New approach for high-peak power lasing based on epitaxially integrated AlGaAs/GaAs laser-thyristor heterostructure

Abstract

A new approach to generation of high optical peak power by epitaxially and functionally integrated high-speed highpower current switch and laser heterostructure (so-called laser-thyristor) has been developed. This approach makes it possible to reduce the loss in external electrical connections, which is particularly important for the short-pulse highamplitude current pumping. In addition, it considerably simplifies the fabrication technology of pulsed laser sources as a commercial product and allows stacking of multiple-element systems. The epitaxially integrated AlGaAs/GaAs heterostructure of low-voltage laser-thyristor has been studied and optimized for generation of high-power pulses at a 900-nm wavelength. It is shown that the incomplete switch-on of the laserthyristor in the initial stage and the nonlinear dynamics of the emitted laser power are due to the insufficient efficiency of the vertical optical feedback in the epitaxially integrated heterostructure. Optimization of the composition and the interband absorption spectra of transistor base layers makes it possible to substantially raise the efficiency of control signals due to the rise in the photogeneration speed. Experimental laser-thyristor samples with a 200-μm aperture have been fabricated and studied. The maximum static blocking voltage does not exceed 20 V. It is shown that the generated laser pulses have a perfect bell-like shape without any indications of a nonlinear dynamics. This confirms that the changes introduced into the heterostructure design provide a sufficient efficiency of photogeneration of the control signal. As a result, the maximum optical peak power reaches 40 and 8 W at FWHM pulse durations of 95 and 13 ns, respectively. An analysis of the potential dynamics has shown that the heterostructure provides pumping of the active layer with up to 90-A pulses.