This thesis consists of two parts. The subject of the first part is the design, control, and characterization of the passively mode locked CW dye laser, which is capable of producing a stable continuous train of subpicosecond pulses. Following a description of the laser's elements, the mode stability of its multi-mirror resonator is studied. The monitoring of the laser operational state by pulsewidth and bandwidth measurements is described.
In the second part, the photoconductive impulse response and excess carrier lifetime of semi-insulating Cr:GaAs is studied experimentally and analytically. In the transient photoconductive experiment, the material is irradiated with a continuous train of picosecond light pulses with photon energy above the band-gap energy, generated by the passively mode locked CW dye laser described in part I. A photoconductive decay time of 67 psec is deduced from the observations and interpreted as the result of both bulk and surface recombination. It is shown that it agrees well with longer carrier lifetime in Cr:GaAs measured under steady state conditions with longer illumination wavelengths.
