Periodic Reporting for period 1 - OSCILLIGHT (Mechanical torsional oscillations driven by the angular momentum of light)
Período documentado: 2023-05-01 hasta 2025-04-30
This project explored the fundamental interaction between light and matter by investigating the transfer of angular momentum from light beams to torsional mechanical oscillators. Building on recent advances in photonics and microfabrication—particularly direct laser writing—the project aimed to design, fabricate, and test torsional micropendulums capable of responding to optical torque. The objective was not only to achieve a proof-of-concept demonstration of light-induced torsional motion via angular momentum transfer, but also to deepen scientific understanding of light–matter interactions at the microscale. To accomplish this, the project combined expertise in oscillator physics, precision microfabrication, and optomechanical pump–probe experimentation. The broader impact pathway includes enabling new types of micro-optoelectromechanical systems, advancing sensing technologies, and providing a novel experimental platform for fundamental studies of optical torque and quantum–classical transitions.
The project tackled the longstanding challenge of demonstrating the non-dissipative transfer of orbital angular momentum orbital angular momentum from light to a mechanical oscillator - an open question in optical physics. Initial experimental tests using a mesoscale torsional pendulum (a centimeter-long wire with a millimeter-scale mirror) revealed that the low-frequency torsional signal expected from light-induced torque was overwhelmed by ambient mechanical noise. This outcome highlighted the need for a microscale system to achieve a sufficient signal-to-noise ratio.
In response, the project developed and validated torsional micropendulums fabricated via direct laser writing. These microstructures exhibited torsional oscillations in the kilohertz range, enabling the effective filtering of mechanical noise even in ambient (non-vacuum) conditions. To support experimental design and interpretation, a theoretical model of optical torque transfer was developed, confirming the expected dynamics of light–matter angular momentum coupling.
A key materials-related outcome was the identification of pure SZ2080 photopolymer as a suitable medium for device fabrication. Unlike earlier microdevices made with addition of a photoinitiator, the new micropendulums reliably withstood high optical intensities, ensuring stable and repeatable measurements. All fabrication data have been made openly available on Zenodo, promoting transparency and reproducibility.
To conduct and automate the experiments, the project built a custom optoelectronic pump–probe system that enabled the precise excitation of micropendulums via orbital angular momentum transfer and the automated measurement of amplitude and phase spectra. Robust and precise, the system remains operational at the host laboratory, supporting ongoing research in optomechanics and integrated photonics. All accompanying Python automation scripts are also available on Zenodo.
A major scientific milestone was achieved with the first experimental demonstration of torsional oscillations driven by non-dissipative transfer of orbital angular momentum - a result that complements the classic 1935 Beth experiment, which confirmed such transfer for spin angular momentum. A journal article reporting this breakthrough is in preparation, with submission expected by the end of 2025.
Throughout the project, the researcher conducted two visits to Vilnius University Laser Research Center, acquiring practical expertise in direct laser writing, refining device design, and fabricating the core samples used in the experiments. These visits also helped reinforce collaboration between the host SINGULAR group (LOMA, Bordeaux, France) and the Laser Nanophotonics group (Vilnius, Lithuania).
The project also fostered international scientific dialogue through exchanges with the research teams of Prof. Filippo Romanato (Padua, Italy) and Prof. Yujie Chen (Guangzhou, China) on ongoing experiments involving optical torque and orbital angular momentum multipliers.
To support dissemination and outreach, a dedicated project website was launched to share research progress, background information, and public-facing materials: https://geotkach.github.io/oscillight-msca/(se abrirá en una nueva ventana).
Finally, the project designed a prototype torsional micropendulum for optical excitation at oblique incidence, offering greater flexibility in future experimental configurations. Although fabrication via direct laser writing is still under refinement, the prototype points to a promising direction for continued development.
In response, the project developed and validated torsional micropendulums fabricated via direct laser writing. These microstructures exhibited torsional oscillations in the kilohertz range, enabling the effective filtering of mechanical noise even in ambient (non-vacuum) conditions. To support experimental design and interpretation, a theoretical model of optical torque transfer was developed, confirming the expected dynamics of light–matter angular momentum coupling.
