Optical Gain Analysis Research Articles

Optical gain analysis of GaInP/AlGaInP nanoscale heterostructure for applications in visible light emission

In quantum well structures, charge carriers are confined in the well region and barrier region due to the discontinuity in the bandgap and larger built-in potential. Thus, for a smaller current, we can have a higher gain. This work reports the energy wavefunction and optical gain analysis of the GaAs-based quantum well structure made of GaInP/AlGaInP material layers. The structure is also examinedsubject to the effect of external pressure and temperature to study the tunability. The designed structure shows stability near the room temperature. The 6 × 6 Hamiltonian matrix is solved and the Luttinger-Kohn model with the conduction band is used for the calculation of band structure. In the quantum well structure, the thickness of the active layers is in our control. This is an important advantage for device fabrication. The material and the size of the layers are selected on the basis of their suitability to generate the radiation in the range of the red spectrum (620-–750 nm).The designed QW heterostructure is thus found to be suitable for photodynamic treatment (PDT) and dermatological treatments.

Optical gain analysis of GaAs-based InGaAs/GaAsSbBi type-II quantum wells lasers.

A novel active region design based on a type-II InGaAs/GaAsSbBi quantum wells on GaAs substrate is proposed and studied in this work. The band structures of the InGaAs/GaAsSbBi type-II quantum wells are studied based on a self-consistent 14-band k·p model. The electronic and optical properties of dilute-bismide InGaAs/GaAsSbBi type-II quantum well structures are investigated theoretically. Moreover, the room temperature gain characteristics of the laser active region are studied with different Bi composition. The theoretical results indicate that adding Bi into InGaAs/GaAsSb type-II active regions on GaAs substrate extends the laser emission wavelength beyond 1550nm without sacrificing the peak gain value. It is shown that these type-II quantum well structures are suitable for 1550nm wavelength region operation at room temperature.

Generalized optical gain analysis in nonparabolic semiconductor laser

SUMMARY A simple generalized theory is developed for optical gain of nonparabolic semiconductor lasers based on the three-band model of Kane, by taking into account the wave-vector () dependence of the optical matrix element. The gain in laser of nonparabolic semiconductors is demonstrated, by taking InAs, InSb, Hg1−xCdxTe and In1−xGaxAsyP1−y lattice matched to InP as examples, and it has been found that the peak of the gain spectra for a given carrier density is higher in the three-band model of Kane than those with parabolic energy band approximations in all the cases. The difference between the peak of gain spectra for three-band model and the parabolic band model is greater for laser of narrow band gap materials in comparisons with that of laser of wide band gap materials, thereby reveals the necessity for inclusion of the nonparabolicity in modeling lasers of small band gap materials. The well-known results for wide band gap materials having parabolic energy bands has also been obtained from our generalized formulation under certain limiting condition. Copyright © 2013 John Wiley & Sons, Ltd.

Carrier transport in THz quantum cascade lasers: Are Green's functions necessary?

We have applied two different simulation models for the stationary carrier transport and optical gain analysis in resonant phonon depopulation THz Quantum Cascade Lasers (QCLs), based on the semiclassical ensemble Monte Carlo (EMC) and fully quantum mechanical non-equilibrium Green's functions (NEGF) method, respectively. We find in the incoherent regime near and above the threshold current a qualitative and quantitative agreement of both methods. Therefore, we show that THz-QCLs can be successfully optimized utilizing the numerically efficient EMC method.

Optical gain analysis of strain-compensated InGaN–AlGaN quantum well active regions for lasers emitting at 420–500 nm

Strain-compensated InGaN quantum wells with tensile AlGaN barriers are analyzed as improved gain media for laser diodes emitting at 420–500 nm. The band structure is calculated using the 6-band k ·p formalism, taking into account valence band mixing, strain effect, and spontaneous and piezoelectric polarizations. The optical gain analysis exhibits significant improvement in the peak optical gain and differential gain for the strain-compensated structures. The calculation also shows a significant reduction of threshold carrier density and current density for diode lasers employing the strain-compensated InGaN–AlGaN QW active regions.