An optical laser works by bouncing photons back and forth
between two mirrors, one totally reflective and one partially
reflective. If the lasing material (usually a crystal) has
the right properties, photons scattering off the atoms in the
crystal will excite cascades of more photons, all in lockstep.
Eventually the beam will escape through the partially
reflective mirror.
cascade of messages escaping to flood nearby systems. By
mid-1993 there had been at least two publicised incidents of
this kind.