http://gsvit.net/wiki/ 2026-04-30T14:28:56+00:00 http://gsvit.net/wiki/ http://gsvit.net/wiki/lib/tpl/dokuwiki/images/favicon.ico text/html 2025-02-19T10:27:48+00:00 Anonymous (anonymous@undisclosed.example.com) http://gsvit.net/wiki/doku.php?id=app:application_examples&rev=1739957268&do=diff Application examples List of application examples Diffraction grating Grating from topography Rough surface scattering Thin film absorption Plasmonic nanoantenna Silicon nanowire Optical force calculation Mie scattering SERS substrate TERS field enhancement Aperture SNOM Infrared scattering SNOM Scanning microwave microscope text/html 2025-02-19T10:27:48+00:00 Anonymous (anonymous@undisclosed.example.com) http://gsvit.net/wiki/doku.php?id=app:diffraction_grating&rev=1739957268&do=diff Diffraction grating As an example of extensive use of Near-to-Far Field (NFFF) transformation we dicuss modeling of a diffractive optical element performance. Scattering from diffraction gratings and similar periodic structures can be evaluated analytically to some extent (e.g. for ideal gratings). However, for analysis of different defects, like shape of a single groove, roughness or faults in periodicity, we need to use some numerical technique. FDTD is one of the options, however as the grat… text/html 2025-02-19T10:27:48+00:00 Anonymous (anonymous@undisclosed.example.com) http://gsvit.net/wiki/doku.php?id=app:irsnom&rev=1739957268&do=diff Infrared scattering SNOM Scattering SNOM is an optical technique that allows obtaining information about sample optical properties with nanoscale resolution. This is based on the local field enhancement effect, similar to the TERS. However, here we don't need to collect a very small Raman signal, so the technique is easier to work even with not so ideal experimental conditions. text/html 2025-02-19T10:27:48+00:00 Anonymous (anonymous@undisclosed.example.com) http://gsvit.net/wiki/doku.php?id=app:mie&rev=1739957268&do=diff Mie scattering Scattering of monochromatic light by a homogeneous dielectric sphere is a traditional problem in the area of light-matter interaction. It has numerous applications, e.g. in aerosols measurements in environmental studies. Calculation on a regular, smooth and homogeneous, sphere can be done using Mie's solution of Maxwell equations and there are numerous codes available for this, even text/html 2025-02-19T10:27:48+00:00 Anonymous (anonymous@undisclosed.example.com) http://gsvit.net/wiki/doku.php?id=app:nanoantenna&rev=1739957268&do=diff Plasmonic nanoantenna Recently, nano-antennas and nano-antenna arrays became very popular examples of nanotechnology in optics. Small metallic rods or high aspect ratio nanoparticles can be used to enhance locally electromagnetic field of desired wavelength, providing tunable absorption properties or secondary excitation of localised luminescence or Raman scattering. Using realistic metal models we can calculate nanoantennas response using FDTD, which seems to be very popular method in this fie… text/html 2025-02-19T14:52:01+00:00 Anonymous (anonymous@undisclosed.example.com) http://gsvit.net/wiki/doku.php?id=app:optical_force&rev=1739973121&do=diff Optical force calculation FDTD is well suited for purposes of optical force calculation in different geometries used in light trapping of nanoparticles (e.g. in optical tweezers). Here we show a simple example of calculation of scattering force acting on dielectric particle under a plane wave illumination and its dependence on particle permittivity. The result is compared to Mie solution (Mie data courtesy of Martin Siler, ISI ASCR). text/html 2025-02-19T10:27:48+00:00 Anonymous (anonymous@undisclosed.example.com) http://gsvit.net/wiki/doku.php?id=app:rough_surface&rev=1739957268&do=diff Rough surface scattering In this example we will use GSvit to simulate scattering from a highly absorbing sample (e.g. metallic). Calculation procedure is very similar to reflection grating example, we again use a height field to setup measurement volume material parameters, however here we do not apply periodic boundary conditions as the surface is not periodic (and we do not want to introduce artificial periodicity to the results). text/html 2025-02-19T10:27:48+00:00 Anonymous (anonymous@undisclosed.example.com) http://gsvit.net/wiki/doku.php?id=app:sers&rev=1739957268&do=diff SERS substrate Surface Enhanced Raman Scattering (SERS) is an advanced experimental technique for measurement of Raman scattering signals. Raman scattering itself is a process with very small yield and to measure Raman signals on some individual molecules or thin film materials is very challenging. By placing the investigated material on a special substrate we can increase the signal intensity by several orders of magnitude. The effect is based on local field enhancement which is a plasmonic ef… text/html 2025-02-19T10:27:48+00:00 Anonymous (anonymous@undisclosed.example.com) http://gsvit.net/wiki/doku.php?id=app:si_grain&rev=1739957268&do=diff Cílem výpočtu bylo získat rozložení absorpce světla dané vlnové délky v objemu vzorku tvořeného amorfním křemíkem a jedním mikrokrystalickým zrnem. Amorfní křemík tvoří samonosnou vrstvu o tloušťce 1 μm. Zrno má tvar kulové výseče s vrcholovým úhlem β. Vrchol kulové výseče je v hloubce d pod povrchem (typicky 500-800 nm); tato hodnota je v textu nazývána hloubkou zrna. Celý povrch je pokryt tenkou neabsorbující vrstvou (tloušťka 100 nm, εr=1.96). text/html 2025-02-19T10:27:48+00:00 Anonymous (anonymous@undisclosed.example.com) http://gsvit.net/wiki/doku.php?id=app:sinw&rev=1739957268&do=diff Silicon nanowire In this application example we calculate the field distribution in a silicon nanowires based solar cell. This is one of many advanced options how to construct better solar cells. As the solar cell performance highly depends on the local absorption of light, FDTD can be an useful tool for exploring in which regions of the sample the light gets absorbed. text/html 2025-02-19T10:27:48+00:00 Anonymous (anonymous@undisclosed.example.com) http://gsvit.net/wiki/doku.php?id=app:smm&rev=1739957268&do=diff Scanning microwave microscope to be completed text/html 2025-02-19T10:27:48+00:00 Anonymous (anonymous@undisclosed.example.com) http://gsvit.net/wiki/doku.php?id=app:snom&rev=1739957268&do=diff Aperture SNOM Scanning near-field optical microscopy based on fiber probes is one of the main two branches of optical scanning probe microscopy techniques. Even if it seems to be overcome by apertureless (scattering) SNOM in recent years, it still has some benefits - low signal to noise ratio, no need of using lock-in techniques or higher harmonics techniques for detection, and probably also higher penetration depth of the volume from which the signal is collected. text/html 2025-02-19T10:27:48+00:00 Anonymous (anonymous@undisclosed.example.com) http://gsvit.net/wiki/doku.php?id=app:ters&rev=1739957268&do=diff TERS field enhancement Tip Enhanced Raman Microscopy is, besides SERS another approach how to locally enhance the Raman scattering signal. There are the few different effects that we can observe when illuminating a nanoscale metallic structure. First of all, we can observe effect of spectral properties of the particular metal from which the structure is formed. Even the simplest possible quantity observed on metals in everyday life - its excellent reflectivity - is material dependent and the d… text/html 2025-02-19T14:49:08+00:00 Anonymous (anonymous@undisclosed.example.com) http://gsvit.net/wiki/doku.php?id=app:thin_film&rev=1739972948&do=diff Thin film absorption Calculation of thin film reflection, transmission or absorption can be done analytically using Fresnel coefficients and related equations. This approach can be used perfectly also for multilayers and use of FDTD for such purposes is absolutely pointless. However, it can be used as a simple benchmark of FDTD performance. Moreover, if we want to address films that are to some extent microstructured or nanostructured, we cannot use conventional methods anymore and we need to s… text/html 2025-02-19T10:27:48+00:00 Anonymous (anonymous@undisclosed.example.com) http://gsvit.net/wiki/doku.php?id=app:topography_grating&rev=1739957268&do=diff Reflection grating based on surface topography In this example we will try to simulate reflection from metallic grating. In contrast to transmission grating example we will be using a realisitic geometry model based on grating topography measurements using atomic force microscope.