Geometric Spin Hall Effect of Light at Polarizing Interfaces

The geometric Spin Hall Effect of Light (geometric SHEL) amounts to a polarization-dependent positional shift when a light beam is observed from a reference frame tilted with respect to its direction of propagation. Motivated by this intriguing phenomenon, the energy density of the light beam is decomposed into its Cartesian components in the tilted reference frame. This illustrates the occurrence of the characteristic shift and the significance of the effective response function of the detector. We introduce the concept of a tilted polarizing interface and provide a scheme for its experimental implementation. A light beam passing through such an interface undergoes a shift resembling the original geometric SHEL in a tilted reference frame. This displacement is generated at the polarizer and its occurrence does not depend on the properties of the detection system. We give explicit results for this novel type of geometric SHEL and show that at grazing incidence this effect amounts to a displacement of multiple wavelengths, a shift larger than the one introduced by Goos-H\"anchen and Imbert-Fedorov effects.Comment: 6 pages, 4 figure

Einsatz von poröser Faserkeramik für Effusionskühlung in Raketenbrennkammern

Seit 1964 hat das DLR seine Forschung auf dem Gebiet der Brennkammertechnologie weiter verstärkt. Ein Schwerpunkt der Arbeiten liegt in der Entwicklung der Effusionskühlung wobei in den letzten Jahren verstärkt die Anwendung von porösen faserverstärkte Keramiken für diese Kühltechnik untersucht wurde. Als Kühlmedium wird dabei wie in Raketenbrennkammern üblich GH2 verwendet. Dieser Bericht beinhaltet die Ergebnisse der jüngsten Experimente zur Effusionskühlung unter Anwendung von C/C (Kohlefasern in Kohlenstoffmatrix) als poröse Brennkammerwand. Die Herstellung von C/C und die Erläuterung einiger Modelle der Effusionskühlung sind ebenfalls Gegenstand dieses Berichts. Die Experimente wurden an der Mikro-Brennkammer M3 des DLR-Lampoldshausen durchgeführt. Der Brennkammerdruck wurde dabei zwischen 0,3 MPa und 1,2 MPa, bei einem konstanten Mischungsverhältnis GO2/GH2 von 6,5, variiert. Die Porosität der Brennkammerwand wurde zwischen Epsilon = 13% und Epsilon = 25% verändert, um die Durchflußrate und den dazugehörigen Druckverlust zu optimieren. Der Kühlmassenstrom wurde in einem weiten Bereich variiert, um Daten für die Modellierung zu sammeln aber auch den Einsatzbereich zu untersuchen. Ein Vergleich der experimentellen mit den theoretischen Daten sowie eine Zusammenfassung und Ausblick schließen diesen Bericht

Effusion Cooling in Rocket Combustors Applying Fiber Reinforced Ceramics

Since 1994 DLR has focused its efforts on combustion chamber technologies within the internal program "High Pressure Rocket Propulsion" (HDR). The main emphasis lays on advanced cooling technologies and especially effusion cooling applying fibre reinforced ceramics as porous media and hydrogen as cooling fluid. This paper summarises the recent experimental work on this cooling technique using Carbon/Carbon (C/C) material for combustion chamber components. After a brief summary of the fabrication process of the specific ceramic and the material properties, the basic equations for the flow situation and appropriate models are presented. Within the experimental campaign which has been performed at the DLR micro combustor facility M3 the combustion chamber pressure has been varied between 0.3 MPa and 1.1 MPa at a constant oxidiser/fuel mixture ratio of 6.5 using ambient hydrogen as coolant. The porosity of the ceramics has been varied in the range from about Epsilon = 13% to Epsilon = 25% in order to optimise the coolant mass flow rate and pressure loss across the porous wall. A wide range of coolant mass flow rates has been tested in order to achieve a broad data base for modelling an check the limits of applicability of the cooling technique and the ceramic wall material. The paper concludes with a presentation of experimental and theoretical results and a brief outlook to future activities

Observation of the Geometric Spin Hall Effect of Light

The spin Hall effect of light (SHEL) is the photonic analogue of the spin Hall effect occurring for charge carriers in solid-state systems. This intriguing phenomenon manifests itself when a light beam refracts at an air-glass interface (conventional SHEL) or when it is projected onto an oblique plane, the latter effect being known as the geometric SHEL. It amounts to a polarization-dependent displacement perpendicular to the plane of incidence. In this work, we experimentally investigate the geometric SHEL for a light beam transmitted across an oblique polarizer. We find that the spatial intensity distribution of the transmitted beam depends on the incident state of polarization and its centroid undergoes a positional displacement exceeding one wavelength. This novel phenomenon is virtually independent from the material properties of the polarizer and, thus, reveals universal features of spin-orbit coupling

Experimental demonstration of the geometric spin Hall effect of light in highly focused vector beams

We demonstrate the geometric spin Hall effect of light by focusing a specially polarization tailored beam of light, resulting in the generation of purely transverse angular momentum in the focal plane. (C) 2011 Optical Society of Americ