Near-resonant two-photon absorption in luminescent CdTe quantum dots

作者：Khatei Jayakrishna^*; Sandeep C S Suchand; Philip Reji; Rao K S R Koteswara

来源：Applied Physics Letters, 2012, 100(8): 081901.

DOI：10.1063/1.3687695

We report the nonlinear optical absorption studies in two differently sized water-soluble cadmium telluride quantum dot (QD) samples, exhibiting first excitonic absorption peaks at 493 nm and 551 nm, respectively. An optical limiting behavior is observed for near-resonant excitation at 532 nm using nanosecond laser pulses, originating from the effective two-photon absorption (TPA) mechanism. The effective TPA coefficient (beta(eff)) is measured to be in the range of 10(-12) m/W. This is one order of magnitude higher than the TPA coefficient (beta) reported for off-resonant excitation. At this excitation wavelength, the smaller QD shows a relatively weaker photoluminescence and stronger nonlinear absorption.

• 出版日期2012-2-20