A stacked image sensor comprises an array of tiles, each comprising a sensor array layer tile comprising a plurality of sensing elements for receiving radiation, one or more electronics layer tiles comprising at least one read-out circuit, connected to at least one subgroup of sensing elements of the sensor array layer tile, a photonics layer tile comprising at least one waveguide and one or more modulators, each connected to the one or more electronics layer tiles. The modulators are adapted for modulating an optical signal travelling within the at least one waveguide. The electronics layer tile comprises at least one driver for driving an optical modulator in the photonics layer tile in accordance with the signals received in each sensing element of the sensor array layer tile. At least one of the layer tiles (sensor array layer, electronics layer and/or photonics layer tiles) is implemented in a single integrated circuit.