Seminarium Fotoniki
2010/2011 | 2011/2012 | 2012/2013 | 2013/2014 | 2014/2015 | 2015/2016 | 2016/2017 | 2017/2018 | 2018/2019 | 2019/2020 | 2020/2021 | 2021/2022 | 2022/2023 | 2023/2024 | 2024/2025 | 2025/2026 | Strona własna seminarium
2025-11-27 (Czwartek)
Zapraszamy do sali B4.58, ul. Pasteura 5 o godzinie 12:15 
mgr Magdalena Furman (Zakład Fizyki Ciała Stałego, Instytut Fizyki Doświadczalnej, WF UW)Observation of new types of optical bistabilities in semiconductor microcavities and use of polymer microlenses for reciprocal space imaging
This seminar will focus on nonlinear optical phenomena in semiconductor optical microcavities and on a novel approach to back focal plane imaging.
In the first part, I will discuss optical bistability observed in CdTe-based microcavities. I will describe the preparation of transmissive optical microcavities using a water-assisted detachment technique, as well as the results of nonlinear transmission measurements performed with a tunable laser source. Two distinct types of hysteresis loops were observed experimentally, including a previously unreported form with an unusual direction and shape. A corresponding theoretical model will be presented that fully reproduces these features and confirms their physical origin.
The second part will be devoted to the fabrication and application of ellipsoidal polymer microlenses, which serve as high-numerical-aperture microscopic objectives printed directly onto the surface of photonic structures. I will outline the numerical design process based on ray-tracing simulations and the 3D microprinting fabrication technique. Experimental optical measurements will demonstrate that these microlenses enable momentum-resolved imaging over extended wavevector ranges that are otherwise difficult to access, particularly under cryogenic conditions. Finally, I will show that integrating such microlenses allows for simultaneous acquisition of multiple spatially resolved momentum-space images of exciton-polaritons (so-called multiplexed back focal plane imaging), while also reducing the excitation pulse energy required to reach the polariton condensation threshold.
In the first part, I will discuss optical bistability observed in CdTe-based microcavities. I will describe the preparation of transmissive optical microcavities using a water-assisted detachment technique, as well as the results of nonlinear transmission measurements performed with a tunable laser source. Two distinct types of hysteresis loops were observed experimentally, including a previously unreported form with an unusual direction and shape. A corresponding theoretical model will be presented that fully reproduces these features and confirms their physical origin.
The second part will be devoted to the fabrication and application of ellipsoidal polymer microlenses, which serve as high-numerical-aperture microscopic objectives printed directly onto the surface of photonic structures. I will outline the numerical design process based on ray-tracing simulations and the 3D microprinting fabrication technique. Experimental optical measurements will demonstrate that these microlenses enable momentum-resolved imaging over extended wavevector ranges that are otherwise difficult to access, particularly under cryogenic conditions. Finally, I will show that integrating such microlenses allows for simultaneous acquisition of multiple spatially resolved momentum-space images of exciton-polaritons (so-called multiplexed back focal plane imaging), while also reducing the excitation pulse energy required to reach the polariton condensation threshold.
2025-11-06 (Czwartek)
Zapraszamy do sali B4.58, ul. Pasteura 5 o godzinie 12:15
mgr Aleksa Denčevski (Laboratory for Biophysics, Institute of Physics Belgrade, Serbia)Development and application of a two-dimensional superresolution microscope
Structured illumination microscopy (SIM) is an advanced optical microscopy technique that can improve the resolution of images beyond the diffraction limit of conventional fluorescence microscopy. The technique is based on the illumination of the sample with a structured light pattern and the subsequent software reconstruction of the high-resolution image from several recorded images. We present the development of a custom-built setup for SIM equipped with a specially developed transmission diffraction grating. Using the analogue microfilming method, we have produced transmission diffraction gratings tailored to the specific requirements of our system. This robust and cost-effective method enables the production of diffraction gratings with customised constants that ensure excellent transmission in both the visible and near-infrared spectrum. To evaluate the performance of our system, we measured the resolution in both epifluorescent and superresolution imaging modalities by applying the knife-edge technique to the MoS2 monolayer flakes. We confirmed an improvement in the resolution of SIM over the epifluorescent imaging modality. Furthermore, we successfully demonstrated the capabilities of our microscope by imaging fluorescently labelled astrocytes in vitro, specifically targeting the vimentin filament protein in these cells. The super-resolved images reveal fine structures of the vimentin cytoskeleton that remain unresolved in the epifluorescent image.