Özüm Emre Aşırım, Mustafa Kuzuoğlu

High intensity wave generation is hard to achieve in certain frequency intervals such as the terahertz frequency range and the ultraviolet frequency range. In this paper we present a numerical study for ultra-wideband spectral broadening (supercontinuum formation) and wideband electromagnetic wave generation in a small infrared-resonant optical microcavity. It was observed that at a given intracavity intensity, spectral broadening occurs profoundly near the resonance frequency of the cavity material, and the broadening effect drastically weakens when the excitation frequency is away from the resonance frequency. A numerical example is presented for an intense, near resonance, infra-red frequency excitation, and the resulting spectral broadening is investigated in the terahertz-ultraviolet frequency range. This numerical example is repeated for some other resonance frequency values that are gradually further from the infrared frequency range, and the resulting cessation of the spectral broadening process is illustrated. It is found that, for an infrared-resonant optical microcavity, supercontinuum can be generated under intense near-resonance excitation and spectrally ultra-tunable electromagnetic waves can be generated at the cavity output with the use of a switch controlled bandpass filter.

Christopher White, Clifton R. Haider, Daniel J. Schwab, Barry K. Gilbert

The use of multi-wavelength optical tests can be found in many applications including industrial manufacturing, food testing, and hospitals. This effort was targeted at making compact devices that could emit multiple wavelengths and detect multiple wavelengths simultaneously. Multiple approaches were considered. The chosen design accomplishes multiple input and multiple output spectral measurements through a direct-sequence spread spectrum (DSSS) technique. The devices demonstrated within this paper are novel in that they allow simultaneous operation of multiple wavelengths and multiple detectors using readily available components in a compact arrangement.

Abdelfatteh Cherif, Sami Youssef

We present a time-resolved emission decay curves for ⁴S_3/2à⁴I_15/2 transition in Er³⁺- doped zinc tellurite glass, with the aim to interpret non-exponential decay. PL results can be described by the stretched exponential function. In this study, we address that this function enables us to a multi-configurational distribution of luminescent ions in a disordered medium.

Abdallah K. Cherri, Nabil I. Khachab, Mahmoud K. Habib

In this paper, the design of one-lens (instead of two-lens) refracting system is proposed to provide particular laser irradiance profiles. Specifically, the one-lens surfaces are derived for three types of laser beam transformations: (i) Gaussian to Annular-uniform; (ii) Annular-Gaussian to Annular-uniform; and (iii) Annular-Gaussian to Gaussian. It will be demonstrated that the one-element designs outperform the two-element ones (for the same system parameters previously reported) for these beams regarding the system length. In particular, the system length is reduced by almost 39% for both the Gaussian and Annular-Gaussian to Annular-uniform beam transformation for the same starting refraction angle. For the beam transformation of Annular-Gaussian to Gaussian beam transformation, this system length is reduced by almost 34% with slightly larger initial refraction angle.

A. Ghlaifan, Y. Tounsi, D. Muhire, A. Nassim

The central goal of this paper is to present an algorithm for optical phase gradient evaluation from only one fringe pattern using the two-dimensional continuous wavelet transform (2D_CWT) analysis. The phase gradient is computed from the extremum scales correspond to the maximum ridge of the wavelet coefficients modulus. Spatial modulation process is realized by combining two shifted fringes patterns, we use only single fringe pattern and we suggest to generate its quadrature using spiral phase transform SPT. The obtained results with computer simulation and image quality index values show a good performance of the proposed algorithm, and eventually, we can reconstruct the spatial phase distribution by integrating numerically the phase gradient along x and y-direction. Also, experimental results are given by exploiting speckle fringe correlation recorded in digital speckle pattern interferometry.

Faramarz E. Seraji, M. Nouri

In this paper, optimization and management of dispersion of photonic crystal fibers (PCF) are presented, using 2D finite difference method in time domain based on an Intelligent Programming. In the analysis, for the proposed PCF structures, by evaluation of the effective refractive indices, the dispersions are calculated for 11 circular air-hole rings in the cladding. The effects of geometrical parameters of the PCFs, such as air-hole diameters, the pitch value, number of air rings on dispersion are investigated for the influence of the structural parameters of the PCFs on the obtained dispersions and the corresponding results are graphically compared. It is shown that when the air-hole diameter decreases, the slope of the negative dispersion would increase, while increase of the pitch would cause a decrease in the negative dispersion values. It is further shown that at pitches of higher than 5μm, irrespective of air-hole diameter, the variation of the dispersion is almost linear. The results presented can help in choosing the PCF parameters for appropriate applications.

