Abstract
Arrayed waveguide grating (AWG) is playing an increasingly important role in dense wavelength division multiplexing (DWDM) system. The regular AWG device consists of an arrayed waveguide region where all the individual waveguides are equally spaced on the Rowland circle and the adjacent ones have constant length difference. The regularity of their positions and lengths leads to the phenomenon that a portion of the Rowland circle is occupied by the adjacent (undesired) order focused beams of the operation wavelength channels. The repetitions of the same wavelengths at different locations affect the device potential capacity. The method of irregularly sampled zero-crossings is discussed in a virtual model first and then extended into the arrayed waveguide grating application. It has proven to be able to solve the abovementioned problem of regular AWG by reducing the undesired order focused beams with only the desired ones left. Therefore, those places on the image plane occupied and useless before are freed now for accommodating new wavelength channels. By employing the BeamPROP software, we implement the layout design and BPM simulation for the new device based on this method. It is shown that the new device can significantly increase the channel capacity compared to the regular device provided similar structural parameters. The random characteristic of such structure also results in better phase error tolerance. The main tradeoff lies in the degraded noise performance. However, the crosstalk between adjacent channels can be reduced by increasing the channel spacing since the limitation due to free spectral range is removed.
Date of this Version
December 2002