Arrayed waveguide gratings (AWG) are commonly used as in (WDM) systems. These devices are capable of many into a single, thereby increasing the capacity of considerably. The devices are based on a fundamental principle of, which states that of different wavelengths linearly with each other. This means that, if each in an In, wavelength-division multiplexing (WDM) is a technology which a number of signals onto a single by using different (i.e., colors) of. This technique enables communications over a single strand of fiber (also called wavelength-division duplexing) as well as multiplication of capacity.