Optical Detector for Improved Signal Amplification

Optical signal amplificationImproved sensitivity

Nuclear reactors and fuel processingCharacterization of nuclear fuel rodsDetection of concealed fissile and radioactive materialsMedical and military imaging systemsCommunication devices

This method of optical signal amplification detects incident photons through absorption, increasing the carrier concentration, thereby modulating the index of refraction and the reflectivity of the semiconductor in a way that can be monitored externally. By operating without the need for other active electronic elements on the photodetector, the device eliminates the concern over active elementsΓÇÖ risk of operational problems compared to passive elements. It enhances detection of weak electromagnetic (EM) signals by amplifying the signal optically instead of traditional electrical amplification. Operating on the principle of photoexcitation, it transfers electrons from the dopant energy level to the conduction band or from the valance band to the dopant energy level, for n- and p-type dopants, respectively. When paired with a laser beam on the semiconductor surface from a diode laser or other source, the device changes the electron density in the conduction of valence bands, which then changes both the refractive index and the semiconductor's reflectivity, resulting in an amplified signal output.

USA