Patent ID: 7187834

Claim:
A sheet-shaped light guide, which includes particles for scattering light in a sheet-shaped optical medium and propagates signal light incident from one end face of the sheet-shaped light guide to the other end face side while scattering the signal light by the particles, wherein a plurality of optical mediums whose refractive indexes are different from each other are used as the optical medium, and an interface between the optical mediums is formed into a curved shape, and has a concave lens effect for the signal light, wherein, when a scattering cross section of the particles is Φ, a length of the optical medium in a light propagation direction is L G , particle density is Np, and a correction coefficient is K C , a value of Φ·Np·L G ·K C is 0.9 or less, and wherein, when rms noise of the system is Noise(System_rms), an acceptable bit error rate is BER(accept), and a probability of occurrence of the Noise(System_rms) is Pr(Noise(System_rms)), the communication system satisfies: Pr(Noise(System_rms)·Q)≦BER(accept) where Q is a proportionality constant.