Narrow Results

Modulating dark optical fiber vector soliton molecules are theoretically investigated in this work. An optical fiber modulation system that out of fiber laser cavity is employed as a simulation model, which can flexibly change orthogonal electric fields’ properties of original optical fiber vector solitons. We consider two cases for simulation, one is original orthogonal polarization modes have the same central wavelength in the frequency domain, the other is original orthogonal polarization modes have different central wavelengths. In the first case, modulated dark vector soliton molecules with two pulse peaks and two pulse dips, accompanied by two wavelengths can always be observed. While in the second case, optical spectra will split in orthogonal directions, and obvious temporal pulse oscillation will occur, when the projection angle changes. The results further explore modulating vector solitons that with unique characteristics, in out-cavity optical fiber modulation systems.

The pulse broadening due to dispersion in optical fiber is studied by solving the nonlinear Schrödinger equation through the Fourier transform method. The expression of pulse width in terms of its root-mean-square and the pulse broadening factor of the Gauss-chirped pulse are given. Meanwhile, the influence of the propagating optical fiber distance on the pulse broadening is given. The influence of the chirped factor on the pulse broadening and the optical fiber dispersion on pulses with different widths are analyzed and discussed.

In this paper, a scheme is presented for generation of W-type entangled states for n atoms trapped in separated cavities connected by optical fibers. The scheme only requires a single atom–cavity–fiber interaction and no classical field is needed. Due to these features, the scheme is simpler and more robust against decoherence than the previous ones. The scheme can also be used to realize quantum state transfer and controlled phase gates between qubits located at distant nodes of a quantum network.

Under investigation in this paper is the $(3+1)$-dimensional coupled nonlinear Schrödinger system for an optical fiber with birefringence. With the Hirota method, bilinear forms of the system are derived via an auxiliary function, and the bright one- and two-soliton solutions are constructed. Based on those soliton solutions, soliton propagation and interaction are investigated analytically and graphically. Non-singular cases of the bright one-soliton solutions are presented, from which the single-peak and two-peak solitons can arise, respectively. Through the analysis on the bright two-soliton solutions, the elastic and inelastic interactions are investigated. Three kinds of the elastic interactions are presented, between the two one-peak solitons, a one-peak soliton and a two-peak soliton, and the two two-peak solitons.

In this paper, a fifth-order variable-coefficient nonlinear Schrödinger equation is investigated, which describes the propagation of the attosecond pulses in an optical fiber. Via the Hirota’s method and auxiliary functions, bilinear forms and dark one-, two- and three-soliton solutions are obtained. Propagation and interaction of the solitons are discussed graphically: We observe that the solitonic velocities are only related to ${\beta }_1(x)$, ${\beta }_2(x)$, ${\beta }_3(x)$ and ${\beta }_4(x)$, the coefficients of the second-, third-, fourth- and fifth-order terms, respectively, with $x$ being the scaled distance, while the solitonic amplitudes are related to ${\beta }_1(x)$, ${\beta }_2(x)$, ${\beta }_3(x)$, ${\beta }_4(x)$ as well as the wave number. When ${\beta }_1(x)$, ${\beta }_2(x)$, ${\beta }_3(x)$ and ${\beta }_4(x)$ are the constants, or the linear, quadratic and trigonometric functions of $x$, we obtain the linear, parabolic, cubic and periodic dark solitons, respectively. Interactions between (among) the two (three) solitons are depicted, which can be regarded to be elastic because the solitonic amplitudes remain unchanged except for some phase shifts after each interaction in an optical fiber.

In this paper, an eighth-order nonlinear Schrödinger equation is investigated in an optical fiber, which can be used to describe the propagation of ultrashort nonlinear pulses. Lax pair and infinitely-many conservation laws are derived to verify the integrability of this equation. Via the Darboux transformation and generalized Darboux transformation, the analytic breather and rogue wave solutions are obtained. Influence of the coefficients of operators in this equation, which represent different order nonlinearity, and the spectral parameter on the propagation and interaction of the breathers and rogue waves is also discussed. We find that (i) the periodic of the breathers decreases as the augment of the spectral parameter; (ii) the coefficients of operators change the compressibility and periodic of the breathers, and can affect the interaction range and temporal–spatial distribution of the rogue waves.

Kerr media are applied in the photonic lattices and optical fibers, while optical fiber communication becomes one of the main pillars of modern communication. In this letter, we study a (3+1)-dimensional nonlinear Schrödinger equation with distributed coefficients for the spatiotemporal optical solitons or light bullets in a diffractive nonlinear Kerr medium with anomalous dispersion. The N-dark soliton solutions in terms of the Gramian is obtained via the Kadomtsev–Petviashvili hierarchy reduction, where N is a positive integer. Via the graphic analysis, we observe the interaction of the two dark solitons. Effects from the diffraction/dispersion coefficient $\beta (z)$ and gain coefficient $\gamma (z)$ are also discussed on the amplitudes and oscillations of the two dark solitons, as well as on the interaction of the two dark parabolic shape solitons.

