Local and mean-field approaches for modeling semiconductor spin-lasers

Abstract

Electrically and optically pumped spin-polarized vertical-cavity surface-emitting lasers (spin-VCSELs) seem to attain improved performance compared to their conventional counterparts. Their dynamical properties are studied mostly in the framework of effective rate equations containing parameters that are difficult to directly relate with fundamental material properties. Consequently, such approaches are not suitable for the precise design and optimization of future spin-lasers with desirable dynamical properties. We propose a method for extraction of dynamics-related parameters for the spin-flip model, which is widely used for the description of spin-laser dynamics. This method is based on the correspondence between robust local computational tools and effective models. A general matrix formalism based on S-matrices and generalized Maxwell–Bloch equations is used to determine approximate values of parameters such as cavity decay rate or birefringence rate. This would allow us to tune laser properties by changing the optical properties of the laser cavities and active media according to our needs. The method is demonstrated on realistic anisotropic spin-VCSEL structures containing a 12-quantum-well InGaAs/GaAsP active region. The potential limitations of already existing effective models are discussed.

Spin-VCSELs with Local Optical Anisotropies: Toward Terahertz Polarization Modulation

“…Compared to the results from Ref. [50], in which we have compared the matrix approach with the conventional spin-flip model, one can see, that separation of amplitude anisotropy into passive (linear dichroism) and active (linear gain anisotropy) contributions increases the precision.…”

“…We consider the linear birefringence and linear dichroism in passive layer, linear gain anisotropy in active layer and additionally spin-polarized electron injection. Very similar calculation has been presented in our previous contribution [50], in which we have used scattering matrix formalism to extract dynamics-related quantities for conventional SFM. However, in this case, our extended SFM based on coupled mode theory, is computationally self-consistent.…”

“…[47]. Motivated by our previous results [50], the theory naturally reduces to extended SFM, which is derived in Sec. V. The extended SFM describes also the linear gain anisotropy, which is often neglected.…”

Threshold behavior in spin lasers: Spontaneous emission and nonlinear gain

“…There is a growing interest to utilize optical anisotropy in spin lasers, such as the high birefringence [39,41,49,[60][61][62][63][64][65][66], to reach ultrafast operation, faster than the best conventional lasers [42]. Even though such efforts focus on quantum-well based lasers (where a nonlinear optical gain is expected) and scaling them down [58], their current description relies on a widely-used spinflip model [67][68][69][70]. While that approach includes optical anisotropies, the assumed linear gain and β = 0 limits its predictive power to elucidate scaled-down spin lasers.…”