Choice of Filters for Pyroelectric Detectors

InGaAs PIN Photodiodes

Modern InGaAs PIN photodiodes are panchromatic and convert broadband light to photocurrents in the Vis-NIR range. Concretely speaking, this means a sensitivity range from 500 nm to 1700 nm for regular InGaAs and – in increments – up to 2600 nm for extended InGaAs. Variations for data transmission are not panchromatic.

PbS and PbSe Detectors

PbS is a standard SWIR semiconductor detector (1 - 3.3 µm) whereas PbSe is used in the MWIR range (1 - 4.7 µm when uncooled; up to 5.2 µm when cooled). Our lead salt detectors are photoconductive; the detector resistance is reduced during illumination. The crystal structure is polycrystalline and is produced via chemical deposition.

Pyroelectric IR Detectors

A pyroelectric IR detector is a thermal detector in that it responds to the change in heat (IR) absorbed on its surface. Thermal detectors are polychromatic with a very wide spectral bandwidth.

The nature of the pyroelectric effect is that in a highly-ordered crystal (or ceramic), a temperature change in the element causes its atoms to move slightly out of position. This rearranges its electrical charge, which is measured in the electrodes on its surface.

The pyroelectric effect is found in many materials.  The most commonly-used materials are deuterated lanthanum α alanine-doped triglycine sulfate (DLaTGS) and lithium tantalate (LTO).