Beam position estimation method for fast beam tracking in free-space optical systems using a quadrant detector

It is of paramount importance to accurately estimate the angular direction of the optical beam incident at the receiver for fast and precise beam alignment between the transmitter and receiver in free-space optical communications. In this work, we propose a beam position estimation method for a quadrant detector and experimentally demonstrate fast beam tracking using the proposed method. The experimental results show that the proposed method tracks the beam 21% and 36% faster than the conventional difference-over-sum and log-ratio methods, respectively.