Gain through losses in nonlinear optics

Instabilities of uniform states are ubiquitous processes occurring in a variety of spatially extended nonlinear systems. These instabilities are at the heart of symmetry breaking, condensate dynamics, self-organization, pattern formation and noise amplification across diverse disciplines, including physics, chemistry, engineering and biology. In nonlinear optics, modulation instabilities are generally linked to the so-called parametric amplification process, which occurs when certain phase-matching or quasi-phase-matching conditions are satisfied. In the present review article, we summarize the principle results on modulation instabilities and parametric amplification in nonlinear optics, with special emphasis on optical fibres. We then review state-of-the-art research about a peculiar class of modulation instabilities and signal amplification processes induced by dissipation in nonlinear optical systems. Losses applied to certain parts of the spectrum counterintuitively lead to the exponential growth of the damped mode themselves, causing gain through losses. We discuss the concept of imaging of losses into gain, showing how to map a given spectral loss profile into a gain spectrum. We demonstrate with concrete examples that dissipation-induced modulation instability, apart from being of fundamental theoretical interest, may pave the way towards the design of a new class of tuneable fibre-based optical amplifiers, optical parametric oscillators, frequency comb sources and pulsed lasers

Poly Economics-Capitalism, Class, and Polyamory

Academic research and popular writing on nonmonogamy and polyamory has so far paid insufficient attention to class divisions and questions of political economy. This is striking since research indicates the significance of class and race privilege within many polyamorous communities. This structure of privilege is mirrored in the exclusivist construction of these communities. The article aims to fill the gap created by the silence on class by suggesting a research agenda which is attentive to class and socioeconomic inequality. The paper addresses relevant research questions in the areas of intimacy and care, household formation, and spaces and institutions and advances an intersectional perspective which incorporates class as nondispensable core category. The author suggests that critical research in the field can stimulate critical self-reflexive practice on the level of community relations and activism. He further points to the critical relevance of Marxist and Postmarxist theories as important resources for the study of polyamory and calls for the study of the contradictions within poly culture from a materialist point of view. © 2013 Springer Science+Business Media New York