In a digital optical switch, an input waveguide and two output waveguides form a Y-shaped splitter or switch. The apparatus and method may pack multiple data objects together in a block of a logical container in a file system. The semiconductor layer of the light absorbing region forms a p-n junction with the first semiconductor layer. The temporal difference filter includes a detection zone image memory, a peripheral zone image memory, a subtracter, and a motion quantity calculator. The map characterizing the die areas based on a first measurement of each individual die area.