An ultra-sensitive HgCdTe (mercury cadmium telluride) avalanche photodiode. Photodiodes are semiconductor sensors that convert light into electrical current, photon by photon. However, when the light signal becomes too weak, it quickly gets lost in electronic noise. Avalanche photodiodes (APDs) amplify weak signals by generating multiple charge carriers for each absorbed photon. Yet, conventional APD technologies are limited: the simultaneous ­multiplication of electrons and holes leads to significant gain fluctuations, causing excess noise and reducing overall sensitivity. This solution is based on the use of a HgCdTe alloy that enables exclusive electron multiplication. This unique mechanism allows gains exceeding 1000, with a noise factor (F) close to 1.0, ensuring ultra-sensitive detection and unmatched precision.