Completely Closed Optical Shell Using Total Internal Reflection with Simple Composition

Abstract

A simple completely closed optical shell is proposed. This shell consists of only a block made of a transparent material with a cave inside, although it is required that the inner and outer surfaces of the shell consist of specially arranged planes and that the refractive index of the material of the shell is larger than √4+2√2≈2.613…. No light ray from the inside of the shell can pass through the outside of the shell because the light ray always totally internally reflects at the outer surface of the shell. On the other hand, no light ray from outside can enter the cave through this transparent shell. It is considered that this shell functions as a very high-Q optical cavity and exists in various sizes from micrometers to submeters. The principle of light confinement in the shell is clarified by ray-tracing analysis.