فهرست مطالب

Journal of Optoelectronical Nanostructures
Volume:3 Issue: 3, Summer 2018

  • تاریخ انتشار: 1397/05/01
  • تعداد عناوین: 7
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  • Ali Moftakharzadeh , Behnaz Afkhami Aghda, Mehdi Hosseini Pages 1-11
    In this paper, the noise equivalent power (NEP) of an optical sensor based on graphene-superconductor junctions in the constant current mode of operation has been calculated. Furthermore, the necessary investigations to optimize the device noise with respect to various parameters such as the operating temperature, magnetic field, device resistance, voltage and current bias have been presented. By simultaneously solving the free energy and charge carrier density equations of graphene at low temperature, the specific heat, thermal interaction of electron-phonon and current responsivity of the sensor have been calculated. Using these parameters, the noise equivalent power of the device has been obtained. The results show that the behavior of device NEP by increasing the magnetic field at a constant temperature is at first ascending and then descending. The NEP value for different temperatures, up to T=80K, has an increasing behavior and then by further increasing the temperature, the NEP will show decreasing behavior which is also dependent on the value of the magnetic field. The NEP value is directly related to the device voltage and current values, therefore by increasing the voltage and current, the NEP will increase. Our investigations show that at the constant current bias mode of operation, the final device NEP is independent of the device resistance
    Keywords: Graphene, Noise Equivalent Power (NEP), Optical Sensors, Superconductor
  • Saeed Olyaee , Masood Sherafat Pages 13-26
    Jones matrix computation is one of the widely used methods in nonlinearity calculation in laser interferometers. In this paper, the nonlinearity error in developed three-longitudinal mode heterodyne interferometer (DTLMI) has been mathematically modeled at various speeds, by using Jones matrix calculations. This review has been done despite the fact that simultaneously the main factors including non-ideal polarization of the laser beam and the non-ideal PBS produce nonlinearity. According to the results, it was found that although nonlinearity error is a pure sinusoid in low velocities, it isn't single-sinus and increases in amplitude in high velocities. It was also observed that the effect of non-ideal PBS on nonlinearity error is less than that of non-ideal laser beam and frequency of nonlinearity error caused by it is twice more
    Keywords: Developed Three-Longitudinal Mode Heterodyne Interferometer (DTLMI), Nonlinearity, Jones Matrix Calculations
  • Zeinab Zare , abdolrasoul gharaati Pages 27-35
    Using the transfer matrix method, the effect of temperature on the transmission spectra of thermal tunable nano metallic photonic crystal filter has been
    investigated. Three different materials H (high refractive index material), L (low refractive index material) and M as a metallic layer, have been used to make this structure. M layer is considered to be Silver. The complex refractive index of Silver is a function of temperature and wavelength simultaneously so, the structure is tunable with temperature and incident angle. It is found that the transmission peaks shift by changing temperature and incident angle. At a given incident angle, they move toward higher wavelengths by increasing the temperature. The temperature dependence of transmission peaks is linear. At a constant temperature, they move toward the shorter wavelengths by increasing the incident angle. Also by increasing the temperature, due to dissipation
    Keywords: Photonic Crystals, Temperature, Filter
  • Lida Safaei, mahmood Borhani Zarandi , Mohsen Hatami Pages 37-46
    In this paper we numerically investigate the effect of relative phase on the stability of temporal bright solitons in a Nano PT- Symmetric nonlinear directional coupler (NLDC) by considering gain in bar and loss in cross. We also study the effect of relative phase on the output perturbed bright solitonsenergies, in the range of  0 to 180 . By using perturbation theory three eigenfunctions and corresponding eigenvalues were derived analytically. These eigenvalues behave like equilibrium points and are not stable in all cases. Stability of these perturbed solitons under the effect of relative phase are examined and show that temporal bright solitons are almost unstable in the range of  0 to 90 , but they keep their solitary shapes in the range of  90 to 180 . In addition the evolution of normalized energies in these ranges are investigated. Output pulse energy at bar and cross strongly depend on the relative phase. This effect in a PT-Symmetric NLDC can be used for designing all-optical ultrafast self-switches and logic gates and Nano structures
    Keywords: Fiber Couplers, Nonlinear Optics, Photonics, Solitons, PT-Symmetry, Nano structures
  • mahnaz mohammadi, alireza zolghadr , mohammad pourmina Pages 47-57
    Since the time public-key cryptography was introduced by Diffie and Hellman in 1976, numerous public-key algorithms have been proposed. Some of these algorithms are insecure and the others that seem secure, many are impractical, either they have too large keys or the cipher text they produce is much longer than the plaintext. This paper focuses on efficient implementation and analysis of two most popular of these algorithms, RSA and ElGamal for key generation and the encryption scheme (encryption/decryption operation). RSA relies on the difficulty of prime factorization of a very large number, and the hardness of ElGamal algorithm is essentially equivalent to the hardness of finding discrete logarithm modulo a large prime. These two systems are compared to each other from different parameters points of view such as performance, security, speed and applications. To have a good comparison and also to have a good level of security correspond to users need the systems implemented are designed flexibly in terms of the key size
    Keywords: Cryptography, Public Key Cryptosystems, RSA, ElGamal
  • ZOHREH RASHKI , Seyed Javad Seyed Mahdavi chabok Pages 59-77
    Photonic crystal ring resonators (PCRRs) are traditional structures for designing optical channel drop filters. In this paper, Photonic crystal channel drop filter (CDFs) with a new configuration of ring resonator is presented. The structure is made of a square lattice of silicon rods with the refractive index nsi=3. 4 which are perforated in air with refractive index nair=1. Calculations of band structure and propagation of electromagnetic field through devices are done by plane wave expansion (PWE) and finite difference time domain (FDTD) methods, respectively. The simulation shows, 100% dropping efficiency and suitable quality factor at 1592. 6 nm wavelength achieved for this filter. Also, in this paper, we investigate parameters which have an effect on resonant wavelength and transmission spectrum in this CDF, such as refractive index of inner rods and whole of dielectric rods of the structure. The proposed structure is small which is more suitable for used in the future photonic integrated circuits, wavelength division multiplexing (WDM) systems and optical communication network applications. Also, we suggested a heterostructure wavelength demultiplexer is composed of four ring resonators. These ring resonators are located in four different regions (heterostructure) which each region has specific dielectric constant
    Keywords: Photonic Crystal, Ring Resonators, Square Lattice, Photonic Integrated Circuits, Optical Communication
  • Hossein Bahramiyan , Somayeh Bagheri Pages 79-99
    In this paper, the effect of pressure, temperature and impurity on the energy levels, binding energy, linear and nonlinear optical properties of a modified Gaussian quantum dot are studied. In this regard, the finite element method is employed to solve the single electron Schrodinger equation in the effective mass approximation with and without impurity at the center of the dot. In addition, the energy levels, the wave functions, biding energy, absorption coefficients and refractive index changes for different pressures and temperatures are calculated. The results show that the energy levels decrease by increasing pressure and increase by increasing the temperature for both, with and without impurity, situations. Also, in the presence of impurity, the refractive index changes are greater than the case without impurity and shift to higher energies. Furthermore, by increasing the pressure, the refractive index changes increase and shift to lower energy for both with and without impurity cases. By increasing the pressure and temperature the absorption coefficients decrease and shift to lower energy for all with and without impurity cases
    Keywords: Optical Properties, Modified Gaussian Quantum Dot, Impurity, Temperature, Pressure Effect