6533b7d0fe1ef96bd125b61f

RESEARCH PRODUCT

Achromatic diffraction of femtosecond light pulses

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Diffraction of electromagnetic waves in free space is a physical phenomenon that explicitly depends on the wavelength of light radiation. As an ultrashort-pulsed waveform consists of many frequency components that are coherently superposed, diffraction of a femtosecond pulse passing through an aperture radically differs from that under continuous wave (CW) monochromatic illumination. Note that the spectral width of a 5 fs pulsed beam is approximately 400 nm, which roughly corresponds to the entire visible spectrum bandwidth. The spectral distribution of the source results in the chromatic distortion, both lateral and axial, of the optical field diffracted by the aperture. This detrimental effect under pulsed-laser illumination has been examinated in free-space diffraction by a screen [1], where the broad spectrum tends to smooth the time-averaged diffracted irradiance, in the context of the Talbot effect [2], and in splitting and focusing of femtosecond pulses [3].