Low impedance nanosecond and sub-nanosecond risetime pulse generators for electro-optical switch applications

There is a growing demand in the laser industry for fast risetime, high repetition rate electro-optical switches. The focus of Fast Transitions, Inc. and its partners Megapulse and Moose Hill Enterprises has been to address the unique needs of the E-O switch driver market. The capabilities of the devices and systems described here also extend into other areas such as streak camera drivers, pulsed laser diode drivers, spark gap triggers, microwave tube drivers and many others. The driver systems now being produced are unprecedented in their capabilities in terms of performance, size, cost, life, reliability and efficiency. These drivers are based on a Russian developed solid state device known as the DSRD (drift step recovery diode). This device allows the generation of low output impedance, short, high voltage pulses with very simple circuits. Most simply stated, the DSRD operates as a high voltage opening switch. The driving circuits utilize inductive energy storage at relatively low input voltages and the DSRD allows the transfer of energy from the storage inductance to the load. Its fast switching time and low junction capacitance allow the rise time to be largely determined by the characteristics of the storage inductance and output circuit.