Holographic optical receiver front end for wireless infrared indoor communications

Multispot diffuse configuration (MSDC) for indoor wireless optical communic ations, utilizing multibeam transmitter and angle diversity detection, is o ne of the most promising ways of achieving high capacities for use in high- bandwidth islands such as classrooms, hotel lobbies, shopping malls, and tr ain stations. Typically, the optical front end of the receiver consists of an optical concentrator to increase the received optical signal power and a n optical bandpass filter to reject the ambient light. Using the unique pro perties of holographic optical elements (HOE), we propose a novel design fo r the receiver optical subsystem used in MSDC. With a holographic curved mi rror as an optical front end, the receiver would achieve more than an 10-dB improvement in the electrical signal-to-noise ratio compared with a bare p hotodetector. Features such as multifunctionality of the HOE and the receiv er's small size, light weight, and low cost make the receiver front end a p romising candidate for a user's portable equipment in broadband indoor wire less multimedia access. (C) 2001 Optical Society of America.