Lead calcium titanate ceramics and integrated optical filters for infrared optical sensors

A novel system for improving the performance of lead calcium titanate (PCT) ceramics for infrared sensor applications is proposed. The main feature of the system is its ability to integrate, on the same substrate, different thin-film optical filters with defined geometries, in order to obtain arrays of optical filters. Each point on the substrate would correspond to a filter with a previously defined wavelength profile. The first achievement of the system is the preparation of a multispectral substrate with different optical filters integrated in the same plane, which correspond to the focal plane of the pyroelectric PCT sensor. This concept would make it possible to obtain multispectral integrated sensors or `retinas´, by hybrid or monolithic coupling of the filters on the pyroelectric detector in the same or a very close substrate (focal plane). Results of preliminary experiments have demonstrated the feasibility of the proposed system. Values of the pyroelectric coefficient, dielectric constant, and a remanent d₃₃ show that Ca-modified lead titanate is an excellent pyroelectric sensor