About me

I am a Research Fellow at the University of Southampton. My research concerns the intersection of condensed matter physics and nonlinear photonics, with the main attention focused on topics related to studies of condensation of polaritons, polariton lasing in coupled microcavities and dynamics of exciton-polaritons. I am also interested in nonlinear effects in novel polariton systems, such as microcavities with 2D materials or perovskites. My goal is to explore light-matter interactions and look for new effects related to microcavity exciton-polaritons.

I started my research during my Master's studies, which led to developing a new photolithography method of marking a single quantum dots position. Unlike previous realizations of marking methods, in this approach, to simplify and speed up the process, the single-colour in-situ method is used. The marking process's effectiveness was confirmed by an experiment in which a single quantum dot with a single manganese dopant was marked in an optical setup. The main result of these studies is published in the article K. Sawicki et al., Applied Physics Letters 106, 012101 (2015).

My PhD thesis draws on the research areas of condensed matter and photonics. My research focused on lasing effects in II-VI-based single and coupled microcavities with CdSe and CdTe QWs. My doctoral studies have developed my experimental and computational abilities and honed my writing and presentation skills. The research findings showed the possibility of observing three different types of lasing in one structure, i.e., polariton lasing, photon lasing involving excitons, and photon lasing with recombination of electron-hole plasma (published in K. Sawicki et al. Communications Physics 2 38 (2019).). The polariton lasing study has also been extended to a system of two coupled semiconductor optical microcavities with quantum wells based on tellurium compounds. The specific design of the sample enabled polariton-mediated energy transfer between excitonic states over a distance exceeding 2 μm, thanks to confining them in semiconductor quantum wells and coupling the initial and final states of the process through the delocalized mode of two coupled optical microcavities (M. Ściesiek, K. Sawicki et al. Communications Materials 1 78 (2020).). Spectroscopic measurements with temporal resolution revealed the complex dynamics of the processes responsible for the excitation transfer between the reservoir of light-created carriers and the polariton levels. Moreover, the presence of condensate on the higher polariton branch is accompanied by the energy-degenerate scattering of exciton-polaritons into the lower energetic polariton branch. Systematic measurements and theoretical modelling made it possible to understand and describe the mechanism responsible for condensate dynamics in the mulitilevel polariton system (published in K. Sawicki et al. Nanophotonics 10(9) 2421-2429 (2021).).

In addition to my academic achievements, I spent six months (January 2020 - July 2020) at the laboratory PhLAM at the University of Lille (France) in the group of dr. Alberto Amo. During this time, I worked on defect states, localized states, a photonic analogue of strain in photonic graphene. Besides, I worked on nonlinear effects in honeycomb polariton lattices. The internship allowed me to gain and ground knowledge in theoretical simulations using the Gross-Pitaevskii equation and tight-binding formalism, in addition to the experience achieved with the experimental work on photonic lattices.

Currently, I am a research fellow at the University of Southampton, where I study the control of the emission properties of trapped polariton condensates and coupled polariton condensates using an external magnetic field.