A key materials-related outcome was the identification of pure SZ2080 photopolymer as a suitable medium for device fabrication. Unlike earlier microdevices made with addition of a photoinitiator, the new micropendulums reliably withstood high optical intensities, ensuring stable and repeatable measurements. All fabrication data have been made openly available on Zenodo, promoting transparency and reproducibility.
To conduct and automate the experiments, the project built a custom optoelectronic pump–probe system that enabled the precise excitation of micropendulums via orbital angular momentum transfer and the automated measurement of amplitude and phase spectra. Robust and precise, the system remains operational at the host laboratory, supporting ongoing research in optomechanics and integrated photonics. All accompanying Python automation scripts are also available on Zenodo.
A major scientific milestone was achieved with the first experimental demonstration of torsional oscillations driven by non-dissipative transfer of orbital angular momentum - a result that complements the classic 1935 Beth experiment, which confirmed such transfer for spin angular momentum. A journal article reporting this breakthrough is in preparation, with submission expected by the end of 2025.
Throughout the project, the researcher conducted two visits to Vilnius University Laser Research Center, acquiring practical expertise in direct laser writing, refining device design, and fabricating the core samples used in the experiments. These visits also helped reinforce collaboration between the host SINGULAR group (LOMA, Bordeaux, France) and the Laser Nanophotonics group (Vilnius, Lithuania).
The project also fostered international scientific dialogue through exchanges with the research teams of Prof. Filippo Romanato (Padua, Italy) and Prof. Yujie Chen (Guangzhou, China) on ongoing experiments involving optical torque and orbital angular momentum multipliers.
To support dissemination and outreach, a dedicated project website was launched to share research progress, background information, and public-facing materials: https://geotkach.github.io/oscillight-msca/(se abrirá en una nueva ventana).
Finally, the project designed a prototype torsional micropendulum for optical excitation at oblique incidence, offering greater flexibility in future experimental configurations. Although fabrication via direct laser writing is still under refinement, the prototype points to a promising direction for continued development.
This project delivers the first experimental demonstration of torsional oscillations driven by the non-dissipative transfer of orbital angular momentum from light to matter. This achievement marks a significant scientific breakthrough, advancing the frontiers of optics and photonics and deepening our understanding of how light can induce rotational motion in mechanical systems.
The laser-written torsional micropendulum developed in this study represents a technological innovation with strong potential to drive progress in microfabricated optomechanical systems. It opens the door to a range of future applications such as ultra-sensitive gyroscopes, torsional magnetometers, spin–orbit coupling devices, and hybrid optical cavities. The platform is robust, scalable, and fully compatible with on-chip nano/microelectronics and integrated photonics, and is well-positioned to evolve in tandem with ongoing advances in multiphoton 3D lithography and free-form optics.
Building on this foundation, further research will pursue:
– Alternative angular momentum converters, such as spiral phase plates or metasurfaces, to enhance optical torque transfer efficiency;
– Post-exposure treatments to improve structural durability and optical quality;
– Development of oblique-incidence designs, enabling more versatile excitation geometries.
These research directions aim to improve performance, expand applicability, and contribute both to fundamental studies and to emerging technologies in optomechanics and photonic systems.
The laser-written torsional micropendulum developed in this study represents a technological innovation with strong potential to drive progress in microfabricated optomechanical systems. It opens the door to a range of future applications such as ultra-sensitive gyroscopes, torsional magnetometers, spin–orbit coupling devices, and hybrid optical cavities. The platform is robust, scalable, and fully compatible with on-chip nano/microelectronics and integrated photonics, and is well-positioned to evolve in tandem with ongoing advances in multiphoton 3D lithography and free-form optics.
Building on this foundation, further research will pursue:
– Alternative angular momentum converters, such as spiral phase plates or metasurfaces, to enhance optical torque transfer efficiency;
– Post-exposure treatments to improve structural durability and optical quality;
– Development of oblique-incidence designs, enabling more versatile excitation geometries.
These research directions aim to improve performance, expand applicability, and contribute both to fundamental studies and to emerging technologies in optomechanics and photonic systems.