Complex sentence: Copper compound vapours also increase the complexity of the pump signal applied to the device; typically two energising pulses in quick succession are required, the first to dissociate vapour molecules, and the second to actually cause the dissociated ions to lase.
Split into simpler sentences: Copper compound vapours also increase the complexity of the pump signal applied to the device. Typically two energising pulses in quick succession are required, the first to dissociate vapour molecules, and the second to cause the dissociated ions to lase.