The effect of the number and position of AlInAs energy barrier layers on the output characteristics of high-power multimode AlGaInAs / InP lasers, spectral range 1400–1600 nm, has been studied. It was shown that the use of energy barriers allows increasing the laser maximum output power 1.5-2 times. It was found that the barrier layer should be installed at the waveguide-cladding heterojunction from the p-side in order to localize electrons in the waveguide layer.
The study was supported by the Russian Science Foundation, project No. 19-79-30072
The first results are presented, which showed general patterns explaining the influence of drift velocity saturation effects on the light-current curve for an example AlGaAs/InGaAs/GaAs laser heterostructure with an ultra-wide asymmetric waveguide emitting in the 1060 nm spectral range at ultrahigh pump currents (tens of kA/cm2 ). The study carried out clearly shows the limitations of the simplest drift-diffusion models that take into account and do not take into account the saturation of the drift velocity. It is shown that when analyzing high-power semiconductor lasers at high pump currents, it is necessary to take into account the effect of heating of charge carriers in the waveguide by an electric field. The inclusion of an additional mechanism of internal optical loss obtained in the energy balance model made it possible to obtain a satisfactory agreement between the calculated light-current curves and the experimental ones.
The design of the AlGaAs/InGaAs/GaAs laser heterostructure with an ultra-narrow waveguide was developed and studies on the generation of high-power laser pulses with high beam quality were carried out. The heterostructure design included a 100-nm-thick waveguide and an InGaAs quantum well for a lasing at 1060 nm. For the studies the mesa-stripe geometry single-mode lasers with a 5.1-μm-width contact were fabricated. The mesa-stripe geometry parameters were optimized using a 2D-simulation of waveguide properties, taking into account the spatial distribution of temperature and gain. As a result, the divergence was of 18.5 and 5 degrees in the growth direction and parallel to the heterostructure layers, respectively. Studies of the light-current characteristics in the range of pulse durations of 5–1000 ns showed that the peak power of 1.75 W was limited by the catastrophic optical damage. The dynamics is associated with modes of high-quality factor that approach their threshold conditions at high pumping level. A spectral line of these modes is redshifted relative to a fundamental one.
The results of research and development of a pulse laser module are presented. The aim was to create and a compact pulse laser source with a peak power of more than 10 W for optical pulses of 10 ns - 10 μs duration, emitting in spectral range 900-1600 nm. Pulsed modules were based on MOCVD-grown edge-emitting multimode semiconductor lasers integrated with a pulse pumping board. It was shown that the laser output characteristics can be optimized via a series resistance in the laser pump circuit. The 1550 nm wavelength modules with free-space outputs showed power levels of 15 and 25 W, for 1 μs and 100 ns pulses respectively, at 25° C temperature with a regular pulse shape.
The results of designing, manufacturing and investigating characteristics of AlGaAs/InGaAs/GaAs lasers with ultranarrow waveguides are presented. Low threshold current density near 40 A/cm2 has been observed for the lasers with quantum wells. We have demonstrated the possibility of obtaining up to 5 W of output power in continuous mode and up to 40 W in pulsed mode, with a beam convergence (FWHM) of 17.8° It is demonstrated that such lasers can exhibit main characteristics similar to conventional laser heterostructures and allow a potential for further improvement and optimization.