Measurements of Ultrafast Phenomena by a Picosecond Pulse Laser (II）-Operation Characteristics of a Saturable Dye -

摘要

The bleaching time or recovery time of saturable absorber dye (NDL1l2) for a Nd3+: glass lase was measuredby the pump-probe method with its delayed weak pulse. The measurement for low concentration (10-6～10-5M in dichloroethane) was performed by probing the transmission of the dye cell within the laser cavity，while that for high con-centration (10-4～1O-3M) was done by probing it out of the lascr cavity. Either the rising time or the decay time of the saturable dye was hortened with increasing its concen-tration. However，the transient bleaching behavior does not obey a simple exponential characteristics. The sharpened profile nearby the transmission peak may suggest that the coherent interaction between the pump and probe pulses shall steepen the bleaching behavior of a saturable absorber. The stability of ists operation characteristics was alse observed by probing the transmission as a function of the laser shot number. From the experimental results it is suggested the optical dye concentration is about 1.5 x 10-5M.