Studies on micromanipulation capabilities of micro-objects and combined Raman spectroscopy based on photonic jet fiber optic

Both, optical tweezers and Raman spectroscopy are well-established methods in biomedicine. In combination they allow spectroscopic studies on single isolated micro-components. The aim of this work is to investigate micro-objects for noncontact micromanipulation with simultaneous acquisition of the Raman spectrum using a Photonic Jet (PJ) fiber optic. This optic consists of a fiber with a curved fiber-tip through which a low-divergence and highly concentrated Laser beam is achieved that can be focused below the diffraction limit. Based on this, a measurement setup has been designed and implemented which allows the excitation of Raman scattering of selected substances via the fiber optic. These samples could be analyzed and confirmed via the backscatter signal of the fiber in the wavenumber range of the detected Raman spectrum of 1200 cm^-1 – 4000 cm^-1. As for micromanipulation, particles with a size of 3 μm could be shifted transversely in the direction of the propagating Laser radiation and to a small extent (μm regime) laterally to the beam propagation, which corresponds to the behavior of a two-dimensional optical trap. The realized measurement setup provides the basis for extended investigations of combined Raman spectroscopy and manipulation of micro-objects.