Dual-core Optical Fiber Research Articles

A novel dual-core fiber-optic gyroscope with independent rotation rate measurements in different cores of a dual-core optical fiber

A novel dual-core fiber-optic gyroscope with independent rotation rate measurements in different cores of a dual-core optical fiber

Hybrid Si-Au plasmonic sensor on the end-facet of a dual-core optical fiber enhanced by hotspots: a theoretical study

We propose an efficient hybrid Si-Au sensor on the end-facet of a dual-core single-mode optical fiber. The design incorporates slanted Si grating couplers on the two cores, interconnected by a plasmonic waveguide bearing subwavelength corrugations. The corrugations enhance the surface sensitivity by creating regions of strongly enhanced fields - plasmonic hotspots. Unlike conventional Si waveguide grating couplers, we employ slanted slits for unidirectional coupling/decoupling between TM-polarized core light and surface plasmon polaritons. Our structure results in about 3% core-to-core (TM-to-TM) coupling efficiency, while also providing high bulk and surface sensitivities of about 1000 nm RIU−1 and 1.66 nm nm−1, respectively. The sensor can be interrogated remotely in a transmission arrangement. The sensing medium can be probed by dipping the fiber tip directly therein. Potential applications include remote sensing, brain studies, or in-vivo biosensing.

Optical fractional solitonic structures to decoupled nonlinear Schrödinger equation arising in dual-core optical fibers

This paper explores a specific class of equations that model the propagation of optical pulses in dual-core optical fibers. The decoupled nonlinear Schrödinger equation with properties of M fractional derivatives is considered as the governing equation. The proposed model consists of group-velocity mismatch and dispersion, nonlinear refractive index and linear coupling coefficient. Different types of solutions, including mixed, dark, singular, bright-dark, bright, complex and combined solitons are extracted by using the integration methods known as fractional modified Sardar subequation method and modified F-expansion method. Optical soliton propagation in optical fibers is currently a subject of great interest due to the multiple prospects for ultrafast signal routing systems and short light pulses in communications. In nonlinear dispersive media, optical solitons are stretched electromagnetic waves that maintain their intensity due to a balance between the effects of dispersion and nonlinearity. Furthermore, hyperbolic, periodic and exponential solutions are generated. A fractional complex transformation is applied to reduce the governing model into the ordinary differential equation and then by the assistance of balance principle the methods are used, depending upon the balance number. Also, we plot the different graphs with the associated parameter values to visualize the solutions behaviours with different parameter values. The findings of this work will help to identify and clarify some novel soliton solutions and it is expected that the solutions obtained will play a vital role in the fields of physics and engineering.

Hosting exceptional point in all-lossy dual-core optical fiber and its exotic chiral light dynamics

Exploration of exceptional points (EPs) and associated unique features in gain-loss assisted optical systems to develop future all optical devices have been a great interest in recent years. However, incorporation and adjustment of gain distribution in a system is quite challenging. Here, we design a fabrication feasible dual-core optical fiber where only the customized transverse loss profile controls the interaction between two coupled modes and results in hosting an EP. Parametric encirclement of the identified EP and corresponding chirality-driven asymmetric mode conversion phenomenon between the supported modes have been reported. The proposed structure features ease of fabrication using state-of-the-art techniques with possible applications in all-optical components for communication and all fiber photonic devices.

Broadband 1.5-2.1 µm emission in gallo-germanate dual-core optical fiber co-doped with Er3+ and Yb3+/Tm3+/Ho3.

The near-infrared emission in fabricated low-phonon energy, gallo-germanate glass, and double-core optical fiber has been investigated. Broadband amplified spontaneous emission (ASE) was obtained in optical fiber with cores doped with: 1st - 0.2Er2O3 and 2nd - 0.5Yb2O3/0.4Tm2O3/0.05Ho2O3 as a result of the superposition of emission bands from both cores corresponding to the Er3+:4I13/2→4I15/2 (1st core) and Tm3+:3F4 → 3H6/Ho3+:5I7 → 5I8 (2nd core) transitions. The effect of fiber length and pump wavelength on the near-infrared amplified spontaneous emission (ASE) properties has been analyzed for 1 m and 5 m optical fiber. The widest emission bandwidth (355 nm - 3 dB level) was obtained for a 5 m length optical fiber pumped by a 940 nm laser.

