Mumbai University > Electronics and telecommunication > Sem 7 > optical communication and networks

Marks: 08

Years: DEC 2015

Arrayed Waveguide Grating:

i. Arrayed waveguide grating (AWG) is used for demultiplexing. These are based on diffraction principle. The input consists of several channels carrying different wavelengths.

ii. Light propagating in the input waveguides are coupled to the arrayed waveguides after propagating through a free space region (FPR).

iii. The AWG consists of an array of curved waveguides. Each curved waveguide has a length $ΔL = m\space λc /n$ which is more than the array element immediately below it, where $λc$ is the central operating wavelength, n is the effective refractive index and m is an integer.

iv. Thus at the central wavelength, the light will focus at the center of the image plane. Different wavelengths have different phase differences and the focal point for each will be shifted. A second coupler will deliver different wavelengths to different waveguides.