Browsing by Subject "Transparent optical networks"

Now showing 1 - 8 of 8

Open Access
Characteristic equations for the lasing Modes of infinite periodic chain of quantum wires
(IEEE, 2008-06) Byelobrov, V. O.; Benson, T. M.; Altıntaş, Ayhan; Nosich, A.I.
In this paper, we study the lasing modes of a periodic open optical resonator. The resonator is an infinite chain of active circular cylindrical quantum wires standing in tree space. Characteristic equations for the frequencies and associated linear thresholds of lasing are derived. These quantities are considered as eigenvalues of specific electromagnetic-field problem with "active" imaginary part of the cylinder material's refractive index - Lasing Eigenvalue Problem (LEP). ©2008 IEEE.
Open Access
A comparative study of single-layer and multi-layer traffic engineering approaches on transparent optical networks
(IEEE, 2007) Şengezer, Namık; Puype, B.; Karasan, Ezhan; Pickavet, M.
This paper comparatively studies single-layer and multi-layer traffic engineering strategies on an IP/MPLS/WDM network. These strategies are evaluated and compared in two different scenarios. In the first scenario, the strategies make use of statistical information on the traffic patterns. In the second scenario, the traffic engineering decisions are based on the instantaneous traffic information only. The performance and benefits of both approaches are discussed based on simulations considering both throughput and network resource usage. © 2007 IEEE.
Open Access
Generation of new frequencies in toroid microcavities
(IEEE, 2008) Akbulut, Duygu; Tülek, Abdullah; Bayındır, Mehmet
Microtoroid cavities with ultra high Q-factor have been fabricated using a combined process of photolithography and reflow technique for observing non-linear effects such as generation of new frequency components. For this purpose SiO2 material was used to form the toroidal cavity shape, and chalcogenide material of As2S3 maintaining very high nonlinear refractive index was thermally evaporated on top with varying thicknesses. Simulation results of the fabricated structure have exhibited new frequency components around the excitation window of 1520 nm produced by non-linear interactions.
Open Access
Laser action studies of π-conjugated polymer microcavities
(IEEE, 2008) Tülek, Abdullah; Vardeny, Z. V.
Unidirectional laser emission was observed from φ-conjugated polymer microcavities with spiral geometry, and from microdisks containing line defects. For both type of cavities directionality contrast of the laser emission was found to be ̃ 10, with far-field lateral divergence angle of ̃ 15°. No significant increase in the laser threshold intensity was observed compared with simple microdisk cavities. In addition we also studied the emission spectra of microring polymer lasers fabricated on nylon microfibers upon application of uniaxial stress with strain up to ̃ 12%. Substantial change in the laser emission spectrum was observed when stress was applied; showing enhanced optical sensitivity to stress larger than the changes induced in the emission spectrum caused by the microfiber diameter change. We explain the enhanced sensitivity to stress as due to the induced change in the polymer refractive index dispersion, in particular at the laser emission wavelength (̃ 635 nm).
Open Access
Lasing modes of infinite periodic chain of quantum wires
(IEEE, 2009-06-07) Byelobrov, V. O.; Benson, T. M.; Sewell, P.; Altıntaş, Ayhan; Nosich, A. I.
In this paper, we study the scattering and eigenvalue problems for a periodic open optical resonator that is an infinite chain of active circular cylindrical quantum wires standing in free space. The scattering problem is solved by the method of partial separation of variables. The eigenvalue problem differs from the first one by the absence of the incident field and presence of "active properties" of cylinders and yields the frequencies and thresholds of lasing. ©2009 IEEE.
Open Access
Performance of WDM transport networks
(Institute of Electrical and Electronics Engineers, 1998-08) Karasan, E.; Ayanoglu, E.
Wavelength division multiplexed point-to-point transport is becoming commonplace in wide area networks. With the expectation that the next step is end-to-end networking of wavelengths (in the optical domain without conversion to electronics), there is a need for new design techniques, a new understanding of the performance issues, and a new performance evaluation methodology in such networks. This paper describes approaches to that end, summarizes research results, and points to open problems.
Open Access
Plasmon and grid resonances in the electromagnetic scattering by finite grids of silver nanowires
(IEEE, 2010) Natarov, D. M.; Benson, T. M.; Altıntaş, Ayhan; Sauleau, R.; Nosich, A. I.
The problem of the H-polarized wave scattering by finite chains of circular nanowires is considered. A two-dimensional diffraction problem with rigorous boundary conditions is solved by partial separations of variables method using local polar coordinates of each scatterer. The obtained results demonstrate convergence of the algorithm and good agreement with data known for the conducting and dielectric cylinders. Plasmonic and grid resonances are found and calculated for grids from a big number of silver nanowires. This opens a way to the accurate numerical simulation of various finite configurations of wires met in today's nano and microsize photonic devices.
Open Access
Simulating a wavelength-size 2-D lens with an accurate numerical method
(IEEE, 2001) Boriskin, A. V.; Nosich, A. I.; Altıntaş, Ayhan
The effect of a localized light source directivity improvement due to an arbitrarily shaped dielectric cylinder taken as a 2-D model of a dielectric lens is studied. The source is simulated by the field of a complex source-point (CSP). An efficient algorithm for the solution of 2-D problem of wave scattering by a smooth dielectric cylinder is developed, based on the concept of analytical regularization. The basic properties of the algorithm are studied. Numerical results for the accuracy of the algorithm and sample far-field characteristics such as the total radiated power, directivity and radiation patterns for various lens parameters are presented.