Influence of the relaxation time of a dye on the pulse shape of self-locked modes generated in a ruby crystal at room temperature

A study was made of the influence of the relaxation time of cryptocyanine on the shape of pulses and the width of the emission spectrum of a ruby laser operated at a low temperature under mode-locking conditions. The relaxation time was altered by the addition of quenching substances (acetone and carbon tetrachloride) to the solution of cryptocyanine. The relative quantum efficiency of the luminescence of cryptocyanine was determined as a function of the concentration of the quenching substance. The width of the laser emission spectrum was measured as a function of the concentration of the quenching substance using dye filters with an initial transmission of 3–50%. The measurements were carried out with an image converter and they showed that the duration of single pulses which passed through a filter with a 3% initial transmission was 35 psec in the presence of a quenching substance and 80 psec in the absence of this substance; the corresponding durations obtained using a filter with a 50% initial transmission were 180 and 260 psec, respectively.