Free-Space Optical Communication link : performance analysis and optimization

Free Space Optical Communications (FSOC) systems are being increasingly developed, particularly for the use of satellite communication. However, the development of such links present numerous challenges due their complexity. At Aerospacelab, such a link is in development, for the specific use of On-Off Keying (OOK) and Differential Phase- Shift Keying (DPSK) modulations. The objective of this thesis is to analyze the current state of the receiver link. This is achieved through the use of a simplified link setup, allowing to focus on the receiver challenges. After a detailed discussion of the basic link setup, including the analysis of the challenges associated with DPSK transmissions, a performance analysis of both modulation schemes is carried out. The addition of an optical amplifier into the link is equally investigated. The more thorough analysis of the DPSK link has in fact enabled a functioning closed-loop transmission for the first time. Finally, through both theoretical developments and experimental measurements, the OOK and DPSK transmission are quantified and compared, indicating a slight DPSK advantage over OOK, with a BER of 10e−7 [-] achieved for receiver optical input powers of −19.4dBm and −18.3dBm, respectively.