120 results about "Few mode fiber" patented technology

The invention discloses an optical fiber transmission image recovery method and device based on a complex amplitude regulation metasurface diffraction device, and the method comprises the steps: obtaining the complex amplitude distribution of each diffraction layer through the training of a diffraction neural network, designing a corresponding metasurface array, and preparing a cascaded metasurface diffraction device with a complex amplitude regulation function, deploying a cascade metasurface diffraction device to the far end of the multimode optical fiber and performing complex amplitude modulation on emergent circularly polarized light to realize high-resolution or high-sampling-rate image recovery; or an optical fiber transmission inverse matrix is solved by using an analytical method, and a corresponding metasurface array is designed, so that the single-layer metasurface diffraction device with a complex amplitude regulation and control function is prepared; and deploying the single-layer metasurface diffraction device to the far end of the few-mode optical fiber and carrying out complex amplitude modulation on emergent circularly polarized light to realize low-resolution or low-sampling-rate image recovery. Miniaturization of a multimode optical fiber imaging system can be realized, and the image recovery quality is effectively improved based on complex amplitude modulation of the metasurface diffraction device.

The invention discloses a vernier effect and Sagnac ring-based dual-parameter optical fiber sensor, which belongs to the technical field of optical fiber sensors and comprises a broadband light source SLED (1), a coupler (2), a sensing structure A (3), a circulator (4), a sensing structure B (5) and a spectrum analyzer (6). The device comprises a first single-mode fiber (301), a polarization-maintaining photonic crystal fiber (302), a few-mode fiber (303), a fiber Bragg grating (304), a second single-mode fiber (501), a first hollow-core fiber (502) and a second hollow-core fiber (503). Parasitic interference is avoided by grinding the end face of the hollow-core optical fiber, and the reliability of the sensor is improved; two transmission peaks appear on the fiber bragg grating inscribed on the few-mode fiber through different mode numbers in the few-mode fiber, and gas concentration and temperature sensitivity of two signals can be calculated by observing drifting of the transmission peaks; an optical vernier effect can be formed through superposition of a Sagnac interferometer formed by polarization-maintaining photonic crystal fibers and an F-P interferometer formed by hollow core dislocation, and the gas concentration and the temperature sensitivity of the sensor are improved. The sensor has the characteristics of high sensitivity, wide measurement range, simple structure, small size and the like.

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.

The invention discloses a directional coupling type mode group demultiplexer for a graded-index few-mode optical fiber, which comprises four demultiplexing regions, the first demultiplexing region is an LP31a, LP31b, LP12a and LP12b mode group demultiplexing region, an orthogonal two-mode directional coupling structure consisting of a graded-index few-mode optical fiber core and two same two-mode optical fiber cores is used, and the second demultiplexing region is an LP31a, LP31b, LP12a and LP12b mode group demultiplexing region. The two-mode optical fiber core is located in the horizontal direction and the vertical direction which are the same in distance with the few-mode optical fiber core. The LP11a mode and the LP11b mode in the two-mode optical fiber core are matched with the LP31a mode group, the LP31b mode group, the LP12a mode group and the LP12b mode group in the few-mode optical fiber core in phase. The second region is an LP21a, LP21b and LP02 mode group demultiplexing region, and the mode group is demultiplexed by using a similar structure; the third region is an LP11a and LP11b mode group demultiplexing region, and demultiplexing of the mode group is carried out by using a two-mode optical fiber matched with a few-mode optical fiber; and the fourth region is an LP01 mode group demultiplexing region, and demultiplexing of the mode group is carried out by using a single-mode optical fiber matched with the few-mode optical fiber. According to the invention, the mode group can be demultiplexed.

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.

