碩士 / 國立臺北科技大學 / 光電工程系 / 106 / With the speedy progress in underwater wireless laser transmission (UWLT) system, increasing demands drive the requirements for long-range and high-speed underwater links. However, the transmission performance of UWLT systems can be limited by the fact that light transmission in water is attenuated by absorption and scattering, which are affected by energy transfer during interaction with water and the density of particulate matters, respectively. Indeed, the effects of absorption in piped water and scattering in highly turbid harbor water can degrade UWLT systems.
A laser beam reducer/expander, which can reduce/expand the collimated beam diameter, is used in free-space optical (FSO) links to improve the transmission performance of FSO systems UWLT systems present several similarities compared to FSO systems because they both utilize optical wavelengths to transmit data signals between dedicated point-to-point links. Thus, a laser beam reducer/expander is anticipated to improve the transmission performances of UWLT systems for different water types.
This thesis propose and experimentally demonstrate a 24 Gb/s four-level pulse amplitude modulation (PAM-4) underwater wireless laser transmission (UWLT) system with a laser beam reducer/expander for reducing/expanding collimated beam diameter over a 10 m piped water link and 2 m highly turbid harbor water link. Laser beam reducer/expander, which can reduce/expand the collimated beam diameter, is adopted to improve the transmission performances of PAM-4 UWLT systems for different water types. In piped water link, the transmission performances of PAM-4 UWLT systems improve with the decrease of the collimated beam diameter due to lower amounts of light absorbed by piped water. In highly turbid harbor water link, the transmission performances of PAM-4 UWLT systems improve with the increase of the collimated beam diameter due to more forward-scattered light received by optical receiver.
| Identifer | oai:union.ndltd.org:TW/106TIT05124011 |
| Date | January 2018 |
| Creators | De-Yu,Chen, 陳德雨 |
| Contributors | 呂海涵 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 60 |
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