How to Build an Ultra-Fast High-Power Laser DriverThe simplest and most common laser driver is the resonant capacitive discharge driver, shown in figure 3. FET Q1 discharges C1 resonantly through the stray inductance L1 and laser DL. To overcome inductance L1 and achieve the fast current rise-time desired, C1 is charged to a relatively high voltage (usually 25 V to 150 V). FET Q1 must be able to withstand the voltage, conduct the peak current, and turn on in 1 ns or less. The eGaN FET is the only readily available, cost-effective semiconductor switch that can meet these requirements.