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Resonance Modes Extremely Sensitive to the Asymmetry of Cavity Shape

In 1958, Roger Penrose proposed an interesting two-dimensional geometry (known as the Penrose unilluminable room) which always has dark regions unreachable by optical rays regardless of where a point light source is set within the cavity. In the present work, the dependency of resonance modes on the asymmetry of the cavity shape of the Penrose unilluminable room was investigated using numerical calculations based on the finite element method. It was found that there exist resonance modes which are extremely sensitive to the asymmetry of the cavity shape. The formation mechanism of these resonance modes can be explained by the modal interaction between two resonance modes confined in different cavity regions.