Near band-gap optical nonlinearities and bistability in Cd1-xMnxTe

Strong thermally induced self-focusing of laser beam near the band-edge in Cd1-xMnxTe with 0 < x < 0.6 at room temperature has been investigated. Due to low thermal conductivity of the CdMnTe, it is possible to obtain large v alues of the nonlinear refractive index, even in the order of 10(-4) cm(2)/ W, without light-induced damage to the crystal. Large thermal nonlinearitie s at room temperature lead to the optical bistability. The results indicate that Cd1-xMnxTe is a suitable material for cavityless, large contrast, the rmally induced absorptive bistable operation in visible region in spite of slow response time. In contrast to self-induced absorption at room temperat ure, at low temperatures light-induced transparency has been observed in Cd Te and Cd0.85Mn0.15Te, which has been ascribed to the Burstein-Moss effect in this material. This effect is much faster than the self-focusing due to its electronic nature. (C) 2000 Elsevier Science B.V. All rights reserved.