Q switch driver with Offset		Pockels Cell links Designing a system Q switching Q switch with offset Pulse Clean Up End of Pulse Slicer Pulse Chopping Stage Isolation Cavity Dumping Pulse Picking Fast regen systems AWG opto shapes STG systems Hi rep. rate systems

Some crystals used for pockels cell have significant peizzo electric effects. When the voltage accross such a crystal is changed quickly, strain can be induced in the material. Often the strain will produce bifringence within the cell that counteracts the bifringence being induced by the pockels effect. In pulsed systems this effect is simply overcome by increasing the amplitude of the applied pulse to greater than that required for DC induced retardation. However, in simpler systems that just apply a voltage and then remove it, the fast removal can result in strain and the cell may not return to its quiescent state for some time, related to acoustic time scales. To overcome this some Q switch drivers offer the possibility to switch beyond ground, i.e. charge to some voltage V and then switch down to -ΔV.
This new Q switch driver offers completely independent setting of the initial votage and the size of the voltage step applied to the cell. For example for simple piezzo electric effect compensation the output could be set at -2kV DC and then switched up by 2.5kV to 0.5kV. However, the output DC level can be set over a range at least equal to that of the switch so that at zero DC output the switch will take it to 2.5kV or at -4.5kV the switch will take it to -2kV. In principal one could bias the cell at V_λ/2 and then switch it to V_-λ/2. this would result in transmission only over the transition time of around 5ns (depending upon the load capacitance).

This product is currently available as a -4.5kV switch and -4.5kV bias but higher voltages are possible, certainly up to -8.5kV. Positive voltages can also be manufactured for applications that are polarity sensitive.