In this paper, under investigation is a (2 + 1)-dimensional variable-coefficient nonlinear Schrödinger equation, which is introduced to the study of an optical fiber, where $t$ is the temporal variable, variable coefficients $a(t)$ and $b(t)$ are related to the group velocity dispersion, $c(t)$ and $d(t)$ represent the Kerr nonlinearity and linear term, respectively. Via the Hirota bilinear method, bilinear forms are obtained, and bright one-, two-, three- and N-soliton solutions as well as dark one- and two-soliton solutions are derived, where $N$ is a positive integer. Velocities and amplitudes of the bright/dark one solitons are obtained via the characteristic-line equations. With the graphical analysis, we investigate the influence of the variable coefficients on the propagation and interaction of the solitons. It is found that $d(t)$ can only affect the phase shifts of the solitons, while $a(t)$, $b(t)$ and $c(t)$ determine the amplitudes and velocities of the bright/dark solitons.

In this work, the soliton solutions of a (3 + 1)-dimensional coupled nonlinear Schrödinger system with time-dependent coefficients arising in optical fiber has been studied analytically. A complex traveling wave ansatz is used to transform the proposed coupled partial differential equations into ordinary differential equations (ODEs). Then, we solved the obtained nonlinear ODEs for the envelope function in the traveling wave parameter. The obtained waves envelope have the forms of bright and dark soliton-like solutions which are considered as new solutions of the studied system. As a kind of completing the analysis, the modulation instability is discussed based on the linear stability analysis.

Nonlinear optics plays a crucial part in the progress of laser-based technologies and optical science. In this paper, we investigate the three-coupled variable-coefficient nonlinear Schrödinger system, which describes the amplification or attenuation of the picosecond pulses in an inhomogeneous multicomponent optical fiber with different frequencies or polarizations. Based on the existing Lax pair, we construct the first-/second-order generalized Darboux transformations and obtain the second-order semirational rogue-wave solutions, which represent the slowly varying envelopes of optical modes, under a constraint among the fiber gain/loss, nonlinearity and group velocity dispersion. We obtain the influences of nonlinearity and group velocity dispersion: when the value of the nonlinearity increases, amplitudes of the second-order semirational rogue waves decrease and when the value of the group velocity dispersion increases, amplitudes of the second-order semirational rogue waves increase. Baseband modulation instability (MI) through the linear stability explanation is obtained. When the characteristic roots have the negative imaginary parts, the system appears the baseband MI. When the MI occurs, it is of baseband type. With the positive parts, however, there is no MI occurring.

In this paper, an $N$-coupled high-order nonlinear Schrödinger system, which describes the properties of the ultrashort optical pulses in an optical fiber, is investigated with the Darboux transformation (DT) method and asymptotic analysis. Starting from the given $(2N+1)$th-order Lax pair, we construct a new form of the DT (with some complex eigenfunctions of a Lax pair involved) to derive the formulas of the $n$th-iterated solutions, where $n$ and $N$ are the positive integers. On the zero background, the first- and second-order solitons are obtained and analyzed through the asymptotic analysis. Multi-parameter adjustment is proceeded since there are $3N+4$ real parameters in the second-order solitons. We find that under certain conditions each of the two interaction patterns (elastic and/or inelastic) holds in the second-order solitons. On the plane wave background, the first-order bright and dark–bright solitons are obtained. Velocities, amplitudes, widths and characteristic lines of the first-order bright and dark–bright solitons are presented and analyzed.

Accurate wavelength scanned four-wave mixing (FWM) measurement results in an optical fiber are presented with two tunable laser sources near the dispersion-zero wavelength of the fiber. By comparing the measured FWM data with a simple analytic expression, we have demonstrated that important linear and nonlinear optical properties such as zero-dispersion wavelength, dispersion slope and nonlinear refractive index of the sample fiber. Highly accurate and repeatable measurement results for a sample fiber are presented. Temperature-dependent change in the chromatic dispersion of a fiber is also investigated.

