Holographic Diffusers for Indoor Infrared Communication Systems

Diffused infrared transmission is one of the preferred techniques used in indoor wireless communications. Tolerance to shadowing and a lack of alignm ent requirements are among the many advantages offered by this technique compared to the line-of-sight techniques. However, it has its disadvantages, namely high path loss and multipath dispersion. The limitation imposed by eye-safety requirements restricts the transm itted power. Therefore, ef® cient use of transmitted optical power is the key for practical broadband infrared systems. In this paper, we report on using a holographic diffuser for shaping of infrared radiation pattern in an indoor infrared transmission system. The holographic diffusers have the advantage of light weight and added ̄ exibility in the system design. The reported measurements show that employing a properly designed holographic diffuser can reduce the path loss of a nondirected optical link. The results also show another advantage of using the proposed holographic diffuser, which is additional tolerance of the transmission to shadowing.