The invention discloses an ultrashort pulse generation method and device based on a single-mode and dual-mode fiber laser. The method comprises the steps that pump light enters an erbium-doped fiber through a dual-mode wavelength division multiplexer, erbium ions are excited to an upper energy level to form population inversion, stimulated radiation is generated, and a laser signal is amplified; through the dual-mode optical fiber coupler, a small amount of laser is output to the outside of the cavity for measurement, and the remaining laser continues to oscillate in the cavity; the polarization state of the remaining laser in the resonant cavity is adjusted through a polarization controller so as to ensure that the laser is stably transmitted in the resonant cavity, and mode locking of the laser is realized by using a carbon nanotube saturable absorber so as to ensure that stable ultrashort pulses are generated; the laser passes through the dual-mode isolator to ensure that the light pulse runs unidirectionally in the resonant cavity and enters the dual-mode wavelength division multiplexer again to form circulation; and through periodic mode coupling, a stable mode-locked pulse is finally formed. The device is suitable for a few-mode optical fiber mode-locked laser, is simple in structure, is easy to construct and maintain, and is extremely high in stability and reliability.

An object of the present disclosure is to provide a few-mode fiber testing method and a few-mode fiber testing device capable of acquiring a loss and inter-mode crosstalk for each mode at a connection point of a few-mode fiber by measurement only from one end of FUT. The few-mode fiber testing method according to the present disclosure includes receiving a test light pulse in a basic mode from one end of an optical fiber under test that is connected in series with few-mode fibers of the same type, measuring an intensity distribution relating to a distance from the one end of backward Brillouin scattering light generated by receiving a test light pulse, obtaining a transmittance of the backward Brillouin scattering light at a connection point of the optical fiber under test from the measured intensity distribution, and calculating a connection loss of the basic mode from the transmittance, calculating a ratio of an axial deviation amount to a mode field radius of the optical fiber under test at the connection point from the calculated connection loss, and calculating a connection loss of a higher-order mode and inter-mode crosstalk between different modes from the calculated ratio.

The invention belongs to the field of optical measurement and detection, and particularly relates to a coherence tomography wavefront measurement device and method based on optical fiber interconnection and point diffraction, the measurement device separates a fundamental mode and a high-order mode of test light through a few-mode optical fiber, the fundamental mode generates a reference spherical wave through point diffraction to serve as reference light, and the high-order mode serves as the test light; after the test light and the reference light are subjected to optical fiber coupling interference, an interference pattern is obtained by a detector, and wavefront error measurement and optimization are realized through wavefront calculation and correction. The method has high precision and high stability, and can realize rapid closed-loop feedback correction.

The application discloses a device and method for coexistence of bright-dark solitons based on a mode division multiplexing resonant cavity, and relates to the technical field of lasers.The device for coexistence of bright-dark solitons based on the mode division multiplexing resonant cavity comprises an erbium-doped fiber amplifier, a first optical coupler, an acousto-optic frequency shifter, a second optical coupler, a third optical coupler, a first mode selection coupler, a second mode selection coupler and a fiber ring resonant cavity, and the fiber ring resonant cavity is a non-uniform dispersion few-mode fiber.The device and method for coexistence of bright-dark solitons based on the mode division multiplexing resonant cavity can realize stable coexistence of bright-dark solitons.

The invention discloses a bending endoscopic imaging method and system based on a few-mode optical fiber, and belongs to the technical field of optical fiber imaging. According to the method, an MNIST handwritten digital image is loaded through a digital micromirror device (DMD), a speckle pattern is generated through few-mode optical fiber transmission, image restoration in a bending state is achieved through a deep learning model, and reconstruction effects under different bending degrees are quantized through a Dice coefficient. The system comprises a light beam collimation module, a pattern loading module, an image transmission module and an image acquisition-processing module. The image transmission module adopts a step refractive index few-mode optical fiber, and mode coupling caused by bending is inhibited by increasing the effective refractive index difference between modes; and the image acquisition-processing module is combined with a shallow U-shaped convolutional neural network to reconstruct a speckle pattern acquired by the CCD camera. While miniaturization of the probe is ensured, the imaging quality in a bending environment is remarkably improved, and the probe is suitable for miniaturized high-resolution imaging scenes such as medical endoscopes and the like.

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.

