Response linearization of a 2D optical position-sensitive detector

This paper presents an alternative layout for a two-dimensional optical position-sensitive detector, namely a quad-cell, where the sensitivity (i.e. quantum efficiency) of the central region is higher than that of the peripheral region. Simulation results show that this approach improves the linearity of the quad-cell response at the central region, which is relevant in applications where high position resolution is demanded. A numerical model provides indication to an optimal spot-radius range and experimental results confirm good linearity for a spot within this range.