We propose a novel high resolution microscopy technique for enantio-specific detection of chiral samples based on force measurement down to sub-100 nm where spectroscopic techniques for chirality detection encounter major challenges due to the very weak interaction of light with chiral nanoparticles. Specifically, we delve into the differential photo-induced optical force exerted on an achiral plasmonic probe in the vicinity of a chiral sample, when left and right circularly polarized beams separately excite the sample-probe interactive system. We analytically prove that the differential force is entangled with the enantiomer type of the sample enabling enantio-specific detection of chiral inclusions. Moreover, we demonstrate that the aforementioned differential force is linearly dependent on both the chiral response of the sample and the electric response of the tip and is inversely related to the quartic power of probe-sample distance. We support our theoretical achievements by several numerical examples, highlighting the potential application of the derived analytic properties. Lastly, we demonstrate the sensitivity of our method to enantio-specify nanoscale chiral samples. By establishing this high resolution measurement technique for biomedical applications, we essentially advance the characterization of chiral samples for controlling constructive reaction between drugs and receptors.
Mohammad Kamandi, Mohammad Albooyeh, Jinwei Zeng, Mohsen Rajaei, Caner Guclu, Kumar Wickramasinghe, and Filippo Capolino, "Nanoscale chirality detection using photo-induced force microscopy (Conference Presentation)," Proc. SPIE 10549, Complex Light and Optical Forces XII, 1054916 (Presented at SPIE OPTO: February 01, 2018; Published: 14 March 2018); https://doi.org/10.1117/12.2291406.5751548352001.
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