InGaAs Avalanche Photodiode (APD) chips are semiconductor devices that are designed to detect weak optical signals in the infrared region. They are used in a variety of applications, such as fiber optic communications, LIDAR, and sensing. An APD is a type of photodiode that incorporates an internal gain mechanism, which allows it to achieve higher sensitivity than a standard photodiode. The gain is achieved through a process called avalanche multiplication, where a single photon creates an electron-hole pair, which then undergoes impact ionization, producing additional electron-hole pairs. This process results in an amplified output signal. InGaAs APDs are particularly useful for detecting wavelengths between 800 and 1700 nm.LD-PD INC is a company who design and manufacture InGaAs APD Chips.