Quantum 2025 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

MON: Monday Contributed Sessions

MON 23: Poster Session: Fundamental Aspects and Model Systems

MON 23.3: Poster

Monday, September 8, 2025, 18:30–20:30, ZHG Foyer 1. OG

Influence of longitudinal laser modes on the generation of time varying interference pattern — •Jelena Jovanović, Saša Ivković, and Bratislav Obradović — University of Belgrade, Faculty of Physics, 11001 Belgrade, Serbia

The primary goal of this work was to explain the interesting effect of time varying interference obtained using a birefringent crystal and an unstabilized He-Ne laser. Used laser operates in two longitudinal modes with mutually orthogonal polarizations. These modes represent the range of allowed discrete frequency values that a laser resonator can support, each corresponding to a quantized energy level within the laser cavity. The intensities of the modes vary in time, resulting that interference patterns also change in time: interference fringes appear, then disappear and appear again, but with changed positions. To explain this phenomenon, a simple analysis of the polarization states of the laser modes, which propagate through the crystal as ordinary and extraordinary rays was performed. This experiment not only demonstrates classical interference and polarization effects, but also offers an accessible way to explore the quantum nature of longitudinal modes. It highlights how quantum principles manifest in seemingly classical optical setups, providing students with a hands-on opportunity to investigate fundamental aspects of quantum optics using an interesting experiment.

Keywords: quantum optics; longitudinal laser modes; interference; polarization; calcite