Ultra high capacity wavelength division multiplexing/demultiplexing by phased -array systems
Abstract
In ultra high capacity WDM, much research interest focuses on very large number of channels, good filter characteristics for each channel such as flat passing band, ease of implementation and implementation with minimized device size. We propose novel WDM schemes in 2-D as well as 3-D geometry. The proposed methods utilize irregular and zero-crossing sampling techniques. The nonuniform-sampling of zero-crossing apertures where phase is zero (or a constant) is realized by choosing the initial nonuniformly distributed points first and then calculating the closest zero-crossing points which satisfy the zero phase condition. Both linear and spherical reference waves can be used. We have a scheme which can be used to suppress higher harmonic order diffractions when used in grating structures and also to improve conventional arrayed waveguide gratings. In order to simplify implementation and achieve better results, we extend our method with MMSE iterative optimization. In this approach, regular arrayed apertures are pre-assigned along the input-focusing plane and then we choose the best end points (sampling points) which satisfy the zero phase condition closely. This approach again results in an irregular array. Next the MMSE algorithm is applied to improve output amplitudes. The aperture points proposed in 2-D geometry are generalized into aperture points in 3-D geometry. In addition, a sampled phase modulation method is introduced to generate and to perform multiplexing/demultiplexing. The optical waveguide is located at the sampling quantized point in input aperture plane and all reconstruction images can be achieved through specially chosen quantized points approximating zero-crossing points. An input aperture plane is composed of some sub-input planes, and each sub-input plane is designed to produce one row of image points (corresponding to different channels) on the image plane with a central wavelength. These can be arranged in to M rows with each row having N image points, corresponding to a total of MN channels.
Degree
Ph.D.
Advisors
Ersoy, Purdue University.
Subject Area
Electrical engineering
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.