Led by researchers at the University of Eastern Finland, a recent study demonstrates that random light acquires an additional phase factor, known as the geometric phase, when its oscillation direction (i.e., polarisation) is altered in a deterministic manner.
Light is an electromagnetic wave that oscillates periodically, and its phase refers to a specific point in the cycle. Light can be highly organised, meaning the waves oscillate in a specific direction, or its direction may involve randomness.
Previous studies have shown that altering the polarisation of well-organised light leads to an accumulation of an additional phase. The current study extends the analysis to random light.
Changes in the phase of light can be experimentally studied using an interferometer, which operates by splitting and recombining light. The phase change can be obtained from the interference patterns formed on the measurement plane. In the experiment, light was divided into two parts, one of which underwent changes in its oscillation state before eventually returning to its original state. By comparing the interference patterns, the phase shift was experimentally confirmed.
The study adds to the understanding of how random light behaves and expands previous knowledge, which has primarily focused on organised light. The results could be beneficial for applications in optical devices, imaging and information processing.
For further information, please contact:
Doctoral Researcher Kaisa Rantaeskola, +358 50 470 1439, anna-kaisa.rantaeskola@uef.fi
Research article:
Kaisa Rantaeskola, Kimmo Saastamoinen, Andreas Norrman, Yahong Chen, Ari T. Friberg, and Tero Setälä. Pancharatnam’s connection and geometric phase of partially polarized light. Optica Vol. 12, Issue 1, pp. 62-68 (2025). DOI:10.1364/OPTICA.544338 https://doi.org/10.1364/OPTICA.544338
