| B. Peng, Ş. K. Özdemir, S. Rotter, H. Yilmaz, M. Liertzer, F. Monifi, C. M. Bender, F. Nori, L. Yang
This article explores the counterintuitive effects of loss-induced suppression and revival of lasing in coupled microresonators near an exceptional point (EP). The study demonstrates that by steering system parameters to the vicinity of an EP, where eigenvalues and eigenstates coalesce, loss can be transformed into gain, enabling lasing to recover despite increasing loss. This behavior contrasts with conventional laser theory, where increasing loss typically suppresses lasing.
The research focuses on two directly-coupled silica whispering-gallery-mode resonators (WGMRs), each coupled to a fiber-taper. By adjusting the inter-resonator coupling strength and introducing additional loss via a chromium-coated nanofiber tip, the system is tuned to explore the behavior near an EP. The results show that as loss increases, the eigenfrequencies of the system evolve in a complex manner, with the real parts approaching each other and the imaginary parts diverging after passing the EP. This leads to one mode becoming less lossy and the other more lossy.
The study also examines the effect of the EP on intracavity field intensities. As loss increases, the intensity initially decreases but then recovers, demonstrating the EP's role in reversing the effects of loss. This phenomenon is attributed to the localization of supermodes in the less lossy resonator, leading to a non-monotonic evolution of the total intracavity field intensity.
Furthermore, the research investigates the impact of loss on thermal nonlinearity and Raman lasing in WGMRs. Thermal broadening of resonance lines and the recovery of Raman lasing upon increasing loss are observed, highlighting the EP's influence on nonlinear processes. The results show that near an EP, increased loss can actually enhance certain processes, such as Raman lasing, due to the reconfiguration of supermodes.
The study provides a comprehensive platform for exploring non-Hermitian systems and their behavior, with potential applications in controlling and reversing the effects of loss in various physical systems. The findings underscore the unique properties of EPs and their role in enabling counterintuitive phenomena in optical systems.This article explores the counterintuitive effects of loss-induced suppression and revival of lasing in coupled microresonators near an exceptional point (EP). The study demonstrates that by steering system parameters to the vicinity of an EP, where eigenvalues and eigenstates coalesce, loss can be transformed into gain, enabling lasing to recover despite increasing loss. This behavior contrasts with conventional laser theory, where increasing loss typically suppresses lasing.
The research focuses on two directly-coupled silica whispering-gallery-mode resonators (WGMRs), each coupled to a fiber-taper. By adjusting the inter-resonator coupling strength and introducing additional loss via a chromium-coated nanofiber tip, the system is tuned to explore the behavior near an EP. The results show that as loss increases, the eigenfrequencies of the system evolve in a complex manner, with the real parts approaching each other and the imaginary parts diverging after passing the EP. This leads to one mode becoming less lossy and the other more lossy.
The study also examines the effect of the EP on intracavity field intensities. As loss increases, the intensity initially decreases but then recovers, demonstrating the EP's role in reversing the effects of loss. This phenomenon is attributed to the localization of supermodes in the less lossy resonator, leading to a non-monotonic evolution of the total intracavity field intensity.
Furthermore, the research investigates the impact of loss on thermal nonlinearity and Raman lasing in WGMRs. Thermal broadening of resonance lines and the recovery of Raman lasing upon increasing loss are observed, highlighting the EP's influence on nonlinear processes. The results show that near an EP, increased loss can actually enhance certain processes, such as Raman lasing, due to the reconfiguration of supermodes.
The study provides a comprehensive platform for exploring non-Hermitian systems and their behavior, with potential applications in controlling and reversing the effects of loss in various physical systems. The findings underscore the unique properties of EPs and their role in enabling counterintuitive phenomena in optical systems.