Pulse shaping with saturable absorbers

An active pulse shaper which can generate time waveforms which are very different from those produced naturally by laser oscillators has been devised. The system, which is in effect an optical shutter with variable transmission, consists of an array of bleachable dye cells. The transmittance of each cell is controlled by gating signals that are standard exponential or gaussian optical pulses. The system is applied to the production of the superexponential pulse waveform required for laser initiated nuclear fusion. It is demonstrated that the pulse intensity I(t) = I_o(1-t/T)-a with T = 9.45 ns, a = 15/8 and 0 ≤ t ≤ 9.4 ns, can be approximated to within 10% by a triple dye cell system modulating an incident pulse with a 4 ns time constant. The gating signals are two exponentials; one with 1 ns and other 250 ps time constant; and a 250 ps FWHM gaussian.