Wide field-of-view optical broadcasting for bi-directional indoor optical wireless communications employing PAM-4 modulation

We present wide field-of-view (FOV) bi-directional point-to-multipoint indoor optical wireless communications operating over a range of 4 m. The system is designed to integrate with fiber-to-the-home/building networks realized by a passive optical network. A phase-only spatial light modulator (SLM)-based beam steering base station with a ±30° FOV broadcasts downstream transmissions to two nomadic user terminals that use mirror-based beam steering to provide a ±50° FOV. At the base station, a composite phase mask is constructed on the SLM not only to perform optical broadcasting, but also to steer upstream optical transmissions from user terminals at a different wavelength. Successful upstream and downstream data transmission of 25 Gbit/s PAM4 is achieved.