Periodic Reporting for period 1 - BESCLING (Beam self-cleaning beyond its current understanding)
Berichtszeitraum: 2025-04-01 bis 2027-03-31
The BESCLING project explored a recently discovered optical effect called beam self‑cleaning, which allows light travelling in multimode optical fibres to become more stable and easier to control. Multimode fibres are widely used in modern technologies such as medical imaging, industrial laser processing, and sensing. However, their performance is often limited by unstable light patterns caused by temperature changes or mechanical vibrations. Beam self‑cleaning offers a promising solution by naturally reshaping the light into a cleaner and more stable form when the power exceeds a certain level.
The goal of BESCLING was to better understand the physical mechanisms behind this effect. While earlier studies focused only on the spatial behaviour of light, this project investigated how space and time interact during beam self‑cleaning. Understanding these mechanisms can contribute to the development of more robust fibre‑based technologies, with potential benefits in healthcare, manufacturing, and environmental monitoring.
The project was carried out over a limited duration and focused on establishing new knowledge that can support future research in nonlinear and multimode fibre optics.
The goal of BESCLING was to better understand the physical mechanisms behind this effect. While earlier studies focused only on the spatial behaviour of light, this project investigated how space and time interact during beam self‑cleaning. Understanding these mechanisms can contribute to the development of more robust fibre‑based technologies, with potential benefits in healthcare, manufacturing, and environmental monitoring.
The project was carried out over a limited duration and focused on establishing new knowledge that can support future research in nonlinear and multimode fibre optics.
The project activities were organised around three main research directions.
1. Understanding thermalisation processes in optical fibres. The project studied how energy redistributes among different components of light travelling in a fibre. To do this, experiments were first carried out in a simpler system—single‑mode fibres—where only temporal effects play a role. This approach made it possible to distinguish two different behaviours: one where the system evolves towards a stable equilibrium, and another where strong phase relationships prevent such equilibrium from being reached. These findings help clarify the mechanisms that may also occur during beam self‑cleaning in multimode fibres. A scientific article describing these results is currently being finalised and will be submitted in a high‑impact international journal.
2. Exploring new fibre platforms. Although the project ended earlier than originally planned, important steps were taken toward extending the study of beam self‑cleaning to fibres made from alternative materials, such as polymers. During the fellowship, the fibre‑drawing tower was upgraded, and hands‑on experience was gained in the fabrication of polymer optical fibres. These developments will enable future research in fibre platforms where nonlinear optical effects can be stronger or operate at different wavelengths.
3. Review on extreme nonlinear optics. A comprehensive review article was prepared, summarising current knowledge on extreme nonlinear effects in optical fibres. This work combined expertise from both the researcher and the host institution and provides a useful reference for the scientific community. The manuscript has been submitted in a high‑impact international journal.
1. Understanding thermalisation processes in optical fibres. The project studied how energy redistributes among different components of light travelling in a fibre. To do this, experiments were first carried out in a simpler system—single‑mode fibres—where only temporal effects play a role. This approach made it possible to distinguish two different behaviours: one where the system evolves towards a stable equilibrium, and another where strong phase relationships prevent such equilibrium from being reached. These findings help clarify the mechanisms that may also occur during beam self‑cleaning in multimode fibres. A scientific article describing these results is currently being finalised and will be submitted in a high‑impact international journal.
2. Exploring new fibre platforms. Although the project ended earlier than originally planned, important steps were taken toward extending the study of beam self‑cleaning to fibres made from alternative materials, such as polymers. During the fellowship, the fibre‑drawing tower was upgraded, and hands‑on experience was gained in the fabrication of polymer optical fibres. These developments will enable future research in fibre platforms where nonlinear optical effects can be stronger or operate at different wavelengths.
3. Review on extreme nonlinear optics. A comprehensive review article was prepared, summarising current knowledge on extreme nonlinear effects in optical fibres. This work combined expertise from both the researcher and the host institution and provides a useful reference for the scientific community. The manuscript has been submitted in a high‑impact international journal.
BESCLING delivered new insights into how light behaves in optical fibres under strong nonlinear conditions. The identification of two distinct regimes—one reversible and one leading to thermalisation—provides a clearer understanding of the mechanisms that may drive beam self‑cleaning. This knowledge may support future improvements in fibre‑laser technologies, multiphoton imaging, and advanced sensing.
The work on polymer‑fibre fabrication also opens opportunities for exploring nonlinear effects in materials beyond standard silica fibres. Such alternative fibres may enable new applications that operate at lower power, different wavelengths, or with enhanced nonlinear responses.
The work on polymer‑fibre fabrication also opens opportunities for exploring nonlinear effects in materials beyond standard silica fibres. Such alternative fibres may enable new applications that operate at lower power, different wavelengths, or with enhanced nonlinear responses.