Incident Direction Independent Wave Propagation and Unidirectional Lasing.

L Jin,Z Song

doi:10.1103/physrevlett.121.073901

Abstract

We propose an incident direction independent wave propagation generated by properly assembling different unidirectional destructive interferences (UDIs), which is a consequence of the appropriate match between synthetic magnetic fluxes and the incident wave vector. Single-direction lasing at spectral singularity is feasible without introducing nonlinearity. UDI allows unidirectional lasing and unidirectional perfect absorption; when they are combined in a parity-time-symmetric manner, the spectral singularities vanish with bounded reflections and transmissions. Furthermore, the simultaneous unidirectional lasing and perfect absorption for incidences from opposite directions is created. Our findings provide insights into light control and may shed light on the explorations of desirable functionality in fundamental research and practical applications.

Highlights

Introduction.—Parity-time (PT ) symmetry has been theoretically and experimentally investigated in a variety of non-Hermitian systems [1–22]; non-Hermiticity controls the exact and broken PT -symmetric phases [18–22]
Typical phenomena include unidirectional reflectionlessness [49,50] and unidirectional spectral singularity that allows unidirectional perfect absorption (UPA) and unidirectional lasing (UL) [51,52]; the transmissions there protected by symmetry are reciprocal [60–63]
Benefited from synthetic magnetic flux realized for photons [71–79] and progress in non-Hermitian physics [22], non-Hermiticity associated with synthetic magnetic flux

Summary

Introduction

Introduction.—Parity-time (PT ) symmetry has been theoretically and experimentally investigated in a variety of non-Hermitian systems [1–22]; non-Hermiticity controls the exact and broken PT -symmetric phases [18–22]. At φα 1⁄4 π þ k, the scattering of left incidence with wave vector k is fixed even though Vα varies; the perfect absorption occurs for the right incidence when Vα 1⁄4 −eik [Fig. 1(b)].

Results

Conclusion