The APD/avalanche photo diode (3G InGaAs pulse APD diode pins for OTDR) is a p-n junction photodetector made of silicon or germanium.By applying a reverse bias voltage to the p-n junction,the incident light photons will strike the electrons in order to push them through a junction,thus achieving photoelectric current flows.When the applied reverse voltage increases,an avalanche current flow will occur.The avalanche effect of the current carrier is then used to amplify the photoelectric signal in the detection system in order to improve detector sensitivity. 
This photo diode series features a small dark current, low operating voltage, and high sensitivity.It can operate in the pulse output mode or DC output mode, and is often used in OTDR systems and detection equipment for Raman backscattering systems.

The 0.2-2mw 1310nm FP pigtailed laser diode module plug in type is provided in a coaxial plug-in package. It also uses a Fabry–Pérot cavity,which means it features a low threshold and operating current.In addition, the device can be supplied with an SC,ST,or FC connector. It is commonly used in handheld and desktop light sources,optical multi-meters, and communication test equipment.

The large area of the InGaAs PD/photodiode pin for instrumentation features an InGaAs large area detector chip with a long wavelength, giving it a small dark current,a low power consumption,high sensitivity, small volume, and diverse structural designs.It also features a replaceable structure,allowing most fiber optic connector types to be compatible,and thus, facilitate maintenance and use.This product series is most often used in power detection equipment,hand held power meters, desktop power meters and optical multi-meters.