Enhanced optical guiding of colloidal particles using a supercontinuum light source

We demonstrate enhanced optical guiding distances for microscopic particles using a supercontinuum light beam. The enhanced spectral bandwidth of the source leads to an elongated focal region. As a result we obtain a significant radial gradient force and axial radiation pressure force over a longer distance when compared to a monochromatic Gaussian beam. The guiding distances of up to 3mm that are observed for micron-sized particles with the supercontinuum beam are approximately twice those observed using continuous wave and femtosecond laser sources when considering beams of equivalent diameter. This guiding scheme is expected to be applicable to colloidal particles, biological cells and cold atom ensembles.