NARROWING OF MIDINFRARED LASER-PULSES BY 2-PHOTON ABSORPTION IN SEMICONDUCTOR ETALONS

We present a theoretical analysis of how the nonlinearity of the free carriers produced by two-photon absorption in an InSb etalon could be used to shorten 10.6 mu m laser pulses. The etalon can be tuned from a n initial low-intensity minimum of transmittance to a maximum and back to a minimum by the laser pulse, as a consequence of free carrier gen eration. Simulations show that, for an adequate choice of parameters, pulse narrowing by a factor of 30 can be achieved. The influence of pe ak intensity, etalon thickness and incidence angle on pulse narrowing is investigated, as well as the spectral reshaping of the transmitted pulses. (C) 1998 Elsevier Science B.V. All rights reserved.