Ultrashort transients of variable duration have been generated at 10.6 μm by operating a fast optical switch with picosecond pulses from a mode-locked Nd: glass laser. The switch, which takes advantage of the large free-carrier contribution to the infrared optical susceptibility in Ge, has been used to generate megawattt picosecond pulses at 10.6 μm by synchronous operation of a TEA CO2 laser with the 1.06 μm source.