Laser warning receiver

As part of the increasing range of sensors of hostile electronic warfare, a laser warning receiver detects the energy of laser rangefinders or laser designators. It is often necessary for them to contain multiple semiconductor detectors to cover the multiple wavelengths used by military lasers. The receiver must detect optical signals from all angles, and provide information on their wavelength, possibly modulation, and direction of arrival.

While uncooled detectors are available for shorter wavelengths, the basic technologies for long-wave infrared tend to require cryogenic detectors. The infrared seekers of missiles can rely on compressed gas cooling, since they only need to operate for a short time, but this is much more problematic for a continuously operating warning receiver.

Wavelength	Detector technology	Comments
Ultraviolet, visible and short infrared (0.3-1.1 nm)	uncooled silicon
Short and middle infrared	(< 2.5 nm) uncooled PbS (< 3.5 nm) uncooled InAs PbSe (<4 mm) InSb (<5 mm)
10.6 nm far infrared	Challenging: four-stage thermal-electric cooled (to 200 K) HgCdTe photoconductors take 5W power Thermopiles are too slow photoconductivity (R005, PCI-L, MPC), photoelectromagnetic (PEM-L, PEMI-L) or photodiffusion effects (PDI-L).	Range of CO2 lasers