Dr. Gerhard Seifert Profile

Dr. Gerhard Seifert

at Martin-Luther Univ. Halle-Wittenberg

SPIE Involvement:

Author

Publications (11)

Proceedings Article | 15 May 2014 Paper

Rate equation analysis of nanocrystal-enhanced upconversion in neodymium-doped glass ceramics

U. Skrzypczak, Charlotte Pfau, G. Seifert, Stefan Schweizer

Proceedings Volume 9140, 91400J (2014) https://doi.org/10.1117/12.2051764

KEYWORDS: Upconversion, Glasses, Neodymium, Ions, Absorption, Ceramics, Nanocrystals, Near infrared, Luminescence, Phonons

Read Abstract +

Rare-earth ions embedded in glassy matrices are promising materials for photon upconversion processes, e.g. to convert near infrared light to frequencies above the band gap of a solar cell to make it available for electrical power generation. One strategy to optimize the efficiency of such upconversion processes is to embed the active ions in a host matrix with minimal losses to non-radiative relaxation. For the model system of trivalent neodymium in fluorochlorozirconate (FCZ) glass it has been shown recently that a uniform growth of BaCl₂ nanocrystals inside such glasses can decrease the probability of multi-phonon relaxation (MPR) drastically, leading to a huge increase in upconversion intensity for monochromatic illumination. To identify the key processes which may enhance or diminish the total upconversion efficiency, a comprehensive description for the optical dynamics of neodymium in FCZ glass ceramics has been developed on the basis of a rate equation system, including ion-photon, ion-phonon, and ion-ion interactions. An effective medium approach is utilized to account for the neodymium located in BaCl₂ nanocrystals or the FCZ glass bulk, respectively. The numerous parameters required to enable for a reliable numerical simulation of the processes are obtained from theoretical approaches like Judd-Ofelt theory, as well as from experimental studies of luminescence decay after femtosecond excitation at various wavelengths and luminescence spectra under cw illumination at 800 nm wavelength. This rate equation model enables for a convenient, self-consistent description of all time-resolved and cw experiments on samples with different neodymium concentration. On this basis, the power dependence of upconversion spectra can be simulated in good agreement with the experimental result for 800 nm cw illumination. The model therefore forms an excellent tool for optimizing the upconversion efficiency of rare-earth doped luminescent material also under realistic (broadband illumination) conditions.

Proceedings Article | 30 January 2012 Paper

Mechanism of selective removal of transparent layers on semiconductors using ultrashort laser pulses

Tino Rublack, Stefan Hartnauer, Michael Mergner, Markus Muchow, Martin Schade, Hartmut Leipner, Gerhard Seifert

Proceedings Volume 8247, 82470Z (2012) https://doi.org/10.1117/12.905741

KEYWORDS: Silicon, Dielectrics, Absorption, Laser ablation, Silica, Semiconductor lasers, Pulsed laser operation, Laser damage threshold, Ultrafast phenomena, Atomic force microscopy

Read Abstract +

Proceedings Article | 29 November 2011 Paper

Laser ablation mechanism of transparent layers on semiconductors with ultrashort laser pulses

Tino Rublack, Stefan Hartnauer, Michael Mergner, Markus Muchow, Gerhard Seifert

Proceedings Volume 8190, 81901Z (2011) https://doi.org/10.1117/12.899066

KEYWORDS: Laser ablation, Silicon, Dielectrics, Silica, Semiconductor lasers, Pulsed laser operation, Atomic force microscopy, Semiconductors, Ultrafast phenomena, Absorption

Read Abstract +

Proceedings Article | 18 May 2010 Paper

Co-doping of glasses with rare earth ions and metallic nanoparticles for frequency up-conversion

S. Wackerow, G. Seifert

Proceedings Volume 7725, 77251H (2010) https://doi.org/10.1117/12.854867

KEYWORDS: Nanoparticles, Silver, Glasses, Ions, Particles, Scanning electron microscopy, Absorption, Plasmons, Luminescence, Hydrogen

