Asia Pacific Physics Week 2023 (APPW2023)

Tuesday, Nov. 7, 2023 

2:40 PM - 3:20 PM  Plenary Talk  Nathaniel Hermosa (University of the Philippines Diliman) 

Beamshifts: a new method for optical metrology

Nathaniel Hermosa

National Institute of Physis, University of the Philippines Diliman

Quezon City, 1101 Philippines

Samahang Pisika ng Pilipinas (Physics Society of the Philippines)

University of the Philippines Diliman, Quezon City 1101 Philippines

In this presentation I will introduce beamshifts, a collective term for the spatial and angular Goos-Hänchen and Imbert-Fedorov shifts, for optical metrology. These shifts are diffractive corrections to the displacement and/or travel of a reflected beam as compared to geometric optics predictions. The presence of these shifts depends on the polarization, degree of coherence, and the modal structure of the incident beam, the refractive index gradient seen by the beam, and the beam’s divergence. I will present three examples we are currently working on where these beamshifts can be used. Two are experimental work while one is a theoretical calculation. These are: (1) to extract refractive index of low-loss dielectrics by analyzing the spatial Goos-Hänchen shift. This is especially significant when differentiating materials with nearly identical index of refraction.[1]; (2) for sensing molecular monolayer with angular Goos-Hänchen shift[2]; and (3) to investigate the spatial Imbert-Fedorov shifts of a beam incident on the ionosphere. These shifts are measurable and can be utilized as a potential tool to profile the ionosphere using reflected radio waves.[3] Lastly, I will discuss methods to further enhance these beamshifts.

[1] Operaña, Jared Joshua, and Nathaniel Hermosa. "Distinguishing dielectric materials with similar refractive indices using Spatial Goos-Hänchen shift." In JSAP-Optica Joint Symposia. 2023.

[2] Olaya, Cherrie May, Norihiko Hayazawa, Maria Vanessa Balois-Oguchi, Nathaniel Hermosa, and Takuo Tanaka. "Molecular Monolayer Sensing Using Surface Plasmon Resonance and Angular Goos-Hänchen Shift." Sensors 21, no. 13 (2021): 4593.

[3] Simon, Niña Zambale, and Nathaniel Hermosa. "Ionosphere induced spatial Imbert Fedorov shifts." Journal of Quantitative Spectroscopy and Radiative Transfer 301 (2023): 108539.