Nonlinear Optical Transmission Research Articles

Reduction of four wave mixing efficiency in DWDM systems using optimal PMD

Investigation of polarization mode dispersion (PMD) effect on the performance of nonlinear optical transmission system, in terms of bit error rate and mixing efficiency was conducted. It shows an improvement in the system performance, in the presence of PMD. The effect of PMD was considered for different link lengths and the resulting effects on system performance were studied. It was demonstrated that fiber nonlinearities can be reduced in the presence of optimal amount of PMD, and have achieved average reduction in four wave mixing efficiency of 6.9 dB within the interval of − 18 to 4 dBm launch power, and maximum of 14.5 dB at 2 dBm launch power for an 80 Gbps non-return-to-zero dense wavelength division multiplexing system. OptiSystem software was used for the simulation.

Self-Assembly of Silver and Gold Nanoparticles in a Metal-Free Phthalocyanine Liquid Crystalline Matrix: Structural, Thermal, Electrical and Nonlinear Optical Characterization

The properties of self-assembled supramolecular structures change remarkably upon the dispersion of a minute amount of metal nanoparticles in them. Here we present, for the first time, investigations of the effect of dispersing alkyl thiol functionalized group-XI metal nanoparticles (silver and gold) in a phthalocyanine-based discotic liquid crystal on their structural, electrical, thermal and nonlinear optical transmission properties, and supramolecular order. Results indicate uniform dispersion of about 0.5-3 % metal nanoparticles in the columnar matrix which results in an increase of the electrical conductivity of the system by two to four orders of magnitude, without disrupting the mesophase. We also show that dispersing metal nanoparticles in these nanocomposites enhances their nonlinear optical absorption, when measured under excitation by nanosecond laser pulses at 532 nm. These results indicate that the present self-assembling supramolecular soft nanocomposites are potential candidates for applications in optoelectronic devices such as thin film transistors, photovoltaic solar cells, and optical limiters.

Globalk-space analysis of electron-phonon interaction in graphene and application toM-point spectroscopy

Recently, optical probes have become available that can access and observe energy renormalization due to electron-phonon interaction in graphene away from the well-studied Dirac $K$ point. Using an expanded deformation potential approach, we present a theoretical study of the electron-phonon self-energy and scattering matrix elements across the entire Brillouin zone. We elucidate the roles of modulated hopping and conventional deformation potential coupling, parameterized via standard deformation potentials, the in-plane phonon modes, intra- and interband contributions, and umklapp processes. Applying the theory to nonlinear optical transmission spectroscopy in the vicinity of the $M$ point, we find very good agreement with recently published experimental data.

Optical bistability in Ag-Al2O3 one-dimensional photonic crystals

Here, we demonstrate the nonlinear optical responses of Ag-Al2O3 one-dimensional photonic crystals (1D PCs). The linear transmission spectra of the proposed 1D PC show higher transmission at shorter wavelengths and lower transmission at longer wavelengths with “N” pairs of Ag-Al2O3 will support “N − 1” transmission peaks. By using 5 pairs of Ag-Al2O3, the optical bistability behavior of light transmission at low input intensity for the resonant modes is numerically demonstrated. Then, we performed a Z-scan experimental technique to show the enhanced nonlinear optical transmission of Ag-Al2O3 1D PC. These results can pave the way for achieving all-optical control of light for potential applications such as all-optical switching, optical logic, optical computation, etc.

Nonlinear optical transmission of cyanobacteria-derived optical materials

Cyanobacteria-derived optical materials for optical limiting applications have been studied in this work. Six samples have been prepared from cyanobacteria including cyanobacteria suspension in water, extracts in water, methanol, and N,N-dimethylformamide, and pyrolyzed cyanobacteria (PCYB) dispersed in dsDNA (sodium salt from salmon testes) solution and sodium dodecyl sulfate solution, respectively. The extracts contain phycocyanin, chlorophyll a, and carotenoids as measured by optical absorption spectroscopy, while the PCYB is a nanostructural composite composed of multi-walled carbon nanotubes, carbon nanoringes, and multilayer graphenes, as revealed by transmission electron microscopy. The optical limiting responses of the samples have been measured at 532 and 756nm. The PCYB in dsDNA solution has the best limiting performance out of all the cyanobacteria-derived samples. It outperforms carbon black suspension standard at 532nm and is a broadband limiter, which makes it attractive for optical limiting applications.