Read Abstract +

Proceedings Article | 28 August 2008 Paper

Optimization of dichroism in laser-induced transformation of silver nanoparticles in glass

A. Stalmashonak, A. Akin Unal, G. Seifert, H. Graener

Proceedings Volume 7033, 70331Z (2008) https://doi.org/10.1117/12.793667

KEYWORDS: Nanoparticles, Surface plasmons, Silver, Dichroic materials, Particles, Spherical lenses, Glasses, Polarization, Transmission electron microscopy, Femtosecond phenomena

Read Abstract +

Proceedings Article | 26 August 2008 Paper

Femtosecond shape transformation dynamics of silver nanoparticles in glass

A. Akin Unal, A. Stalmashonak, G. Seifert, H. Graener

Proceedings Volume 7032, 703225 (2008) https://doi.org/10.1117/12.793706

KEYWORDS: Nanoparticles, Picosecond phenomena, Silver, Glasses, Electrons, Dichroic materials, Plasmons, Particles, Absorption, Femtosecond phenomena

Read Abstract +

Proceedings Article | 20 April 2006 Paper

Silver-doped nanocomposite glass as a base material for fine metallodielectric microstructuring

Amin Abdolvand, Alexander Podlipensky, Sven Matthias, Frank Syrowatka, Gerhard Seifert, Heinrich Graener

Proceedings Volume 6195, 61950V (2006) https://doi.org/10.1117/12.661929

KEYWORDS: Nanoparticles, Glasses, Silver, Electrodes, Nanocomposites, Silicon, Scanning electron microscopy, Metals, Image segmentation, Ions

Read Abstract +

Proceedings Article | 1 March 2006 Paper

Production of dichroitic 3D structures by fs laser irradiation in composite glass containing Ag nanoparticles

Gerhard Seifert, Alexander Podlipensky, Amin Abdolvand, Heinrich Graener

Proceedings Volume 6106, 61061Q (2006) https://doi.org/10.1117/12.646412

KEYWORDS: Silver, Nanoparticles, Glasses, Surface plasmons, Femtosecond phenomena, Polarization, Data storage, Etching, Nanocomposites, Absorption

Read Abstract +

Proceedings Article | 15 February 2006 Paper

Ultrafast deformation dynamics of silver nanoparticles in glass induced by femtosecond laser pulses

Gerhard Seifert, Alexander Podlipensky, Jens Lange, Herbert Hofmeister, Heinrich Graener

Proceedings Volume 6118, 61180R (2006) https://doi.org/10.1117/12.646423

KEYWORDS: Silver, Nanoparticles, Glasses, Particles, Luminescence, Femtosecond phenomena, Surface plasmons, Dichroic materials, Ions, Absorption

Read Abstract +

Proceedings Article | 5 October 2005 Paper

Effective medium models for metal-dielectric composites: an analysis based on the spectral density theory

Jordi Sancho-Parramon, Salvador Bosch, Amin Abdolvand, Alexander Podlipensky, Gerhard Seifert, Heinrich Graener

Proceedings Volume 5963, 596320 (2005) https://doi.org/10.1117/12.625125

KEYWORDS: Dielectrics, Composites, Particles, Surface plasmons, Rubidium, Numerical simulations, Metals, Absorption, Barium, Radium

Read Abstract +

Proceedings Article | 26 August 2005 Paper

Surface enhanced Raman spectroscopy on monodisperse silver and nickel nanowires

P.-T. Miclea, G. Sauer, G. Brehm, S. Schneider, H. Graener, G. Seifert, K. Nielsch, J. Choi, P. Goring, U. Gosele, S. Schweizer, R. Wehrspohn

Proceedings Volume 5927, 59270O (2005) https://doi.org/10.1117/12.616315

KEYWORDS: Metals, Nickel, Surface enhanced Raman spectroscopy, Silver, Molecules, Mie scattering, Particles, Dielectrics, Raman spectroscopy, Nanowires

Read Abstract +

Showing 5 of 11 publications

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years