We have observed a strong transient optical absorption inn‐InSb (n=1016cm−3) induced by an intense (2 MW cm−2) 10.6‐&mgr;m laser beam at 2 K. Detailed studies of the time history of the transmitted 10.6‐&mgr;m beam and the spin‐flip Raman laser pulse produced in the InSb show that the 10.6‐&mgr;m absorption lasts for ≳100 ns, and that spin‐flip lasing occurs only at the beginning of the intense portion of the 10.6‐&mgr;m pump pulse and after the absorption has disappeared.
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