Deformed microcavity quantum cascade lasers with directional emission

We report the experimental realization of deformed microcavity quantum cascade lasers (QCLs) with a Lima on-shaped chaotic resonator. Directional light emission with a beam divergence of theta(parallel to) approximate to 33 degrees from QCLs emitting at lambda approximate to 10 mu m was obtained in the plane of the cavity for deformations in the range 0.37 < epsilon < 0.43. An excellent agreement between measured and calculated far-field profiles was found. Both simulations and experiments show that the Lima on-shaped microcavity preserves whispering gallery-like modes with high Q-factors for low deformations (epsilon < 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 Lima on