Multiple position sensitive photodetector for optical differential detection

A Position Sensitive Detector (PSD) array formed by 64 one-dimensional PSDs is presented and characterized. Shallow and low-doped p–n junctions are formed by boron implantation in n-type silicon substrate to fabricate the PSD structure. The Lateral Photo-Voltage (LPV) of the device has shown a linear position characteristic within its whole length of about 2 cm when irradiated by a He–Ne laser beam with a power of 1.74 μW. The dependence of the LPV on the incident optical power was studied and saturation effects were observed for values above 10 μW. Dual beam experiments were performed to study the concept of using single PSD as dual optical signal subtraction detector.