查看更多>>摘要：In this research work, anti-cubic and generalized anti-cubic nonlinearity are taken into consideration. The Jacobi elliptic function method and Jacobi elliptic function expansion method is to nonlinear optical fiber for obtaining dark soliton structure. Dark solitons emerged from this method. Furthermore, we establish the physical significance and dynamical behaviors of the dark soliton solutions by using the physical parameter namely dispersion coefficient.
查看更多>>摘要：In this work, Selenium (Se) thin film substrates are coated with tungsten oxide thin layers. The Se/WO3 interfaces are fabricated using a vacuum deposition technique. The substrates displayed stable polycrystalline structure of hexagonal selenium when coated with amorphous WO3. The surface morphology revealed preferred growth of Se nanowires. The coating of Se with WO3 enhanced the light absorbability in the visible and infrared ranges of light spectrum. In addition, the Se/WO3 heterojunctions exhibited conduction and valence band offsets of values of 1.31 eV and 0.0.09 eV, respectively. The band offsets are sufficiently large to force quantum confinement at the interface. It was observed that Se/WO3 behaves as good dielectric resonator revealing resonance peaks in the infrared, visible and ultraviolet ranges of light. Moreover, computing the optical conductivity parameters for these dielectric oscillators revealed drift mobility and plasmon frequency values that are suitable for optical communications. Furthermore, as a terahertz resonator, the Se/WO3 dielectric media displayed terahertz cutoff frequency values in the range of 0.6-75 THz depending on the exciting photon energy. As practical application, when photo excited with daylight light, the carbon contacted planner Se/WO3 interfaces displayed a light power dependent photosensitivity. The photosensitivity increases 38 times upon irradiation of 0.9 W. With these features, the Se/WO3 heterojunction devices can be nominated for applications in optical communications.
Rasool, S. K. NayabShabeena, S. K.Kesavulu, C. R.Sekhar, E. Chandra...
10页
查看更多>>摘要：Neodymium (III) ions doped sodium fluoro-borate (BCNF) glass materials have been prepared by the melt quenching method and Fourier transform infrared (FTIR) method was intended for the identification of the functional groups present in the BCNF host glass. X-ray diffraction (XRD) analysis is used for the study of structural details of the prepared glass composite materials. In order to study the spectroscopic properties of fabricated glasses, absorption, emission and decay measurements has been performed. Additionally, the spectroscopic properties of Nd3+ ions were analyzed using Judd-Ofelt theory. UV-Vis and Near-IR absorption spectra of glass composite samples reveal eleven significant peaks. Under the excitation of 808 nm laser diode, three near-IR emission bands are at around 876 nm, 1058 nm and 1331 nm from F-4(3/2) -> I-4(9/2), I-4(11/2) and I-4(13/2) radiative transitions, respectively, were observed in the Nd3+ ions doped glass composite mate-rial. The lifetimes of this transition has been experimentally determined through decay profile studies. For all Nd3+ ion concentrations, the decay time curves of the F-4(3/2) level were essentially single exponential.
Ahmed, Anas A.Hashim, M. R.Qahtan, Talal F.Rashid, Marzaini...
14页
查看更多>>摘要：Spin-coated and RF-sputtered NiO films were grown over Si substrate. FESEM analysis showed porous morphology for spin-coated NiO film and compact surface morphology for RF-sputtered NiO film. The photodetection properties were explored in metal-semiconductor-metal (MSM) configuration and were found to be greatly affected by the surface morphology of NiO. The responsivity of spin-coated NiO/Si PD was measured as 6.90, 3.68 and 4.39 A/W, whereas it was measured as 1.73, 1.81 and 2.07 A/W for RF-sputtered NiO/Si photodetector (PD), under exposure to 365, 625 and 850 nm lights, respectively. The photo-to-dark current ratio (PDCR) was calculated as 303, 172, 206 and 31, 35, 41 for spin-coated and RF-sputtered NiO/Si PDs, respectively. The higher photoresponse of spin-coated NiO/Si PD over RF-sputtered NiO/Si PD, especially at 365 nm wavelength, resulted from the larger surface area of porous structured spin coated NiO film. Both PDs exhibited stable and repeatable photoresponse at different switching frequencies of the illumination source. The rise/fall time were estimated as 1.96/9.76 and 3.49/ 7.68 ms for spin-coated and RF-sputtered NiO/Si PDs, respectively.
查看更多>>摘要：We propose and demonstrate a novel scheme of multi-functional all-optical ultrafast signal pro-cessor for femtosecond pulse shaping based on programmable differential group delay (DGD), which is capable of performing both all-optical differentiation and integration simultaneously, and can easily switch two functionalities by simply tuning the orientation of a polarizer. The differentiation waveforms and integration windows length can be adjusted by programming the DGD time. Utilizing numerical simulation we obtain the differential pulses and their autocorre-lation of-400-fs Gaussian signal for DGD of 0.5 ps and 4 ps, while achieve its integral pulses and their autocorrelation for DGD of 0.5 ps, 1.5 ps, and 3.5 ps. We further experimentally demonstrate the all-optical differentiation and all-optical integration of-400-fs Gaussian signals whose results agree well with the theoretical prediction and simulation result. Using autocorrelation method, we observe in detail the differential and integral processing of femtosecond pulses at various DGD for the first time according to our knowledge. Our scheme can work over the whole communi-cation band with variable operation wavelength, and is competitive in ultrafast pulse shaping for quantum control due to highly reconfigurable and flexible features.
