Ultrafast study of near-field hexagonal array illumination

Hexagonal array devices are widely used in optical communication and optical computing. Near field Talbot array illuminator is an ideal method for the illumination of these devices. Ultrafast pulse provides high transmission bit-rate and high peak energy, thus it is favorable for optical communication, diffractive optics, and other applications. In this paper we studied the hexagonal array Talbot effect under ultrafast pulse illumination. Ultrafast pulse has wide wavelength spectra range, and each spectral component corresponds to a unique wavelength that is directly relating to the Talbot distance. Thus the Talbot effect of hexagonal array is different from those of continuous wave in a whole. From the experimental result we can see that, comparing with that of the monochromic illumination, the efficiency and contrast of ultrafast pulse illumination are decreased. The result should be highly interesting for ultrafast fiber communication as well as other optical devices.