Research On Transmission Distance Extension Of Tunable V-Cavitv Laser

In recent years,high-definition television,interactive internet TV,online digital movies and games,3D TV,mobile multimedia,video conference,cloud storage and cloud computing,social networking,and short video sharing have sprung up.The bandwidth demand of these emerging businesses in the access network is getting higher and higher.Passive optical networks with large-capacity data and low operation and maintenance costs have become the first choice to solve the broadband bottleneck of the access network.At present,passive optical networks have been upgraded from 2.5Gbps to lOGbps to meet the rapid growth of internet traffic.It is urgent to develop low-cost,high-speed tunable optical transmitters.In the C-band,as the transmission distance increases,the fiber dispersion will distort the pulse signal and increase the bit error rate.For high-rate long-distance transmission systems,electro-absorption modulators and lithium-niobate modulators are still the mainstream choices,but they are as costly and energy-consuming as dispersion compensation modules.Therefore,it is very meaningful to develop a low-cost,simple-structured and low energy consumption tunable transmitter.V-cavity tunable laser is a low-cost,simple-structured,excellent and reliable semiconductor laser,and it is an attractive choice for future metropolitan area networks,access networks and data centers.This topic addresses the needs of next-generation passive optical networks,and proposes two schemes to increase the signal transmission distance based on V-cavity tunable lasers:one is to monolithically integrate the V-cavity Tunable lasers with Mach-Zehnder modulators;the second is to use chirp management to control the frequency chirp of V-cavity tunable lasers with array waveguide gratings to increase the transmission distance.First of all,in this thesis,a new process of quantum well intermixing induced by an excimer laser with a wavelength of 248nm was successfully developed on a five-quantum well wafer of InGaAsP material.By rationally selecting the energy density and pulse number of the laser irradiation,as well as the temperature and time of the rapid thermal annealing,the process can adjust the degree of quantum well intermixing in the active region,and a wavelength blue shift of up to 120nm can be obtained.FP lasers and V-cavity tunable semiconductor lasers have been successfully fabricated using excimer laser-induced quantum well intermixing technology,which has successfully demonstrated that excimer laser-induced quantum well intermixing technology is simple in process,good in performance,and does not require secondary regrowth.Excimer laser-induced quantum well intermixing technology will be a very potential monolithically integration solution.Secondly,this thesis proposes a design scheme based on monolithically integration of V-cavity tunable laser and Mach-Zehnder modulator.Offset quantum well technology was chosen as the monolithically integration platform.The active part of epitaxial layer structure uses a 5-quant?m well structure,and the passive waveguide part uses a 350nm thick 1.4Q InGaAsP material.Single-ended input structure and double-ended input structure are designed.Thirdly,this thesis proposes a scheme to increase the signal transmission distance by using a Gaussian arrayed waveguide grating to perform chirp management of V-cavity tunable laser.After testing,a 10-Gbps directly-modulated V-cavity laser can transmit over 20 kilometers without bit error(BER<10-12)without any dispersion compensation.The power penalty of 10km and 20 km transmission is only 2dB and 4dB.Both the wavelength division multiplexing device AWG and the tunable semiconductor laser are used as the core unit in the WDM network.It is very practical to use the cooperation of the two to extend the transmission distance of the directly modulated signal.