The invention belongs to the field of optical fiber sensing, and particularly relates to a temperature-insensitive Brillouin curvature sensor based on an odd-even optical mode. The influence of temperature is eliminated through respective excitation of odd and even modes of an optical mode in the optical fiber, so that the problem of cross sensitivity of two-parameter sensing is solved, and the accuracy of the curvature sensor is improved. Specifically, by researching and comparing a circular few-mode optical fiber and an annular optical fiber, the temperature-insensitive curvature sensing principle based on a high-order odd-even mode is firstly explored, and then the effective refractive index of the odd-even modes of an optical basic mode and a second-order optical mode and the change of the effective mode area along with the curvature radius are explored; and finally researching the offset of the center of the power field and the Brillouin frequency shift change. According to the invention, the mechanism of realizing temperature-insensitive curvature sensing in odd and even modes is determined by comparing circular and annular optical fibers, the problem of cross sensitivity is solved, and a competitive choice is provided for optical fiber distributed curvature sensing.

The invention discloses a few-mode optical fiber and silicon optical chip dual-polarization mode coupler, which relates to the technical field of optical communication and photoelectronics, and comprises a few-mode optical fiber, a transmission type diffraction neural network structure and a waveguide array, the transmission-type diffraction neural network structure comprises a plurality of optical spacing layers and a silicon-based super-structure surface which are in surface connection in sequence. Super units which are uniformly arranged are arranged in the surface of the silicon-based super structure; wherein the two-way diffraction neural network based on a gradient descent algorithm determines phase distribution, and according to the phase distribution and a constructed phase-size lookup table, the structure distribution of the super-unit is obtained; and the waveguide array is used for connecting the silicon optical chip. According to the invention, the structure distribution of the super unit is determined according to the phase distribution and the phase-size lookup table, so that the few-mode fiber and silicon optical chip dual-polarization mode coupler has the characteristics of simple structure, high expansibility and low loss.

The invention provides a cooperative communication and sensing optical transmission system based on an elliptical core few-mode optical fiber. The system comprises a transmitting end, the elliptical core few-mode optical fiber and a receiving end. The transmitting end converts a digital signal into a mode encoding sequence through a mode encoder and couples the mode encoding sequence into the elliptical core few-mode optical fiber; the elliptical core few-mode optical fiber effectively reduces crosstalk between modes by utilizing a relatively large effective refractive index difference between different mode groups of the elliptical core few-mode optical fiber, and effectively improves the security of information transmission by utilizing a mode coding mode; the receiving end detects the position of the end face of the output optical fiber through an imaging system and a camera, compensates the position of the end face of the optical fiber through an electric displacement table to improve the mode demodulation performance of the receiving end, and recovers a mode coding sequence into original digital information through a mode decoder and a signal processor. According to the invention, the security of the optical fiber communication system can be effectively improved, crosstalk between modes is reduced, the robustness of mode demodulation of the receiving end is increased, and the performance of the space division multiplexing optical fiber communication system is effectively improved.

The invention relates to the technical field of optical communication, and discloses a mode diversity receiving system and method based on all-fiber coherent synthesis, and the system comprises a photon lantern receiving module, a cascade double-coupling module, a signal monitoring module, a control and feedback module, and a coherent detection module. Spatial optical signals influenced by atmospheric turbulence are firstly coupled into the few-mode optical fiber of the photon lantern to be received, multi-mode optical signals are excited and converted into multiple paths of single-mode signals, then coherent combination is carried out through the cascade double-coupling module, and the signal monitoring module monitors a beam combination result in real time. And the control and feedback module actively controls and compensates the phases of the multiple paths of single-mode signals, and photoelectric conversion and digital signal processing of the combined optical signals are completed by the coherent detection module. The influence of atmospheric turbulence on power imbalance in optical domain mode diversity is eliminated through active control and cascade double coupling, so that mode diversity gain is obtained, and adaptability of a space laser communication or radar system to the atmospheric turbulence is remarkably enhanced.

The application discloses a few-mode fiber double-cascaded mode converter and a high-power few-mode fiber laser. A core base mode and a core high-order mode converter and a core high-order mode and a cladding mode converter are cascaded on the few-mode fiber. The refractive index modulation distribution of the core base mode and the core high-order mode converter is uniformly distributed in the core center, and is used for coupling the core base mode to the core high-order mode. The refractive index modulation distribution of the core high-order mode and the cladding mode converter is distributed at the junction of the core and the cladding, and is used for coupling the core high-order mode to the cladding to form loss. The few-mode fiber double-cascaded mode converter is connected before an output end cap of the high-power few-mode fiber laser, and can inhibit stimulated Raman scattering in the large-mode-field few-mode fiber laser, so as to improve the output performance of the fiber laser.

