A wide field-of-view receiver that incorporates fluorescent fibers and a SiPM.

A conference presentation at the 2nd Optical Wireless Communications Conference in 2021, with Dr Wajahat Ali as first author. Fluorescent fibers act as 'light antennas': they collect light over a wide field of view (FOV) and couple it into a SiPM, while also filtering out ambient light. The paper is a one-page extended abstract, so it has no separate abstract.

Key Findings

A short length of Kuraray SCSF-81J fiber has a 3 dB frequency of about 117 MHz, against 249 MHz for the J-30020 SiPM it feeds. Coupling 28 fibers, each 12 cm long, to one J-30020 cuts the irradiance needed for OOK at 200 Mbps to 1.4 Gbps by a factor of about 20, compared with a single fiber. Under 500 lux of white LED light, the irradiance needed rises by less than 4.5 dB. Above 800 Mbps, the fluorophore’s bandwidth means a well-chosen absorption filter is the better way to protect the SiPM at normal incidence. The group of 28 fibers keeps a wide FOV until the fibers start to shadow each other, and performance falls quickly between 70° and 90°. In a modelled 3 m high room, the data rate of the fiber receiver depends less on its horizontal distance from the transmitter than that of a planar receiver with an absorption filter.

Further work is needed to improve the coupling between the fibers and the SiPM, and to find the best multi-fiber designs for different applications and host systems. The follow-up paper looks at how long the fibers should be.