The complex Jacobi iterative method for non-paraxial beam propagation in nonlinear optical waveguides

The recently introduced beam propagation method using complex Jacobi iteration adapted for modeling of non-paraxial beam propagation in nonlinear optical waveguides is presented in this paper. The beam propagation equation is based on our recently proposed modified Pad,(1,1) approximant operator. The resulting approach is very efficient and well-suited for large structures with long propagation paths

Three-dimensional higher-order pade approximant-based wide-angle beam propagation method using complex jacobi iteration

Wide-angle scalar beam propagation methods (BPMs) for effective modelling of optical propagation in three-dimensional (3D) waveguides are usually limited to the low-order-accurate Pade (1,1) approximant. Presented is a 3D wide-angle scalar BPM based on higher-order Pade approximant operators which is factored into a series of simpler first-order Pade (1,1) approximants. This results in a multistep method where each step can be cast in terms of a 2D Helmholtz equation with source term, which can be treated accurately and effectively by the new complex Jacobi iterative technique

Plasmonic nano-antennas for absorption enhancement in thin-film silicon solar cells

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Modified Padé-approximant-based wide-angle beam propagators

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Towards efficient three-dimensional wide-angle beam propagation methods and theoretical study of nanostructures for enhanced performance of photonic devices

In this dissertation, we have proposed a novel class of approximants, the so-called modified Padé approximant operators for the wide-angle beam propagation method (WA-BPM). Such new operators not only allow a more accurate approximation to the true Helmholtz equation than the conventional operators, but also give evanescent modes the desired damping. We have also demonstrated the usefulness of these new operators for the solution of time-domain beam propagation problems. We have shown this both for a wideband method, which can take reflections into account, and for a split-step method for the modeling of ultrashort unidirectional pulses. The resulting approaches achieve high-order accuracy not only in space but also in time. In addition, we have proposed an adaptation of the recently introduced complex Jacobi iterative (CJI) method for the solution of wide-angle beam propagation problems. The resulting CJI-WA-BPM is very competitive for demanding problems. For large 3D waveguide problems with refractive index profiles varying in the propagation direction, the CJI method can speed-up beam propagation up to 4 times compared to other state-of-the-art methods. For practical problems, the CJI-WA-BPM is found to be very useful to simulate a big component such as an arrayed waveguide grating (AWG) in the silicon-on-insulator platform, which our group is looking at. Apart from WA beam propagation problems for uniform waveguide structures, we have developed novel Padé approximate solutions for wave propagation in graded-index metamaterials. The resulting method offers a very promising tool for such demanding problems. On the other hand, we have carried out the study of improved performance of optical devices such as label-free optical biosensors, light-emitting diodes and solar cells by means of numerical and analytical methods. We have proposed a solution for enhanced sensitivity of a silicon-on-insulator surface plasmon interference biosensor which had been previously proposed in our group. The resulting sensitivity has been enhanced up to 5 times. Furthermore, we have developed an improved model to investigate the influence of isolated metallic nanoparticles on light emission properties of light-emitting diodes. The resulting model compares very well to experimental results. Finally, we have proposed the usefulness of core-shell nanostructures as nanoantennas to enhance light absorption of thin-film amorphous silicon solar cells. An increased absorption up to 33 % has theoretically been demonstrated

The complex Jacobi iterative method for three-dimensional wide-angle beam propagation

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Dual-interface gratings for broadband absorption enhancement in thin-film solar cells

We numerically study complex dual-interface grating systems to enhance absorption efficiency in thin-film silicon solar cells. We combine a plasmonic grating at the back side of the solar cell with a dielectric grating at the front side of the cell. We show a proof of principle, with one-dimensional gratings, that the distinctly different nature of the gratings can provide complementary enhancement mechanisms, which we further exploit by tailoring the specific periodicities, and by introducing blazing. Having different periods at specific interfaces allows for more efficient diffraction into both plasmonic and dielectric guided modes. In addition, grating specific blazing exposes extra modes to normal incident light through symmetry breaking. Multiple optimization routes are possible depending on the choice of photonic phenomena