Zinc doped germano-silicate glass optical fiber was developed by using the modified chemical vapor deposition and the drawing tower process. Absorption peaks of the germano-silicate glass optical fiber preform appeared at 240 nm and 330 nm were due to the incorporated Zn metal nano-particles (MNPs) and ZnO semiconductor nano-particles (SNPs), respectively and the average diameter of nano-particles (NPs) was estimated to be about 2 nm by transmission electron microscopy. However, the absorption peak of the zinc doped optical fiber due to ZnO SNPs was found to appear at 490 nm red-shifted from 330 nm can be explained by the increase in average size of ZnO SNPs in the fiber core due to growth or recrystallization of ZnO SNPs during the fiber drawing process about 2150°C. The nonlinear refractive index coefficient, n₂, of the fiber was estimated to be 5.62 × 10^-20 m²/W due to the stable dispersion of ZnO SNPs using the continuous-wave self-phase modulation method.

Small-signal gain spectrum of one-pump fiber optical parametric amplifiers (1-P FOPAs) is investigated in the presence of dispersion fluctuations. By assuming the dispersion fluctuations along the fiber as a stochastic process and using the matrix approach, the full gain spectrum of 1-P FOPAs is simulated. We have examined the gain spectrum of 1-P FOPAs for a wide range of fluctuation parameters, and it is shown for the first time that there are two specific wavelengths at which the dispersion fluctuations play no role. Analytical formulas are also presented to design 1-P FOPAs for amplifying signals with a gain insensitive to dispersion fluctuations.

In this paper, the extended simplest equation method is utilized to construct the novel exact optical solitons solutions of the perturbed time fractional Chen–Lee–Liu equation with conformable fractional derivative. The acquired optical solitons and other solutions are expressed via the rational functions, the trigonometric functions, and the hyperbolic functions; in addition to guaranteeing the existence of the acquired results, the constrain conditions are provided. Furthermore, to elucidate the magnitude of the proposed equation, various obtained solutions are plotted via two-dimensional (2D) and three-dimensional (3D) graphs using appropriate values of parameters. It is observed that the present technique is a powerful tool and efficient for finding the analytical solution for nonlinear differential equations of integer and fractional orders.

Sunlight Found to Affect Serotonin Levels.

Brisbane Researchers to Lead Study on HPV Skin Cancer Link.

China Develops its First Automatic Biochemical Analyzer.

Hepatitis Biochip Marks Breakthrough in China.

Chinese Scientists Successfully Breeds Ten Pandas in 2002.

Damaged Hearts Treated with Stem Cells.

Genetically Modified Potatoes to Combat Malnutrition.

Japan to Start Genetic Data Project.

Japanese Researchers Link Kidney Disease to Rat Virus.

Researchers Achieve Diagnostic Breakthrough Using Optical Fiber.

This study developed a smart sock system using optical fiber technology to measure the toe grip function of individual toes. The system comprised Fiber Bragg grating (FBG) sensors incorporated into a sock garment for measuring maximum toe flexion displacements. Calibration equation of each FBG sensor was determined from 3D motion capture system on 10 female subjects. The validity of the smart sock system was checked by comparing maximum toe flexion displacement against the gold standard of 3D motion capture. The root mean squared error was 0.95 (0.57) cm across 10 toes. The magnitude of toe displacement and error was similar between the left and right feet. In conclusion, the FBG-based smart sock system can successfully measure maximum toe flexion displacements of individual toes simultaneously. This system can be developed to support the evaluation of toe grip function in clinical and field settings.

The interaction between identical two-level atoms with a system that consists of two coupled cavities connected by an optical fiber was investigated. With new bosonic operators, the interaction Hamiltonian between the fiber and the cavities can be diagonalized (Pellizzari's model¹). In the strong coupling regime (cavity field-fiber), the interaction between atoms and the non-resonant normal modes can be eliminated, simplifying our system to that of one atom interacting with a single-mode cavity. For this interaction, we have analyzed the entanglement between distant atoms. We present two simple procedures to generate two atoms in a maximally entangled state, interacting (i) successively and (ii) simultaneously with the coupled cavities system.

We propose a scheme for generating maximally entangled states for three atoms trapped in three distant cavities connected by two identical single-mode fibers. During the operation, neither the atomic system nor the fibers are excited, which is important in view of decoherence. Under certain conditions, the probability of the excited cavities can be negligible. Taking advantage of adiabatic passage, the GHZ state can be generated deterministically, and the fidelity of entanglement is insensitive to fluctuation of experimental parameters. Compared to the previous schemes, the significant advantage of the proposed scheme is that each cavity can interact with the other two directly, which can avoid the effect of indirect interaction brought about using only local quantum operator and nonlocal resources.

We present a scheme to implement a quantum gate for two-atom trapped in distant cavities connected via an optical fiber. In the whole process, the atomic system, the cavity modes and the fiber are not excited ensuring that the operation is insensitive to atomic spontaneous emission, cavity decay and the fiber loss. This scheme is significant for distributed and scalable quantum computation.