Midinfrared Optical Manipulation Based on Molecular Vibrational Resonance

Midinfrared light is extensively used for identifying molecules because their characteristic vibrational modes commonly exist in the midinfrared spectral region. In this paper, a midinfrared quantum cascade laser is utilized for sorting silica particles with resonant enhancement of the optical force by exciting their vibrational mode. Silica particles on an evanescent wave drift rapidly along the prism surface, whereas identical-sized polystyrene particles drift at 7-10 times lower speed. We suggest the application of this principle for optical force chromatography in the midinfrared region.