The present invention proposes a few-mode fiber Bragg grating and a laser system that can suppress high-order mode reflection. A circular refractive index modulation zone concentric with the core is arranged in the core of the few-mode fiber. The radius of the refractive index modulation zone is smaller than the radius of the core. The refractive index modulation zone and the optical fiber vector mode are both circularly symmetrical. 01 Module and LP 11 The two modes will not be mutually coupled, and no energy exchange will occur between the two modes. 11 The self-coupling coefficient of the mode is lower than that of LP 01 Mode self-coupling coefficient, LP 11 The reflectivity of the mode is lower than that of LP 01 mode reflectivity, achieving LP 11 The few-mode fiber Bragg grating of the present invention can be used as a cavity mirror in a high-power fiber laser oscillator, which can realize both light reflection and mode control.

The invention relates to a multi-parameter fusion distributed optical fiber sensing system and method based on a few-mode optical fiber, and relates to the technical field of distributed optical fiber sensing, and the system is characterized in that emergent light of a laser is subjected to beam splitting and is respectively processed; part of the light is modulated to generate LP01 and LP11 mode light for detection, and the other part of the light generates Rayleigh local oscillation light and Brillouin local oscillation light. The detection light is combined and then injected into the sensing optical fiber to generate backscattered light. And the scattered light is separated into LP01 Brillouin scattered light, LP11 Brillouin scattered light and LP11 Rayleigh scattered light through a mode demultiplexer. And performing beat frequency processing on the different types of scattered light and the corresponding local oscillation light by using a balance detector to obtain a first low-frequency signal, a second low-frequency signal and a beat frequency signal. The data processing module analyzes the signals and can obtain a Brillouin frequency shift spectrum and a vibration signal frequency spectrum reflecting a vibration event. The method has the effect of realizing high-precision measurement.

The application provides an optical communication method applied to the field of optical communication. The optical communication method comprises the following steps: a first optical communication device acquires a first mode division multiplexing optical signal and a first wavelength division multiplexing optical signal. The first optical communication device performs beam combination on the first mode division multiplexing optical signal and the first wavelength division multiplexing optical signal to obtain a first multiplexing optical signal. The first optical communication device transmits the first multiplexing optical signal to a second optical communication device through a first optical fiber. The first optical fiber is a multimode optical fiber or a few-mode optical fiber. The wavelength of the first wavelength division multiplexing optical signal is greater than the cutoff wavelength of the first optical fiber. The wavelength of the first mode division multiplexing optical signal is less than the cutoff wavelength of the first optical fiber. In the application, the mode division multiplexing optical signal and the wavelength division multiplexing optical signal are transmitted through one optical fiber, so that the communication bandwidth can be improved.

The present application relates to the technical field of optical fiber characteristic measurement, and discloses a differential group delay measurement method, device, equipment, storage medium and computer program product, including: obtaining a mixed signal transmitted in a few-mode optical fiber to be tested, the mixed signal including at least two spatial mode optical signals; collecting electrical signal change information based on the mixed signal, and generating a light field interference signal according to the electrical signal change information; performing a cepstrum analysis on the light field interference signal through Fourier transform to determine the peak position in the light field interference signal; and calculating the differential group delay between two spatial modes in the few-mode optical fiber to be tested according to the peak position. Performing a cepstrum analysis on the received signal data, extracting the cepstrum features of the signal through Fourier transform, and then extracting the feature information of the differential mode group delay, while ensuring high measurement accuracy and reliability, reducing the dependence on special signal sources and expensive equipment, and reducing the cost of actual operation.

