Generation of Laser Pulses in the Megahertz Range of Repetition Frequencies by Low-Voltage AlGaAs/GaAs Laser-Thyristors

Abstract

The process of generation of a high-frequency train of laser pulses in laser-thyristors (LTs) based on AlGaAs/GaAs heterostructures with various optical activation efficiencies has been studied. It was found that the main factors affecting the frequency and peak power of the laser pulses are the charging current of the barrier capacitance of the collector p-n junction and the holding current. The charging current of the barrier capacitance determines the condition for an LT to pass to the uncontrollable turn-on mode. The holding current determines the condition for the transition of an LT to the sticking mode in the turned-on state. It was shown that the holding current reached a value of 0.2 mA for the LT heterostructure with high optical activation efficiency, which limited the maximum repetition frequency to 470 kHz at a peak power of 4 W. A decrease in the optical activation efficiency made it possible to raise the holding current to 100 mA, with the maximum repetition frequency reaching as a result 12 MHz at a peak power of 0.7 W. Lowering the repetition frequency to 8 MHz made it possible to raise the peak power to 3.2 W at a pulse width of 17 ns.