FG Nichtlineare Optik

13 Items

Recent Submissions
Tuning trion binding energy and oscillator strength in a laterally finite 2D system: CdSe nanoplatelets as a model system for trion properties

Ayari, Sabrine ; Quick, Michael T. ; Owschimikow, Nina ; Christodoulou, Sotirios ; Bertrand, Guillaume H. V. ; Artemyev, Mikhail ; Moreels, Iwan ; Woggon, Ulrike ; Jaziri, Sihem ; Achtstein, Alexander W. (2020-06-22)

We present a theoretical study combined with experimental validations demonstrating that CdSe nanoplatelets are a model system to investigate the tunability of trions and excitons in laterally finite 2D semiconductors. Our results show that the trion binding energy can be tuned from 36 meV to 18 meV with the lateral size and decreasing aspect ratio, while the oscillator strength ratio of trions...

Optical properties of quasiparticles in monolayer and bilayer TMDCs

Helmrich, Sophia (2020)

In this thesis, we investigate the optical properties of excitonic quasiparticles in different transition metal dichalcogenides (TMDCs). These novel two-dimensional (2D) semiconductor materials exhibit remarkable mechanical, optical and electronic properties and feature an additional valley degree of freedom. Due to their atomically thin nature, excitons form as quasiparticles with high binding...

Symmetric cladding thin-film waveguides

Pufahl, Karsten Simon (2020)

Intrinsic absorption is often considered an undesirable effect in waveguiding applications, severely limiting the propagation length. However, with appropriate design of a symmetric cladding, waveguiding can be achieved even with highly absorbing media, to the degree that increasing absorption has a positive effect on the propagation length. Here, this counterintuitive concept is developed furt...

Two-photon based pulse autocorrelation with CdSe nanoplatelets

Quick, Michael T. ; Owschimikow, Nina ; Khan, Ali Hossain ; Polovitsyn, Anatolii ; Moreels, Iwan ; Woggon, Ulrike ; Achtstein, Alexander W. (2019-09-06)

We investigate broadband two-photon absorption autocorrelators based on II–VI semiconductor nanoplatelets as an alternative to common second harmonic generation based techniques. As compared to bulk materials the exceptionally high enhancement of two-photon absorption in these 2D structures results in very efficient two-photon absorption based autocorrelation detected via PL emission. We compar...

Submonolayer-grown quantum dots for nonlinear device applications

Herzog, Bastian (2019)

The submonolayer (SML) growth method was developed as an alternative to the established Stranski-Krastanow (SK) technique in order to produce quantum dots (QDs) with higher areal density and consequently larger optical gain. In this dissertation, fundamental and applied aspects of SML-grown QDs as active media in optoelectronic devices are investigated using different optical spectroscopy metho...

Exploiting Nonlinear Photoacoustic Signal Generation in Gold Nanospheres for Selective Detection in Serial 3D PA Tomography

Schrof, Susanne ; Pang, Genny ; Buchmann, Jens ; Laufer, Jan (2018-12-08)

The photoacoustic (PA) signal amplitude measured in gold nanosphere suspensions has been shown to increase nonlinearly with the incident excitation fluence. In this work, this effect is exploited to recover the spatial distribution of gold nanoparticles in tomographic 3D photoacoustic (PA) images against the background contrast provided by absorbers that exhibit a linear relationship between th...

Synergy Effect of Combining Fluorescence and Mid Infrared Fiber Spectroscopy for Kidney Tumor Diagnostics

Bogomolov, Andrey ; Belikova, Valeria ; Zabarylo, Urszula ; Bibikova, Olga ; Usenov, Iskander ; Sakharova, Tatiana ; Krause, Hans ; Minet, Olaf ; Feliksberger, Elena ; Artyushenko, Viacheslav (2017-11-05)

Matching pairs of tumor and non-tumor kidney tissue samples of four patients were investigated ex vivo using a combination of two methods, attenuated total reflection mid infrared spectroscopy and fluorescence spectroscopy, through respectively prepared and adjusted fiber probes. In order to increase the data information content, the measurements on tissue samples in both methods were performed...

