Bandgap-resonant optical phase conjugation in n-type Hg(1-x) Cd(x) Te at 10.6 microm

We have observed phase-conjugate signals in n-type Hg(1-x) Cd(x) Te through bandgap-resonant degenerate fourwave mixing by using a chopped cw-CO(2) laser pump operating at 10.6 microm and ~1 W/cm(2). The observed signals are attributed to the strong resonant third-order nonlinearity [chi((3))] arising from the electron-hole pair production the pump laser. Our data translate into a value of chi((3))~3 x 10(-2) esu, which is in good agreement with that calculated using the model of Jain et al. [Appl. Phys. Lett. 35, 494 (1979)].