Design of a pulse stacker

AbstractThe design of a simple pulse stacker is described. It enables pulses of variableduration in the nanosecond regime, and of predefined shape, to be synthesised from a short pulse. A pulse stacker of this type has been tested and used for laser compressionexperiments.IntroductionIt is necessary for the effective diagnosis of laser plasma interaction experiments andlaser compression to generate synchronously pulses of about 1 ns for the main experimentalbeam and about 100 ps for diagnostics. It may well also be necessary to generate temporallyshaped pulses to achieve optimum laser compression.Both of these requirements can be satisfied by using a pulse stacker to synthesise anappropriately shaped long pulse from a short pulse. The stacker divides a short pulse intoa number of components and recombines them after imposing an appropriate time delay andintensity control on each component. In principle any pulse shape and duration can beachieved in this way.Design of pulse stackerSeveral types of pulse stacker have been investigated.1'2'3 The stacker describedhere has the advantages of simplicity, low cost and high efficiency. It consists of a stackof parallel sided glass plates at normal incidence, see Figure 1. The reflections areseparated in time by the difference in their optical path lengths, and the resultant pulseshape is shown in Figure 2(a).The pulse stacker is designed so that the separation of sequential pulses is greater thantheir individual pulse length; if the separation is too great then the stacked pulse willnot approximate very well to a long continuous pulse. If the separation time is shorter