One-dimensional Townes solitons in dual-core systems with localized coupling.

The recent creation of Townes solitons (TSs) in binary Bose-Einstein condensates and experimental demonstration of spontaneous symmetry breaking (SSB) in solitons propagating in dual-core optical fibers has drawn renewed interest in the TS and SSB phenomenology in these and other settings. In particular, stabilization of TSs, which are always unstable in free space, is a relevant problem with various ramifications. We introduce a system which admits exact solutions for both TSs and SSB of solitons. It is based on a dual-core waveguide with quintic self-focusing and fused (localized) coupling between the cores. The respective system of coupled nonlinear Schrödinger equationsgives rise to exact solutions for full families of symmetric and asymmetric solitons, which are produced by the supercritical SSB bifurcation (i.e., the symmetry-breaking phase transition of the second kind). Stability boundaries of asymmetric solitons are identified by dint of numerical methods. Unstable solitons spontaneously transform into robust moderately asymmetric breathers or strongly asymmetric states with small intrinsic oscillations. The setup can be used in the design of photonic devices operating in coupling and switching regimes.

(Invited) Quiescent solitary waves in dual-core systems with separated Bragg grating and cubic–quintic nonlinearity

The existence and stability of zero-velocity solitons in a dual-core optical fiber, where one core possesses cubic–quintic nonlinearity and the other core is linear with a Bragg grating, are investigated. The frequency spectrum for the model consists of three bandgaps, of which only the central band gap is a genuine one. There are no soliton solutions in the central gap. On the other hand, the upper and lower gaps are filled with two distinct and disjoint families of soliton solutions, termed Type-1 and Type-2 solitons, that differ in their shapes and phase characteristics. When the relative group velocity in the linear core is zero, implicit analytical solutions for Type-1 and Type-2 quiescent solitons are found. For nonzero values of the relative group velocity, soliton solutions can only be found using numerical techniques. The stability of solitons has been analyzed systematically by means of numerical stability analysis. It is found that Type-2 solitons are always unstable. In the case of Type-1 solitons, stability regions are identified in the upper and lower bandgaps. The effects and interplay of the relative group velocity and the Bragg grating-induced linear coupling coefficient on the stability of the solitons are also analyzed.

Innovative and diverse soliton solutions of the dual core optical fiber nonlinear models via two competent techniques

It becomes an interesting part for the researchers to analyze the dynamical behavior of soliton propagation in optical fibers for trans-oceanic and trans-continental distances. In this paper, we desire to retrieve distinct and innovative accurate wave solutions to the dual core optical fiber nonlinear equations by adopting the improved tanh method and the rational [Formula: see text]-expansion method. Consequently, a bundle of accurate wave solutions is achieved in diverse sense. The acquired solutions are made visible in the profiles of three-dimensional (3D), two-dimensional (2D) and contour shapes. The effects of the wave speed in soliton transmission are highlighted by plotting different 2D outlines in a single diagram for some obtained solutions. The employed techniques perform as before to unravel the suggested governing models for appropriate wave solutions and hence deserve to contribute in further research.

Solitons in dual-core optical fibers with chromatic dispersion

Solitons in dual-core optical fibers with chromatic dispersion

Dual-core optical fiber tweezers based on all-dielectric metasurface

A transverse multi-position optical fiber tweezer is designed and studied by integrating an all-dielectric metasurface on the end of the dual-core optical fiber. The emitted beams from two cores of the fiber deflect towards two opposite directions with the same deflection angle and converge to form interference fringes in the far field. The dependences of optical force characteristics on light deflection angle, size and refractive index of the nanoparticle are discussed. The calculated results show that the proposed fiber device can achieve multi-position optical trapping of nanoscale nanoparticles in far field. Compared with the metal-based metasurface, dielectric metasurface-based fiber tweezer has higher efficiency and stronger capturing force. Our research expands applications of all-dielectric metasurface to optical tweezers and provides new ideas on the emerging platform of fiber-based metasurface.

