Transient gratings in InSb at two-photon excitation

Abstract

We report a study of transient phase grating in InSb at room temperature induced by two-photon absorption of pulsed CO< <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> laser radiation. From our results, we deduce a value of the ambipolar diffusion coefficient <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D \simeq 26</tex> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> and of the lifetime of carriers <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T_{R} \simeq 54</tex> ns. The behavior of the grating and the change of refractive index confirms the free-carrier plasma being dominant in the modulation of nonlinear optical properties.