Pulling force enabled by unlocking the optical phase

We demonstrate the possibility of achieving an optical pulling force without complex beam-shaping techniques. By using optical pulses detuned from the resonant frequency of the structure, we create conditions in which the spectral maxima of the excited current and of the incident field do not match. Therefore, the phase shift between the two, which controls the optical force, becomes time dependent, thus enabling unexpected optical effects. Particularly, it is shown that tuning the central frequency of the pulse produces a temporary pulling force directed towards the illumination source.