Development and Testing of an LED-Based Near-Infrared Sensor for Human Kidney Tumor Diagnostics

Bogomolov, Andrey ; Zabarylo, Urszula ; Kirsanov, Dmitry ; Belikova, Valeria ; Ageev, Vladimir ; Usenov, Iskander ; Galyanin, Vladislav ; Minet, Olaf ; Sakharova, Tatiana ; Danielyan, Georgy ; Feliksberger, Elena ; Artyushenko, Viacheslav (2017-08-19)

Optical spectroscopy is increasingly used for cancer diagnostics. Tumor detection feasibility in human kidney samples using mid- and near-infrared (NIR) spectroscopy, fluorescence spectroscopy, and Raman spectroscopy has been reported (Artyushenko et al., Spectral fiber sensors for cancer diagnostics in vitro. In Proceedings of the European Conference on Biomedical Optics, Munich, Germany, 21–2...

Size-dependent exciton substructure in CdSe nanoplatelets and its relation to photoluminescence dynamics

Specht, Judith F. ; Scott, Riccardo ; Castro, Marta Corona ; Christodoulou, Sotirios ; Bertrand, Guillaume H. V. ; Prudnikau, Anatol V. ; Antanovich, Artsiom ; Siebbeles, Laurens D. A. ; Owschimikow, Nina ; Moreels, Iwan ; Artemyev, Mikhail ; Woggon, Ulrike ; Achtstein, Alexander W. ; Richter, Marten (2019-06-12)

CdSe nanoplatelets can be synthesized with different lateral sizes; very small nanoplatelets have almost quantum dot like features (almost discrete exciton states), while very large ones are expected to have properties of colloidal quantum wells (exciton continuum). However, nanoplatelets can be in an intermediate confinement regime with a rich substructure of excitons, which is neither quantum...

Broadband ultrafast spectroscopy on mixed–dimensional InAs/GaAs systems

Kolarczik, Mirco (2019)

This thesis deals with light matter interaction and electron dynamics in coupled systems of nanostructured III-V semiconductors, particularly with quantum dots embedded in quantum wells. Its focus is on the role of dimensionality and the characterization of quantum dot states with respect to their two- and many-level nature. The sample under investigation is a semiconductor optical amplifier un...

A comparative study demonstrates strong size tunability of carrier–phonon coupling in CdSe-based 2D and 0D nanocrystals

Scott, Riccardo ; Prudnikau, Anatol V. ; Antanovich, Artsiom ; Christodoulou, Sotirios ; Riedl, Thomas ; Bertrand, Guillaume H. V. ; Owschimikow, Nina ; Lindner, Jörg K. N. ; Hens, Zeger ; Moreels, Iwan ; Artemyev, Mikhail ; Woggon, Ulrike ; Achtstein, Alexander W. (2019-01-30)

In a comparative study we investigate the carrier–phonon coupling in CdSe based core-only and hetero 2D as well as 0D nanoparticles. We demonstrate that the coupling can be strongly tuned by the lateral size of nanoplatelets, while, due to the weak lateral confinement, the transition energies are only altered by tens of meV. Our analysis shows that an increase in the lateral platelet area resul...

Colloidal synthesis and optical properties of type-II CdSe-CdTe and inverted CdTe-CdSe core-wing heteronanoplatelets

Antanovich, Artsiom ; Prudnikau, Anatol ; Melnikau, Dimitry ; Rakovich, Yury P. ; Chuvilin, Andrey ; Woggon, Ulrike ; Achtstein, Alexander W. ; Artemyev, Mikhail (2015)

We developed colloidal synthesis to investigate the structural and electronic properties of CdSe-CdTe and inverted CdTe-CdSe heteronanoplatelets and experimentally demonstrate that the overgrowth of cadmium selenide or cadmium telluride core nanoplatelets with counterpartner chalcogenide wings leads to type-II heteronanoplatelets with emission energies defined by the bandgaps of the CdSe and Cd...

Temperature dependent radiative and non-radiative recombination dynamics in CdSe-CdTe and CdTe-CdSe type II hetero nanoplatelets

Scott, Riccardo ; Kickhöfel, Sebastian ; Schöps, Oliver ; Antanovich, Artsiom ; Prudnikau, Anatol ; Chuvilin, Andrey ; Woggon, Ulrike ; Artemyev, Mikhail ; Achtstein, Alexander W. (2016)

We investigate the temperature-dependent decay kinetics of type II CdSe-CdTe and CdTe-CdSe core-lateral shell nanoplatelets. From a kinetic analysis of the photoluminescence (PL) decay and a measurement of the temperature dependent quantum yield we deduce the temperature dependence of the non-radiative and radiative lifetimes of hetero nanoplates. In line with the predictions of the giant oscil...