Quantum design of a 1.3 μm InGaPAs semiconductor laser
Semiconductor wafer growth can now produce heterostructures of very high quality with stoichiometrically correct growth of individual monolayers. Despite significant advances in MBE and MOCVD growth technologies, a critical void has remained in predicting the performance of final packaged functional amplifier or laser devices. The lack of predictive semiconductor device design and growth monitoring capability can be traced to the extreme complexity of calculating the semiconductor optical response and radiative-nonradiative recombination rates from first principles. Considering the critical role of the above recombination processes in not only, determining gain and slope efficiency but, also all dynamic properties (modulation rates, gain switching, injection locking etc) of SOAs and SLs, it is clear that the impact of this work reaches well beyond the accurate prediction of an L-I characteristic.
Microscopic evaluation of spontaneous emission- and Auger-processes in semiconductor lasers
A fully microscopic approach is used to compute the losses in semiconductor lasers due to spontaneous emission and Auger recombination. The model is based on the semiconductor-Bloch equations and generalized quantum-Boltzmann type scattering equations in the second Born-Markov approximation. As input the theory only needs the structural layout and fundamental bulk-bandstructure parameters. It is demonstrated that such a comprehensive model that calculates gain/absorption, spontaneous emission and Auger processes on the same microscopic level can reliably predict these usually dominant loss processes. Examples of the results are compared to measurements on lasers in the 1.3-1.5 /spl mu/m range demonstrating very good agreement without empirical fitting.
The influence of tensile strain on differential gain and Auger recombination in 1.5-/spl mu/m multiple-quantum-well lasers
A systematic study has been undertaken including growth, characterization, and modeling of tensile-strained multiple-quantum-well (MQW) lasers with emission wavelengths in the neighborhood of 1.5 /spl mu/m. The laser threshold increases between 0% and -0.5% mismatch, switching from TE to TM polarized emission at -0.5%, then decreases to -1.3 % mismatch, with TM polarized emission. The threshold current density has a much weaker dependence on inverse cavity length in the highly tensile-strained lasers than has previously been observed for lattice-matched and compressive lasers emitting in the same wavelength range. We present theoretical calculations which show that the observed differences are well explained, both qualitatively and quantitatively, by the calculated variation with strain of the optical confinement factor /spl Gamma/ and the differential gain at transparency, dg/dn (n/sub tr/). More detailed comparison with experiment suggests that Auger recombination provides the dominant contribution to the threshold current density. Estimated Auger coefficients C are in good agreement with those previously obtained using other techniques.