Dynamics of optical pulses in dual-core optical fibers modelled by decoupled nonlinear Schrodinger equation via GERF and NEDA techniques

Dynamics of optical pulses in dual-core optical fibers modelled by decoupled nonlinear Schrodinger equation via GERF and NEDA techniques

Exceptional-point-induced asymmetric mode conversion in a dual-core optical fiber segment

The engineering of exceptional points (EPs) in open optical systems has lately attracted much attention for developing future all-optical devices. However, investigation of the fascinating features of EPs in fiber geometries is lacking. We design a fabrication feasible dual-core optical fiber segment, where non-Hermiticity in terms of a symmetric customized gain-loss profile is introduced to modulate the interaction between two corresponding coupled modes toward hosting a dynamical EP encirclement scheme in the gain-loss parameter space. An asymmetric conversion process between two supported modes is reported by exploiting the chirality of the encountered EP. The proposed scheme can lead to an advanced platform to design mode-manipulative all-optical components in communication and all-fiber photonic devices.

Dual-core optical fibers for efficient mid-infrared generation via third-order frequency mixing and coupling-length phase matching

Appropriately designed dual-core fibers using coupling-length phase matching (CLPM) allow for phase-matched frequency downconversion over wide frequency intervals using the third-order optical nonlinearity of glass. By tuning the distance between the two cores, CLPM allows continuously tunable phase matching for widely different wavelengths for the process in which a pump wave at a frequency ω 2 generates or amplifies two waves with frequencies ω 3 > --> ω 2 and ω 1 = 2 ω 2 − ω 3 . The intensity-dependent correction that accounts for nonlinear phase modulation is derived in general. In addition, a specific CLPM configuration is found to be insensitive to phase modulation, and can achieve 100% theoretical quantum yield for pump wave injection in one core. Fiber-based frequency converters can thus be designed for large differences between pump wavelengths and generated wavelengths, with the phase-matched interaction enabling the use of meter-long fibers to compensate for low third-order susceptibilities. Examples of fiber designs for pump wavelengths at 1.3 and 1.55 µ m , to generate radiation with wavelengths longer than 2 µ m , are discussed for silica and fluoride fibers.

Study of the parametric effects on soliton propagation in optical fibers through two analytical methods

The dual-core optical fiber has significant applications in optical electronics for long-wave propagation, especially in telecommunication fibers. The aim of this article is to study the parametric effects on solitary wave propagation and characteristic aspects of long-wave traveling through optical fibers by establishing some standard and wide-spectrum solutions via the improved Bernoulli sub-equation function (IBSEF) method and the new auxiliary equation (NAE) approach. The investigated solitary wave solutions are ascertained as an integration of hyperbolic, exponential, rational and trigonometric functions and can be extensively applicable in optics. The physical significance of the solutions attained is illustrated for the definite values of the included parameters through depicting the 3D profiles. The solitons profile represents different types of waves associated with the free parameters which are related to wave number and velocity. It turns out that the solutions obtained through both the methods are potential and can be used to interpret signals in telecommunication fibers and other works which can reduce casualties that ensue in essence.

A Twin-Core and Dual-Hole Fiber Design and Fabrication

We have proposed and demonstrated novel twin-hole and dual-core optical fiber. We used the normal MCVD technology to fabricate a single core fiber preform with a thin cladding. Then, two small holes were drilled in the center and on the side of the pure silica rod, the fabricated single-core fiber preform was inserted into the two holes, and then the combined preform was heated until three parts were fused. Finally, two larger holes were drilled close the center core and twin-core and dual-hole are vertically distributed. In order to retain the shape of air hole, we filled nitrogen gas in the two holes to against the ambient pressure, which made the holes collapse during the fiber drawing. The dual-hole microstructure may be used as micro-containers to inject modulation medium and aside the center core, and to induce accumulated interaction between flow material and evanescent field of the center core, therefore, it can be used as a modulation function fiber to fabricate a very compact in-fiber integrated device.

