Single mode lasing in transversely multi-moded PT-symmetric microring   resonators
  Single mode lasing is experimentally demonstrated in a transversely multi-moded InP-based semiconductor microring arrangement. In this system, mode discrimination is attained by judiciously utilizing the exceptional points in a parity-time (PT) symmetric double microring configuration. The proposed scheme is versatile, robust to small fabrication errors, and enables the device to operate in a stable manner considerably above threshold while maintaining spatial and spectral purity. The results presented here pave the way towards a new class of chip-scale semiconductor lasers that utilize gain/loss contrast as a primary mechanism for mode selection. 
Hoseein Hodaei, Mohammad-Ali Miri, Absar U. Hassan, William E.   Hayenga, Matthias Heinrich, Demetrios N. Christodoulides, M...
physics.optics