Loss is one of the main factors that lead to the increase of power consumption and deterioration of performance in optical devices and systems. Therefore, in the process of device design and system construction, people desperatelyavert the introduction of loss. However, in recent years, some new aspects arise that in non-Hermitian systems, the loss can induce modal gain when the parity-timesymmetry is broken. This provides a novel method to manipulate the lasing ofa singleactive cavity.
Fig.1.(a) Schematic diagram of single-cavity PT symmetric system. (b) The polarization evolution for different coupling strengths.(c-d)Experimental results in the forms of (c) optical spectra and (d) electrical spectra.
Thescientists from Wuhan National Laboratory for Optoelectronics and Prof. P.K.A.Wai from the Hong Kong Polytechnic University have designed and demonstrated the suppression and revival phenomenon of single-cavity lasing induced by polarization-dependent loss. The system employed an intensity modulator to adjust gain/loss difference and the coupling between polarization states is controlled by a polarization controller. By increasing cross-polarization loss, the lasing poweris initially declined and then increased after a critical point. The parameters of the system were carefully managed to achieve single-mode lasing. This Letter suggests that the polarization loss can be employed to manipulate the lasing of a singleactive cavity with a new perspective, and similar ideas can beadapted for other applications such as nonreciprocal devices,single-mode lasers, and photonic lattices.
This work has been on-line published in Optics Letters on 24 June 2021. The works were partially supported by Science, Technology and Innovation Commission of ShenzhenMunicipality (SGDX2019081623060558); by National Key Research andDevelopment Program of China (2020YFB1805901); by National Natural Science Foundation of China (61805090, 62075075); by China Postdoctoral Science Foundation (2017M622419); by Hong Kong Scholars Program 2018(XJ2018018).
1. Y. Wei, h. zhou, D. Huang, F. Li, J. Dong, X. Zhang, and P. K. Wai, "Suppression and revival of single-cavity lasing induced by polarization-dependent loss," Opt. Lett. (2021).
