*2.3.4 Arrayed waveguide grating (AWG)-based devices*

AWG works on the principle of interference on a specially designed structure as shown in **Figure 7**. It has two free space propagation regions (S1 and S2), an array of waveguides (Wn) in the middle and fibers for input and output. A WDM signal incident on S1 through F traverses the free space and enters the arrayed waveguide region. The length of each waveguide in the arrayed waveguide section is varied such that it introduces a wavelength-dependent phase delay in S2. This phase delay causes the interference points of each wavelength to be spatially separated, where a fiber is connected to collect each wavelength, hence attaining DeMux.

AWG has some interesting features as follows which makes it very attractive.

• AWG has a flat spectral response.

**Figure 6.** *Diffraction grating-based Mux configuration [10].*

**Figure 7.** *AWG-based Mux/DeMux configuration [10].*


AWG suffers from drawbacks like polarization dependency and temperature sensitivity. A lot of works have been done in addressing these issues.
