| Author | Niththiyanathan, Jeyaratnarajah |
| Call Number | AIT Thesis no.TC-97-9 |
| Subject(s) | Optical communications
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering. |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. TC-97-9 |
| Abstract | The use of optical intersatellite links in low-earth-orbit (LEO) satellite systems is being considered for high data rate operations in recent times. Since the optical intersatellite link terminals (OISL's) are preferred for their low power, light weight and compactness, in this study we evaluate the performance of some of the commonly used optical modulation schemes to determine as to whether the laser power requirements for LEO links with varying distances can be met at high data rates, while having a modest telescope aperture and the BER of 1 o-6 . The teclmiques such as optical coherent modulation, optical preamplification and the use of error control codes are also studied. AlGaAs, InGaAs, InGaAsP and Nd:Y AG lasers are considered due to their high reliability, relatively high power output, high efficiency and compactness. We have found that in many an instance InGaAs semiconductor lasers meet transmitter power requirements with intensity-modulated direct-detection (IM-DD) schemes. However, for very high data rate, relatively large LEO intersatellite links require either an increase in receive aperture for IM-DD or the use of optical coherent modulation schemes if the modest receive aperture size is to be used. InGaAs laser is found to be very promising laser technology due to its recent development of high power monolithic Master Oscillator Power Ampliifers (MOPA) for both in intensity- and optical coherentmodulation systems. We also have found that InGaAsP laser with optical post- or preamplification would not permit compact and light-weight OISL terminals compared to InGaAs or AlGaAs semiconductor lasers as Erbium Doped Fiber Amplifiers (EDFA's) are heavy and bulky. Finally a case study is made on the use of optical intersatellite links in the proposed Iridium network. OISL in Iridium offers low power, modest aperture size and better performance. |
| Year | 1997 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. TC-97-9 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Information and Communications Technologies (DICT) |
| Academic Program/FoS | Information and Communication Technology (ICT) |
| Chairperson(s) | Ahmed, Kazi Mohiuddin |
| Examination Committee(s) | Sharma, A. B.;Erke, Tapio |
| Scholarship Donor(s) | Telecom Finland. |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1997 |