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Development Of Short Pulses Source Of Optical Communication And Its Application In Wavelength Conversion

Posted on:2005-05-20Degree:DoctorType:Dissertation
Country:ChinaCandidate:H YangFull Text:PDF
GTID:1118360125450117Subject:Microelectronics and Solid State Electronics
Abstract/Summary:PDF Full Text Request
In order to satisfy the enormous communication capability, the fibercommunication with abundant band width sources has been the only choices.The spectrum width of optical pulses decides the transmission length due to thelimitation of the fiber dispersion. If short pulses source can make the TL opticalpulses, it can minimize the effect of the fiber dispersion. So the optical pulsessource in the fiber communication system must make the pulses reach theFourier transform limited pulses. There are initial chirps in optical pulsesgenerated by gain switch DFB laser and DFB LD+EAM respective in thecommunication system. For the sake of long distances transmission, it musteliminate the chirps. So it needs to build a measuring system to measure thepulses chirps accurately. How to effectively use the source of the fiber bandwidth has been one of the hottest optoelectronic R & D projects in the world.From 1990s, people more and more put their eyes on the WDM communicationsystem and used it to enlarge the communication capability. The key technologyof the WDM all-optical net is the wavelength conversion. It means thereassigning and reutilizing of the wavelength. It can settle the wavelengthchannel contentions in OXC (optical cross-connection), make the routingselection effectively and reduce the block ratio of the net, then improve theflexibility and expandability of the net. Due to its simplicity, the wavelengthconversion by the semiconductor optical amplifier cross gain modulation hasbeen focused more in the wavelength conversion technology. Since O/E/Owavelength conversion can realize the 3R regeneration (re-timing ,re-amplifying, re-shaping)function, it can erase the noise accumulation anddispersion accumulation, then improve net transmission capability. It will beused widely in the core-net of the whole optical net in the future. Combining our research projects, this paper concentrates on the ultra-shortoptical pulses generation, its measurement, and the wavelength conversion, etc.1,After resolving the rate function of the DFB laser numerical, we got the rules that the chirp of the optical pulses change with external driving condition. We studied the key technology of the encapsulation of SLD: One is the design of microwave matching net. In condition of the qusi-static approximation, calculation of wave characteristic impendence and effective dielectric constant by conformal mapping techniques were first presented for asymmetrical coplanar waveguide with finite ground width and substrate thickness. In the same method, the symmetrical coplanar waveguide with121吉林大学博士学位论文 finite ground width and the asymmetrical coplanar waveguide with infinite ground width are analyzed and the results are coincident with other methods. So this method is proved to be widely used. For the first time, we calculated the relationship of characteristic impedance and configuration size, designed the graded microwave impedance transformed line based on background coplanar wave-guide, got the impedance conversion from 50? to 5? and had the good matching at least 7GHz.The other is the coupling of laser and single mode optical fiber. According to the specific condition of lab and the need of the system, we analyzed the tapered fibers and the self-focus lens respectively from the theory analyzing and the experiment. We made the ultra-short pulses source of the output fiber with microwave matching net gain switch DFB laser and did the measurement experiment of the output characteristic.2,We simulated the ultra-short generation based on the single EAM and the tandem EAM. Measuring the absorption character of EAM, we built the calculation model of pulses generation based on single EAM and tandem EAM, then educed the calculating formula of extinction ratio and pulse width, analyzed the varied principle of pulse width and extinction ratio according to the modul...
Keywords/Search Tags:Communication
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