A study of nonlinear lasing dynamics of an InGaAs/AlGaAs/GaAs heterostructure power laser-thyristor emitting at 905 nm

Abstract

The results obtained demonstrate that the lasing dynamics reflects the current dynamics formed as a result of complex nonlinear couplings within the laser-thyristor heterostructure. The observed specific features mainly result from the appearance of new channels for generation of excess carriers in the p-base. These channels enhance the main optical activation channel formed by the photogeneration due to the absorption of the spontaneous emission from the active region of the laser part of the heterostructure. The additional channels of excess carrier generation may have an optical nature in the case of scattered laser light upon appearance of new high-Q modes. For nearly critical blocked voltages, generation of carriers can be initiated by an avalanche multiplication of photogenerated carriers.

High-Power Laser Thyristors With High Injection Efficiency ($\lambda =890$ –910 nm)

“…To further improve the efficiency of accumulation of photogenerated holes, we also made thinner the p-base because, according to our calculations, only a part of the p-base is overlapped by the space charge region at the maximum blocking voltage. An estimation made using the Bouguer-Lambert-Beer law gives the following concentrations relation for photogenerated carriers in the p-base of heterophototransistor of designed structure and the structure in [5] and [8] n p2 n p1…”

“…From this relation it is seen that photogenerated carriers concentration increase is determined by the following factors: photon intensity flux at p-collector and p-base boundary, defined by absorbed layer thickness in p-collector W C of the structure from [5] and [8]; absorption coefficient α and thicknesses of base layers of the investigated structure W B2 and the structure from [5] and [8] W B1 . Besides, at initial stage of laser-thyristor turn-on, when collector junction is reverse-biased, quasineutral region thickness of the p-base in the designed structure W nat2 and the structure from [5] and [8] W nat1 plays an important role.…”

“…Besides, at initial stage of laser-thyristor turn-on, when collector junction is reverse-biased, quasineutral region thickness of the p-base in the designed structure W nat2 and the structure from [5] and [8] W nat1 plays an important role. At absorption coefficient value of 10 4 cm −1 [10] and quasi-neutral region thicknesses coinciding with the corresponding base regions thicknesses, photogenerated carriers concentration is increased by a factor of 9.…”

“…As a result, 10-100 mA low signal current control has been demonstrated, which is used to generate laser pulses on the order of 100 ns and up to 28 W output optical power [5], [6]. The results of a detailed study of the output characteristics of lasersthyristors, reported in [8], demonstrated a strong nonlinearity of the dynamics of radiative processes.…”

“…The reason is that the main part of the laser emission propagates along the waveguide layer of the heterostructure and does not overlap with the p-base region in order to minimize the internal optical loss of the laser mode. In addition, as shown in [8], the photogeneration of a control signal in the p-base via absorption of the scattered laser light or mode rearrangements gives rise, in the case of a weak optical feedback, to a nonlinear dynamics in the course of laser generation, which is a negative effect for the target device. Then the most efficient photogeneration is achieved by the absorption of the spontaneous emission just within the heterophototransistor p-base.…”