Fouad El-Diasty, Manal Abdel-Baki, Safia Ibraheem

Spectroscopic properties for P₂O₅(0.55-x)-MgO(0.45)–xBi₂O₃ glass system were studied, where the range of molar fraction was 0 ≤ x ≤ 0.07 mol%. Glass series were prepared by melt quenching technique to be used as a host glass for upconversion applications. Both density and molar volume were determined. The structural changes have been studied by FT-IR spectroscopy. The adding up of Bi₂O₃ decreases the P―O―P covalent bond by forming P―O―Bi bonds which were associated with a conversion from Bi³⁺ into Bi⁶⁺ ions. The calculated optical dielectric constant was increased with increasing bismuth oxide contents due to the high polarizing power of Bi³⁺ and Bi⁶⁺ ions and their small field strength. The different factors that affect the radiative lifetime of electronic transitions for luminescent dopant ions impeded in the host glasses were studied as well.

Leila Hajshahvaladi, Hassan Kaatuzian, Mohammad Danaie

In this paper, a simple and non-complex structure for an optical double Bandpass Filter (BPF) based on two-dimensional (2D) Photonic Crystal Ring Resonators (PCRRs) is suggested for ITU-T G.694.2 8-channel Coarse Wavelength Division Multiplexing (CWDM) optical systems. It is centred at wavelengths of 1491 nm and 1551 nm with the aim of minimum attenuation. The desired BPF is composed of a 20×19 square lattice of dielectric rods using semiconductor InAs rods. The normalized transmission spectra simulations and the Photonic Band Gap (PBG) calculations for the desired filter are done using two-dimensional finite-difference time-domain (2D-FDTD) and Plane Wave Expansion (PWE) methods, respectively. The simulation results confirm the normalized output transmission efficiencies, quality factors (Q) and Full Width at Half Maximum (FWHM) for desired BPF are equal to about 99%, 497 and 3 nm (for 1491 nm) and nearly 100%, 310.2 and 5 nm (for 1551 nm), respectively. High transmission efficiencies, acceptable quality factors and low FWHM are important characteristics of proposed filter.

Saeed Abdolhosseini, Hassan Kaatuzian, Reza Kohandani

In this paper, a slow light device, which is composed of GaAs/AlGaAs [110] strained quantum wells, has been studied to realize V-type electromagnetically induced transparency phenomenon. Influences of applying electric and magnetic fields are investigated theoretically on main properties of the slow light devices, such as slow down factor and refractive index, based on Bloch equations approach. This is the first study of applying external magnetic and electric fields impacts on proposed structure by using V-type electromagnetically induced transparency. By changing the external fields, we are able to modify central frequency of presented structure that provides appropriate conditions in order to be utilized in optical storages, optical buffers and all-optical switches. According to the simulation results, the peak value of slow down factor is estimated to near 5000 when power intensity of pump and signal are 10 kW/cm² and 0.1 kW/cm², respectively. With optimization the amount of external fields, the central frequency of system can reach positive shift as high as 1.1 THz and negative shift close to -1.1 THz.

Behnoush Babaghorbani, Hassan Kaatuzian

Single - and double-waveguide coupled resonators are designed and analyzed according to Silicon On Insulator (SOI) technology. In the last few decades much study has been done on the Microring Resonators (MRRs). In order to enhance group delay, many different structures have been proposed and constructed. In this theoretical study, by variation of coupling coefficient in terms of altering distance gap between ring and waveguide, we’ve successfully simulated and estimated high group delay for slow and fast light in microring with radius of 50µm. Compared with previously reported experimental results, time delay is improved significantly from 32 ps to 166 ps, which is increased considerably. Also, fast light is observed in single waveguide structure with a maximum time advance of 114 ps. For double waveguide structure, by changing the coupling coefficient, time delay is also improved significantly. Another port of this structure is monitored, simultaneous slow and fast light achieved at single frequency with certain coupling condition.