Optimization And Circuit Model Of Quantum Well Vertical Cavity Surface Emitting Semiconductor Lasers

Semiconductor laser (LD) which is a current-driven device has gotten a drastic development since it was invented in 1960s. With new structures and materials emerging and continuous expanding of device functions, LD is applied for more and more domains extensively such as optical communication and access , military affairs, biology and so forth .Vertical-cavity surface-emitting lasers (VCSEL) have become the ideal light sources for optical interconnections, optical free space communications, optical signal processing and neural networks by their attractive features such as low divergence angles, circular beams compatible with optical fibers, inherent single longitudinal mode operation due to short cavity lengths, surface-emitting easy to the high density 2D arrays, and possible lower driving voltage which enables direct drive by CMOS circuits. At the same time, the developments of molecular beam epitaxy (MBE) and metal organic chemical vapor deposition (MOCVD) have made the characteristics of the devices improved rapidly.The functions of VCSEL have made great process because of the application of quantum well structure. But which is the optimal quantum well numbers is a important subject.Normally as for a system which is concerned with LD, the situation of LD has important impact upon the system function because of its nucleus status. So it is imperative to analyse the character of LD integrated with external driven circuit. Obviously structuring its circuit model is useful for its applications.My paper's main works are mentioned as follow:1. Based on changing the logarithmic relation of gain on carrier density. Therate equations are described for multi-quantum well of vertical cavity surface emitting laser (VCSEL) taking into account the influence of nonradiative depopulation rate . We have discussed the relation of device parameter (cavity length and the reflect coefficient of mirror) on threshold current and optimal well numbers. It will provide theoretical basis for improvement of threshold properties and optimization of device constitution.2. Introducing several classical circuit models concerning LD such as below threshold value LD, double hetero structure LD and multimode LD. It can make aguide to consequent QW-LD's circuit model by acquainting some principles, methods and techniques of structuring model.3. Illustrating some methods that can determine the important parameters of LD's rate equation explicitly. For instance, Carrier transportation time in SCH region ;Quantum capture is a complicated process and capture time computation and experiment test are provided. Optical gain whose formula is complicated is a critical parameter and it is useful for structuring model to obtain a concise formula by means of experiment curve.4. Circuit model is presented by considering carriers transportation behavior in SCH region and analyzing rate-equations of vertical-cavity surface emitting lasers. The frequency response characteristics are given by circuit simulation and we discuss and compare the result.