High Contrast All-Optical Dual Wavelength Switching of Femtosecond Pulses in Soft Glass Dual-Core Optical Fiber

All-optical switching of 75 fs pulses centered at 1560 nm, driven by 270 fs, 1030 nm pulses in a dual-core optical fiber exhibiting high index contrast is presented. The fiber is made of a thermally matched pair of lead silicate and borosilicate glasses used as core and cladding material, respectively. The novel switching approach is based on nonlinear balancing of dual-core asymmetry, by control pulse intensity induced group velocity reduction of the fast fiber channel. Due to the fiber core made of soft glass with high nonlinearity high switching contrast exceeding 20 dB is reached by using control pulses of only few nanojoule energy. The optimum fiber length is 14 mm, which closely match the calculated coupling length at the signal wavelength. The results express significant progress in comparison to similar studies based on self-switching of solitonic pulses in dual-core fibers and represent high application potential.

All-optical switching of ultrafast solitons at 1560 nm in dual-core fibers with high contrast of refractive index

We present a study of ultrafast solitonic all-optical switching in the C-band using dual-core optical fibers fabricated in-house. The two soft glasses used for the fiber express high contrast of refractive index at the level of 0.4. The core was made of a highly nonlinear lead-silicate glass, which, combined with the anomalous dispersion, allowed the solitonic propagation at low pulse energies. A convincing switching performance was demonstrated using the optimized fiber at hundreds of picojoule level of the in-coupled energy. The dedicated numerical simulations unveiled the solitonic propagation character of 75 fs excitation pulses influenced by dual-core asymmetry. All the key parameters of the switching, such as the optimal fiber length (38 mm), the switching contrast (4.5 dB) and the switching energy levels (200–700 pJ), were confirmed by the numerical results.

Connecting Technologies for Coaxial Dual Core Optical Fiber

Coaxial dual core optical fiber (CDCF) with a lensed tip can be used for microparticle trapping, shooting, and spectra analyzing. In this paper, we introduce the connection technology of CDCFs. On the one hand, the CDCFs can be fusion spliced easily and quickly by using the single-mode fiber (SMF) splicing machine, because they have a completely axisymmetric structure. On the other hand, a fan-in device based on the principle of “vanishing core” is designed, and the insertion loss due to fabrication process error is analyzed. Fan-in devices are fabricated and tested. The average insertion loss of the annular core and central core is 1.48 dB and 0.76 dB, respectively.

New exact solutions to the dual-core optical fibers

In this article, new exact solutions of the dual-core optical fibers model are determined by using the Riccati–Bernoulli sub-ODE method. As a result, rational, trigonometric, hyperbolic and exponential functions and a variety of special solutions like kink-shaped, bell-type soliton solutions are established. We also consider the linear stability analysis for the dual-core optical fibers model. We also plot the 3D graphs for some selected solutions with the aid of the MATLAB software. We finally compare our results with the other methods and show that the Riccati–Bernoulli sub-ODE method is superior to other methods.

All-optical switching based on soliton self-trapping in dual-core high-contrast optical fibre

A systematic numerical study of ultrafast nonlinear directional coupler performance based on soliton self-trapping in a novel type of dual-core optical fibre is presented. The considered highly nonlinear fibre structure is composed of a real, intentionally developed soft glass-pair with high refractive index contrast at the level of 0.4 in the near infrared. Nonlinear propagation of picojoule level femtosecond pulses was studied numerically with the aim to identify the best switching performance in input parameter space of 1400–1800 nm in terms of excitation wavelengths, and of 75–150 fs in terms of pulse width, respectively. For every combination of excitation wavelength and pulse width, the switching energies together with the optimal fibre length were determined and their relation to the input and switching parameters is discussed. The highest switching contrast of 46 dB in the time window of the ultrashort soliton was predicted at combination of 1500 nm excitation wavelength and 75 fs pulse width considering 43 mm fibre length. These results represent significant improvement both from point of view of switching contrast and switching energies, which are only at level of 20 pJ, in comparison to the previously published case of air-glass dual-core photonic crystal fibre. Moreover, the simpler fibre design without cladding microstructure together with the all-solid approach holds promise of improved dual-core symmetry and therefore offers high probability of the successful realization of a low power, compact and simple switching device.