Based on the overlap integral of electromagnetic fields in neighboring cores, a calculating method is proposed for obtaining coupling coefficient between two adjacent trench-assisted non-identical cores.And kind heterogeneous multi-core fiber (Hetero-TA-MCF) with 12 cores to achieve large effective area (A eff ) and high density cores.As bending radius becomes larger than 50 mm, crosstalk value at 1550-nm wavelength Hetero-TA-MCF about -42 dB after 100-km propagation A this can reach 100 µm 2 .

A 30-core fiber with heterogeneous cores that achieved large spatial multiplicity and low crosstalk of less than −40 dB at 100 km was demonstrated. The correlation lengths were estimated to be more 1 m.

An analytical expression for the mode coupling coefficient in homogeneous trench-assisted multi-core fibers is derived, which has a simple relationship with one normal step-index structures.The amount of inter-core crosstalk reduction (in dB) structures compared to can then be written by expression.Comparison numerical simulations confirms that obtained very good accuracy estimation.The properties fibers, such as dependence on core pitch and wavelength-dependent crosstalk, this expression.

Abstract Optical communication technology based on the wavelength, time, polarization, and complex amplitude of light is approaching a bottleneck, while spatial dimension relatively unexplored. Orbital angular momentum (OAM) beams are an important group that promising for increasing optical capacity their orthogonality. To effectively utilize this light, broadband low‐crosstalk OAM mode de/multiplexing devices indispensable. In work, by exploiting diffraction neural network, de/multiplexer...

The transport and complex optical properties of the electron-doped iron-arsenic superconductor ${\text{BaFe}}_{1.85}{\text{Co}}_{0.15}{\text{As}}_{2}$ with ${T}_{c}=25\text{ }\text{K}$ have been examined in Fe-As planes above below ${T}_{c}$. A Bloch-Gr\"uneisen analysis resistivity yields a weak electron-phonon coupling constant ${\ensuremath{\lambda}}_{ph}\ensuremath{\simeq}0.2$. low-frequency response normal state appears to be dominated by electron pocket may described weakly interacting...

The detailed optical properties of ${\text{BaFe}}_{2}{\text{As}}_{2}$ have been determined over a wide frequency range above and below the structural magnetic transition at ${T}_{N}\ensuremath{\simeq}138\text{ }\text{K}$. A prominent in-plane infrared-active mode is observed $253\text{ }{\text{cm}}^{\ensuremath{-}1}$ (31.4 meV) 295 K. this vibration shifts discontinuously ${T}_{N}$; for $T<{T}_{N}$ displays almost no temperature dependence, yet it nearly doubles in intensity. This anomalous...

The wavelength dependence of inter-core crosstalk in homogeneous multi-core fibers (MCFs) is investigated, and the corresponding analytical expressions are derived. derived can be used to determine at any necessary for designing future MCF wavelength-division multiplexing (MCF-WDM) networks transmission systems.

The third-order orbital angular momentum (OAM±3) guided mode generation is demonstrated for the first time, to best of our knowledge, by employing an asymmetric long-period fiber grating (AS-LPFG). proposed AS-LPFG modeled coupled local-mode theory, which extended coupling core modes and fabricated multicycle scanning ablation with increasing power in a six-mode fiber. experiments demonstrate that one can convert LP01 third-azimuthal-order (3AO, LP31 or OAM±3) efficiency ∼99.8%. model method...

In a few-mode erbium-doped fiber (FM-EDF), which is key section in space-division multiplexing (SDM) communication system, linearly polarized (LP) and orbital angular momentum (OAM) modes, as two-mode bases with different phase profiles, can be transformed into each other. principle, the LP OAM modes have mode spatial intensity distribution gain difference for FM-EDF amplifiers. How to analyze characterize differential mode-bases (DMBG) important, but still an issue. We build, first time our...

As the bottleneck device of a space-division multiplexing (SDM) communication system that exploits degrees freedom to further increase capacity within transmission band, main challenge facing integrated SDM amplifier is how number amplified modes and reduce difference in mode gain total satisfy performance specifications required by system. Here, cladding-pumped five orbital angular momentum (OAM) group erbium-doped fibre (5MG-EDFA) based on centre-raised ring-core (CRC-EDF) demonstrated,...

As the bottleneck device of a space-division multiplexing (SDM) communication system that exploits degrees freedom to further increase capacity within transmission band, main challenge facing integrated SDM amplifier is how number amplified modes and reduce difference in mode gain total satisfy performance specifications required by system. Here, cladding-pumped five orbital angular momentum (OAM) group erbium-doped fibre (5MG-EDFA) based on centre-raised ring-core (CRC-EDF) demonstrated,...

We present a method for extracting the electron-boson spectral function ${\ensuremath{\alpha}}^{2}F(\ensuremath{\omega})$ from infrared and photoemission data. This procedure is based on inverse theory will be shown to superior previous techniques. Numerical implementation of algorithm presented in detail then used accurately determine doping temperature dependence several families high-${T}_{c}$ superconductors. Principal limitations experimental data pointed out. directly compare IR...