The invention discloses a high-order Poincare light beam characterization measurement method and a high-order Poincare light beam characterization measurement device. According to the method, all parameter information of a high-order Poincare beam is measured based on centroid ellipse information of different polarization components of an interference field. The absolute value of the difference between the reference light and the measured light mode-based orbital angular momentum topological charge number is 1. The rotational symmetry of two paths of cross-polarization interference fields obtained after coaxial interference is broken, the center of mass deviates from the center of a light beam, and the center of mass moves to form an elliptical orbit under the condition of dynamic interference. And synchronously detecting the centroid tracks of the two paths of dynamic interference fields to obtain two centroid ellipses. And adding the two centroid ellipse coordinates and averaging to obtain a third associated ellipse. All Poincare sphere parameters can be calculated according to nine ellipse parameters of the three ellipses, so that the light beam is positioned and displayed on the three mixed Poincare spheres. The device breaks through the measurement limitation of a traditional polarization analyzer, can be used for detecting the dynamic evolution of a few-mode optical fiber high-order mode group, and assists the development of optical sensing and optical measurement technologies.

The application discloses a fiber magnetic field and temperature measuring device and method based on a cascade MZI, and relates to the technical field of optical fiber sensing. The device comprises a broadband light source, a sensor and a spectrum analyzer. The sensor comprises a quartz tube and a first single-mode optical fiber, a first few-mode optical fiber, a magnetic fluid filled side-hole optical fiber, a UV glue film coated hollow-core optical fiber, a second few-mode optical fiber and a second single-mode optical fiber which are sequentially fused. The fiber core and the magnetic fluid cavity in the magnetic fluid filled side-hole optical fiber constitute a first MZI. The hollow-core fiber core and the second cladding in the UV glue film coated hollow-core optical fiber constitute a second MZI. The first few-mode optical fiber expands the light beam introduced by the first single-mode optical fiber, and then introduces the light beam into the second few-mode optical fiber through the first MZI and the second MZI for coupling. The coupled light beam is demodulated, a coefficient matrix is used for calculation, and the dual-parameter measurement of the magnetic field and the temperature is realized. The application aims to realize the simultaneous detection of the dual parameters of the magnetic field and the temperature, and has high sensitivity.

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

The invention discloses a central concave type multi-layer doped gain-balanced few-mode optical fiber structure, which is characterized in that each layer structure in an optical fiber is of a bull's-eye structure on the cross section of the optical fiber and shares the same center, and each layer sequentially comprises a low-refractive-index fiber core, a high-refractive-index fiber core, a groove and a cladding from inside to outside. According to the embodiment of the invention, a mode of combining a central concave type refractive index design and multi-layer doping is adopted, and overlapping integral factor differences among all transmission modes are reduced by adjusting distribution characteristics of all mode fields in the optical fiber, so that similar signal gains of all modes are realized, and a relatively excellent gain equalization characteristic of the amplifier is obtained. The optical fiber structure design can also increase the effective refractive index difference of each mode to a certain extent, reduce the coupling and crosstalk between the modes, and realize the high-purity gain of the few-mode optical fiber amplifier.

The invention relates to the technical field of optical communication devices, in particular to a hybrid integrated space division multiplexer based on 3D printing, which comprises a single-mode array waveguide, a mode multiplexing / demultiplexing device, a 3D printing few-mode waveguide and a multi-core few-mode optical fiber which are connected in sequence, the single-mode array waveguide is used for realizing multi-mode energy coupling between the single-mode array waveguide and a fiber core in the multi-core few-mode optical fiber; the mode multiplexing / demultiplexing device couples energy of a fundamental mode in the single-mode array waveguide to a high-order mode of the 3D printing few-mode waveguide, and the 3D printing few-mode waveguide couples the energy to each fiber core of the multi-core few-mode fiber; and the single-mode array waveguide, the mode multiplexing / demultiplexing device and the 3D printing few-mode waveguide are integrally printed and formed by a 3D two-photon printing technology. The space division multiplexer disclosed by the invention integrates the functions of a mode multiplexer and a space division fan-in and fan-out device, has the characteristics of high integration level, capability of realizing polarization multiplexing, high efficiency and the like, reduces the difficulty of the whole device, and meets the actual requirements in the fields of optoelectronic communication and the like.

