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- ItemStripe-array diode-laser in an off-axis external cavity : theory and experiment(Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2009) Jechow, Andreas; Lichtner, Mark; Menzel, Ralf; Radziunas, Mindaugas; Skoczowsky, Danilo; Vladimirov, AndreiStripe-array diode lasers naturally operate in an anti-phase supermode. This produces a sharp double lobe far field at angles α depending on the period of the array. In this paper a 40 emitter gain guided stripe-array laterally coupled by off-axis filtered feedback is investigated experimentally and numerically. We predict theoretically and confirm experimentally that at doubled feedback angle 2α a stable higher order supermode exists with twice the number of emitters per array period. The theoretical model is based on time domain traveling wave equations for optical fields coupled to the carrier density equation taking into account diffusion of carriers. Feedback from the external reflector is modeled using Fresnel integration.
- ItemImprovement of output beam quality in broad area lasers with off-axis feedback(Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2011) Lichtner, Mark; Tronciu, Vasile; Vladimirov, Andrej G.We report a method to improve the beam quality of broad area lasers by using a V-shaped external cavity formed by two off-axis feedback mirrors that allow to select a single transverse mode with the intensity modulated in the transverse direction. We find that in the case when one of the two feedback mirrors is absent a spontaneous formation of self-induced transverse population grating leading to a reduction of the lasing threshold is observed. Most favorable conditions for stabilization of single transverse supermode and creation of a high power and high brightness plane wave traveling in the extended cavity are obtained for equal re ectivities of the two external reflectors.