Titanium complexes of phosphinimide ligands with pendant hemilabile donars.

Originally published in Optics Express on 23 March 2015 (oe-23-6-7879

General vectorial decomposition of electromagnetic fields with application to propagation-invariant and rotating fields.

A novel decomposition of the transversal part of the electric field vector of a general non-paraxial electromagnetic field is presented, which is an extension of the radial/aximuthal decomposition and is known as gammazeta decomposition. Purely gamma and zeta polarized fields are examined and the decomposition is applied to propagation-invariant, rotating, and self-imaging electromagnetic fields. An experimental example on the effect of state of polarization in the propagation characteristics of the field: its is shown that a simple modification of the polarization conditions of the angular spectrum converts a self-imaging field into a propagation-invariant field

Analysis of all-optically tunable functionalities in sub-wavelength periodic structures by the Fourier modal method

We propose the nonlinear Fourier Modal Method (FMM) [J. Opt. Soc. Am. B 31, 2371 (2014)] as a convenient and versatile numerical tool for the design and analysis of grating based next generation all-optical devices. Here, we include several numerical examples where the FMM is used to simulate all-optically tunable functionalities in sub-wavelength periodic structures. At first, we numerically investigate a 1-D periodic nonlinear binary grating with amorphous TiO2. We plot the diffraction efficiency in the transmitted orders against the structure depth for normally incident plane wave. Change in diffraction efficiencies for different incident field amplitudes are evident from the plots. We verify the accuracy of our implementation by comparing our results with the results obtained with the nonlinear Split Field-Finite Difference Time Domain (SF-FDTD) method. Next we repeat the same experiment with vertically standing amorphous Titanium dioxide (TiO2) nanowire arrays grown on top of quartz which are periodic in two mutually perpendicular directions and examine the efficiencies in the direct transmitted light for different incident field amplitudes. Our third example includes analysis of a form birefringent linear grating with Kerr medium. With FMM we demonstrate that the birefringence of such a structure can be tuned by all-optical means. As a final example, we design a narrow band Guided Mode Resonance Filter (GMRF). Numerical experiments based on the nonlinear FMM reveal that the spectral tunability of such a filter can be obtained by all-optical means.This work is partially supported by the Academy of Finland (contract 285880)

Split-field finite-difference time-domain method for second-harmonic generation in two-dimensionally periodic structures

The split-field finite-difference time-domain method is extended to second-harmonic generation in two-dimensionally periodic structures. Making use of the full coefficient-tensor formalism, a coupled nonlinear system of equations, which must be solved at each update of the electromagnetic field, is developed. The accuracy of the method is verified by comparing the results to well-known one-dimensional problems. The results for L-shaped arrays are compared with results obtained with the Fourier modal method.This work is partially supported by the “Ministerio de Economía y Competitividad” of Spain under project FIS2011-29803-C02-01; by the “Generalitat Valenciana” of Spain under projects PROMETEO/2011/021, ISIC/2012/013, and GV/2014/076; and by the “Universidad de Alicante” of Spain under project GRE12-14

Efficient split eld FDTD analysis of third-order nonlinear materials in two-dimensionally periodic media

In this work the split-field finite-difference time-domain method (SF-FDTD) has been extended for the analysis of two-dimensionally periodic structures with third-order nonlinear media. The accuracy of the method is verified by comparisons with the nonlinear Fourier Modal Method (FMM). Once the formalism has been validated, examples of one- and two-dimensional nonlinear gratings are analysed. Regarding the 2D case, the shifting in resonant waveguides is corroborated. Here, not only the scalar Kerr effect is considered, the tensorial nature of the third-order nonlinear susceptibility is also included. The consideration of nonlinear materials in this kind of devices permits to design tunable devices such as variable band filters. However, the third-order nonlinear susceptibility is usually small and high intensities are needed in order to trigger the nonlinear effect. Here, a one-dimensional CBG is analysed in both linear and nonlinear regime and the shifting of the resonance peaks in both TE and TM are achieved numerically. The application of a numerical method based on the finite- difference time-domain method permits to analyse this issue from the time domain, thus bistability curves are also computed by means of the numerical method. These curves show how the nonlinear effect modifies the properties of the structure as a function of variable input pump field. When taking the nonlinear behaviour into account, the estimation of the electric field components becomes more challenging. In this paper, we present a set of acceleration strategies based on parallel software and hardware solutions.This work was supported by the Ministerio de Economa y Competitividad of Spain under project FIS2014-56100- C2-1-P and by the Generalitat Valenciana of Spain under projects PROMETEOII/2015/015, ISIC/2012/013 and GV/2014/076