We describe and explain the design methods for cores, trench layers core number in multi-core fibers (MCFs) detail. According to such method, we propose relative optimized schemes heterogeneous trench-assisted fiber (Hetero-TA-MCF), inside which cores are arranged one-ring structure. This Hetero-TA-MCF is a kind of bend-insensitive MCF with high density ultra-low crosstalk.

We proposed a novel torsion sensor based on inter-core mode coupling in seven-core fiber (SCF). The is fabricated by tapering commercially available SCF spliced with two single fibers. Waist diameter and length of the taper structure were experimentally optimized to achieve good transmission spectrum. Based this structure, measurement was conducted, experimental results demonstrated that spectrum shows red shift twist. sensitivity increases twisting angle, which can as high 1.00 nm/°....

Temperature dependent optical conductivities and dc resistivity of c-axis oriented superconducting (T(c) = 39.6 K) MgB2 films (approximately 450 nm) have been measured. The normal state ab-plane can be described by the Drude model with a temperature independent plasma frequency omega(p,D) 13 600+/-100 cm(-1) or 1.68+/-0.01 eV. is fitted Bloch-Grüneisen formula an electron-phonon coupling constant lambda(tr) 0.13+/-0.02. conductivity spectra below T(c) these suggest that multigap superconductor.

Optical properties of ultrathin layers (<50 A) Au and Pb quench condensed on amorphous germanium (alpha-Ge) have been measured in situ at 10 K. The development these films from an insulating state to a metallic is traced as function the film thickness well sheet resistance, R(square). Of particular interest regime R(square) near 3000 Omega where there anomaly optical transmission. This due singularity dielectric when system undergoes electronic percolation or insulator-to-metal (I/M) transition.

Improved resolution in both energy and momentum angular-resolved photoemission spectroscopy (ARPES) data has led to the establishment of a definite scale dressed quasiparticle dispersion relations. The observed structure around $80\mathrm{meV}$ been taken as evidence for coupling phonons refocused debate about mechanism superconductivity cuprates. Here we address relative merits phonon opposed spin-fluctuation mechanisms. Both possibilities are consistent with ARPES. On other hand, when...

We present magnetic measurements in a single crystal of the newly discovered superconducting iron-pnictide $\text{Ba}{({\text{Fe}}_{0.925}{\text{Co}}_{0.075})}_{2}{\text{As}}_{2}$. The magnetization loops exhibit second peak (SMP) similar to that observed most high-temperature superconductors (HTSs). Magnetic relaxation reveal minimum normalized rate, $S=d\text{ }\text{ln}\text{ }M/d\text{ }t$, located between SMP onset and fields. HTSs is commonly associated with vortex order-disorder phase...

We propose a kind of heterogeneous multi-core fiber (Hetero-MCF) with trench-assisted multi-step index few-mode core (TA-MSI-FMC) deployed inside. After analyzing the impact each parameter on differential mode delay (DMD), we design couple TA-MSI-FMCs A(eff) 110 μm2 for LP01 mode. DMD TA-MSI-FMC is smaller than |170| ps/km over C + L band and total can approach almost 0 if adopt managed transmission line technique by using only one Hetero-TA-FM-MCF. For such Hetero-TA-FM-MCF, crosstalk about...

We propose and design a kind of heterogeneous rod-assisted trench-assisted multi-core fiber (Hetero-RA-TA-MCF) with 32 cores arranged in square-lattice structure (SLS), then we introduce the method for Hetero-RA-TA-MCF. Simulation results show that Hetero-RA-TA-32-Core-Fiber achieves average effective area (Aeff) about 74 μm2, low crosstalk (XT) -31 dB/100km, threshold value bending radius (Rpk) 7.0 cm, relative core multiplicity factor (RCMF) 8.74, cable cutoff wavelength (λcc) less than 1.53 μm.

Orbital angular momentum (OAM) beams with different indices l have the potential to greatly increase communication capacity. However, finite aperture of optical systems limits value index. In order fully use orthogonal mode channels supported in fiber for high-capacity communications, we propose extending radial p OAM modes as an additional multiplexing dimension. this paper, introduce spatially discrete multiple phase planes multiplex and simultaneously. Due property central symmetric...

We investigate the orbital angular momentum (OAM) mode-generating process of a long-period onefold chiral fiber grating (L-1-CFG) based on helically twisted hollow-core antiresonant (HC-ARF). Taking right-handed L-1-CFG for an example, we theoretically and experimentally prove that first-order OAM+1 mode can be generated by only inputting Gaussian beam. fabricated three samples HC-ARF with twist rates (α) -0.42, -0.50, -0.60 rad/mm, where α -0.42 rad/mm achieve high purity 94%. Subsequently,...

Systematic temperature-dependent optical studies of optimally doped ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$ (OP Bi2212) single crystals have been carried out. An electron-boson spectral function peaked at 43 meV is derived in the normal state 100 K, indicating that most significant feature OP Bi2212 a resonance meV. The data below ${T}_{c}$ show this boson directly involved pair formation Bi2212. Origins mode are discussed.