New forms of regional industrial policy in Europe: How do policy makers understand 'competitiveness' and 'clusters'?

The last decade has seen a revival of regional industrial policy in the Western world. New policies have been built on recent insights into the drivers of competitive advantage and are characterized by a focus on local production systems, on networking and partnerships, and more strategic forms of policy intervention. In addition, policy formulation and implementation has generally become part of an interactive process of consultation and consensus building, and, to a large extent, involves the co-ordination and reshaping of existing instruments rather than the development of entirely new ones. This paper will discuss the emergence of new forms of industrial policy targeted on regional ?competitiveness? on the basis of case studies undertaken in Germany, the UK and Spain. The aim of the paper is to understand how the concept and understanding of ?competitiveness? by local makers and other actors has influenced the shaping of local industrial policy. Since all the case studies involve laggard regions, one of the key issues of the debate is how policy makers perceive the balance between more ingenious, innovation-oriented approaches and approaches targeted in foreign investments. To understand the different outcomes in the various regions, account is taken of the governance framework for industrial policy making and implementation, the concepts and models invoked and used by policy makers, the impact of external factors such as funding conditions and European programs and, most fundamentally, the industrial and political traditions which characterize each region. The paper will point at some of the remarkable changes concepts have made on their way from theoretical and conceptual thinking to policy implementation, and will discuss the implications of these changes for academic research as well as policy-making. The work for this paper has been funded under the European Programmes ADAPT (Core project) and HCM (EUNIT network)

Anisotropic enhanced backscattering induced by anisotropic diffusion

The enhanced backscattering cone displaying a strong anisotropy from a material with anisotropic diffusion is reported. The constructive interference of the wave is preserved in the helicity preserving polarization channel and completely lost in the nonpreserving one. The internal reflectivity at the interface modifies the width of the backscatter cone. The reflectivity coefficient is measured by angular-resolved transmission. This interface property is found to be isotropic, simplifying the backscatter cone analysis. The material used is a macroporous semiconductor, gallium phosphide, in which pores are etched in a disordered position but with a preferential direction

Periodicity enclosed in boundaries: local density of states in photonic clusters\ud

We have studied the effect of the boundaries on the local density of states (LDOS) in one-, two-, and three-dimensional finite size photonic structures. The LDOS was calculated with the help of the local perturbation method (LPM) and a new LPM-Bloch method using periodicity of the system. The methods are applicable for the clusters made of small (relative to the incident wavelength) particles or for the clusters which can be considered as made of such particles. It was demonstrated that the LPM-Bloch method is an accurate numerical tool for calculation of the LDOS in the finite size photonic structures with weak interference. \ud \u

Spontaneous-emission rates in finite photonic crystals of plane scatterers

The concept of a plane scatterer that was developed earlier for scalar waves is generalized so that polarization of light is included. Starting from a Lippmann-Schwinger formalism for vector waves, we show that the Green function has to be regularized before T-matrices can be defined in a consistent way. After the regularization, optical modes and Green functions are determined exactly for finite structures built up of an arbitrary number of parallel planes, at arbitrary positions, and where each plane can have different optical properties. The model is applied to the special case of finite crystals consisting of regularly spaced identical planes, where analytical methods can be taken further and only light numerical tasks remain. The formalism is used to calculate position- and orientation-dependent spontaneous-emission rates inside and near the finite photonic crystals. The results show that emission rates and reflection properties can differ strongly for scalar and for vector waves. The finite size of the crystal influences the emission rates. For parallel dipoles close to a plane, emission into guided modes gives rise to a peak in the frequency-dependent emission rate.Comment: 18 pages, 6 figures, to be published in Phys. Rev.

Light propagation and emission in complex photonic media

We provide an introduction to complex photonic media, that is, composite materials with spatial inhomogeneities that are distributed over length scales comparable to or smaller than the wavelength of light. This blossoming field is firmly rooted in condensed matter physics, in optics, and in materials science. Many stimulating analogies exist with other wave phenomena such as sound and seismology, X-rays, neutrons. The field has a rich history, which has led to many applications in lighting, novel lasers, light harvesting, microscopy, and bio optics. We provide a brief overview of complex photonic media with different classes of spatial order, varying from completely random to long-periodically ordered structures, quasi crystalline and aperiodic structures, and arrays of cavities. In addition to shaping optical waves by suitable photonic nanostructures, the realization is quickly arising that the spatial shaping of optical wavefronts with spatial light modulators dramatically increases the number of control parameters. As a result, it is becoming possible for instance to literally see through completely opaque complex media. We discuss a unified view of complex photonic media by means of a photonic interaction strength parameter. This parameter gauges the interaction of light with any complex photonic medium, and allows to compare complex media from different classes for similar applications.Comment: 8 pages, 2 figures, Light Localisation and Lasing: Random and Quasi-Random Photonic Structures, Eds. M. Ghulinyan and L. Pavesi, (Cambridge Univ. Press, Cambridge, 2015) Ch. 1, p.

Wavelength dependence of light diffusion in strongly scattering macroporous gallium phosphide

We present time-resolved measurements of light transport through strongly scattering macroporous gallium phosphide at various vacuum wavelengths between 705 nm and 855 nm. Within this range the transport mean free path is strongly wavelength dependent, whereas the observed energy velocity is shown to be independent of the wavelength. We conclude that microscopic resonances, which can strongly slow down the diffusion process in, e.g., granular TiO2, are absent in macroporous gallium phosphide in the wavelength region of concern

Gain narrowing in few-atom systems

Using a density matrix approach, we study the simplest systems that display both gain and feedback: clusters of 2 to 5 atoms, one of which is pumped. The other atoms supply feedback through multiple scattering of light. We show that, if the atoms are in each other's near-field, the system exhibits large gain narrowing and spectral mode redistribution. The observed phenomena are more pronounced if the feedback is enhanced. Our system is to our knowledge the simplest exactly solvable microscopic system which shows the approach to laser oscillation

Transport of quantum noise through random media

We present an experimental study of the propagation of quantum noise in a multiple scattering random medium. Both static and dynamic scattering measurements are performed: the total transmission of noise is related to the mean free path for scattering, while the noise frequency correlation function determines the diffusion constant. The quantum noise observables are found to scale markedly differently with scattering parameters compared to classical noise observables. The measurements are explained with a full quantum model of multiple scattering