The Complex Way to Laser Diode Spectra: Example of an External Cavity Laser With Strong Optical Feedback

An external cavity laser with strong grating-filtered feedback to an antireflection-coated facet is studied with a time-domain integral equation for the electric field, which reproduces the modes of the oscillation condition as steady-state solutions. For each mode, the stability and spectral behavior is determined by analysis of the location of side modes in the complex frequency plane. The complex frequency diagrams are shown to be a useful tool to determine the self-stabilization effect of mode coupling and its dependence on laser parameters and external cavity design. The model is used to simulate the large signal time evolution after start from unstable mode

Electromagnetic corrections for the analysis of low energy pi-p scattering data

We calculate the electromagnetic corrections to the isospin invariant mixing angle and to the two eigenphases for the s and p-waves for low energy pi-p elastic and charge exchange scattering. These corrections have to be applied to the nuclear quantities obtained from phase shift analyses of the experimental data in order to obtain the hadronic phases. We compare our results with earlier calculations and estimate the uncertainties in the corrections.Comment: 19 pages, 5 figures. Uses elsart.cls Accepted for publication in Nuclear Physics

When welfare states retrench : the relationship between median voter prferences, government debt and welfare state outcomes in established democracies

Title from PDF of title page (University of Missouri--Columbia, viewed on November 5, 2012).The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Thesis advisor: Dr. Robin BestIncludes bibliographical references.M.A. University of Missouri--Columbia 2012."July 2012"Welfare state spending cuts constitute one of the most economically efficient ways to achieve fiscal consolidation, but some policymakers prefer other methods of fiscal consolidation when government debt levels are high. In this paper I examine this phenomenon and hypothesize that the economic incentive to cut welfare spending when government debt levels are high can be undermined by the political incentive to stay in power. Specifically, I hypothesize that government debt and median voter preferences interact to shape welfare state outcomes; high levels of government debt lead to welfare retrenchment, but only if the median voter does not oppose cuts in welfare spending. Using data on government spending and median voter preferences from 18 OECD countries, I estimate a series of regressions, showing that government debt does lead to overall welfare spending cuts when the median voter does not oppose overall welfare retrenchment, and that government debt has a negative impact on unemployment spending, but not on old age pension spending. This is consistent with the theoretical framework as unemployment spending is consistently less popular with the median voter than old age pension spending because unemployment benefits protect against labor market risks, whereas old age pensions protect against life course risks

Dynamical properties of nanolasers based on few discrete emitters

We investigate the dynamical properties of nanolasers comprising a few two-level emitters coupled to an optical cavity. A set of rate equations is derived, which agree very well with a solution of the full master equation model and makes it simple to investigate the properties of the system. Using a linearized version of these rate equations, we can analytically express the response of the nanolaser to a modulation of the pumping rate. These results are compared to the modulation response obtained directly from the master equation using a novel method. Using the rate equation method, we calculate the modulation bandwidth and show that, contrary to conventional semiconductor lasers, the nanolaser is typically over-damped and displays a dip in the modulation bandwidth as the two-level systems become inverted. Both these features can be traced back to the modeling of the emitters as two-level systems that are incoherently pumped.Comment: 11 pages, 5 figure