title: Single-mode laser by parity-time symmetry breaking.
abstract: Effective manipulation of cavity resonant modes is crucial for emission control in laser physics and applications. Using the concept of parity-time symmetry to exploit the interplay between gain and loss (i.e., light amplification and absorption), we demonstrate a parity-time symmetry-breaking laser with resonant modes that can be controlled at will. In contrast to conventional ring cavity lasers with multiple competing modes, our parity-time microring laser exhibits intrinsic single-mode lasing regardless of the gain spectral bandwidth. Thresholdless parity-time symmetry breaking due to the rotationally symmetric structure leads to stable single-mode operation with the selective whispering-gallery mode order. Exploration of parity-time symmetry in laser physics may open a door to next-generation optoelectronic devices for optical communications and computing.
authors.affiliation: NSF Nanoscale Science and Engineering Center, University of California, Berkeley, CA 94720, USA.
authors.forename: Liang
authors.initials: L
authors.lastname: Feng
authors.affiliation: NSF Nanoscale Science and Engineering Center, University of California, Berkeley, CA 94720, USA.
authors.forename: Zi Jing
authors.initials: ZJ
authors.lastname: Wong
authors.affiliation: NSF Nanoscale Science and Engineering Center, University of California, Berkeley, CA 94720, USA.
authors.forename: Ren-Min
authors.initials: RM
authors.lastname: Ma
authors.affiliation: NSF Nanoscale Science and Engineering Center, University of California, Berkeley, CA 94720, USA. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: NSF Nanoscale Science and Engineering Center, University of California, Berkeley, CA 94720, USA. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. xiang@berkeley.edu.
authors.forename: Xiang
authors.initials: X
authors.lastname: Zhang