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Far-field patterns and lasing threshold of limaçon − and quadrupole-shaped microlasers with InGaAs quantum well-dots
We demonstrate that microlasers with an anisotropic cavity (limaçon- or quadrupole-shaped) containing quantum well-dots in the active region are able to operate under continuous wave current injection at 90 °C. Deviation of the cavity shape from circular leads to the directionality of the emission in the lateral direction, while the quality factor of the structures and threshold current remain almost unchanged. The quality factor is estimated to be at least 10^5. A single lobe dominates in the far field of limaçon-shaped microlasers, while quadrupole-shaped microlasers are characterized by two lobes emitted in opposite directions. The lobe of the directional diagram of the limaçons has an angular size of about 50° in the lateral direction and about 8° in the vertical direction. The measured far-field profiles of these microlasers are in excellent agreement with simulations results.