Polarization stabilization in vertical-cavity surface-emitting lasers through asymmetric current injection

We present experimental evidence that asymmetric current injection in intracavity contacted vertical-cavity surface-emitting lasers (VCSELs) stabilizes the polarization of the emitted light. Anisotropies in the gain and loss mechanisms introduced by asymmetric current injection are considered to explain this effect. The design scheme opens perspectives to obtain actual polarization control in VCSEL

Phytochrome-Based Extracellular Matrix with Reversibly Tunable mechanical Properties

Interrogation and control of cellular fate and function using optogenetics is providing revolutionary insights into biology. Optogenetic control of cells is achieved by coupling genetically encoded photoreceptors to cellular effectors and enables unprecedented spatiotemporal control of signaling processes. Here, a fast and reversibly switchable photoreceptor is used to tune the mechanical properties of polymer materials in a fully reversible, wavelength‐specific, and dose‐ and space‐controlled manner. By integrating engineered cyanobacterial phytochrome 1 into a poly(ethylene glycol) matrix, hydrogel materials responsive to light in the cell‐compatible red/far‐red spectrum are synthesized. These materials are applied to study in human mesenchymal stem cells how different mechanosignaling pathways respond to changing mechanical environments and to control the migration of primary immune cells in 3D. This optogenetics‐inspired matrix allows fundamental questions of how cells react to dynamic mechanical environments to be addressed. Further, remote control of such matrices can create new opportunities for tissue engineering or provide a basis for optically stimulated drug depots

Modeling Storage and Demand Management in Electricity Distribution Grids

Storage devices and demand control may constitute beneficial tools to optimize electricity generation with a large share of intermittent resources through inter-temporal substitution of load. We quantify the related cost reductions in a simulation model of a simplified stylized medium-voltage grid (10kV) under uncertain demand and wind output. Benders Decomposition Method is applied to create a two-stage stochastic program. The model informs an optimal investment sizing decision as regards specific 'smart grid' applications such as storage facilities and meters enabling load control. Model results indicate that central storage facilities are a more promising option for generation cost reductions as compared to demand management. Grid extensions are not appropriate in any of our scenarios. A sensitivity analysis is applied with respect to the market penetration of uncoordinated Plug-In Electric Vehicles which are found to strongly encourage investment into load control equipment for 'smart' charging and slightly improve the case for central storage devices

Balancing supply and demand of fresh water under increasing drought and salinisation in the Netherlands

The latest climate impact assessments show that climate change will cause an increasing mismatch between demand and supply of fresh water in many densely populated deltas around the world. Recent studies for the Netherlands show that the current water supply strategy is not climate proof in the long-run. Therefore, a future ‘climate proof’ fresh water supply is national priority on the Dutch water policy agend

The influence of experiential augmentation on product evaluation

Purpose: The purpose of this paper is to examine the influence of experiential augmentation on product evaluation by consumers. An important distinction is made between product-related experiential augmentation and experiential augmentation of the environment. Furthermore, the research examines how brand familiarity moderates the effect of experiential augmentation. Design/methodology/approach: In two experiments (N = 210 and N = 70), both product-related and environmental experiential augmentation were varied. Participants tasted and evaluated a new coffee product from either a well-known or a fictitious brand. Findings: The findings of the first experiment indicate that product-related experiential augmentation contributes positively to product evaluation for both an unfamiliar and a familiar brand. Experiential augmentation of the environment influences product evaluation negatively, but only in the absence of product-related experiential augmentation. The second experiment tests some possible explanations for this negative effect and shows that it occurs only in the case of a familiar brand. Practical implications: The findings offer implications for marketing managers seeking to positively influence consumer product evaluations through experiential augmentation. First, marketing managers are advised to make a distinction between product-related experiential augmentation and experiential augmentation of the evaluation environment, and, second, they should take brand familiarity into account when employing experiential augmentation of the environment. Originality/value: This research contributes to the literature by showing that product-related experiential augmentation and experiential augmentation of the environment differ in the impact they have on product evaluation and providing insight into the relationship between brand familiarity and experiential augmentation

Intra-cavity contacted VCSELs with polarization control

Top-emitting intra-cavity VCSELs have been fabricated by reactive-ion etching of a double mesa and applying p and n contact metallizations at the bottom of both mesas, respectively, where highly doped layers are inserted into the cavity on either side of the active region. The VCSELs are designed to emit around 980 nm, and use two strained InGaAs quantum wells and AlAs/GaAs DBR mirrors. Efficient lateral current constriction is realized by selective oxidation of two AlAs layers in the second mesa. A sealing method has been developed to prevent simultaneous oxidation of the top-DBR. A novel asymmetric contacting scheme is introduced in order to avoid current crowding at the inner edges of the oxidized AlAs layers and to stabilize the polarization. Devices with various mesa shapes and either symmetric or asymmetric contacts have been fabricated on the same wafer. Experimental analysis of these VCSELs demonstrates polarization control by asymmetric current injection, where the polarization perpendicular to the current path is favored due to anisotropy of both gain and optical losses. The strength of this effect relative to others (anisotropic loss in rectangular mesas, crystal anisotropy) and its use in electrically controlled polarization switching is explored