  Previous and ongoing searches for extraterrestrial optical and infrared
nanosecond laser pulses and narrow line-width continuous emissions have so far
returned null results. At the commonly used observation cadence of $\sim
10^{-9}\,$s, sky-integrated starlight is a relevant noise source for large
field-of-view surveys. This can be reduced with narrow bandwidth filters,
multipixel detectors, or a shorter observation cadence. We examine the limits
of short pulses set by the uncertainty principle, interstellar scattering,
atmospheric scintillation, refraction, dispersion and receiver technology. We
find that optimal laser pulses are time-bandwidth limited Gaussians with a
duration of $\Delta t \approx\,10^{-12}\,$s at a wavelength
$\lambda_{0}\approx1\,\mu$m, and a spectral width of $\Delta \lambda \approx
1.5\,$nm. Shorter pulses are too strongly affected through Earth's atmosphere.
Given certain technological advances, survey speed can be increased by three
orders of magnitude when moving from ns to ps pulses. Faster (and/or parallel)
signal processing would allow for an all-sky-at-once survey of lasers targeted
at Earth.
