科研之友
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摘要
Layered semiconductor compound CdI(2) has been grown with the Bridgman technique and studied by nonlinear transmittance spectroscopy. The optical absorption in CdI(2) shows a nonlinear transmission of the incident laser power (P(0)) within a lower power limit. The transmission, however, is found to saturate at high powers, giving a clamped output. The value of the incident power (P(0C)) at which clamping starts is also found to depend on the crystal temperature (T(L)) The values of P(OC) ranges from 55 to 65 MW cm(-2) for T(L) = 4.2-180 K. The dynamic range (D(R)) as a function of T(L) is calculated and the values are found to range from D(R) = 2 to 1.6. The optical limiting mechanisms are discussed. The two-photon absorption (TPA) coefficient (beta) of the optical nonlinear process in CdI(2) is estimated. The values are found to be within a range from beta = 47 to 25 cm GW(-1) and be decreasing with increasing T(L). As expected for the TPA process, the experimental data within a certain range follows the linear relation: log (P(0)/P(T)) = A(G) + Omega(P(0) - P(T)), where P(T) is the transmitted power, A(G) is the absorbance of the ground state and Omega is a constant depending on the absorption cross-section and the relaxation time. The values of A(G) and Omega estimated from the fits to the measured data vary with T(L). The findings resulting from this investigation might have potential applications in optical sensors protection.
- 出版日期2010-2-15
