Duration: 12 months
Sun sensors have many applications including, for instance, the orientation of satellites. These sensors determine the direction of light based on geometrical principles under a ray approximation of light. This usually involve some sort of light projection or non-planar structures, which can limit accuracy and reliability, and require precise alignment. In this project we aim to develop a new concept of light angle detection based on the wave nature of light. In particular, the sensor will be based on the angle-dependence of the transmittance spectrum through a layer designed to interfere with light (e.g. rugate filter, grating or a 2D metasurface, among others). In order to obtain a compact sensor design, the transmission spectra will be sampled at different spectral regions through a small matrix of photodetectors and absorptive filters (see the figure as an example of one ‘pixel’ detector). The angle of light will be determined from the relative intensity detected by the individual pixels of the matrix. Notice that the structure would be somewhat similar to a CCD image sensor but with a just few large pixels and the inclusion of the interference layer, which might also differ between "pixels". Also notice that, here, pixels do not play an imaging role. And some implementations might require as few as two "pixels". We envisage that a sensor based in this principle would present several advantages over the standard approaches: (1) The sensor will work on the full hemisphere, (2) superior sensitivity with peak sensitivity outside the normal incidence direction, (3) better performance in the prescience of diffuse or stray light, and (4) fully-integrated MOS-compatible on-chip solution. However, further investigation, both theoretically and experimentally, needs to be performed in order to demonstrate whether all these potential advantages can be realized.
