# Deformed Microcavity Quantum Cascade Lasers with Directional Emission

 Title: Deformed Microcavity Quantum Cascade Lasers with Directional Emission Author: Wang, Qi; Yan, Changling; Diehl, Laurent; Hentschel, Martina; Wiersig, Jan; Yu, Nanfang; Pflügl, Christian; Edamura, Tadataka; Yamanishi, Masamichi; Kan, Hirofumi; Belkin, Mikhail A.; Capasso, Federico Note: Order does not necessarily reflect citation order of authors. Citation: Wang, Qi Jie, Changling Yan, Laurent Diehl, Martina Hentschel, Jan Wiersig, Nanfang Yu, Christian Pflügl, et al. 2009. Deformed microcavity quantum cascade lasers with directional emission. New Journal of Physics 11(12): 125018. Full Text & Related Files: Wang_NewJP_11_125018_2009.pdf (1.958Mb; PDF) Abstract: We report the experimental realization of deformed microcavity quantum cascade lasers (QCLs) with a Limaçon-shaped chaotic resonator. Directional light emission with a beam divergence of $$\theta_{\|} \approx 33^{\circ}$$ from QCLs emitting at λ ≈ 10µm was obtained in the plane of the cavity for deformations in the range 0.37 < ε < 0.43. An excellent agreement between measured and calculated far-ﬁeld proﬁles was found. Both simulations and experiments show that the Limaçon-shaped microcavity preserves whispering gallery-like modes with high Q-factors for low deformations (ε < 0.50). In addition, while the measured spectra show a transition from whispering gallery-like modes to a more complex mode structure at higher pumping currents, we observed ‘universal far-ﬁeld behavior’ for different intracavity mode distributions in the Limaçon microcavity, which can be explained by the distribution of unstable manifolds in ray optics simulations. Furthermore, the performance of the deformed microcavity lasers is robust with respect to variations of the deformation near its optimum value ε = 0.40, which implies that this structure reduces the requirements on photolithography fabrication. The successful realization of these microcavity lasers may lead to applications in optoelectronics. Published Version: doi:10.1088/1367-2630/11/12/125018 Other Sources: http://www.seas.harvard.edu/capasso/publications/Wang_NewJP_11_125018_2009.pdf 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:9141129

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