29. Photo diode When a photon of sufficient energy strikes the diode, it excites an electron, thereby creating a mobile electron and a positively charged electron hole.
31. P-I-N diode The intrinsic "i" region is flooded with charge carriers from the "p" and "n" regions. Its function is similar to filling up a water bucket with a hole on the side. If,water reaches the hole's level it will begin to pour out. Similarly the Pin diode will conduct where the number of electrons is equal to the number of holes in the intrinsic region
32.
33.
34. Fiber optic sensors – temperature & displacement