This website presents the results of my research conducted during the MSCA fellowship (2023–2025). The project builds on the pioneering 1935 experiment by R. Beth, which demonstrated the transfer of spin angular momentum (AM) from light to a mechanical torsional pendulum. Decades later, in 1992, L. Allen and colleagues proposed a related experiment to observe torsional oscillations induced by the orbital AM of light through the conversion of modes carrying optical vortices. However, implementing that concept experimentally proved to be quite challenging.
In 2009, Etienne Brasselet (Bordeaux, France) proposed using the emerging technique of direct laser writing (DLW) to fabricate a monolithic torsional micropendulum incorporating a spiral phase plate (SPP) as an AM converter based on optical vortex generation. The first prototypes were produced in 2010 by Saulius Juodkazis, then at Hokkaido University, Japan. Although the early results were not ideal, they were promising.
The project gained momentum when Mangirdas Malinauskas took over fabrication in his Laser Nanophotonics Group at the Vilnius University Research Center (VULRC, Lithuania). By 2013, well-formed SPP micropendulums were developed, thanks to the dedicated efforts of Albertas Žukauskas. However, subsequent optomechanical experiments (2013–2015, Bordeaux, France) failed to detect any light-induced motion in the microdevices — largely due to the absence of a reliable detection method.
Eventually, in 2023 I was entrusted with reviving the project and bringing it to completion. I developed a suitable detection technique, only to discover that the precious micropendulums disintegrated under the pump laser. Faced with no other option, I traveled to Vilnius, learned DLW firsthand, and fabricated new samples myself — using a modified material, adjusted fabrication conditions, and an improved design.