Study On Structure Design And Performance Optimization Of Ultraviolet Band DFB Semiconductor Laser Based On MgZnO/ZnO

In the Internet age,there is a stricter requirement for the competence of optical information exchange,transmission,storage and display with the rapid development of the Internet of things,cloud computing and artificial intelligence.With the Application of dense wavelength Division Multiplexing,the 100 Gbit / s system is commercially available,the 400Gbit/s system will quickly appear in people's lives.Operators are also stepping up the deployment of 5G which requires higher output power and higher modulation rates for semiconductor lasers.The emission wavelengths of semiconductor lasers gradually develop to longer infrared band,terahertz band and shorter ultraviolet band.Blue and ultraviolet lasers based on nitride and ZnO wide gap semiconductor materials have attracted more and more attention.At present,random laser diode lasers based on ZnO compounds have been reported many times.However,there are few reports of electrically pumped ZnO compound DFB lasers with heterojunction or multiple quantum well structures.The ZnMgO / ZnO ultraviolet band distributed feedback(DFB)semiconductor laser is simulated and designed by using the transfer matrix method(TMM).A peak wavelength of 364.8nm is obtained when the duty cycle is 0.5,the grating period is 93.5nm,and the height of the grating is 65 nm.By changing the thickness of active layer,the influence of different active layer thickness on the performance of the laser is analyzed.The numerical simulation results indicate that when the active layer is too thick,the threshold current is increased as the limitation on the carrier is weakened.When the active layer is too thin,the limiting effect of the waveguide layer on the photon decreases,which result in a higher threshold current and a lower output power.Therefore,the proper selection of active layer thickness can improve the performance of DFB laser.On the other hand,the application of REC technology to the design of ZnO short band DFB laser is presented.As the ZnO short band DFB laser grating is small,it is difficult to process the grating structure with multi-phase shift and complex structure.By contrast,REC technique can realize the same structure with large grating period by equivalent phase shift.Based on TMM theory,the passive transmission spectrum,time-delay spectrum and optical field distribution of single-phase and three-phase shifted DFB lasers based on REC technology are analyzed by simulation.The parameters of ZnO short band DFB laser grating based on REC technology are obtained.In addition,the effects of different grating parameters such as phase shift position,ca vity length,phase shift and refractive index modulation amplitude on the performance of the grating are also investigated.The output power can be increased by changing the position of phase shift properly,and the efficiency of excitation source can be improved.Increasing the cavity length and refractive index modulation amplitude can improve the output power of the laser,but also enhance the hole burning effect,so in the design of the grating,the relationship between the effect of hole burning and the output power should be measured.The cavity length and refractive index modulation amplitude are reasonably selected.It provides a numerical reference and theoretical basis for the design of ZnO visible or ultraviolet band DFB lasers.