# Directional Emission and Universal Far-Field Behavior from Semiconductor Lasers with Limacon-Shaped Microcavity

 Title: Directional Emission and Universal Far-Field Behavior from Semiconductor Lasers with Limacon-Shaped Microcavity Author: Capasso, Federico; Yan, Changling; Wang, Qi Jie; Diehl, Laurent; Hentschel, Martina; Wiesig, Jan; Yu, Nanfang; Belkin, Mikhail A.; Edamua, Tadataka; Yamanishi, Masamichi; Kan, Hirofumi; Pflügl, Christian Note: Order does not necessarily reflect citation order of authors. Citation: Yan, Changling, Qi Jie Wang, Laurent Diehl, Martina Hentschel, Jan Wiersig, Nanfang Yu, Christian Pflügl et al. 2009. Directional emission and universal far-field behavior from semiconductor lasers with limacon-shaped microcavity. Applied Physics Letters 94(25): 251101. Full Text & Related Files: Yan_APL_94_251101_2009.pdf (422.8Kb; PDF) Abstract: We report experimental demonstration of directional light emission from limaçon-shaped microcavity semiconductor lasers. Quantum cascade lasers (QCLs) emitting at $$\lambda \approx 10 \mu m$$ are used as a model system. Both ray optics and wave simulations show that for deformations in the range $$0.37< \epsilon <0.43$$, these microcavities support high quality-factor whispering gallerylike modes while having a directional far-field profile with a beam divergence $$\theta \approx 30°$$ in the plane of the cavity. The measured far-field profiles are in good agreement with simulations. While the measured spectra show a transition from whispering gallerylike modes to a more complex mode structure at higher pumping currents, the far field is insensitive to the pumping current demonstrating the predicted “universal far-field behavior” of this class of chaotic resonators. Due to their relatively high quality factor, our microcavity lasers display reduced threshold current densities compared to conventional ridge lasers with millimeter-long cavities. The performance of the limaçon-shaped QCLs is robust with respect to variations of the deformation near its optimum value of $$\epsilon = 0.40$$. Published Version: http://dx.doi.org/10.1063/1.3153276 Terms of Use: This article is made available under the terms and conditions applicable to Other Posted Material, as set forth at http://nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of-use#LAA Citable link to this page: http://nrs.harvard.edu/urn-3:HUL.InstRepos:5096753 Downloads of this work:

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