Proposed far-infrared difference-frequency generation using the Lorentz nonlinearity of a solid-state plasma

A calculation is made of the efficiency of laser difference-frequency power generation in the far infrared by reflection from the surface of metals and semiconductors. It is assumed that the essential nonlinearity is that associated with the Lorentz force on conduction electrons for which
P^{NLS} = \alpha(E_{L} \times H_{L})
. It is shown that, when two 1-kW separately tuned CO
2
lasers are used as primary sources, as much as 10
^-4
watts in the
100-1000 \mu
range may be generated under favorable conditions. No phase matching of primary and difference-frequency waves is required.