Unidirectional spectral singularity lasing in a defective atomic lattice

TL;DR

This paper introduces a novel scheme for unidirectional reflection lasing using a defective atomic lattice that combines gain, feedback, and symmetry breaking, enabling efficient, tunable, and integrated photonic devices.

Contribution

It presents a new method to achieve mode-tunable unidirectional lasing with a defective atomic lattice that acts as a distributed feedback mechanism and breaks spatial symmetry.

Findings

Achieves nonreciprocity and lasing oscillation simultaneously.

Demonstrates control of spectral singularity via external fields and lattice design.

Enhances optical transmission efficiency and integration in quantum networks.

Abstract

We propose an efficient scheme for achieving mode-tunable unidirectional reflection lasing (URL) by establishing a coherent gain atomic system to amplify the probe field and ingeniously designing the one-dimensional (1D) defective atomic lattice. This lattice not only replaces the resonant cavity to provide a distributed feedback mechanism but also breaks the spatial symmetry of the probe susceptibility. Correspondingly, the URL can be characterized by a non-Hermitian degenerate spectral singularity (NHDSS), where the two eigenvalues of the inverse scattering matrix are engineered to satisfy $\lambda _{{S^{-1}}}^{+}\simeq \lambda _{{S^{-1}}}^{-}\rightarrow 0$. This intriguing NHDSS depends on the probe susceptibility and the Bragg condition, both of which can be modulated by adjusting the external optical field and lattice structure, rendering the scheme experimentally feasible. Our approach achieves both nonreciprocity and lasing oscillation in a single system, significantly enhancing the efficiency of optical information transmission and facilitating the integration of active photonic devices into compact quantum networks.