Dynamical Relaxation Processes of Excitonic Polaritons in CuCl Studied by Picosecond Induced Absorption

抄録

The dynamics of excitonic polaritons initially photoexcited in the upper branch have been investigated by observing the transient induced absorption from the excitonic polariton to excitonic molecule state in CuCl. Upper branch polaritons generated by picosecond tunable laser pulses are quickly scattered to the lower branch. Lower branch polaritons are relaxed within the lower branch by the LA phonon emission undergoing the frequent mutual collisions and finally annihilated radiatively. As a result of these relaxation processes the bottleneck effect is clearly observed. The observed mean lifetime of polaritons dependent on the sample thickness supports the interpretation of the lifetime of exciton based on the polariton concept.