Proposed OCDMA encoders and decoders based on silica‐on‐silicon integrated optics

Abstract

RESULTS Comparison with 2D ResultsTo test our code, we simulate the same problem as [8], used there to check focus properties of LHM. The problem consists of an infinitely long line source located 0 /2 above an LHM slab with thickness d ϭ 0 / 2, which is surrounded by free space. The LHM slab was located exactly in the middle of our domain, occupying x ϭ [0 120], y ϭ [40 80], and z ϭ [0 30] cells, including the PML region. The line source was located at (60, 100, [0 30]), 20 cells away from the slab and the resonant frequency used for expression (3) was set to be p ϭ 266.6 ϫ 10 11 rad/s, which gives r ϭ r Ӎ Ϫ1. The computational domain for this example is 120 ϫ 120 ϫ 30 grid points, in the x, y, and z directions, respectively. With the PML approach, we were able to reproduce the results in [8] in a much smaller domain. Figure 2 shows the E z -field distribution corresponding to the time t ϭ 1250⌬t. The field is shown down to 40 dB below its maximum. In order to compare our simulation to [8], we did not place a PML layer on the front and back faces, perpendicular to the z axis, in the 2D simulations. It should be noted that the field distribution is the same as in Fig. 7 in [8], even with a different precision due to larger time steps and larger cell sizes in our simulation. The same field distribution is also seen in [12].Another simulation was done in comparison with rad/s. The field is plotted down to 40 dB below its maximum and at a time t ϭ 1250⌬t. As shown in Figure 3, paraxial foci are located at the center of the slab and at the opposite side from the source. 3D Simulation of a /2 DipoleFinally, we apply our code to 3D problems. The problem is to simulate a 0 /2 dipole 0 /2 above an LHM slab with thickness d ϭ 0 / 2. We reproduced similar geometry to the 2D problems, but with a finite line source. The computational domain for all 3D examples has 120 ϫ 120 ϫ 120 grid points. Figure 4 illustrates the problem's geometry, with the xy-plane cutting at the middle of our domain and the yz-and zx-planes cutting along the dipole. All the fields are plotted down to 60 dB below their maxima.For the first example, the dipole was located at ( Figure 6.For all the examples presented here, the colored animation can be found at http://iris-lee3.ece.uiuc.edu/ ϳ jjin/jin_home.html, where the wave propagation and focus property are shown more clearly. CONCLUSIONA complete 3D formulation, adding the PML approach to the previous formulation of the Drude medium model, has been developed in this paper. The simulation results show good accuracy as compared to the previously published results. The phenomenon of backward-wave propagation can now be analyzed in any arbitrary direction inside an LHM and more complex and realistic structures can be simulated with our code.

Modelagem de redes CDMA-PON baseadas em técnicas de cancelamento paralelo e códigos corretores de erros

“…Na primeira, uma fonte de luz, como o diodo emissor de luz (LED) [79], apresenta seu espectro dividido através da utilização de filtros ópticos em um grande número de canais de comprimentos de onda, os quais são utilizados para efetuar as transmissões. Além dos tradicionais decodificadores utilizando linhas de atraso em fibra óptica [37], têm sido sugeridos outros artifícios como o emprego de cristais fotônicos [82] e óptica integrada [83]. Assim, cada bit é codificado em uma forma de onda s(t) que corresponde à sequência de assinatura do código [84].…”

Single and multirate FFH-OCDMA networks based on PSK modulation formats

“…represented by an optical pulse of high amplitude and a short duration, where the duration of each chip is related to the code weight adopted by the specific code algorithm. Therefore, the full width at half maximum width (FWHM) of a chip is given by = / , where is the In addition to traditional ODLs [54], other artifices which use photonic crystals [55] and integrated optics [56] have been suggested. Each data information bit is encoded in a waveform that corresponds to a code signature.…”

“…After substituting (57) and (58) into (56), it can be observed that the bipolar signal characteristics pushes the optimal threshold level to zero, i.e., , = 0. Then, after simple algebraic substitutions, and assuming that the interfering users are statistically independent, the average interference variance for interfering users can be expressed as the minimal BER for QPSK based networks as…”

Proposal of a new approach for BER evaluation of multirate, multiservice OCDMA systems

“…When going through the process of coding, this bit period will be divided into L subintervals of duration T c denominated as chips. In addition to traditional ODLs [64], other techniques have been suggested such as the use of photonic crystals [65] and integrated optics [66].…”