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Lasers have both ubiquitous applications and roles as model systems in which non-equilibrium and cooperative phenomena can be elucidated.sup.1. The introduction of novel concepts in laser operation thus has potential to lead to both new applications and fundamental insights.sup.2. Spintronics.sup.3, in which both the spin and the charge of the electron are used, has led to the development of spin-lasers, in which charge-carrier spin and photon spin are exploited. Here we show experimentally that the coupling between carrier spin and light polarization in common semiconductor lasers can enable room-temperature modulation frequencies above 200 gigahertz, exceeding by nearly an order of magnitude the best conventional semiconductor lasers. Surprisingly, this ultrafast operation of the resultant spin-laser relies on a short carrier spin relaxation time and a large anisotropy of the refractive index, both of which are commonly viewed as detrimental in spintronics.sup.3 and conventional lasers.sup.4. Our results overcome the key speed limitations of conventional directly modulated lasers and offer a prospect for the next generation of low-energy ultrafast optical communication. Room-temperature modulation frequencies exceeding 200 GHz are demonstrated in birefringent semiconductor spin-lasers by coupling the spin of the charge carriers to the light polarization., Author(s): Markus Lindemann [sup.1] , Gaofeng Xu [sup.2] , Tobias Pusch [sup.3] , Rainer Michalzik [sup.3] , Martin R. Hofmann [sup.1] , Igor Zutic [sup.2] , Nils C. Gerhardt [sup.1] [...]

Polarization dynamics in spin‐polarized vertical‐cavity surface‐emitting lasers (spin‐VCSELs) with high birefringence have recently been demonstrated to offer very high potential for optical data‐transmission systems that outperform their counterparts based on conventional direct current modulation by far. For polarization dynamics in spin‐VCSELs, the birefringence determines the resonance frequency and thus the modulation bandwidth. In previous work, birefringence was controlled using mechanical strain, which lacks the ability to be integrated in standard VCSEL manufacturing processes. In this work the polarization dynamics of a VCSEL with an integrated birefringence control mechanism is demonstrated based on custom designed integrated surface gratings. It is found that, despite the surface grating which is commonly known to stabilize the polarization, the presented spin‐VCSELs are able to generate polarization oscillations with frequencies corresponding to the birefringence induced by the surface grating and show polarization dynamics up to 68 GHz. [ABSTRACT FROM AUTHOR]

The article examines the polarization-resolved spatial emission and turn-on dynamics of oxide-confined vertical-cavity surface-emitting lasers (VCSELs) with an integrated surface-relief grating. Findings reveal guaranteed stable turn-on on a single polarization due to the high dichroism of the grating.

The extension of the concept of inverting grating relief for single-mode vertical-cavity surface emitting lasers (VCSELs) to that of an inverted full-aperture grating for multimode VCSELs is investigated. Results establish that the simulations and experimental results show in very good agreement, that the dependence of the polarization control on the grating parameters is strongly reduced by changing the thickness of the cap layer of the vertical-cavity surface-emitting lasers (VCSEL) structure.

An investigation is carried out to find experimentally the effect of isotropic optical feedback from an extremely short external cavity on the emission properties of vertical-cavity surface-emitting lasers (VCSELs). Results show a modulation of the PS currents and the hysteresis width when changing the external cavity length with a period a half the wavelength of operation.

A two modes rate equation model for vertical-cavity surface-emitting lasers (VCSELs) subject to optical feedback from an extremely short external cavity (ESEC) is presented. A map of bistability is developed to investigate the parametric dependence of the polarization properties of VCSELs in such configuration, finding out a periodic dependence of the polarization switching (PS) currents on the ESEC length.

The electrical, thermal, and optical behaviour of broad-area traveling-wave semiconductor amplifiers are studied, using finite-element thermal analysis and carrier transport mechanisms, integrated into the beam propagation method. The beam filamentation in broad-area semiconductor amplifiers with residual facet reflectives is simulated by self-consistent iteration. The observed periodic filamentation shows intensity minima close to zero.

The performance of gain-guided vertical-cavity lasers in a self-consistent manner was analyzed. The models were studied using quantitative analysis to optimize the features of the proton-implanted mesa-etched devices. The one-dimensional transfer acatrix technique was employed to determine the threshold status of the laser. Data from these experiments were employed to define the spatial distribution of power reduction in structures with cylindrical symmetry and implantation-induced continuous variation of the electric conductivity.