Based On Inas/inp Quantum Dot 1.55 Mu M Tunable External Cavity Laser

Due to the narrow linewidth and wide tuning range, quantum dot (QD) broadbandexternal-cavity lasers (TECL) play an essential role in numerous areas such as environmentmonitoring, spectroscopy and optical telecommunication. Quantum dot lasers are really suitablefor future optical communication systems, because of their small size, high efficiency, stableperformance, and etc. But for the nature of S-K growth mode, QD lasers have very broad gainprofile, which restrict the application in optical telecommunication field. TECL solve the broadlinewidth and poor frequency stability of semiconductor laser, and have many advantages fortheir widespread utilization, such as high efficiency, long life, stable frequency, broadbandtunable, and etc. The special structure of quantum dot determines that DFB and DBR can not beapplied in QD lasers as that in quantum well lasers. Wide tunable range and narrow linewidthcan be obtained by external cavity technology based on QD lasers with the wide gain spectrum.So the external cavity technology is very important for QD lasers.In this thesis, we report the QD lasers of InAs grown on InP substrate by gas sourcemolecular beam epitaxy(GSMBE), with central wavelength at1.55μm. And we also introducethe principle and structure of external-cavity InAs/InP QD lasers. The main results aresummarized as below:1. The fundamental principle and structure of tunable external cavity lasers are introduced. Aftercomparing the Littrow and Littman external-cavity structures, and analyzing the characteristic ofQD lasers, Littrow structure is much more suitable for our system.2. We introduce the electronic circuits of tunable external-cavity QD lasers: precise currentsource, temperature controller and PZT controller. Analyzed the schematic diagrams and testedthe electronic devices, parameters fit the reality properly. The current source’s maximum outputcurrent reaches to1.5A with stability in1μA. The stability of temperature controller is0.1℃,covering from5℃to60℃. Output voltage of PZT controller could achieve110V, and thestability is10mV.3. We characterized the TECL based on InAs/InP QD lasers successfully obtained highperformance TECL operating in continuous-wave mode and pulse-wave mode at roomtemperature. A tuning range of70nm has been achieved, based on QD laser, covering thewavelengths from1563to1633nm, which can be used for L band（1570～1605nm）in WDMsystem. The threshold current densities are lower than1.6kA/cm2in the tuning range. More than23mW output power was obtained at lasing wavelength of1.59μm. An even wider tuning rangeof73nm has been obtained from the TECL in pulse-wave mode, with lower threshold currentdensities than in continuous-wave mode. 4. The cavity length of InAs/InP QD laser, test temperature and the operation current all willaffect the performance of TECL. As the cavity length of QD laser decreases, the tuning range ofthe TECL becomes wider, but the threshold current densities also increase. Temperature affectsthe threshold current densities. As the operation current increases, the output longitudinal modesof TECL shift to lower energy side and mode hopping was observed.5. Developing a wireless system based on Zigbee and MCU, realizing intelligent control, we alsoinstall RS-232and USB interface in order to communicating with computer. These expandfunctions will create future application.