Control of directional emission of resonance modes in an asymmetric cylindrical microcavity

Abstract Multimode laser emission in the visible spectral range has been demonstrated using deformed cylindrical microcavity based on Rhodamine B dye doped hollow polymer optical fiber upon optical pumping. A detailed study of the spectral features of the emission shows that an asymmetric cylindrical microcavity can have simultaneous excitation of different Q modes. We observed two different cavity dependent resonant laser modes; fundamental whispering gallery high Q modes (HQMs) and leaky unidirectional low Q modes (LQMs). The Q value of HQMs and LQMs were found to be 1.2 × 10 4 and 5 × 10 3 respectively. Numerical results obtained were also supported the experiment that an asymmetric resonant cavity (ARC) with suitably positioned air hole can support LQM with highly directional emission. These findings open up an efficient way to control the emission directionality by controlled breaking the symmetry within the microcavity.