Matrix approach for modeling of emission from multilayer spin-polarized light-emitting diodes and lasers

Spin-polarized light sources such as the spin-polarized light-emitting diodes (spin-LEDs) and spin-polarized lasers (spin-lasers) are prospective devices in which the radiative recombination of spin-polarized carriers results in emission of circularly polarized photons. The main goal of this article is to model emitted radiation and its polarization properties from spin-LED and spin-controlled vertical-cavity surface-emitting laser (spin-VCSEL) solid-state structures. A novel approach based on 4 × 4 transfer matrix formalism is derived for modeling of the interaction of light with matter in active media of resonant multilayer anisotropic structure and enables magneto-optical effects. Quantum transitions, which result in photon emission, are described using general Jones source vectors.Web of Science166art. no. 06500

Spin vertical-cavity surface-emitting lasers with linear gain anisotropy: Prediction of exceptional points and nontrivial dynamical regimes

It is shown that when the linear gain anisotropy is properly accounted for, spin-injected vertical-cavity surface-emitting lasers (spin-VCSELs) offer interesting functionalities. Using the extended spin-flip model (SFM), we predict the existence of exceptional points (EPs) in spin-VCSELs and two interesting phenomena which accompany EPs, namely, (i) the polarization switching manifesting as induced change of field helicity sign and (ii) frequency comb generation without the need of external injection locking. Both effects have tremendous technological potential such as fast on-chip polarization switching, and most importantly, their concepts are not limited only to spin-VCSEL technology. We discuss the concept of anisotropy-engineered non-Hermitian microlasers and we provide a theoretical background to study their polarization dynamics near EPs.Web of Science1073art. no. 03350

Mueller matrix ellipsometric study of multilayer spin-VCSEL structures with local optical anisotropy

Spin-laser structures such as spin-polarized vertical-cavity surface-emitting lasers are semiconductor devices in which the radiative recombination processes involving spin-polarized carriers result in an emission of circularly polarized photons. Nevertheless, additional linear in-plane anisotropies in the cavity, e.g., interfacial and surface anisotropies, generally lead to preferential linearly polarized laser emission and to possible coupling between modes. We present Mueller matrix ellipsometric study of non-intentionally doped InGaAs/GaAsP laser structures devoted for optical pumping operations in the spectral range from 0.73 to 6.4eV in order to disentangle surface and quantum wells contributions to the linear optical birefringence of the structures. The measurement of full 4 x 4 Mueller matrix for multiple angles of incidence and in-plane azimuthal angles in combination with proper parametrization of optical functions has been used for extraction of optical permittivity tensor components along [110] and [1 (1) under bar0] crystal axis of surface strained layers and quantum wells grown on [001]-substrate. Such spectral dependence of optical tensor elements is crucial for modeling of spin-laser eigenmodes, resonance conditions, and also for understanding of sources of structure anisotropies.Web of Science11222art. no. 22110

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

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.Web of Science225art. no. 05500

Hybrid Q-switch Laser Source With Low Frequency Jitter

Poster : LASERS-6-P-6International audienc

Eigenmodes of spin vertical-cavity surface-emitting lasers with local linear birefringence and gain dichroism

We present a generalmethod for the modeling of semiconductor lasers such as a vertical-cavity surface-emitting laser and a vertical-external-cavity surface-emitting laser containing multiple quantum wells and involving anisotropies that may reveal (i) a local linear birefringence due to the strain field at the surface or (ii) a birefringence in quantum wells due to phase amplitude coupling originating from the reduction of the biaxial D-2d symmetry group to the C-2v symmetry group at the III-V ternary semiconductor interfaces. From a numerical point of view, a scattering S-matrix recursive method is implemented using a gain or amplification tensor derived analytically from the Maxwell-Bloch equations. It enables one to model the properties of the emission (threshold, polarization, and mode splitting) from the laser with multiple quantum well active zones by searching for the resonant eigenmodes of the cavity. The method is demonstrated on real laser structures and is presently used for the extraction of optical permittivity tensors of surface strain and quantum wells in agreement with experiments. The method can be generalized to find the laser eigenmodes in the most general case of circular polarized pumps (unbalance between the spin-up and spin-down channels) and/or dichroism allowing an elliptically polarized light emission as recently demonstrated experimentally when the linear birefringence is almost compensated.Web of Science964art. no. 04382

Linear and quadratic magneto-optical measurements of the spin reorientation in epitaxial Fe films on MgO

We have undertaken a detailed study by magneto-optical techniques of in-plane magnetization reversal behaviour in epitaxial Fe films grown by MBE on (10 0) oriented MgO substrate. We measure M---H loops for both orthogonal in-plane magnetization components Mt (component parallel to the magnetic field) and Mt (component perpendicular to the field) and for various orientations of the magnetic field with respect to the crystalline axis. These measurements show the classical four-fold cubic anisotropy for large Fe film thickness and confirm the appearance of weak uniaxial in-plane anisotropy superimposed for thinner films (t = 20 Å). We have demonstrated the appearance of strong asymmetrical hysteresis loop for p-polarized incident light. We explain this behaviour as the mixing of transverse magnetization contribution to the longitudinal magnetization measurements on the basis of quadratic magneto-optical effects. The calculation of these effects based on eigenmode propagation in anisotropic layered media are developed by including the second-order magneto-optical terms in the permittivity tensor characteristic of a cubic crystal. The second-order reflection coefficients are discussed in the case of the normal incidence of the laser beam and for the magnetic field along the hard axis of the Fe film