The invention belongs to the technical field of few-mode optical fibers, and discloses an ultralow differential mode group delay few-mode optical fiber and a preparation method thereof. The ultralow differential mode group delay few-mode optical fiber provided by the invention comprises a core layer structure, an inner cladding layer structure and an outer cladding layer from inside to outside, the core layer structure comprises a first core layer and a second core layer from inside to outside; the two core layers are provided with gradient sections, the distribution index alpha 1 of the first core layer is 1.5-1.9, and the distribution index alpha 2 of the second core layer is 1.4-1.9; the minimum relative refractive index difference 1 of the first core layer is 0.3% to 0.6%; the maximum relative refractive index difference of the first core layer and the maximum relative refractive index difference of the second core layer are the same and marked as 2, 2 is 0.6%-0.9%, and 2 > 1; the second core layer has a minimum relative refractive index difference 3 of-0.2% to-0.1%. According to the invention, extremely low differential mode group delay can be realized.

This invention provides a mode-division multiplexing (MDF) system, method, device, and storage medium, relating to the field of optical communication technology. The MDF system includes at least: multiple cascaded optical fiber transmission units across multiple spans and a central controller. Each optical fiber transmission unit includes multimode or few-mode fiber and a mode adjustment unit. The mode adjustment unit calculates the transmission parameters of the optical fiber transmission unit and sends these parameters to the central controller. The central controller acquires the transmission parameters of the optical fiber transmission units in each span, generates a target mode round-robin strategy for the corresponding span, and sends it to the mode adjustment unit to update the optical signal module. The central controller adaptively selects the target mode round-robin strategy based on the real-time transmission environment, adaptively adjusting each span to reduce differential mode group delay (DMD) and mode-dependent loss (MDL), adapting to different span lengths and different transmission environments, and improving the transmission performance of multimode or few-mode fiber.

The present invention provides an intermodal parameter measurement device and method based on tunable electrical time delay, which relates to the technical field of optical communication measurement, and solves the problem that the current differential group delay measurement method for few-mode fibers cannot distinguish the differential group delay DMGD with negative values. Two fundamental mode optical signals are generated at the transmitting end, and a tunable electrical time delay Δτ1 is loaded on one of the fundamental mode optical signals. The two fundamental mode optical signals are converted into optical signals with different spatial modes by the first photon lantern and transmitted to the few-mode fiber under test, and then are converted into fundamental mode signals again by the second photon lantern. The analysis module acquires the spectra of the fundamental mode optical signals, records the absolute power difference between the +1st order and -1st order sidebands in the spectra, determines the value of the tunable electrical time delay Δτ1 based on the absolute power difference, and obtains the differential group delay DMGD of the few-mode fiber under test based on the value of the tunable electrical time delay Δτ1, realizing the distinction of the differential group delay DMGD with positive or negative values and broadening the measurement range of the differential group delay DMGD.

The present invention provides a three-band mode multiplexing self-matching photon lantern and its manufacturing method, belonging to the field of optical communications. The photon lantern comprises: a fiber array, a transition region, and a few-mode port connected in sequence. The fiber array comprises a predetermined number of 980nm single-mode fibers with cladding, a single 1310nm few-mode fiber with cladding, and a single 1550nm few-mode fiber with cladding, placed in a quartz capillary tube. The fiber array is the portion that remains unchanged after adiabatically tapering to a predetermined length according to a predetermined stretch ratio. The transition region is the portion that changes shape after tapering, and the few-mode port is the port portion that changes shape after tapering. The photon lantern can achieve selective mode conversion at the 980nm wavelength, maintain the 1550nm and 1310nm wavelength modes, and transmit low-loss closed-loop signals. It can be used to construct a fiber ring laser cavity, enabling direct oscillation and output of multiple high-order modes within the all-few-mode fiber ring laser cavity, thus avoiding single-mode and few-mode incompatibility issues.

A sourceless co-packaged optical-electrical chip can include a plurality of different optical transceivers, each of which can transmit to an external destination or internal components. Each of the transceivers can be configured for a different modulation format, such as different pulse amplitude, phase shift key, and quadrature amplitude modulation formats. Different light sources provide light for processing by the transceivers, where the light source and transceivers can be configured for different applications (e.g., different distances) and data rates. An optical coupler can combine the light for the different transceivers for input into the sourceless co-packaged optical-electrical chip via a polarization maintaining media (e.g., polarization maintaining few mode fiber and polarization maintaining single mode fiber), where another coupler operates in splitting mode to separate the different channels of light for the different transceivers according to different co-packaged configurations.