Passiivienergiatalon suunnittelu

Työn tarkoituksena oli suunnitella passiivienergiatalo, sijoittaa se tontille mah-dollisimman viisaasti energiatehokkuuden kannalta ja suojata rakennus sää-olosuhteilta. Opinnäytetyön toimeksiantajana toimi oululainen pariskunta, joka haluaa rakentaa puurakenteisen matalaenergiatalon meren rannalle, Haukiputaan Keskiniemeen. Talosta tuli ympäri vuoden asuttava vapaa-ajan asunto. Työn tavoitteena oli saavuttaa Pohjois-Euroopan ilmastoon määritetty passiivienergiatalon energiatehokkuus. Työssä perehdyttiin passiivienergiatalon määritelmään, toteutustapoihin, rakenne-, LVI-, ovi- ja ikkunaratkaisuihin. Yhdeksi tarkastelun kohteeksi otettiin myös ilmaston ja talon sijainnin vaikutukset rakennukseen. Käytetty aineisto ja tietoperusta ovat peräisin internetistä, ammattilaisten raporteista, tutkimuksista, ohjeistuksista ja RT-kortistosta. Lupa- ja työkuvat suunniteltiin AutoCad-ohjelmalla, talon energiatehokkuus laskettiin Energiajunior 7.1 -ohjelmalla ja vinokattoa kannattavien palkin ja pilarien kestävyydet Finnwood-ohjelmalla. Työssä suunnitellun omakotitalon energiatehokkuus ei saavuttanut Pohjois-Euroopassa sijaitsevan passiivienergiatalon energiatehokkuutta. Rakennuksen muoto ja lämmitettävä ilmatilavuus ovat merkittäviä asioita energiatehokkuuden kannalta. Samanlainen rakennus, joka olisi muodoltaan neliskanttinen ja jossa kattokorkeus pysyisi matalana, saavuttaisi passiivitalolle määritetyn energiatehokkuuden. Opinnäytetyötä voi hyödyntää suunniteltaessa matalaenergia- tai passiivienergiataloa sekä rakennuksen tontille sijoittamista energiatehokkaasti ja sääolosuhteilta suojautumista.The purpose of this thesis was to plan a passive energy house, to position it on the lot as well as possible from the viewpoint of energy efficiency and to protect the building from adverse weather conditions. The client of the thesis was a couple from Oulu, who wanted to build a timber structure, low energy house on the coast, in Keskiniemi of Haukipudas. The objective of the thesis was to reach the energy efficiency level required of a passive energy house in Northern Europe. The project comprised of studying the definition of a passive energy house, its implementation methods and the structural, HVAC, door, and window solutions. One focus of analysis was also the climate and house locations’ effects of the building. Reference material and information was taken from the internet, professional reports, research papers, instructions and the Finnish Building Regulations database. Architectural and structural plans were made with AutoCad, house energy efficiency was calculated using Energiajunior 7.1 and diagonal roof supporting beam and column tolerances were calculated with Finnwood -programme. The house designed in the project did not meet the energy efficiency of a Northern European passive-energy house. The shape and the heated air ca-pacity of the house are of major importance to its energy efficiency. One can thus use this thesis for designing either a low-energy or a passive-energy house

Split-Field Finite-Difference Time-Domain scheme for Kerr-type nonlinear periodic media

The Split-Field Finite-Difference Time-Domain (SF-FDTD) formulation is extended to periodic structures with Kerr-type nonlinearity. The optical Kerr effect is introduced by an iterative fixed-point procedure for solving the nonlinear system of equations. Using the method, formation of solitons inside homogenous nonlinear media is numerically observed. Furthermore, the performance of the approach with more complex photonic systems, such as high-reflectance coatings and binary phase gratings with high nonlinearity is investigated. The static and the dynamic behavior of the Kerr effect is studied and compared to previous works.The work is partially supported by the Academy of Finland (project 118951), the Strategic Funding of the University of Eastern Finland, by the "Ministerio de Economía y Competitividad" of Spain under project FIS2011-29803-C02-01 and by the "Generalitat Valenciana" of Spain under projects PROMETEO/2011/021 and ISIC/2012/013

Visibility parameters in Young's interference experiment with unpolarized light

International audienceWe analyze the recently introduced Polarization contrast parameters and their relation to degrees of coherence in electromagnetic Young's interference experiment in the case of unpolarized illumination. We show that in the general case only two of the parameters can be made non-vanishing if suitable unitary transformations are applied to the field at pinholes. The result implies elegant relations between the contrast parameters and the intrinsic degrees of coherence in the case of unpolarized light at pinholes

Minimum number of modulated Stokes parameters in Young's interference experiment

International audienceThe contrast parameters associated with the generalized Stokes vector in a Young's interference experiment are analyzed. It is shown that there are two unitary transformations that can be applied to the electric fields so that a partially polarized light can be described with no more than two non-zero generalized Stokes parameters. Furthermore, general conditions are derived which indicate when totally unpolarized light can be described with only one non zero generalized Stokes parameter after unitary transformations

A temporal-coherence anisotropy of unpolarized light

International audienceWe analyze the anisotropic behavior of unpolarized, temporally partially coherent light. We demonstrate that unpolarized light with different intrinsic degrees of coherence can present an anisotropic behavior which is experimentally observable while it is not the case if both intrinsic degrees are equal. This behavior is analyzed in comparison with the standard anisotropy property of partially polarized light