Resonance and transparency

Jinyong Ma, Jiayi Qin, Geoff Campbell +5 more

Induced transparency is a common but remarkable effect in optics. It occurs when a strong driving field is used to render an otherwise opaque material transparent. The effect is known as electromagnetically induced transparency in atomic media and optomechanically induced transparency in systems that consist of coupled optical and mechanical resonators. In this work, we introduce the concept of photothermally induced transparency (PTIT). It happens when an optical resonator exhibits nonlinear behavior due to optical heating of the resonator or its mirrors. Similar to the established mechanisms for induced transparency, PTIT can suppress the coupling between an optical resonator and a traveling optical field. We further show that the dispersion of the resonator can be modified to exhibit slow or fast light. Because of the relatively slow thermal response, we observe the bandwidth of the PTIT to be 2π × 15.9 Hz, which theoretically suggests a group velocity of as low as 5 m/s.

Shachar Klaiman, Ido Gilary

Shuting Guo, Yuhong Zhang, Liu-Le Wu +2 more

Electromagnetically induced transparency and absorption in atomic systems have applications such as slow-light generation. Coupled-resonator-induced transparency (CRIT) and absorption (CRIA) are the optical analogy to them. Here we theoretically and experimentally study CRIT and CRIA in two directly coupled whispering-gallery-mode microresonators. The theoretical results give conditions for observing CRIT and CRIA, and predict that a transition between them will happen if we change the coupling strength between the two microresonators or the coupling strength between the fiber taper and the first microresonator. The experimental results demonstrate the transitions between CRIT and CRIA using a microsphere coupled to a sausagelike microresonator. The obtained results give some guidelines to observe CRIT and CRIA.

Frederic R. Morgenthaler

Andrei I. Maimistov, Ashat M. Basharov

Danfeng Cui, Chenyang Xue, Chao Liu +3 more

In the paper, Coupled-resonator-induced-transparency (CRIT) phenomenon in a novel integrated on-chip optical resonator system is experimentally demonstrated. The system is composed of a four-ring resonator with 20 μm diameter on silicon, whose spectrum has a narrow transparency peak with low group velocity. The CRIT effect is observed in the optical coupled-resonator due to the classical destructive interference. This system can be used to study the slow and fast light experiments because of its simplicity and flexibility. In this work, a CRIT resonance with a quality factor of 7.2×104is demonstrated with the same cavity size and the power coupling of the system is 60%, which agree well with the theoretical analysis. The through and drop transmission spectra of the resonator are coincided well with each other.