title: Parity time-symmetric vertical cavities: intrinsically single-mode regime in longitudinal direction.
abstract: We explore a new class of distributed feedback (DFB) structures that employ the recently-developed concept of parity-time (PT) symmetry in optics. We show that, based on PT-symmetric pure reflective volume gratings, a vertical surface-emitting cavity can be constructed. We provide a detailed analysis of the threshold conditions as well as the wavelength and angular spectral characteristics using the Kogelnik coupled-wave approximation, backed up by an exact solution of the Helmholtz equation. We show that such a PT-symmetric cavity can be configured to support one and only one longitudinal mode, leading to inherently single-mode lasing.
authors.forename: Hugh F
authors.initials: HF
authors.lastname: Jones
authors.forename: Mykola
authors.initials: M
authors.lastname: Kulishov
authors.forename: Bernard
authors.initials: B
authors.lastname: Kress