Dynamics of Photogenerated Charge Carriers in Cuprates

New results of infrared photoexcitation experiments on undoped ${\mathrm{La}}_{2}$Cu${\mathrm{O}}_{4}$ and ${\mathrm{Nd}}_{2}$Cu${\mathrm{O}}_{4}$ are reported. We observed two broad electronic excitations within the charge-transfer energy gap and an associated phonon bleaching, possibly originating from strong charge-lattice coupling. Our results are discussed in terms of the condensation of self-localized photocarriers in the Cu${\mathrm{O}}_{2}$ planes at low temperatures.