Self-induced transparency in a perfectly absorbing chiral second-harmonic generator

Abstract

Transparency and perfect absorption are two contradictory terms; a perfect absorber never permits waves to transmit through. However, this statement only remains true in the linear regime, where the nonlinearity has been omitted and the physical system like the perfect absorber is not affected by the incoming waves. Here we experimentally demonstrate an intriguing self-induced transparency effect in a perfectly absorbing optical microcavity, which perfectly absorbs any incoming waves at the low power level, but allows a portion of waves to be transmitted at the higher power due to the nonlinear coupling between the fundamental and its second harmonic modes. Moreover, the asymmetric scattering nature of the microcavity enables a chiral and unidirectional reflection in one of the input ports, this leads to asymmetric and chiral coherent control of the perfect absorption states through phase varying. More importantly, such chiral behaviors also empower the chiral emission of second-harmonic generation with a high distinct ratio in the transparency state. These results pave the way for controllable transparency in a wide range of fields in optics, microwaves, acoustics, mechanics, and matter waves.

Light squeezing enhancement by coupling nonlinear optical cavities

“…( 9 ) and ( 10 ) are similar with the temporal coupled-mode theory used in Refs. 43 , 44 . After solving these equations in the steady-state regime and considering the case of , we plot in Fig.…”

Scattering exceptional point in the visible

“…In the early stage of implementing EPs, the optical gain and loss were integrated as non-conservative components in a simple one-dimensional transmission system to achieve Eps 18 , 19 , while the optical gain often leads to complex and unstable systems. EPs can also be observed by designing complex permittivity in all-passive systems, which inspires the study of EP-related phenomena 20 , for instance, the one-way cloaking 21 – 23 . However, one-dimensional transmission systems have limited capabilities in controlling lightwaves 24 – 28 .…”

Backscattering-Induced Chiral Absorption in Optical Microresonators

“…Due to the high quality ( Q ) factor and small mode volume, whispering-gallery-mode (WGM) optical microresonators provide a prominent platform for various applications, such as ultralow-threshold lasers, − highly sensitive sensors, − nonlinear optics, − and optomechanics. − Recently, there has been a great deal of interest in chiral optical states of WGM microresonators. In a WGM microresonator, light fields in the clockwise (CW) and counterclockwise (CCW) directions are coupled with each other due to the backscattering, which originates from the imperfections in the microresonator. , Generally, chiral optical states of WGM microresonators appear when the chiral symmetry of the CW and CCW light propagation is broken, which can be realized by asymmetrical scattering, − deformed resonators, − and spontaneous symmetry breaking based on optical nonlinearity. − Chiral optical states are important and can be used to manipulate the propagating direction of a light field, − which is crucial for the realization of novel functional devices, such as unidirectional lasers, ,, gyroscopes, , and single-nanoparticle sensors …”