查看更多>>摘要：In this work, Cu, Ag, In, and S based qu aternary quantum dots (Cu2AgInS4 QDs) were synthesized by a hot-injection method, and Zinc doped (0, 1, and 2 wt%) Titania nanoparticles (Zn-TiO2 NPs) were synthesized by a sol-gel method. The synthesized QDs were anchored onto Zn-TiO2 NPs film through a linker-based assembly method to form Cu2AgInS4 QDs/Zn-TiO2 NPs to use as the photoanodes for Quantum dot sensitized solar cells (QDSCs). The physio-chemical behavior of the Cu2AgInS4 QDs, Zn-TiO2 NPs, and Cu2AgInS4 QDs/Zn-TiO2 photoanodes was examined by various spectroscopic analyses. Optical analysis of the fabricated photoanodes revealed that Cu2AgInS4 QDs/Zn-TiO2 NPs photoanode has a high redshift of light absorbance than Zn-TiO2 NPs. Moreover, due to the proper band alignment of Cu2AgInS4 QDs and 2 wt% Zn-TiO2 NPs, Cu2AgInS4 QDs/Zn-TiO2 NPs has high electron transfer ability than Cu2AgInS4 QDs/TiO2 NPs. On the other hand, the electrochemical impedance analysis confirms that Cu2AgInS4 QDs/Zn-TiO2 photoanode has lower charge transfer resistance (9.53 ohm) with high photocatalytic behavior than that of Cu2AgInS4 QDs/ TiO2 NPs as the photoanode. Hence Cu2AgInS4 QDs/Zn-TiO2 NPs photoanode based QDSC shows 36% improvement in the photoconversion efficiency (5.43%) than that of Cu2AgInS4 QDs/TiO2 NPs (3.92%) based QDSC.
查看更多>>摘要：A novel optical logic device based on plasmon-induced transparency (PIT) effect is designed. It is composed of two semicircular resonators coupled with the metal-insulator-metal (MIM) waveg-uide. By monitoring the different wavelengths, six logic operations (AND, OR, NAND, NOR, XOR, and XNOR) can be achieved simultaneously in the proposed structure. The performance of the device is analyzed by temporal coupled-mode theory and finite-difference time-domain (FDTD) method. Moreover, the influence of structure parameters on device performance such as the radius of semicircular resonator, the coupling distance between two semicircular resonators, and the coupling distance between waveguide and semicircular resonator are discussed in detail. The proposed device that can implement six logic operations greatly improves the integration of photonic integrated circuits (PIC), and it has the potential to provide new idea for designing of optical logic device on-chip.
查看更多>>摘要：It is shown that Gross-Pitaevskii equation with parabolic potential has solutions in form of localized wave packets, which are self-similar and undergo periodic spatial oscillations. The proposed solutions combine some properties of coherent states of quantum optics and solitons of the nonlinear Schrodinger equation, and are expressed in terms of spatially shifted and phase-modulated solutions of nonlinear second order ordinary differential equation.
查看更多>>摘要：In this paper, a simple generation technique and the propagation characteristics, of a practically possible double exponential pulse are proposed and numerically analyzed. Solutions of non-linear Schrodinger's equation (NLSE) has mostly been used to analyze the same in comparison with Gaussian ultrashort pulses, for various classes of optical fibers. The Double exponential pulses have shown a bandwidth-efficiency ~& nbsp;23% over Gaussian pulses, making it suitable for time-and wavelength-division-multiplexed passive optical networks (TWDM-PON) applications in optical communication, as recommended by ITU-T G-989. Non-linear behavior of the pulse was also investigated for super-continuum (SC) generation. Super-continuum generated by Double exponential pulses was found to have ~& nbsp;12% higher Spectral Broadening factor compared to Gaussian pulse. Overall, the proposed double exponential pulse, generated by the proposed method, potentially displays comparable, and sometimes better sensing and communication properties, compared to the Gaussian pulses.
查看更多>>摘要：Broadband operation is a critical feature for high-speed electro-optic modulators in optical signal processing. To overcome the obstacle of material absorption-induced optical bandwidth shrinkage, graphene optical modulators based on the tip plasmonic concept have been proposed. The modulator is composed of buried double-layer graphene and Ag-SiO2-Si-SiO2-Ag hybrid structure with taper slots. Due to the tightened field confinement induced by the tip plasmonic effect, the light-graphene coupling is significantly enhanced. The direct metal layers contact with graphene is exploited to serve as the electrode. The simulation results based on the finite element method present a graphene modulator with a high modulation depth (MD) of 1.1 dB/pm and a relatively low propagation loss of 0.14 dB/pm. The power consumption is about 43.80 fJ/bit at the modulation length of 20 mu m. The 3 dB-bandwidth is estimated to be around 340 GHz. Comparison with reported graphene modulators adopting hybrid plasmonic slot waveguide proves favorable modulation depth of proposed design, which promise its potentials in hybrid integration and on-chip signal processing.
NSTL
Elsevier