ratio mode can be realized; the method is especially suitable for receiving few-mode signals in a mode division multiplexing (MDM) optical transmission system and constructing optical switching nodes in a multi-dimensional multiplexing optical network.

An optical fiber comprises a core having an elliptical cross section and a cladding having a circular cross section. The core has an ellipticity between 2 and 40. The core and the cladding have a common central axis with the core being enclosed by the cladding. The difference of a refractive index of the cladding to a refractive index of the core is between 1 x 10-2 and 1.5 x 10-1. A trench is located between the core and the cladding. The trench has a uniform width and encircles the core. The refractive index of the trench is lower than the refractive index of the cladding.

An optical power adjustment system includes a multi-mode light source, a mode demultiplexer, and an optical power adjustment apparatus. The multi-mode light source is configured to output a multi-mode optical signal, where the multi-mode optical signal includes N transverse-mode optical signals, N=2M, and M is an integer greater than 1. The mode demultiplexer is configured to convert the N transverse-mode optical signals into N fundamental-mode optical signals, and output the N fundamental-mode optical signals. The optical power adjustment apparatus includes M optical power adjustment modules and a control apparatus, each optical power adjustment module includes a plurality of phase shifters, and the control apparatus is electrically connected to the M optical power adjustment modules. A Kth optical power adjustment module includes 2K-1 multi-mode interferometers MMIs.

The invention discloses a mode division multiplexing device based on topological optimization and a mode division multiplexing circulating system, and relates to the field of photon integration and optical communication. The manufacturing method of the mode division multiplexing device comprises the following steps: dispersing the whole design area into adjustable material pixels, wherein the design area is silicon on insulator; determining a target function of a mode division multiplexing device by taking maximization of mode conversion efficiency as a target; by taking the objective function as an optimization objective, automatically updating the distribution of material pixels in the whole design area to obtain a quasi-optimal structure; and optimizing the pixels which cannot meet the manufacturing requirements in the optimal structure until the manufacturing requirements can be met. When a mode division multiplexing device is manufactured, an optimal structure can be automatically searched in a continuous or discrete material parameter space, so that a complex geometrical shape which is difficult to intuitively conceal can be excavated, and ultra-compact, low-loss, low-crosstalk, broadband and robust mode division multiplexing multifunctional photonic devices and the like can be realized in an extremely small size.

The application relates to the technical field of multi-plane light converters, and more particularly to an on-chip multi-plane light conversion device and an optimization design method thereof. A grating coupling unit, a multi-plane phase sheet and a mirror are integrated on the same glass substrate, three-dimensional monolithic integration of input coupling, light path folding and light field transformation functions is realized, precise mechanical alignment requirements among discrete components are completely eliminated, the integration degree is high, high-precision alignment is avoided, stability is improved, and the volume is reduced to a certain extent. The application realizes efficient conversion of a light field between an on-chip waveguide and free space through the grating coupling unit, and performs arbitrary unitary transformation in the free space by using an MPLC composed of the multi-plane phase sheet and the mirror, the two work cooperatively, the high mode capacity and low crosstalk advantages of the MPLC are combined with the on-chip integration advantages of the grating coupling unit, and high-performance and small-volume light field transformation can be realized.

The present invention relates to the technical field of multiplexing and demultiplexing devices in space division multiplexing, and more specifically, to a mode group demultiplexing method and device based on a cascade diffraction network. The mode group demultiplexing method adopts a strategy of non-deterministic mode conversion to design and optimize the cascade diffraction network, which improves the freedom of the output mode field, so that the phase plate design can be carried out with greater freedom, thereby significantly improving the efficiency of beam conversion and greatly reducing the number of phase plates required. The present invention overcomes the shortcomings of low energy efficiency and stability in mode group demultiplexing, and reduces device loss by improving and optimizing the design.

Embodiments of an optical amplification apparatus are disclosed which include a first optical amplifier, a second optical amplifier, and a mode exchanger. The first optical amplifier is connected to an input port of the mode exchanger, and the second optical amplifier is connected to an output port of the mode exchanger. The first optical amplifier is configured to amplify optical signals carried in a plurality of transmission modes of a few-mode fiber, the plurality of transmission modes of the few-mode fiber may be grouped into N groups, each group includes two transmission modes, and N is a positive integer greater than or equal to 1. The mode exchanger is configured to exchange the two transmission modes carrying optical signals in each group. The second optical amplifier is configured to amplify the optical signals that are carried in the two transmission modes in each group and whose modes are exchanged.

To provide a stair type multi-mode fiber capable of further reducing a differential mode delay (DMA) while simultaneously reducing the differential mode delay (DMD) and a propagation loss, and an optical transmission system.SOLUTION: A stair type multi-mode fiber including: an inner core; an outer core having a refractive index lower than that of the inner core, surrounding the inner core and constituted of silica glass; and a clad having a refractive index lower than that of the outer core and surrounding the entire outer core propagates two or more modes at a used wave length. The loss coefficient difference between the modes is less than 0.005 dB / km.SELECTED DRAWING: Figure 1