Ultrashort Laser Pulse Phenomena, 2nd Edition

356 Ultrashort Sources II: Examples

wells on a GaAs substrate. The lens has a focal distance of 50 mm. The output

power from the laser was attenuated not to damage the MQW. The maximum

power density in the focal point was 10 MW/cm

2

. The spatial profile of the radi-

ation transmitted through the sample was analyzed, using a CCD camera, as a

function of the position of the sample. The various profiles are shown in Fig. 6.8.

From this picture we can see that the initial low power transmission of 23% far

from the focal point increases to 45% close to the focal point. The transmission

of the GaAs plate alone is 52%, indicating that the nonsaturable losses ...