Optical trapping of microparticles at or near the focus of a laser beam via gradient forces has become useful in science, and in particular the life sciences, where biological cells can be held in place for sorting or experimentation. Creating an optimum focused beam for optical tapping is the object of intense research; one approach is to use plasmonic structures, including chiral structures (which have a right- or left-handed twist). The use of arrays of nanoplasmonic structures enables a technique called self-induced back-action (SIBA) that allows reduced laser intensity, reducing potential damage to the trapped microparticles, as well as more options for handling and sorting. Saulius Juodkazis, professor of nanophotonics at Swinburne University of Technology (Melbourne, Australia), and his group have developed a plasma-etch procedure that easily produces these arrays for laser trapping and other uses.
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