5 ms·

I wonder if some combination of different materials and different modulations could allow these pulses to arrive at the same point at the same time? If so, how

• jlokier 6y ago
  That's more or less how an ultrashort pulse laser works already. Different wavelengths (colors) take different paths so the high energy of the pulse is spread out for processing over different parts of the optical components. The spreading is obvious in space. Less obvious is that this also spreads it in time, because each region of space gets a narrower frequency range than if the different wavelengths weren't taking different paths, and a narrower frequency range corresponds directly to a longer timescale for the pulse (see Fourier transforms). Then the different wavelengths are focused back together to a small spot. This obviously focuses them in space. Their path lengths are arranged carefully so they also arrive in just the right relative phase, and this causes the longer pulses at each narrower frequency to combine into a short pulse at a broad range of frequencies. The careful attention to relative phase is literally focusing the pulse in time as well as space, to make an ultrashort pulse. The current record for "most focused in time" pulse is 43 attoseconds, which is 43 nano-nanoseconds, 43 micro-micro-microseconds, and 43 milli-milli-milli-milli-milli-milliseconds. It uses this technique.