In this paper, we have proposed a step separate confinement heterostructure (SCH) based lasing nano-heterostructure In 0.90 Ga 0.10 As 0.59 P 0.41/ InP consisting of single quantum well (SQW) and investigated material gain theoretically within TE and TM polarization modes. In addition, the quasi Fermi levels in the conduction and valence bands along with other lasing characteristics like anti-guiding factor, refractive index change with carrier density and differential gain have also been investigated and reported. Moreover, the behavior of quasi Fermi levels in respective bands has also been correlated with the material gain. Strain dependent study on material gain and refractive index change has also been reported. Interestingly, strain has been reported to play a very important role in shifting the lasing wavelength of TE mode to TM mode. The results investigated in the work suggest that the proposed unstrained nano-heterostructure is very suitable as a source for optical fiber based communication systems due to its lasing wavelengths achieved at ~1.35 μm within TM mode, while ~1.40 μm within TE mode.

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This paper deals with the studies of lasing characteristics along with the gain spectra of compressively strained and step SCH based In 0.71 Ga 0.21 Al 0.08 As/InP lasing nano-heterostructure within TE polarization mode, taking into account the variation in well width of the single quantum well of the nano-heterostructure. In addition, the compressive conduction and valence bands dispersion profiles for quantum well of the material composition In 0.71 Ga 0.21 Al 0.08 As at temperature 300 K and strain ~1.12% have been studied using 4 × 4 Luttinger Hamiltonian. For the proposed nano-heterostructure, the quantum well width dependence of differential gain, refractive index change and relaxation oscillation frequency with current density have been studied. Moreover, the G–J characteristics of the nano-heterostructure at different well widths have also been investigated, that provided significant information about threshold current density, threshold gain and transparency current density. The results obtained in the study of nano-heterostructure suggest that the gain and relaxation oscillation frequency both are decreased with increasing quantum well width but the required lasing wavelength is found to shift towards higher values. On behalf of qualitative analysis of the structure, the well width of 6 nm is found more suitable for lasing action at the wavelength of 1.55 μm due to minimum optical attenuation and minimum dispersion within the waveguide. The results achieved are, therefore, very important in the emerging area of nano-optoelectronics.

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