Scientists from the University of the Philippines Diliman have made a groundbreaking measurement. They recorded the elusive Goos-Hänchen (GH) shift in common, low-loss materials like silicon and gallium arsenide. This effect, where a laser beam’s reflection point shifts slightly on a surface, is usually too small to see. It’s smaller than a strand of hair. Their work proves this tiny shift can become surprisingly large in materials used for semiconductors and photonics. This discovery opens new doors for research and industry tools.
The GH shift happens even when light reflects off ordinary glass. The reflection doesn’t perfectly follow the “angle in equals angle out” rule. But measuring it in materials that barely absorb light, like pure silicon, was extremely difficult. Such materials are vital for computer chips and optical devices. Previously, scientists mainly saw larger GH shifts in metals or special layered structures. Theory suggested that large shifts should occur in low-loss dielectrics as well. But no one had measured it experimentally until now.
Jared Joshua Operaña, Dr. Niña Zambale Simon, and Dr. Nathaniel Hermosa achieved this first. They are from UP Diliman’s Materials Science and Engineering Program and the National Institute of Physics. Their key finding is remarkable. Silicon, which absorbs very little light, produced a GH shift up to 100 times the laser’s wavelength. “We showed that silicon… produces a shift up to 100 times the wavelength of the laser beam,” Operaña explained. This size depends heavily on the material’s tiny light absorption properties. Measuring it required extreme precision. The large shifts only appear within a very narrow range of reflection angles.
The team currently measures shifts using specific green and red laser wavelengths. They plan to test more wavelengths next. This includes light outside the visible spectrum. Other researchers can now adapt their method. They can study different materials based on their specific needs.
This discovery has significant potential. The GH shift’s sensitivity to minute changes in light absorption is key. It could lead to practical new tools. “Compact instruments based on GH-shift detection could be developed for quality control,” Operaña stated. Industries like semiconductors and photonics need precise material control. Such tools would be valuable for them. For scientists, the method offers a powerful new way to study light-matter interactions. It paves the way for deeper understanding and future innovations.
Additional Information:
This research was funded by the Department of Science and Technology, Philippine Council for Industry, Energy, and Emerging Technology Research and Development (DOST-PCIEERD), and the University of the Philippines Office of the Vice Chancellor for Research and Development (OVCRD). The findings were published in Optics Letters (Operaña, J. J., Zambale Simon, N., & Hermosa, N. (2025). Observation of the spatial Goos–Hänchen shift due to low-loss dielectrics. Optics Letters, 50(11), 3533. https://doi.org/10.1364/ol.550141). For media inquiries, contact UPD-CS Science Communications at media@science.upd.edu.ph, (+632)8981-8500 loc. 3805, or visit science.upd.edu.ph.
Tiny Light Shift, Big Discovery at UP Diliman
