Observation of a manifold in the chaotic phase space of an asymmetric optical microcavity

Chaotic dynamics in optical microcavities, governed dominantly by manifolds, is of great importance for both fundamental studies and photonic applications. Here, we report the experimental observation of a stable manifold characterized by energy and momentum evolution in the nearly chaotic phase space of an asymmetric optical microcavity. By controlling the radius of a fiber coupler and the coupling azimuth of the cavity, corresponding to the momentum and position of the input light, the injected light can in principle excite the system from a desired position in phase space. It is found that once the input light approaches the stable manifold, the angular momentum of the light experiences a rapid increase, and the energy is confined in the cavity for a long time. Consequently, the distribution of the stable manifold is visualized by the output power and the coupling depth to high-Q modes extracted from the transmission spectra, which is consistent with theoretical predictions by the ray model. This work opens a new path to understand the chaotic dynamics and reconstruct the complex structure in phase space, providing a new paradigm of manipulating photons in wave chaos.