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Focus-engineered sub-diffraction imaging in infrared-sensitive third-order sum frequency generation microscope

Manattayil, JK and Lal Krishna, AS and Biswas, R and Kim, H and Raghunathan, V (2022) Focus-engineered sub-diffraction imaging in infrared-sensitive third-order sum frequency generation microscope. In: Optics Express, 30 (14). pp. 25612-25626.

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Official URL: https://doi.org/10.1364/OE.459620

Abstract

We experimentally demonstrate sub-diffraction imaging in infrared-sensitive third-order sum frequency generation (TSFG) microscope using focal-field engineering technique. The TSFG interaction studied here makes use of two mid infrared photons and a single 1040 nm pump photon to generate up-converted visible photons. Focal field engineering scheme is implemented using a Toraldo-style single annular phase mask imprinted on the 1040 nm beam using a spatial light modulator. The effect of focal field engineered excitation beam on the non-resonant-TSFG process is studied by imaging isolated silicon sub-micron disks and periodic grating structures. Maximum reduction in the measured TSFG central-lobe size by ∼43% with energy in the central lobe of 35% is observed in the presence of phase mask. Maximum contrast improvement of 30% is observed for periodic grating structures. Furthermore, to validate the infrared sensitivity of the focus engineered TSFG microscope, we demonstrate imaging of amorphous Germanium-based guided-mode resonance structures, and polystyrene latex beads probed near the O-H vibrational region. We also demonstrate the utility of the focus engineered TSFG microscope for high resolution imaging of two-dimensional layered material. Focus-engineered TSFG process is a promising imaging modality that combines infrared selectivity with improved resolution and contrast, making it suitable for nanostructure and surface layer imaging.

Item Type: Journal Article
Publication: Optics Express
Publisher: Optica Publishing Group (formerly OSA)
Additional Information: The copyright for this article belongs to the Optica Publishing Group (formerly OSA).
Keywords: Diffraction; Diffraction gratings; Interferometry; Light modulators; Photons, Engineering techniques; Focal fields; Generation process; Grating structures; Midinfrared; Periodic gratings; Phase masks; Sub-diffraction imaging; Sum frequency generation; Third order, Microscopes
Department/Centre: Division of Electrical Sciences > Electrical Communication Engineering
Date Deposited: 20 Jul 2022 11:55
Last Modified: 20 Jul 2022 11:55
URI: https://eprints.iisc.ac.in/id/eprint/74938

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