Spectral phase coding of broadband incoherent light and beat noise comparison in optical coherence multiplexing systems
Abstract
Asynchronous transmission schemes, such as optical code-division multiple-access (CDMA) and coherence multiplexing (CM) communication systems, show potential in applications such as local area networks (LAN) because frequency stabilization is not required. The demand of CDMA schemes with high transmission efficiency, high security and low cost calls for precise spectral phase coding on broadband incoherent light. To be more competitive with other optical multiple-access techniques, reducing beat noise becomes a crucial challenge for CM/CDMA systems using incoherent light sources, such as an amplified spontaneous emission (ASE) source. In this thesis, both issues of precise spectral phase filtering of incoherent light and the possibility of reducing the beat noise by using mode-locked lasers in CM systems are discussed. In the first part of the thesis, by performing meticulous setup alignment and employing a programmable pulse shaper, precise binary and gray-level spectral phase coding were demonstrated, which were in excellent agreement with theory. It was also demonstrated that by using a computer-controlled liquid crystal modulator, complete dispersion compensation of distorted optical signals and the correction of nonlinear spectral dispersion can be achieved. In the second half of the thesis, a complete fiber CM system with dispersion compensation, polarization control, system phase stabilization and differential detection are presented. Through theoretical analysis and experimental verification, it is demonstrated that in the case of a CM system using a single mode-locked laser, the beat noise can be reduced significantly.
Degree
Ph.D.
Advisors
Weiner, Purdue University.
Subject Area
Optics|Electrical engineering
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