Optical Design Of Coupling System For DFB Laser Array Tunable Laser

The dense wavelength division multiplexing(DWDM)system has a wide application in optical communication system.Distributed feedback laser array tunable laser(DFB-TL),as a key component of DWDM system,have attracted great attention from both home and abroad.DFB-TL provides high reliability,wavelength stability.At the same time,it possesses wavelength tunability of wide range.It reduces the number of standby equipment as well as the cost of operational maintenance services and inventory greatly.In addition,the dynamic flexibility of the optical network and the utilization of the bandwidth are improving through the automatic wavelength controlling.Thereby it becomes one of the most attractive light sources of the next-generation optical networks,and its application prospect is very broad.This thesis firstly presents the types of the tunable laser,and goes over the development of coupling systems for DFB-TL specifically.Then it introduces the beam characteristics of the semiconductor laser and the coupling characteristics between semiconductor laser and optical fiber.On the basis of analyzing the structure and principle of the DFB-TL optical coupling system,an ideal optical coupling system is established.Beam characteristics of DFB laser array are simulated by ZEMAX.After comparing and analyzing the collimation effects of three collimating lens structure,the whole optical coupling system are established by adding micro electromechanical system(MEMS)tilt mirror and focusing lens on optimized aspherical lens which is adopted for collimation.The system’s performance is optimized by setting the optimization function and adding a focusing lens.Finally beams of the twelve lasers can be coupled into the fiber,and all of the coupling efficiency are over 58.5%after optimizing.In the end,the thesis analyzes the adjustment error of elements of optical coupling system,including position error?x,?y,?z and angle errorβ_x,β_y,β_z.The joint error of the optical fiber is also analyzed,including the vertical axis error in the x,y direction,axial direction error in the z direction,angular error in the x,y direction.Finally the ranges of assembly precision of each element are discussed.