Sensitivity of optical mass sensor enhanced by optomechanical coupling

Optical mass sensors based on cavity optomechanics employ radiation pressure force to drive mechanical resonator whose mechanical susceptibility can be described by nonlinear optical transmission spectrum. In this paper, we present an optical mass sensor based on a two-cavity optomechanical system where the mechanical damping rate can be decreased by adjusting a pump power so that the mass sensitivity which depends on the mechanical quality factor has been enhanced greatly. Compared with that of an optical mass sensor based on single-cavity optomechanics, the mass sensitivity of the optical mass sensor is improved by three orders of magnitude. This is an approach to enhance the mass sensitivity by means of optomechanical coupling, which is suitable for all mass sensor based on cavity optomechanics. Finally, we illustrate the accurate measurement for the mass of a few chromosomes, which can be achieved based on the current experimental conditions.

Analytic study on solitons in the nonlinear fibers with time-modulated parabolic law nonlinearity and Raman effect

In this paper, the nonlinear optical transmission equation with time-modulated cubic–quintic nonlinearity and Raman effect term, describing the ultrashort optical pulse propagate along the nonlinear media, has been studied by using the non-auto-Bäcklund transformation (NATB) and subsidiary ordinary differential equation (sub-ODE) expansion method. As a result, analytical solution expressions to that equation are obtained. Finally, two simple examples, including systems with the external potential in exponential form and periodic form, are provided to show the solution steps.

Optical transmission control in graphene oxide and its organic composites with ultrashort laser pulses

Nonlinear optical transmission of graphene oxide–(Cu, Zn, Sn, H2) porphyrin composites was investigated using the Z-scan technique at 532 nm with picosecond (ps) and 800 nm with femtosecond laser pulses. Pure porphyrins show saturable absorption (SA) in reverse saturable absorption (RSA) behaviour and graphene oxide shows complete RSA behaviour, observed in an open aperture Z-scan curve. Interestingly, composites have shown a switch-over from reverse RSA to SA and back to RSA behaviour, observed with variation of intensity towards the focus, due to strong two-photon absorption as well as excited state absorption in the ps regime. This switching behaviour was interpreted as due to long lifetimes and saturation of the excited states. This may find application in optical switching.

Improving channel capacity by nonlinearity compensation and noise suppression in high-speed multi-span optical transmission systems

In this paper, the channel capacity of 40Gb/s multi-span nonlinear optical transmission systems with nonlinearity compensation and self-adapting Wiener filtering is studied by use of Finite State Machine (FSM) approach. The comparison of channel capacity of the system with differential phase shift keying (DPSK) and on–off keying (OOK) modulation is also investigated. The channel capacity increases monotonically with the input power for transmission systems with simultaneous compensation of dispersion and nonlinearity, which performs as well as linear system. DPSK shows a much better performance and the channel capacity has an improvement of at least 48 percent over that OOK modulation. A further reduction of the amplified spontaneous emission (ASE) noise accumulation is obtained by Wiener filtering, which improves the channel capacity considerably when the input peak power is less than 3mW.

Analytical study of optical solitons in media with Kerr and parabolic-law nonlinearities

The nonlinear optical transmission equation was investigated in the presence of detuning, inter-modal dispersion, time- and space-modulated external potentials, and dissipation. Optical solitons, triangular periodic solutions, and Jacobian elliptic periodic solutions are constructed with the aid of the self-similarity transformation and Jacobian elliptic equation expansion methods. The conditions for analytical solutions to exist are obtained. Both Kerr-law as well as parabolic-law nonlinear media are considered.

