PROPAGATION OF FEMTOSECOND PULSES THROUGH LENSES, GRATINGS, AND SLITS

Wave optical studies have been made for ultrashort pulse propagation through a lens, a grating, and a slit. The intensity distribution of an ultrashort pulse was calculated in the vicinity of the focal point of a lens. Analytical expression was found for the temporal and radial intensity distributions in the focal plane. For the case of a grating, the pulse front becomes curved far away from the grating and there is a time difference between the edges of the pulse. An analytical form was obtained for both the pulsewidth and the shape of the pulse front. For the case of a slit, calculations were made for a short pulse with tilted pulse front based on the Fraunhofer diffraction theory. A small, additional pulse appears behind the slit, which is off by the angle of the pulse front tilt from the direction of the original propagation. This pulse was predicted by the boundary wave theory. For white light illumination behind the slit, no interference can be seen at the maximum of the intensity; the interference pattern diverges from the maximum of the intensity.