Development of the Emission Pulse in the Case of Passive Switching

Abstract

We mentioned in Chapter I that certain characteristics of a giant pulse emitted by a laser with a passive shutter are well accounted for on the basis of the theory of lasers with an instantaneous shutter. The passive shutter, however, also has its own specific peculiarities, which distinguish it from other types of shutters. In this chapter we consider one of its more remarkable properties, which, as stated earlier, makes it possible to vary the width of the stimulated emission spectrum through several orders of magnitude by rather simplistic structural modifications of the cavity of lasers using such a shutter. In the case of a neodymium glass laser this variation amounted to about four orders of magnitude, ranging from 2△v_osc ≈ 30 cm^-1 to 2△v_osc < 3 · 10^-3 cm^-1 [22, 82]. This property is caused by a certain singularity in the formation of the giant pulse in a laser with a passive shutter, being attributable to the fact that the formation period, measured from the time at which the gain in the active medium offsets the cavity losses to the instant at which the pulse intensity attains its peak value, is considerably larger than for other types of shutters.