Non-hydrothermal synthesis and optical limiting properties of one-dimensional Se/C, Te/C and Se–Te/C core–shell nanostructures

A single step, nontoxic, non-hydrothermal, low temperature and reproducible method for the preparation of carbon-coated selenium and tellurium nanowires (Se/C and Te/C, respectively), and selenium–telluride (Se–Te/C) nanorods, is presented. Sodium dodecyl sulfate is used as the surfactant, and glucose is employed as the reducing and carbonizing agent. Uncoated nanowires of trigonal Se and Te without the carbon shell are obtained as products, at lower glucose concentrations, whereas at higher glucose concentrations carbon-coated nanowires of trigonal Se and Te are formed. Structural, morphological and compositional properties of the prepared products are examined using X-ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy, and energy dispersive X-ray spectroscopy, respectively. The formation of amorphous carbon shell and the model depicting the growth of core–shell nanowires and nanorods are discussed on the basis of the experimental results. Nonlinear optical transmission of the samples is studied at 532nm using the open-aperture Z-scan technique employing 5ns laser pulses. Results show that the samples are efficient optical limiters, and that a three-to-four-fold enhancement in the value of the effective two-photon absorption coefficient (β) can be achieved by coating the nanowires and nanorods with carbon.

Structural evaluation and nonlinear optical properties of Ni/NiO, Ni/NiCo2O4 and Co/Co3O4 nanocomposites

Nanocomposites of Ni/NiO, Ni/NiCo2O4 and Co/Co3O4 have been synthesized by a chemical reduction technique. X-ray diffraction (XRD) and transmission electron microscopy (TEM) images confirm the mixed composite nature of the sample and uniform particle size of approximately 13nm. Formation of Ni/NiCo3O4 solid solution or NiCo2O4 spinel phase in the mixed composite is confirmed by energy dispersive X-ray (EDX) spectrum. Magnetic hysteresis (M–H) curves of the nanocomposites show excellent ferromagnetic (FM) nature at room temperature. Nonlinear optical transmission of the nanocomposites is measured using the open aperture Z-scan technique employing 7 nanosecond laser pulses at 532nm. Experimental results show that NiO/NiO–Co3O4/Co3O4 nanocomposites exhibit good optical limiting performance. From the measurements and numerical fitting of the data to theory, it is found that nonlinear absorption has contributions from excited state absorption and two-photon absorption. Optical limiting is enhanced in Co3O4 and Ni/NiCo2O4 in which the Co3O4 content has a larger volume ratio.

Optical solitons in gas-filled, hollow-core photonic crystal fibers with inter-modal dispersion and self-steepening

The optical solitons in a gas-filled, hollow-core photonic crystal fiber with higher-order dispersion, inter-modal dispersion, Raman effect, self-steepening, detuning, external potential, and dissipation have been studied theoretically by employing the Bäcklund transformation and Hirota’s direct method. The bilinear forms and exact optical one-soliton solutions to the nonlinear optical transmission equation are obtained under the constraint conditions. The influence of correlation coefficients on the width, amplitude, and phase of optical solitons are analyzed. These results have important application features in optical soliton control in gas-filled, hollow-core photonic crystal fibers.

High gain pulsed erbium-doped fiber amplifier for the nonlinear characterization of SWCNTs photodeposited on optical fibers

We report the experimental setup of a high power pulsed erbium-doped fiber amplifier. An optical signal at 1550nm emitted by a distributed feedback laser is amplified by two identical stages in reflective configuration using one fiber Bragg grating at each one of those. We demonstrated that for pulses with a frequency of 20kHz and temporal duration of 10, 50, 100, and 500ns, it is possible to obtain output peak powers of 41, 22, 18, and 11W, respectively. We applied our high power amplifier in the characterization of nonlinear optical transmission of single-wall carbon nanotubes deposited on single mode optical fibers end-face by the photodeposition technique. Our results show that the high power system is ideal for carrying out studies of nonlinear effects in optical fibers as well as nonlinear characterization of nanostructured materials deposited on optical fibers.

