This thesis studies spatial and temporal filtering techniques and their applications in fiber optic communication systems. Differential mode delay (DMD) in multimode fibers (MMFs) and multipath interference (MPI) are two major impairments in fiber optic communication systems. DMD lends to inter symbol interference in MMF communication systems which seriously limit the bit rate-distance product of the system. MPI leads to interference pattern at the output of a single mode fiber link which increases the bit error rate of the system. In this thesis, we propose a method which uses spatial filtering technique in a 4F system to reduce DMD and MPI effects. Typically, higher order modes have higher spatial frequency components and therefore, they are spatially separated from the lower mode after Fourier transform. By optimizing the bandwidth of a spatial filter, unwanted higher order modes can be suppressed. Therefore, DMD and MPI effects in fiber optic communication systems can be reduced at the cost of losing some fraction of the signal power.
In this thesis, we also propose a new application of temporal filtering technique. A time lens is a phase modulator which introduces a quadratic phase factor in time domain. Combined with single mode fibers, a time lens can be used to perform Fourier transform in time domain. A tunable optical filter can be implemented using a modified temporal 4F system which is analogy with the spatial 4F system. The merit of this method is that no additional signal processing is needed to reverse the bit sequence at the output of the 4F system and that the channels to be demultiplexed at a node can be dynamically reconfigured. / Thesis / Master of Applied Science (MASc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/23283 |
| Date | 12 1900 |
| Creators | Wang, Hao |
| Contributors | Kumar, Shiva, Xu, Changqing, Electrical and Computer Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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