Anisotropic semiconductor or semimetal films can produce large transverse voltage under lightening. PbSeand PbS films show a room temperature intense sub nsec response ( - V/MW) in the 10Ã‚Âµm region due to freecarrier photon drag ,but the direct matched response on a 50 LI impedance is lower ( - 0.1 V/MW for lcm2film ) due to the film resistance ( > ICQ) . CO2 700ps mode locked pulses are easily detected in the scope limit .
S. Marchetti, S. Marchetti,
"Transverse MIR fast reponse in PbSe films", Proc. SPIE 2104, 18th International Conference on Infrared and Millimeter Waves, 21041N (30 August 1993); doi: 10.1117/12.2298491; https://doi.org/10.1117/12.2298491