Size-dependent optical properties of Au nanorods

In the fast evolving field of nanoscience and nanotechnology, where size and shape are crucial in deciding the optoelectronic properties of nanomaterials, the understanding of size and shape dependent behavior is of direct relevance to device applications. Present study reports the synthesis of Au nanorods with well controlled aspect ratios, and the influence of the aspect ratio on the surface enhanced Raman scattering (SERS) activity using crystal violet (CV) as the probe molecule. The influence of pH and the concentrations of reducing agent and Ag ions in controlling the aspect ratio of gold nanorods are also investigated. The structural and optical properties of the synthesized samples have been characterized by transmission electron microscopy (TEM) and UV–visible absorption spectroscopy. The nonlinear optical (NLO) transmission of the Au nanorods investigated using the open aperture Z-scan technique revealed the absorption saturation followed by an optical limiting behavior, which may find potential applications in optoelectronic nanodevices.

Spectral and nonlinear optical transmission studies of Zr4+-doped TiO2 nanoparticles

Zr4+-doped TiO2 nanoparticles with a homogeneous anatase structure were synthesized through sol–gel technique. The crystalline phase and particle sizes of the resultant particles were investigated by X-ray diffraction (XRD), Raman and transmission electron microscopy (TEM) techniques. Results indicated that Zr4+ was incorporated into the lattice and interstices of titania nanocrystals. The amount of Zr4+ doping decreased the size of particle, and enhanced “blue-shift” in the UV–vis absorption spectra. The optical limiting property of the samples was assessed by a Z-scan technique in which the Zr4+/TiO2 nanoparticles dispersed in ethylene glycol were excited at 532nm using 7ns Nd:YAG laser pulses. Experimental results indicated that at 0.5 and 1.0mol% doping of Zr4+ the particles exhibit three-photon absorption while for at 2.0 and 3.0mol% dopant concentration the data fitted to saturable absorption followed by two-photon absorption.

Mechanisms of nonlinear transmission in solutions and thin films of the COANP-C70 fullerene system

The process of nonlinear optical transmission in solutions and thin films of 2-cyclooctylamine-5-nitropyridine (COANP) sensitized by C70 fullerene additions has been studied. Possible mechanisms responsible for the attenuation of light flux intensity are considered. Comparative DSC data for a pure COANP and one sensitized by C70 fullerene are presented that confirm the existence of one of these mechanisms.

Nonlinear Far-Infrared Transmission of Antiferromagnetic Fabry-Perot Resonator

The magnetically nonlinear optical transmission of the Fabry-Perot resonator tilled with an antiferromagnetic medium is discussed. In a proper incident power range, we find the bistable switches can appear even for a very thin medium film, such as of half-wavelength thickness. All results are based on antiferromagnetic FeF2 medium with far-infrared resonant frequencies.

Exact solutions of the cubic-quintic nonlinear optical transmission equation with higher-order dispersion terms and self-steepening term

By using the subsidiary ordinary differential equation method, many explicit Jacobian elliptic periodic solutions of the cubic-quintic nonlinear optical transmission equation with higher-order dispersion nonlinear terms and self-steepening term are obtained. The results are discussed.

Analysis of the optical transmission through a nonlinear thin layer near the critical angle of incidence

In this communication, we present a numerical study of the linear and nonlinear optical transmission through a thin layer near the critical angle of incidence. The optical linear transmission presents very important variations according to the optical Kerr effect. The study of the linear optical transmission allows defining the operation point of the thin layer in nonlinear regime. This study effects are important for optical applications such the all optical switching and the sensitive determination of the nonlinear refractive index (n2) of materials.