The temporal development of intracavity absorption in a dye laser

Intercavity absorptions is known to lead to an enormous enhancement in the detectability of absorbing species. Here the time development of this enhancement of this enhancement is investigated in order to fix a typical time scale such measurements. This is done with a Pockles cell in front and inside a flashlamp pumped dye laser resonator. The enhancement of absorption steeply increases at laser threshold and then levels off during the letter part of the laser pulse. By Q-switching a dye laser it is demonstrated that on a time resolution of 20 nsec extinctions as low as 10^-4 can be measured with an enhancement of two orders of magnitude.